A simply supported to continuous track beam bridge and its support design method and construction method

Abstract

The present invention provides a simply supported to continuous track beam bridge and a support design method and a construction method, which are applied to the technical field of simply supported to continuous track beam bridge design and construction. The bridge includes track beams, bridge piers, permanent supports for continuous piers, post-cast wet joints and upper prestressed short beam assemblies. Adjacent track beams are connected by post-cast wet joints, and the post-cast wet joints are strengthened to be connected to the track beams by upper prestressed short beam assemblies. The support design method solves the friction coefficient of the support to ensure that the track beams do not slide under traction braking force. The construction method is a method for erecting track beams and setting post-cast wet joints, upper prestressed short beam assemblies, and lower edge prestressed short beam assemblies. The present invention effectively reduces the beam end rotation angle and live load deflection, ensures that the butt end maintains prestress and is not prone to cracking, realizes a smooth transition between the two spans of track beams, avoids the phenomenon of vehicle jumping at this location, and has better mechanical properties, durability, construction convenience and economic and social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of design and construction of medium-span straddle-type monorail track beams, and in particular to a simply-supported-to-continuous track beam bridge and a support design method and a construction method. Background Art Existing technology

[0002] like Figure 1 As shown, in a straddle-type monorail system, train vehicles cling to the track beams, which simultaneously provide vertical support, longitudinal guidance, and lateral stability. This type of rail transit system is generally used in low- to medium-volume urban rail transit. The top surface of the track beams in a straddle-type monorail supports the running wheels of the straddle-type monorail vehicles, while the sides support the guide and stabilizing wheels. The track beams serve as both the load-bearing structure and the running track, requiring millimeter-level horizontal and vertical alignment accuracy during prefabrication, erection, and bridge construction. However, cast-in-place construction cannot guarantee this accuracy, so a "factory prefabrication, on-site assembly, and partial cast-in-place" construction method is generally used.

[0003] Currently, only a few straddle-type monorail lines have been built or are in operation in Chongqing, Yinchuan, Liuzhou, and Wuhu. The structural systems of their span structures include simply supported beams, continuous beams, and continuous rigid frames. However, each system has some long-standing problems that have limited its widespread application. The advantages and existing shortcomings of each system are analyzed as follows:

[0004] The advantages of the simply supported beam system are: (1) no secondary internal forces are generated by foundation settlement, concrete shrinkage and creep, temperature, etc.; (2) the control of the line shape during on-site erection is easy, and the line shape adjustment is relatively convenient. After the bridge is completed, the line shape can be adjusted for each span; (3) the on-site construction is easy, the construction process is few, and the construction speed is fast, which is very suitable for prefabricated assembly construction. Its disadvantages are: (1) poor integrity, low rigidity, poor earthquake resistance, anti-roll and anti-torsion capabilities; (2) many expansion joints and high unit price, poor driving comfort, and large tire wear; (3) the large turning angle at the end of the simply supported beam leads to a smaller span than that of the continuous beam, denser piers, which is not conducive to avoiding underground pipelines, and the landscape is average; (4) there are many expansion joints and supports, and the maintenance and inspection workload is large.

[0005] 2. The advantages of the continuous beam system are: (1) good integrity, greater rigidity, and certain seismic and torsional resistance; (2) fewer expansion joints, good driving comfort, and less tire wear; (3) moderate span, and good coordination between the pier height and span; (4) fewer expansion joints and supports, and moderate maintenance workload. Its shortcomings are: (1) secondary internal forces will be generated under the action of uneven foundation settlement; (2) rigid wet joints with dense steel bars and steel bundles need to be cast on the top of the middle pier, the amount of steel bar connection work is large, and the efficiency of prefabricated assembly construction is low; (3) the track beam bears a large proportion of live load, which makes it difficult to control the tensile stress in the negative bending moment area. For example, after the negative bending moment area cracks, it is difficult to repair and seriously affects the driving comfort; when the commonly used prestressed short bundle method is used to control the stress in the negative bending moment area, it is necessary to groove and anchor the short bundles on the top of the track beams on both sides of the middle pier, but the concrete at the groove has no compressive stress reserve in the bridge state, so the durability of this area, especially the new and old concrete interface, cannot be guaranteed; when the less common top edge full-length bundle method is used to control the stress in the negative bending moment area, the full-length bundle needs to pass through a whole beam after the precast beams of each span are erected. The difficulty and workload of the bundle-passing construction are large, and the arrangement of the full-length bundle in the non-negative bending moment area is an obvious waste of materials and increases The problem of excessive compressive stress on the upper edge of the precast beam is exacerbated. When the through-beam is tensioned, the vertical and especially the horizontal linear shape of the precast beam is greatly affected, and the tensioning operation is very demanding. (4) Since the live load of the straddle-type monorail traffic accounts for a large proportion, the traction and braking forces are very large. In order to avoid the situation where only one fixed hinge support is arranged, the horizontal force borne by the fixed pier at this location is much greater than that of other non-fixed piers, resulting in excessive horizontal displacement of the pier top affecting driving smoothness and different external dimensions of each pier, the existing technology adopts the design of arranging fixed hinge supports at multiple piers along the bridge in a bridge, that is, multiple fixed piers are designed in a bridge, resulting in large secondary internal forces under the action of overall temperature rise and fall and shrinkage creep, and the secondary internal forces will have a superimposed effect with the traction and braking effects, increasing the material consumption of the track beam and bridge piers. The fixed hinge supports need to adopt horizontal and vertical tensile and compressive supports, which are expensive and have poor durability.

[0006] 3. The advantages of the continuous rigid frame system are: (1) good integrity, high rigidity, and strong anti-seismic and anti-torsion capabilities; (2) few expansion joints, good driving comfort, and low tire wear; (3) moderate span, good coordination between pier height and span; (4) few expansion joints and supports, and less maintenance and repair work; (4) the longitudinal horizontal force is shared by multiple piers, which can reduce the horizontal displacement of the pier top and the number of lower pile foundations. Its disadvantages are: (1) the structural system is greatly affected by uneven foundation settlement, concrete shrinkage creep, temperature, etc.; (2) rigid wet joints with dense steel bars and steel bundles need to be cast in place at the top of the middle pier, which requires a large amount of steel bar connection work and low prefabrication and assembly construction efficiency; (3) the proportion of live load borne by the track beam is too large, which makes it difficult to control the tensile stress in the negative bending moment area. If the negative bending moment area cracks, it is difficult to repair and seriously affects driving comfort; (4) the linear control requirements are very high, and it needs to be adjusted in place before the bridge is completed. The linear shape cannot be adjusted after the bridge is completed. Summary of the Invention

[0007] Theoretically, the continuous beam system can best balance the bearing performance, driving performance, aesthetics, construction and maintenance difficulty, and is the most suitable bridge type for the assembled construction of medium-span straddle-type monorail bridge span structures of 30 to 40 meters. Therefore, in response to the long-standing unresolved problems of the above-mentioned existing continuous beam systems, the present invention provides a simply supported to continuous track beam bridge and a design and construction method. Starting from the root problem of the overall structural system of the bridge, the four major deficiencies of the existing continuous beam system are solved at the same time, and it has better mechanical properties, durability, construction convenience and economic and social benefits.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] A simply supported to continuous track beam bridge, comprising a track beam, a pier, a permanent support for the continuous pier, a post-cast wet joint and an upper prestressed short beam assembly, wherein the track beam width B is less than or equal to 100 cm, and the adjacent track beams erected at the continuous pier in the pier are respectively a first track beam and a second track beam, and the opposite butt ends of the first track beam and the second track beam are connected by a post-cast wet joint, and the top and bottom surfaces of the post-cast wet joint are respectively flush with the top and bottom surfaces of the first track beam and the second track beam, and the post-cast wet joint is supported on the top of the continuous pier through the permanent support of the continuous pier, and the post-cast wet joint is provided with a tensioned beam pipe running through both ends thereof, and the opposite butt ends of the first track beam and the second track beam are provided with a tensioned beam pipe running through both ends thereof. The built-in pipeline is connected by pipelines, and the upper prestressed short bundle assembly includes an upper tensioned bundle, a transverse through hole, and an upper post-cast concrete. The first track beam and the second track beam are respectively provided with a transverse through hole on the same side. The transverse through hole is a hole that passes through along the transverse direction of the bridge, and the top surface of the transverse through hole is located below the top surface of the track beam. The built-in pipeline is connected to the transverse through hole, and the upper tensioned bundle is arranged in the tensioned bundle pipeline and the built-in pipeline. The two ends of the upper tensioned bundle are respectively tensioned to the corresponding transverse through holes of the first track beam and the second track beam, and the two ends of the upper tensioned bundle are anchored in the corresponding transverse through holes through the upper post-cast concrete. The length L1 of a single upper tensioned bundle along the bridge direction is ≤ half of the sum of the spans of adjacent track beams. Among them, the bridge piers are divided into continuous piers and branch piers. The simply supported track beam bridge includes multiple sections of track beams. The adjacent track beams are erected on the continuous piers, while the track beams at both ends of the bridge are erected on the branch piers. The top surface of the track beam is for the running wheels of the straddle-type monorail vehicles to run, and the side surface of the track beam is for the guide wheels and stabilizing wheels to run, and the stabilizing wheels are vertically located below the guide wheels. The track beams are all precast concrete structures, and the beam height of both ends is H0. The precast prestressed tendons are embedded and anchored in the track beams when the track beams are precast. The post-cast wet joints are cast-in-place concrete structures and are connected after the track beams at both ends are erected. A continuous pier is provided below it, and the post-cast wet joints provide a way for the running wheels, guide wheels and stabilizing wheels to pass through the continuous piers. Driving surface and support; when erecting track beams on continuous piers, it is necessary to first set up a first temporary support for supporting the first track beam, and a second temporary support for supporting the second track beam. The permanent support of the continuous pier is set below the post-cast joint when setting the post-cast joint. The permanent support of the branch pier is set on the branch piers at both ends of the bridge. The permanent support of the branch pier is used to support the end of the track beam at both ends of the bridge. After the bridge construction is completed, the first temporary support and the second temporary support will be removed; the expansion joint is the gap between the track beam at both ends of the bridge and the adjacent track beams. Below the expansion joint is the branch pier. An expansion joint device is arranged at the expansion joint and provides a driving surface and support for the running wheels, guide wheels and stabilizing wheels to pass through the branch pier.

[0010] The technical principles and effects of the above invention are as follows: (1) by using the post-wetting joint in conjunction with the upper prestressed short beam assembly, the beam end rotation angle and live load deflection are effectively reduced, ensuring that the concrete in the negative bending moment area of the continuous pier maintains a certain prestress in the operational state and is not prone to cracking, achieving a smooth transition between the two spans of the track beams, and avoiding the occurrence of the vehicle jumping phenomenon at this location, thereby solving the shortcomings of the simply supported beam system that is not suitable for medium-span straddle-type monorail track beams, reducing the expansion joint device to improve driving comfort, reduce tire wear, and reduce the maintenance and repair workload; (2) by setting the transverse through hole with the top surface of the notch below the top surface of the track beam, the anchoring of the upper prestressed short beam assembly is achieved, avoiding the situation that the concrete at the notch has no compressive stress reserve in the bridge state when the short beam is anchored in the top notch, and cannot guarantee the durability of the interface between the new and old concrete, especially at this location. Problem: Although the concrete at the transverse through hole has no compressive stress reserve in the bridge state, it is not the running surface of the running wheels of the straddle-type monorail vehicle, so the problem of cracking of the new and old concrete interfaces under the direct impact of the wheels is avoided. Even if micro cracks are generated, they will not aggravate and affect the driving smoothness. (3) By setting the upper prestressed short beam components to control the stress in the negative bending moment area, the difficulty and workload of the beam threading construction when the top edge full-length beam method is adopted are avoided, and the material waste of the existing full-length beam in the non-negative bending moment area and the problem of excessive compressive stress on the upper edge of the precast beam are avoided. At the same time, the influence of the negative bending moment beam on the vertical and especially the horizontal line shape of the precast beam during tensioning is reduced, and the control requirements for the tensioning operation accuracy are reduced. (4) Since the width of the straddle-type monorail track beam is very narrow, it is completely feasible to complete the tensioning and anchoring of all the upper prestressed short beam components from the side of the track beam at the transverse through hole.

[0011] In a preferred embodiment of the present invention, the above-mentioned post-cast wet joint includes a post-cast T-shaped concrete block, the longitudinal section of the post-cast T-shaped concrete block along the bridge is T-shaped, the first track beam and the second track beam are respectively provided with notches at the top of the butt end, the transverse part of the post-cast T-shaped concrete block matches the notch, and the vertical part of the post-cast T-shaped concrete block is butt-jointed between the first track beam and the second track beam.

[0012] The technical principles and effects of the above invention are as follows: the T-shaped post-cast wet joint increases the contact surface with the track beams at both ends, avoiding shear failure along the vertical contact interface between the new and old concrete; at the same time, the top space of the T-shaped post-cast wet joint is larger, which is more convenient for the construction of dense steel bars and steel bundles there, and by arranging steel bars there, the connection with the first track beam and the second track beam can be further strengthened; in addition, the T-shaped post-cast wet joint can also facilitate the connection of the upper steel bars of the track beams on both sides while ensuring that the lower part can be directly erected on the continuous pier, without increasing the size of the continuous pier or setting up brackets on both sides of the continuous pier as temporary support for the erection of the track beam.

[0013] In a preferred embodiment of the present invention, the above-mentioned post-cast wet joint further includes top edge embedded steel bars, top edge connecting steel bars, non-top edge embedded steel bars, non-top edge connecting steel bars, and vertical connecting bars; the top edge embedded steel bars are L-shaped, and the first track beam and the second track beam respectively correspond to horizontal sections of top edge embedded steel bars, the vertical sections of the top edge embedded steel bars are located in the post-cast T-shaped concrete blocks and are arranged vertically, the top edge connecting steel bars are in an inverted U-shape and are placed in the post-cast wet joint, the top edge embedded steel bars embedded in the first track beam and the second track beam are respectively tied and fixed with the top edge connecting steel bars, the non-top edge embedded steel bars are U-shaped, and a single non-top edge embedded steel bar is placed horizontally, Multiple non-top edge embedded steel bars are arranged in a vertical array, the open ends of the non-top edge embedded steel bars are embedded in the first track beam and the second track beam, and the closed ends thereof extend into the post-cast T-shaped concrete blocks. The non-top edge connecting steel bars are annular and horizontally placed on the horizontally adjacent non-top edge embedded steel bars. The non-top edge connecting steel bars are tied and fixed to the non-top edge embedded steel bars. Multiple vertical connecting bars are arranged alternately and vertically. The lower ends of the vertical connecting bars are embedded in the first track beam and the second track beam at the notch, and the upper ends of the vertical connecting bars extend into the post-cast T-shaped concrete blocks. The post-cast T-shaped concrete blocks are connected to the first track beam and the second track beam as a whole through the vertical connecting bars.

[0014] The technical principles and effects of the above invention are as follows: the steel bar connections at the T-shaped post-cast wet joint of the present invention can be completely free of welding operations, and the dense reinforcement area at the upper edge of the wet joint has a larger construction working space, so the construction speed of the wet joint is significantly improved, and the construction difficulty is reduced, thereby improving the prefabricated assembly construction efficiency of the continuous beam system track beam; the vertical connecting reinforcement strengthens the connection between the post-cast wet joint and the first track beam and the second track beam, and the non-top edge connecting steel bars and the non-top edge embedded steel bars can be set with a longer overlap range along the bridge direction to enhance the mutual anchoring effect; in addition, the T-shaped joint top plate has a larger size along the bridge direction, so that the joint between the top and the track beam is to a certain extent away from the most unfavorable position with the largest negative bending moment, further reducing the risk of cracking at the joint.

[0015] In a preferred embodiment of the present invention, the width L3 of the vertical part of the post-cast T-shaped concrete block along the bridge direction is ≥30cm, the width L2 of the transverse part of the post-cast T-shaped concrete block along the bridge direction is >L3, and the thickness H2 of the transverse part of the post-cast T-shaped concrete block is ≥max(10cm, H0 / 20), where H0 is the height of the post-cast T-shaped concrete block.

[0016] The technical principle and effect of the above invention are: when the size of the post-cast T-shaped concrete block meets L3≥30cm and H2≥max(10cm, H0 / 20), it has sufficient vertical shear resistance and anti-uplift performance and ensures the structural requirements of its internal steel bars and the on-site construction space requirements.

[0017] In a preferred embodiment of the present invention, the vertical length H of the top edge embedded steel bar is 42≥0.6H0.

[0018] The technical principle and effect of the above invention are: the vertical section length H of the top edge embedded steel bar 42 When ≥0.6H0, it can ensure that the end of the top edge embedded steel bar extends below the neutral axis of the section and is anchored in the compression zone to have a reliable anchoring effect, thereby realizing a welding-free connection between the top edge embedded steel bars of the two spans of track beams.

[0019] In a preferred embodiment of the present invention, the minimum horizontal clearance L between the pre-embedded steel bars at the top edges of the first and second track beams is 42 ≥4cm.

[0020] The technical principles and effects of the above invention are: 42 When the distance is ≥4cm, collisions caused by construction accuracy errors when erecting the two span track beams can be avoided.

[0021] In a preferred embodiment of the present invention, the vertical dimension H of the top edge connecting steel bar is 43 ≥0.6H0, H0 is the height of the post-cast T-shaped concrete block, and the longitudinal dimension L of the top edge connecting steel bar 43 >L 42 +4*max(d 42 , d 43 ), d 42 and d 43 They are the nominal diameters of the top edge embedded steel bars and the top edge connecting steel bars respectively.

[0022] The technical principle and effect of the above invention are: the above size structure can ensure that the top edge connecting steel bars and the top edge embedded steel bars have a certain overlapping length in the direction of the bridge, ensuring that the top edge steel bars pass through any section of the track beam in the direction of the bridge.

[0023] In a preferred embodiment of the present invention, the minimum horizontal clearance L between the non-top edge embedded steel bars of the first track beam and the second track beam is 44 >L 43 +4*max(d 43 , d 45 ), d 45 The maximum nominal diameter of the non-top edge connecting steel bar, the bridge-direction dimension L of the non-top edge connecting steel bar 45 >L 44 +4*max(d 44 , d 45 ), d 44 It is the maximum nominal diameter of the non-top edge embedded steel bars.

[0024] The technical principles and effects of the above invention are: 44 >L 43 +4*max(d43 , d 45 ), the non-top edge connecting steel bars can be passed through the gap between the non-top edge embedded steel bars of the two span track beams in a vertically deflected state, and then placed horizontally on the non-top edge embedded steel bars on both sides; when L45 meets the above size requirements, it can be directly placed on the non-top edge embedded steel bars on both sides to facilitate binding construction.

[0025] In a preferred embodiment of the present invention, the length L of the non-top edge connecting steel bars in the transverse portion of the post-cast T-shaped concrete block is 45 >L3, the length of the non-top edge connecting steel bars in the vertical part of the post-cast T-shaped concrete block 45 <L3。

[0026] The technical principle and effect of the above invention are: the L of the non-top edge connecting steel bar located vertically within the range of H2 45 When L>L3, the top space of the T-shaped post-cast wet joint can be fully utilized to set a longer overlap range along the bridge direction between the non-top edge connecting steel bars and the non-top edge embedded steel bars within this range to enhance the mutual anchoring effect.

[0027] In a preferred embodiment of the present invention, the minimum vertical distance H1 between the top surface of the above-mentioned transverse through hole and the top surface of the first track beam or the second track beam is ≥ the single wheel width of the straddle-type monorail vehicle guide wheel, and the upper tension beam extends into the transverse through hole and bends vertically.

[0028] The technical principle and effect of the above invention are: after the transverse through hole avoids the running surface of the guide wheel, the transverse stability of the straddle-type monorail vehicle during travel can be further ensured.

[0029] In a preferred embodiment of the present invention, the above-mentioned upper prestressed short beam assembly also includes a side template, which has grouting holes. The upper post-poured concrete is made by pressing high-strength grouting material into the transverse through hole through the grouting holes.

[0030] The technical principle and effect of the above invention are: the sealing and anchoring construction of the transverse through hole can be easily achieved by grouting the side formwork.

[0031] In a preferred embodiment of the present invention, a plurality of transverse through holes are provided on the same side of the first track beam and the second track beam, and the plurality of transverse through holes are arranged at different positions in the horizontal direction. The upper tensioning bundle includes a first upper tensioning bundle and a second upper tensioning bundle. The length of the first upper tensioning bundle is greater than that of the second upper tensioning bundle. The first upper tensioning bundle passes over the transverse through hole at the anchorage of the second upper tensioning bundle, and the first upper tensioning bundle is tensioned and anchored before the second upper tensioning bundle. The transverse through hole corresponding to the first upper tensioning bundle is arranged in the beam section of the first track beam or the second track beam whose upper edge is compressed under the action of the live load of the train.

[0032] The technical principles and effects of the above invention are as follows: (1) When the span of the track beam is large, setting one length of upper tensioning beam cannot meet the stress requirements of the negative bending moment area or is not economical, so it is necessary to set upper tensioning beams of multiple lengths and stagger them; (2) The transverse through hole corresponding to the shorter upper tensioning beam is closer to the beam end, so the compressive stress reserve under the action of the track beam's own weight is smaller. The longer upper tensioning beam is tensioned and anchored before the shorter upper tensioning beam, which can ensure that the transverse through hole of the shorter upper tensioning beam has sufficient compressive stress reserve when it is anchored, thereby avoiding anchor damage; (3) The longer upper tensioning beam is anchored in the beam section where the upper edge is compressed under the action of the live load of the train, which can ensure that the tensile stress generated by its anchoring force is ≤ the compressive stress generated by other loads, thereby avoiding splitting damage at the transverse through hole.

[0033] In a preferred embodiment of the present invention, a lower edge prestressed short bundle component is further provided at the bottom end of the above-mentioned post-poured wet joint. The lower edge prestressed short bundle component includes a lower edge tensioned bundle, a lower edge notch and a lower edge post-poured concrete. After the first track beam and the second track beam are erected, the lower edge tensioned bundle is inserted into the pre-buried pipes in the first track beam and the second track beam and the short bundle pipes provided with the post-poured T-shaped concrete blocks. The two ends of the lower edge tensioned bundle respectively extend into the lower edge notch. The lower edge notch is provided on the bottom surface of the end of the first track beam and the second track beam. The lower edge post-poured concrete is provided in the lower edge notch. The length of a single lower edge tensioned bundle along the bridge direction is L4≤L1.

[0034] The technical principles and effects of the above invention are as follows: (1) The lower edge prestressed short bundle assembly can not only ensure that the lower edge of the beam section at the continuous pier will not be torn when the prestress of the upper prestressed short bundle assembly is too large, but also resist the tensile stress generated at the lower edge of the beam section at the continuous pier under the action of foundation settlement, thereby reducing the influence of the secondary internal force of uneven foundation settlement; (2) The lower edge tension bundle can be tensioned and anchored after the longest upper tension bundle is tensioned and before the shortest upper tension bundle is tensioned, thereby avoiding the situation where the upper edge of the beam section at the joint is wetted after the prestress of the lower edge tension bundle is too large.

[0035] In a preferred embodiment of the present invention, the above-mentioned simply supported to continuous track beam bridge also includes a prefabricated prestressed beam, and the first track beam or the second track beam is respectively provided with a prefabricated prestressed beam along the bridge direction, and the two ends of the prefabricated prestressed beam respectively pass through the two ends of the first track beam or the second track beam and are anchored.

[0036] The technical principle and effect of the above invention are: after the prefabricated prestressed beams are provided, the track beam can have better durability and a larger span.

[0037] A bearing design method for a simply supported to continuous track beam bridge is applied to the above-mentioned simply supported to continuous track beam bridge, wherein the simply supported to continuous track beam bridge has N span track beams and N+1 bridge piers, wherein the bridge piers are provided with one fixed pier and N movable piers, assuming that the fixed piers are numbered M, a fixed hinged support is provided on the top of the fixed piers, and a movable hinged support is provided on the top of the movable piers;

[0038] The process of determining the friction coefficient μ of the movable hinge support is as follows:

[0039] S1. Calculate the total support reaction force at the top of each pier under all dead loads. Number the total support reaction force at the fixed pier as R along the bridge direction. g 1 ,...,R g M ,...,R g N+1 , R g M ; Align the midpoint of the straddle-type monorail train load with the centerline of the fixed pier, and solve the total reaction force of the pier top under the live load of the train, and number them in sequence along the bridge direction as R q 1 ,...,R q M ,...,R q N+1 , R q M is the total live load reaction force of the train at the fixed pier;

[0040] S2. Under the action of the maximum traction and braking force Q of the running wheels of the straddle-type monorail train, assuming that the fixed pier is regarded as a special movable pier with a support friction coefficient of ∞, when the supports at the top of all movable piers are in a critical state of static and sliding, and the static friction resistance F of the special movable pier is M The most uniform distribution of force Q among the piers is achieved when the maximum static friction resistance of all movable piers is equal. For safety reasons, the maximum static friction resistance of the bearing is calculated based on its sliding friction resistance. μ is defined as the friction coefficient of the movable hinge bearing. The force balance equations corresponding to the most uniform distribution of force Q among the piers are:

[0041]

[0042] The above two equations can be combined to solve the value of μ.

[0043] The technical principle and effect of the above invention are as follows: for special bridge structures such as straddle-type monorail, where the proportion of live load is greater than that of dead load, it has been found through analysis that when the friction coefficient of the support is low, the maximum horizontal force on the pier top generated under the action of "overall heating and cooling + vertical dead load" is generally smaller than the maximum horizontal force on the pier top generated under the action of "traction or braking force + vertical dead load + vertical live load"; therefore, the optimal distribution state of the horizontal force on the pier top is the state when the track beam does not slide under the action of traction and braking force, and the difference between the forces distributed on each pier top is the smallest. At this time, the maximum horizontal force on the pier top generated under the action of "overall heating and cooling + vertical dead load" is still smaller than or at most equal to the maximum horizontal force on the pier top generated under the action of "traction or braking force + vertical dead load + vertical live load". Maximum horizontal force on the pier top; It can be seen that the design method of the present invention can avoid the extreme situation of excessive pursuit of lowering the temperature horizontal force and pursuing an excessively low bearing friction coefficient, and can also avoid the extreme situation of excessive pursuit of uniform distribution of traction and braking force and designing multiple fixed piers along the bridge. At the same time, the support arrangement designed by the present invention can prevent the pier top horizontal force under the action of overall temperature rise and fall and shrinkage creep from being superimposed with the traction and braking forces, and reduce the value of the maximum pier top horizontal force on the entire bridge to the greatest extent, so that the straddle-type monorail bridge structure has a more reasonable bearing and lower structure stress state, reduces the horizontal displacement of the pier top and the number of lower pile foundations, improves driving comfort and saves the cost of the bridge substructure.

[0044] In a preferred embodiment of the present invention, before determining the friction coefficient of the movable hinge support, the method further includes:

[0045] S11, N+1 piers include N-1 continuous piers and 2 branch piers, and the piers are numbered 1, 2, 3, ..., N, N+1 in the longitudinal direction of the bridge;

[0046] S12. When the simply supported continuous track beam bridge has no longitudinal slope, the fixed hinged support is set on the continuous pier closest to the midpoint of the entire bridge along the bridge direction. When the simply supported continuous track beam bridge has a longitudinal slope, the fixed hinged support is set on the continuous pier with the lowest pier top elevation.

[0047] The technical principle and effect of the above invention are as follows: the live load effect of the straddle-type monorail is usually greater than the dead load effect and the temperature effect. Therefore, when there is a longitudinal slope, setting the fixed hinge support on the continuous pier with the lowest pier top elevation can make the fixed hinge support compressed under the tangential component of the gravity of the track beam, thereby partially offsetting the tangential tension generated by the fixed hinge support under the action of traction or braking force.

[0048] In a preferred embodiment of the present invention, after determining the friction coefficient of the movable hinge support, the method further includes:

[0049] S3. To ensure that the track beam does not slide under the action of traction and braking forces, γμ is taken as the optimal design parameter of the movable hinge support, γ is the safety factor, γ∈[1.0,1.3].

[0050] The technical principle and effect of the above invention are as follows: considering that there is a certain discrepancy between the load in actual operation of the bridge and the designed load, a certain safety factor needs to be reserved; according to statistical analysis, when γ is within the range of 1.0~1.3, both the bearing cost and the force transmission requirements can be taken into account.

[0051] A construction method for a simply supported to continuous track beam bridge comprises the following steps:

[0052] A1. Install prefabricated prestressed tendons through the prefabricated pipes of the first and second track beams. Anchor the ends of the prefabricated prestressed tendons to the ends of the track beams. Attach the first and second track beams to the piers, placing their butt ends on the first and second temporary supports of the piers, respectively. Ensure that adjacent top-edge embedded steel bars are positioned opposite each other, and adjacent non-top-edge embedded steel bars are positioned opposite each other.

[0053] A2. Install top edge connecting steel bars and non-top edge connecting steel bars. Tie and secure the top edge connecting steel bars to the two oppositely positioned top edge embedded steel bars. The non-top edge connecting steel bars are inserted vertically through the gap between the non-top edge embedded steel bars of the first and second track beams, then rotated to a horizontal position. They are then placed horizontally on the adjacent non-top edge embedded steel bars on both sides and tied and secured. Finally, formwork is supported and secured at the post-wet joint, and concrete is poured to form the joint.

[0054] A3. Install the upper tensioning bundle. Pass the first upper tensioning bundle through the built-in pipes of the first and second track beams, as well as the tensioning bundle pipes of the post-cast T-shaped concrete blocks. Anchor the two ends of the first upper tensioning bundle in the transverse through-holes of the first and second track beams, respectively. Subsequently, install the permanent support for the continuous pier and remove the first and second temporary supports. Install the lower edge tensioning bundle in the same manner as the upper tensioning bundle. After the post-cast wet joint is cured, tension, grout, and anchor the lower edge tensioning bundle in the lower edge notch. Then, cast the lower edge post-cast concrete. In this way, the two ends of the lower edge tensioning bundle are anchored in the lower edge notches of the first and second track beams.

[0055] A4. Insert the second upper tensioning bundle into the built-in pipes of the first and second track beams, as well as the tensioning bundle pipes of the post-cast T-shaped concrete blocks. Tension the second tensioning bundle in the other pair of transverse through holes in the first and second track beams, and anchor it.

[0056] A5. Set up side formwork on the outside of the upper post-poured concrete, and pour the upper post-poured concrete and the lower edge post-poured concrete in the two pairs of horizontal through holes and the lower edge notch respectively. Remove the side formwork after the upper post-poured concrete solidifies.

[0057] The technical principles and effects of the above invention are as follows: (1) The construction method of the present invention is specifically used for narrow and high-section track beams unique to straddle-type monorail transportation, and its on-site steel bar connection and concrete pouring operations can be conveniently completed from the operating space on both sides or the top of the track beam; (2) With the construction method of the present invention, the post-cast wet joint is free of welding operations, and the dense reinforcement area at the upper edge of the wet joint has a larger construction operation space. The linear control and adjustment of the track beam during on-site tensioning of the upper prestressed short bundle assembly are less difficult. Compared with the continuous beam and continuous rigid frame system of the prior art, the two time-consuming processes of the difficulty of threading the negative bending moment bundle when the existing full-length bundle is used and the large amount of dense steel bar welding operations in the limited space at the pier top wet joint are omitted, which greatly reduces the construction difficulty, saves construction measures costs and shortens the construction period, and improves the prefabrication and assembly construction efficiency of the continuous beam system track beam; (3) Before tensioning the lower edge existing bundle, the temporary support needs to be removed to avoid affecting the prestressing effect of the lower edge existing bundle, and also to avoid the track beam further pressing the temporary support, making the latter difficult to remove.

[0058] Compared with the continuous beam system and continuous rigid frame system in the prior art, the beneficial effects of the simply supported to continuous track beam bridge in the present invention are summarized as follows:

[0059] 1. Higher durability: The present invention realizes the anchoring of the upper prestressed short bundle assembly through the transverse through hole in which the top surface of the notch is located below the top surface of the track beam, avoiding the problem that the concrete at the notch has no compressive stress reserve in the bridge state when the short bundle is anchored in the top notch, and cannot ensure the durability of the interface between the new and old concrete at this location, especially the new and old concrete. Even if microcracks are generated at the transverse through hole, they avoid the running surface of the running wheel, thereby avoiding the possibility of aggravation of the crack development and affecting the driving smoothness under the direct impact of the wheel. At the same time, combined with the setting of the lower edge prestressed short bundle assembly, the influence of excessive prestress of the upper prestressed short bundle assembly and the secondary internal force of uneven foundation settlement on the lower edge of the beam section at the pier top is reduced. In addition, combined with the T-shaped post-cast wet joint, the contact area between the track beams on both sides is increased, and the interface between the new and old concrete is kept away from the most unfavorable position with the largest negative bending moment, further reducing the risk of cracking at the joint. In summary, the durability of the present invention is significantly better than that of the continuous beam and continuous rigid frame system in the prior art.

[0060] 2. Faster construction speed: The present invention achieves welding-free operation through post-cast wet joints. The dense reinforcement area on the upper edge of the wet joint has a larger construction working space. The linear control and adjustment of the track beam during on-site tensioning of the upper prestressed short bundle components are less difficult. Compared with the continuous beam and continuous rigid frame system in the prior art, the present invention eliminates the two time-consuming processes of the difficulty of threading the negative bending moment bundle when the full-length bundle is used and the large-scale and intensive steel bar welding operation in the limited space at the pier top wet joint, which greatly reduces the construction difficulty, saves construction measures costs and shortens the construction period, thereby improving the prefabrication and assembly construction efficiency of the track beam of the continuous beam system. In summary, it can be seen that the construction speed of the present invention is significantly faster than that of the continuous beam and continuous rigid frame system in the prior art.

[0061] 3. Better economic benefits: The present invention controls the stress in the negative bending moment area by arranging an upper prestressed short bundle assembly, avoiding the problems of greater difficulty and workload in bundle threading construction when using the top edge full-length bundle method, waste of materials in the non-negative bending moment area, and aggravation of excessive compressive stress on the upper edge of the precast beam. At the same time, it reduces the influence of the negative bending moment bundle on the vertical and especially the horizontal linear shape of the precast beam during tensioning, reduces the control requirements for the tensioning operation accuracy, and thus directly saves material costs and construction measures costs. In summary, the economic benefits of the present invention are significantly better than those of the continuous beam and continuous rigid frame system in the prior art.

[0062] Furthermore, compared with the prior art simply supported beam system, the simply supported to continuous track beam bridge of the present invention has the following beneficial effects:

[0063] 1. Better overall performance: The post-cast wet joints and the upper prestressed short beam components of the present invention connect the track beams on both sides into a whole, greatly improving the lateral bending stiffness of the entire bridge while enhancing the seismic, torsional and roll resistance of the entire bridge; therefore, the mechanical properties of the present invention are significantly better than those of the simply supported beam system in the prior art.

[0064] 2. Higher driving comfort: The present invention effectively reduces the beam end rotation angle and live load deflection through the use of post-cast wet joints and upper prestressed short beam components, ensures that the concrete in the negative bending moment area of the continuous pier maintains a certain prestress in the operating state and is not prone to cracking, realizes a smooth transition between the two spans of track beams, avoids the occurrence of vehicle jumping at this location, and greatly reduces the number of expensive special expansion joints at the running wheels, stability and guide wheels; therefore, the driving comfort of the present invention is significantly higher than that of the simply supported beam system in the prior art.

[0065] 3. Better economic benefits: On the one hand, the present invention greatly reduces the use of supports and expensive special expansion joints, saving initial construction costs. On the other hand, it also significantly saves the maintenance and inspection workload of supports and expansion joints, reduces tire wear, and saves subsequent operation and maintenance costs. Therefore, the economic benefits of the present invention are significantly better than the simply supported beam system of the prior art.

[0066] 4. More beautiful bridge landscape: The present invention adopts a structural system design that transforms simply supported beams into continuous beams. Compared with the simply supported beam system, it can achieve a lower beam height or a larger span. The pier height and span are better coordinated, which is more conducive to avoiding underground pipelines and more suitable for the construction requirements of medium-span straddle-type monorail beams. Therefore, the bridge landscape of the present invention is significantly more beautiful than the simply supported beam system of the prior art.

[0067] In addition, the support design method of the present invention has a more reasonable lower structure stress: the present invention proposes an optimal support design method suitable for special bridge structures such as straddle-type monorail, where the proportion of live load is greater than that of dead load. It can avoid the extreme situation of excessive pursuit of reducing temperature horizontal force and pursuing too low a support friction coefficient, and can also avoid the extreme situation of excessive pursuit of uniform distribution of traction and braking force and designing multiple fixed piers along the bridge. At the same time, the support arrangement designed by the present invention can prevent the pier top horizontal force under the action of overall temperature rise and fall and shrinkage creep from being superimposed with the traction and braking force, and minimize the value of the maximum pier top horizontal force on the entire bridge, so that the straddle-type monorail bridge structure has a more reasonable support and lower structure stress state, reducing the horizontal displacement of the pier top and the number of lower pile foundations; in summary, it can be seen that the lower structure stress of the present invention is significantly more reasonable than the continuous beam and continuous rigid frame system of the prior art.

[0068] Finally, the construction method of the present invention has better social and environmental benefits: the use of the simply supported to continuous track beam bridge of the present invention shortens the construction period, thereby reducing the interference with the existing traffic under the bridge and the neighboring residents, and is less likely to cause the problem of cracking of the beam section at the continuous pier, which is difficult to repair and seriously affects driving safety and increases noise. It is more suitable for the construction environment and construction requirements of urban rail transit bridges such as straddle-type monorail. In summary, the social and environmental benefits of the present invention are significantly better than the continuous beam and continuous rigid frame systems of the prior art.

[0069] In summary, the present invention is a new type of simply supported to continuous track beam bridge and its design and construction method that is safer, more economical, convenient and reasonable than the existing technology, and can be widely used in the assembly construction of various medium-span straddle-type monorail bridge span structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 A schematic diagram of the positional relationship between the straddle-type monorail vehicle and the track beam of the present invention;

[0071] Figure 2 Schematic diagram of the simply supported to continuous track beam bridge of the present invention;

[0072] Figure 3 This is an elevation view of a simply supported track beam bridge according to Example 1 of the present invention;

[0073] Figure 4This is an elevation view of a simply supported track beam bridge according to Example 2 of the present invention;

[0074] Figure 5 For the present invention Figure 4 AA section view in;

[0075] Figure 6 For the present invention Figure 4 BB cross-sectional view in;

[0076] Figure 7 For the present invention Figure 4 The CC section view in the figure;

[0077] Figure 8 This is a schematic diagram of the construction process of a simply supported track beam bridge with a continuous running surface according to the present invention.

[0078] Markings in the figure: 1-first track beam, 11-first temporary support, 121-permanent support of continuous pier, 122-permanent support of branch pier, 123-precast prestressed tendon, 2-second track beam, 21-second temporary support, 3-track beam, 31-continuous pier, 32-branch pier, 33-expansion joint, 4-post-cast wet joint, 41-post-cast T-shaped concrete block, 42-top edge embedded steel bar, 43-top edge connecting steel bar, 44-non-top Edge embedded steel bars, 45-non-top edge connecting steel bars, 46-vertical connecting bars, 5-upper prestressed short bundle assembly, 51-upper tensioned bundle, 52-transverse through hole, 521-side formwork, 5211-grouting hole, 53-upper post-cast concrete, 6-lower edge prestressed short bundle assembly, 61-lower edge tensioned bundle, 62-lower edge notch, 63-lower edge post-cast concrete, 71-vehicle, 72-traveling wheel, 73-guide wheel, 74-stabilizing wheel. DETAILED DESCRIPTION

[0079] The present invention will be further described in detail below in conjunction with test examples and specific embodiments. However, this should not be understood as limiting the scope of the present invention to the following embodiments, and all technologies implemented based on the present invention fall within the scope of the present invention.

[0080] Example 1

[0081] Please refer to Figure 1 and Figure 2The present embodiment provides a simply supported to continuous track beam bridge, comprising a track beam 3, a pier, a permanent support 121 for the continuous pier, a post-cast wet joint 4 and an upper prestressed short beam assembly 5. The track beams 3 are all precast concrete structures, and the beam height at both ends thereof is H0. The width B of the track beam 3 is ≤ 100 cm. The simply supported to continuous track beam bridge is provided with n-span track beams 3 and n+1 piers, where n is an integer ≥ 2. The n+1 piers include n-1 continuous piers 31 and 2 branch piers 32. In the present embodiment, n=3. The branch piers 32 are located at both ends of the simply supported to continuous track beam bridge, and the continuous pier 31 is arranged between the two branch piers 32. The adjacent track beams 3 erected at the continuous pier 31 in the pier are respectively the first track beam 1 and the second track beam 2, and the expansion joint 33 is the expansion joint 33. The gap between the track beam 3 and the adjacent track beam 3 at both ends of the bridge, the sub-pier 32 is located below the expansion joint 33, and an expansion joint 33 device is arranged at the expansion joint 33 to provide a running surface and support for the running wheels 72, guide wheels 73 and stabilizing wheels 74 when passing through the sub-pier 32, while there is no gap between the first track beam 1 and the second track beam 2. The opposite butt ends of the first track beam 1 and the second track beam 2 are connected by a post-cast wet joint 4. The post-cast wet joint 4 is a cast-in-place concrete structure with steel bars inside. A continuous pier permanent support 121 is set on the continuous pier 31, and a sub-pier permanent support 122 is set on the sub-pier 32. The post-cast wet joint 4 is supported on the top of the continuous pier 31 through the continuous pier permanent support 121. The butt ends of the first track beam 1 and the second track beam 2 and The post-wetting joint 4 between the two forms a butt-end structure, an upper prestressed short beam assembly 5 is arranged inside the butt-end structure, and the opposite ends of the first track beam 1 and the second track beam 2 and the post-wetting joint 4 are strengthened in connection with each other by the upper prestressed short beam assembly 5. The top and bottom surfaces of the post-wetting joint 4 are flush with the top and bottom surfaces of the first track beam 1 and the second track beam 2 respectively. The top surface of the track beam 3 is for the running wheels 72 of the straddle-type monorail vehicle 71 to run, and the side surfaces of the track beam 3 are for the guide wheels 73 and the stabilizing wheels 74 to run. The stabilizing wheels 74 are vertically located below the guide wheels 73. The post-wetting joint 4 provides a running surface and support for the running wheels 72, guide wheels 73 and stabilizing wheels 74 to pass through the continuous pier 31; the simply supported continuous track beam bridge is from the whole bridge Starting from the root problem of the whole structural system, the four major deficiencies of the existing continuous beam system are solved at the same time. Through the coordinated use of the post-cast wet joint 4 and the upper prestressed short beam component 5, the beam end rotation angle and live load deflection are effectively reduced, ensuring that the concrete in the negative bending moment area of the continuous pier 31 maintains a certain prestress in the operating state and is not easy to crack, achieving a smooth transition between the two-span track beams 3, and avoiding the occurrence of vehicle jumping at this location, thereby solving the disadvantage that the simply supported beam system is not suitable for medium-span straddle-type monorail track beams 3, reducing the expansion joint 33 device to improve driving comfort, reduce tire wear, and reduce the workload of maintenance and repair. The simply supported to continuous track beam bridge has better mechanical properties, durability, construction convenience and economic and social benefits.

[0082] Please refer to Figure 3 In this embodiment, the upper prestressed short bundle assembly 5 includes an upper tensioned bundle 51, a transverse through hole 52, and an upper post-cast concrete 53. The upper prestressed short bundle assembly 5 is realized by the following settings: an internal pipe connected to the tensioned bundle pipe is provided at the opposite butt ends of the first track beam 1 and the second track beam 2, and at the same time, a tensioned bundle pipe passing through both ends is provided in the post-cast wet joint 4, and the above-mentioned internal pipe is connected and aligned with the tensioned prestressed bundle pipes at both ends, and the upper tensioned bundle 51 is placed in the tensioned bundle pipe and the internal pipe; by setting the upper prestressed short bundle assembly 5 to control the force in the negative bending moment area, the difficulty and workload of the bundle threading construction when the top edge full-length bundle method is adopted are avoided, the material waste of the existing full-length bundle in the non-negative bending moment area and the aggravation of the excessive compressive stress on the upper edge of the precast beam are avoided, and at the same time, the influence of the negative bending moment bundle on the vertical, especially the transverse, linear shape of the precast beam during tensioning is reduced, and the control requirements for the tensioning operation accuracy are reduced. A transverse through hole 52 is provided at the end of the built-in pipe in the first track beam 1 and the end of the built-in pipe in the second track beam 2, respectively. The transverse through hole 52 is opened on the same side of the first track beam 1 and the second track beam 2. The built-in pipes are connected to the transverse through holes 52, and the two ends of the upper tensioned bundle 51 are respectively tensioned into the corresponding transverse through holes 52 of the first track beam 1 and the second track beam 2. The two ends of the upper tensioned bundle 51 are then anchored by the upper post-cast concrete 53. By setting the transverse through hole 52 with the top surface of the notch below the top surface of the track beam 3, the anchoring of the upper prestressed short bundle component 5 is achieved, avoiding the need to groove the top. When anchoring the short beam, the concrete at the notch has no compressive stress reserve in the completed bridge state, and the durability of the interface between the new and old concrete cannot be guaranteed, especially at this location; although the concrete at the transverse through hole 52 has no compressive stress reserve in the completed bridge state, it is not the running surface of the running wheels 72 of the straddle-type monorail vehicle 71, thereby avoiding the problem of cracking of the interface between the new and old concrete under the direct impact of the wheels, and even if microcracks occur, they will not aggravate and affect the driving smoothness; because the beam width of the straddle-type monorail track beam 3 is very narrow, it is completely feasible to complete the tensioning and anchoring of all the upper prestressed short beam components 5 from the side of the track beam 3 at the transverse through hole 52.

[0083] In this embodiment, two sets of upper prestressed tendons are provided. In other embodiments, three, four, or other sets of upper prestressed short tendon assemblies 5 may be provided. In this embodiment, the two upper prestressed tendons 51 are arranged in a vertical relationship, and the transverse through-holes 52 provided on the sides of the first and second track beams 1 and 2 are staggered. The length L1 of a single upper prestressed tendon 51 along the bridge is ≤ half the sum of the spans of the adjacent track beams 3. This embodiment also includes prefabricated prestressed tendons 123. These tendons 123 are embedded and anchored within the track beams 3 during prefabrication. Specifically, prefabricated conduits, such as corrugated pipes, are provided within the first and second track beams 1 and 2, respectively. These conduits contain the prefabricated prestressed tendons 123. These tendons 123 are arranged along the bridge length of the first or second track beam 1 or 2, with their ends anchored to the ends of the corresponding track beam 3. The provision of these prefabricated prestressed tendons 123 improves the durability and span of the track beams 3. The upper prestressed bundle of this embodiment is tensioned and anchored after the post-cast wet joint 4 is set up, and the post-cast wet joint 4 is cast to form a rigid connection after the first track beam 1 and the second track beam 2 are erected. A continuous pier 31 is provided below the upper post-cast concrete 53 of the post-cast wet joint 4. When the track beam 3 is erected on the continuous pier 31, a first temporary support 11 is provided first to support the first track beam 1, and a second temporary support 21 is provided to support the second track beam 2. The continuous pier permanent support 121 is provided below the post-cast wet joint 4 when the post-cast wet joint 4 is set up, and the branch pier permanent support 122 is provided on the branch pier 32 at both ends of the bridge. The branch pier permanent support 122 is used to support the end portions of the track beam 3 at both ends of the bridge. The first temporary support 11 and the second temporary support 21 are removed after the bridge construction is completed.

[0084] Example 2

[0085] Please refer to Figure 4 This embodiment provides a simply supported continuous track beam bridge. The bridge is the same as that in Example 1. The post-wetting joint 4, the upper prestressed short bundle assembly 5, and the prefabricated prestressed bundle 123 used are substantially the same as those in Example 1. The difference lies in that the specific structure of the post-wetting joint 4 in this embodiment is different, and a lower edge prestressed short bundle assembly 6 is further provided at the bottom of the post-wetting joint 4 in this embodiment. The specific differences are as follows:

[0086] In this embodiment, the post-cast wet joint 4 includes a post-cast T-shaped concrete block 41, top edge embedded steel bars 42, top edge connecting steel bars 43, non-top edge embedded steel bars 44, non-top edge connecting steel bars 45 and vertical connecting bars 46, wherein the top edge embedded steel bars 42, top edge connecting steel bars 43, non-top edge embedded steel bars 44, non-top edge connecting steel bars 45 and vertical connecting bars 46 are arranged in the post-cast T-shaped concrete block 41. The longitudinal section of the post-cast T-shaped concrete block 41 along the bridge is T-shaped, and the first track beam 1 and the second track beam 2 are respectively provided with a notch at the top of the butt end, that is, a step structure is formed at the end of the first track beam 1 and the second track beam 2 at the butt end structure, and a gap is formed at the end of the first track beam 1 and the end of the second track beam 2 here. The shape and size of the post-cast T-shaped concrete block 41 just match the gap structure formed at the end of the first track beam 1 and the two ends of the second track. The T-shaped structure of the post-cast T-shaped concrete block 41 includes a horizontal part and a vertical part. The horizontal part of the post-cast T-shaped concrete block 41 matches the notch, and the vertical part of the post-cast T-shaped concrete block 41 is butt-jointed to the first track beam 1. Between the track beam 1 and the second track beam 2, the transverse and vertical parts of the post-cast T-shaped concrete block 41 also satisfy the following relationship: the width L3 of the vertical part of the post-cast T-shaped concrete block 41 along the bridge direction is ≥30cm, the width L2>L3 of the transverse part of the post-cast T-shaped concrete block 41 along the bridge direction, the thickness H2≥max(10cm, H0 / 20) of the transverse part of the post-cast T-shaped concrete block 41, H0 is the height of the post-cast T-shaped concrete block 41, and when the size of the post-cast T-shaped concrete block 41 satisfies L3≥30cm and H2≥max(10cm, H0 / 20), it has sufficient vertical shear resistance and anti-uplifting performance and ensures the structural requirements of its internal steel bars and the on-site construction space requirements. The T-shaped post-cast wet joint 4 increases the contact surface with the track beams 3 at both ends, avoiding shear failure along the vertical contact interface between the new and old concrete; at the same time, the top space of the T-shaped post-cast wet joint 4 is larger, which is more convenient for the construction of dense steel bars and steel bundles there, and by laying steel bars there, the connection with the first track beam 1 and the second track beam 2 can be further strengthened; in addition, the T-shaped post-cast wet joint 4 can also facilitate the connection of the upper steel bars of the track beams 3 on both sides while ensuring that the lower part can be directly erected on the continuous pier 31, without increasing the size of the continuous pier 31 or setting up brackets on both sides of the continuous pier 31 as temporary support for the erection of the track beam 3.

[0087] Please refer to Figure 5In this embodiment, the top edge embedded steel bar 42 is L-shaped, which forms a horizontal section and a vertical section of the top edge embedded steel bar 42. The horizontal sections of the top edge embedded steel bar 42 are respectively embedded in the first track beam 1 and the second track beam 2. The vertical section of the top edge embedded steel bar 42 is located in the post-cast T-shaped concrete block 41 and is vertically arranged. Most of the horizontal section of the top edge embedded steel bar 42 is embedded in the corresponding track beam 3. The exposed position of the horizontal section of the top edge embedded steel bar 42 is at the gap of the first track beam 1 and the second track beam 2, that is, the horizontal position of the horizontal section of the top edge embedded steel bar 42 corresponds to the position range of the above-mentioned gap. The horizontal section of the top edge embedded steel bar 42 extends from the gap of the corresponding track beam 3 to the other end of the track beam 3 and is not exposed. The vertical section of the top edge embedded steel bar 42 is cast between the first track beam 1 and the second track beam 2 through the post-cast T-shaped concrete block 41; the vertical section length H of the top edge embedded steel bar 42 42 ≥0.6H0, top edge embedded steel bar 42 vertical section length H 42 When H0 is greater than or equal to 0.6H0, it can ensure that the end of the top edge embedded steel bar 42 extends below the neutral axis of the section and is anchored in the compression zone to have a reliable anchoring effect, thereby realizing a welding-free connection between the top edge embedded steel bars 42 of the two span track beams 3; when setting the post-cast T-shaped concrete block 41, the minimum horizontal clear distance L between the vertical sections of the top edge embedded steel bars 42 embedded in the first track beam 1 and the second track beam 2 is greater than or equal to 0.6H0. 42 ≥4cm, L 42 When the thickness is ≥4cm, collisions caused by construction accuracy errors when erecting the two span track beams 3 can be avoided. The top edge connecting steel bar 43 is in an inverted U shape and is placed in the post-wetting joint 4. The U-shaped structure of the top edge connecting steel bar 43 has two vertical sections. The top edge embedded steel bars 42 embedded in the first track beam 1 and the second track beam 2 are respectively fixed to the corresponding top edge connecting steel bars 43 by steel wire binding. The distance between the above two vertical sections is greater than the distance between the corresponding top edge embedded steel bars 42 vertical sections of the first track beam 1 and the second track beam 2 at the joint. The vertical dimension H of the top edge connecting steel bar 43 43 ≥0.6H0, H0 is the height of the post-cast T-shaped concrete block 41, and the longitudinal dimension L of the top edge connecting steel bar 43 43 >L 42 +4*max(d 42 , d 43 ), d 42 and d 43They are the nominal diameters of the top edge embedded steel bars 42 and the top edge connecting steel bars 43 respectively. The above-mentioned size structure can ensure that the top edge connecting steel bars 43 and the top edge embedded steel bars 42 have a certain overlapping length in the longitudinal direction of the bridge, ensuring that the top edge steel bars pass through any section of the track beam 3 in the longitudinal direction of the bridge. In this embodiment, there are multiple vertical connecting bars 46, which are arranged alternately and vertically. The lower ends of the vertical connecting bars 46 are embedded in the first track beam 1 and the second track beam 2 at the notch. The multiple vertical connecting bars 46 are evenly arranged in an array at the notch, and the upper ends of the vertical connecting bars 46 extend into the post-cast T-shaped concrete blocks 41. The post-cast T-shaped concrete blocks 41 are connected to the first track beam 1 and the second track beam 2 as a whole through the vertical connecting bars 46. The vertical connecting bars 46 strengthen the connection between the post-cast wet joint 4 and the first track beam 1 and the second track beam 2. The non-top edge connecting steel bars 45 and the non-top edge embedded steel bars 44 can be set with a longer overlap range in the direction of the bridge, thereby enhancing the mutual anchoring effect. In addition, the top plate of the T-shaped joint has a larger size in the direction of the bridge, so that the joint between the top and the track beam 3 is to a certain extent away from the most unfavorable position with the largest negative bending moment, further reducing the risk of cracking at the joint. The steel bar connections at the T-shaped post-cast wet joint 4 of the present invention can be completely free of welding operations, and the dense reinforcement area at the upper edge of the wet joint has a larger construction working space, so the construction speed of the wet joint is significantly improved, the construction difficulty is reduced, and the prefabrication and assembly construction efficiency of the continuous beam system track beam 3 is improved.

[0088] Please refer to Figure 6 In this embodiment, the non-top edge embedded steel bars 44 are U-shaped, and a single non-top edge embedded steel bar 44 is placed horizontally, and multiple non-top edge embedded steel bars 44 are arranged in an array vertically. The U-shaped open end of the non-top edge embedded steel bar 44 is buried in the first track beam 1 and the second track beam 2, and its closed end extends to the gap between the butt end of the first track beam 1 and the butt end of the second track beam 2. The gap is used for pouring the post-cast T-shaped concrete block 41. The closed ends of the non-top edge embedded steel bars 44 corresponding to the first track beam 1 and the second track beam 2 are opposite to each other. The two non-top edge embedded steel bars 44 are recorded as adjacent non-top edge embedded steel bars 44, and the non-top edge connecting steel bars 45 is annular and in this embodiment is a square with rounded corners. The non-top edge connecting steel bar 45 is horizontally placed on the horizontally adjacent non-top edge embedded steel bar 44, that is, one end of the non-top edge embedded steel bar 44 is placed on the closed end of one non-top edge embedded steel bar 44, and the other end is placed on the closed end of another adjacent non-top edge embedded steel bar 44. The non-top edge connecting steel bar 45 and the non-top edge embedded steel bar 44 are fixed by steel wire binding; the non-top edge connecting steel bar 45 includes a horizontal portion of the post-cast T-shaped concrete block 41 arranged at the notch and a vertical portion of the post-cast T-shaped concrete block 41 arranged below the notch. The length L of the non-top edge connecting steel bar 45 in the horizontal portion of the post-cast T-shaped concrete block 41 is 45 > L3, the length L of the non-top edge connecting steel bar 45 in the vertical part of the post-cast T-shaped concrete block 4145 <The L of the non-top-edge connecting steel bar 45 vertically within the range of H2 of L3 45 >When it is greater than L3, the top space of the T-shaped post-cast wet joint 4 can be fully utilized, so that a longer longitudinal lap range can be set between the non-top-edge connecting steel bar 45 and the non-top-edge embedded steel bar 44 within this range, enhancing the mutual anchoring effect. The minimum horizontal clear distance L between the non-top-edge embedded steel bars 44 of the first track beam 1 and the second track beam 2 44 >L 43 +4*max(d 43 , d 45 ),d 45 is the maximum nominal diameter of the non-top-edge connecting steel bar 45. The longitudinal dimension L of the non-top-edge connecting steel bar 45 45 >L 44 +4*max(d 44 , d 45 ),d 44 is the maximum nominal diameter of the non-top-edge embedded steel bar 44, that is, the distance between the closed ends of adjacent non-top-edge embedded steel bars 44 meets the requirements of the above size relationship. When L 44 >L 43 +4*max(d 43 , d 45 ),the non-top-edge connecting steel bar 45 can pass through the gap between the non-top-edge embedded steel bars 44 of the two-span track beam 3 in a vertically deflected state and then be horizontally placed on the non-top-edge embedded steel bars 44 on both sides; when L45 meets the above size requirements, it can be directly placed on the non-top-edge embedded steel bars 44 on both sides, facilitating the binding construction.

[0089] In this embodiment, the setting of the transverse through hole 52 includes the setting in Example 1, and also includes the following: the minimum vertical distance H1 between the top surface of the transverse through hole 52 and the top surface of the first track beam 1 or the second track beam 2 is ≥ the single wheel width of the guide wheel 73 of the straddle-type monorail vehicle 71, and the upper tension bundle 51 extends into the transverse through hole 52 and is vertically bent. As shown in the figure, the parts of the upper tension bundle 51 at both ends extending into the transverse through hole 52 are divided into two strands, and the upper tension bundle 51 is separated and close to the groove surface of the transverse through hole 52 on the side where it is extended, so that the two ends of the upper tension bundle 51 are vertically bent; after the transverse through hole 52 avoids the running surface of the guide wheel 73, it can further ensure the transverse stability of the straddle-type monorail vehicle 71 during travel. The upper prestressed short beam assembly 5 also includes a side formwork 521. The side formwork 521 is fixed to the outside of the transverse through hole 52 after the upper post-cast concrete 53 anchors the two ends of the upper tensioned beam 51. The side formwork 521 is provided with a grouting hole 5211. The upper post-cast concrete 53 is made by pressing high-strength grouting material into the transverse through hole 52 through the grouting hole 5211; grouting through the side formwork 521 can facilitate the sealing and anchoring construction of the transverse through hole 52. In this embodiment, two transverse through holes 52 are also provided on the same side of the first track beam 1 and the second track beam 2. The two transverse through holes 52 are arranged at different positions in the horizontal direction. Two upper tension bundles 51 are provided, including a first upper tension bundle 51 and a second upper tension bundle 51. The length of the first upper tension bundle 51 is greater than that of the second upper tension bundle 51. The first upper tension bundle 51 passes above the transverse through hole 52 at the anchoring position of the second upper tension bundle 51, and the first upper tension bundle 51 is tensioned and anchored before the second upper tension bundle 51. The transverse through hole 52 corresponding to the first upper tension bundle 51 is arranged in the beam section of the first track beam or the second track beam 2 whose upper edge is compressed under the action of the live load of the train; when the span of the track beam 3 is large, 1 is set The upper tension bundle 51 of a certain length cannot meet the stress requirements of the negative bending moment zone or is not economical enough, so it is necessary to set up upper tension bundles 51 of various lengths and stagger them; the transverse through hole 52 corresponding to the shorter upper tension bundle 51 is closer to the beam end, so the compressive stress reserve under the action of the deadweight of the track beam 3 is smaller, and the longer upper tension bundle 51 is tensioned and anchored before the shorter upper tension bundle 51, which can ensure that the transverse through hole 52 of the shorter upper tension bundle 51 has sufficient compressive stress reserve when it is anchored, thereby avoiding anchor failure; the longer upper tension bundle 51 is anchored in the beam section where the upper edge is compressed under the action of the live load of the train, which can ensure that the tensile stress generated by its anchoring force is ≤ the compressive stress generated by other loads, thereby avoiding splitting failure at the transverse through hole 52.

[0090] Please refer to Figure 7In this embodiment, a lower edge prestressed short bundle component 6 is further provided at the bottom end of the post-cast wet joint 4. The lower edge prestressed short bundle component 6 includes a lower edge tension bundle 61, a lower edge notch 62 and a lower edge post-cast concrete 63. Pre-buried pipes are respectively provided at the bottom ends of the first track beam 1 and the second track beam 2 at the butt end, and a short bundle pipe is also provided at the corresponding position of the bottom end of the post-cast T-shaped concrete block 41. The above-mentioned pre-buried pipes and the short bundle pipes are connected. The lower edge tension bundle 61 is placed in the above-mentioned connected pipes. The length of a single lower edge tension bundle 61 along the bridge direction is L4≤L1. After the first track beam 1 and the second track beam 2 are erected, the lower edge tension bundle 61 is inserted into the pre-buried pipes in the first track beam 1 and the second track beam 2 and the short bundle pipe provided in the post-cast T-shaped concrete block 41. The two ends of the lower edge tension bundle 61 extend into the lower edge notch 62 respectively. The lower edge notch 62 is provided at the first track beam 1 and the butt end. The bottom surface of the second track beam 2, the lower edge notch 62 is a notch formed by the bottom surface of the end of the track beam 3 toward the middle of the track beam 3, and the lower edge post-cast concrete 63 is arranged in the lower edge notch 62. The lower edge post-cast concrete 63 is cast in the lower edge notch 62 after the tensioning of the lower edge tensioning bundle 61 is completed and the lower edge post-cast concrete 63 is anchored; the lower edge prestressed short beam component 6 can not only ensure that the lower edge of the beam section at the continuous pier 31 will not be torn when the prestress of the upper prestressed short beam component 5 is too large, but also resist the tensile stress generated at the lower edge of the beam section at the continuous pier 31 under the action of foundation settlement, thereby reducing the influence of the secondary internal force of the uneven foundation settlement; (2) the lower edge tensioning bundle 61 can be tensioned and anchored after the longest upper tensioning bundle 51 is tensioned and before the shortest upper tensioning bundle 51 is tensioned, thereby avoiding the situation where the upper edge of the beam section at the post-cast joint 4 is torn when the prestress of the lower edge tensioning bundle 61 is too large.

[0091] Example 3

[0092] This embodiment provides a bearing design method for a simply supported to continuous track beam bridge, which is applied to the simply supported to continuous track beam bridge of embodiment 1 or embodiment 2, wherein the simply supported to continuous track beam bridge has N span track beams 3 and N+1 bridge piers, wherein the N+1 bridge piers are provided with one fixed pier and N movable piers, assuming that the fixed piers are numbered M, and the difference between the fixed piers and the movable piers is that a fixed hinged bearing is provided on the top of the fixed pier, and a movable hinged bearing is provided on the top of the movable pier;

[0093] The process of determining the friction coefficient μ of the movable hinge support is as follows:

[0094] ① The N+1 bridge piers include N-1 continuous piers 31 and 2 branch piers 32, and the piers are numbered 1, 2, 3, ..., N, N+1 in the direction of the bridge. It should be noted that the continuous piers 31 and the branch piers 32 are different piers for determining whether the butt ends of the track beams 3 have expansion joints 33, and the fixed piers and movable piers are used to distinguish the piers with different hinged supports. The fixed hinged supports and movable hinged supports and the arrangement of the two on the piers belong to conventional technologies and are directly used in this embodiment.

[0095] ② When the simply supported continuous track beam 3 bridge has no longitudinal slope, the fixed hinge support is installed on the continuous pier 31 closest to the longitudinal midpoint of the entire bridge. When the simply supported continuous track beam 3 bridge has a longitudinal slope, the fixed hinge support is installed on the continuous pier 31 with the lowest pier top elevation. The live load effect of a straddle-type monorail is generally greater than the dead load and temperature effects. Therefore, when a longitudinal slope exists, installing the fixed hinge support on the continuous pier 31 with the lowest pier top elevation allows the fixed hinge support to be compressed by the tangential component of the track beam 3's gravity, thereby partially offsetting the tangential tension generated by the fixed hinge support under traction or braking forces. For special bridge structures such as straddle-type monorail, where the live load ratio is greater than the dead load, analysis has found that when the bearing friction coefficient is low, the maximum pier top horizontal force generated by "overall temperature rise and fall + vertical dead load" is generally smaller than the maximum pier top horizontal force generated by "traction or braking force + vertical dead load + vertical live load."

[0096] ③ Calculate the total reaction force of the pier top under all the dead loads, and number the total reaction force of the dead load at the fixed pier in the direction of the bridge as R g 1 ,...,R g M ,...,R g N+1 , R g M ; Align the midpoint of the straddle-type monorail train load with the centerline of the fixed pier, and solve the total reaction force of the pier top under the live load of the train, and number them in sequence along the bridge direction as R q 1 ,...,R q M ,...,R q N+1 , R q M It is the total live load reaction force of the train at the fixed pier.

[0097] ④ Under the action of the traction force and the maximum braking force Q of the running wheel 72 of the straddle-type monorail train, assuming that the fixed pier is regarded as a special movable pier with a support friction coefficient of ∞, when the supports at the top of all movable piers are in a critical state of static and sliding, and the static friction resistance F of the special movable pier is M The most uniform distribution of force Q among the piers is achieved when the maximum static friction resistance of all movable piers is equal. For safety reasons, the maximum static friction resistance of the bearing is calculated based on its sliding friction resistance. μ is defined as the friction coefficient of the movable hinge bearing. The force balance equations corresponding to the most uniform distribution of force Q among the piers are:

[0098]

[0099] The above two equations can be combined to solve the value of μ. The optimal distribution state of the horizontal force on the pier top is the state when the track beam 3 does not slide under the action of traction and braking force, and the difference between the forces distributed on each pier top is the smallest. At this time, the maximum horizontal force on the pier top generated by "overall heating and cooling + vertical constant load" is still less than or at most equal to the maximum horizontal force on the pier top under the action of "traction or braking force + vertical constant load + vertical live load". It can be seen that the design method of the present invention can avoid the extreme situation of excessive pursuit of reducing the temperature horizontal force and pursuing an excessively low bearing friction coefficient, and can also avoid the extreme situation of excessive pursuit of uniform distribution of traction and braking force and designing multiple fixed piers along the bridge. At the same time, the support arrangement designed by the present invention can prevent the pier top horizontal force under the action of overall heating and cooling and shrinkage creep from being superimposed with the traction and braking force, and minimize the value of the maximum horizontal force on the pier top of the entire bridge, so that the straddle-type monorail bridge structure has a more reasonable bearing and lower structure stress state, reduces the horizontal displacement of the pier top and the number of lower pile foundations, improves driving comfort and saves the cost of the bridge substructure.

[0100] ⑤ To ensure that track beam 3 does not slip under traction and braking forces, γμ is taken as the optimal design parameter for the movable hinge support, and γ is the safety factor, γ∈[1.0,1.3]. Considering that the actual operating load of the bridge differs from the designed load, a certain safety factor must be reserved. Statistical analysis shows that a γ value within the range of 1.0–1.3 can balance the support cost and force transmission requirements.

[0101] Example 4

[0102] Please refer to Figure 8 This embodiment provides a construction method for a simply supported to continuous track beam bridge, comprising the following steps:

[0103] ① When the track beam 3 is prefabricated, a top edge embedded steel bar 42 and a vertical connecting bar 46 are provided. The horizontal section of the top edge embedded steel bar 42 is placed in the notch of the track beam 3. The vertical section of the top edge embedded steel bar 42 is bent downward at the end of the top edge embedded steel bar 42 and is provided vertically. The vertical connecting bar 46 is pre-embedded in the horizontal surface of the notch of the track beam 3 in an array. When the first track beam 1 and the second track beam 2 are prefabricated, a prefabricated prestressed beam 123 is provided through the prefabricated pipes of the first track beam 1 and the second track beam 2. The prefabricated pipes are corrugated pipes. The prefabricated pipes are pre-embedded in the first track beam 1 and the second track beam 2. The ends of the prefabricated prestressed tendons 123 are anchored within track beam 1 and the second track beam 2 and extend to the ends of their respective track beams 3. The first and second track beams 1 and 2 are then mounted on bridge piers, where spaced first and second temporary supports 11 and 21 are installed. The butt joint end of the first track beam 1 rests on the first temporary support 11 of the pier, and the butt joint end of the second track beam 2 rests on the second temporary support 21 of the pier. The adjacent top-edge embedded steel bars 42 and adjacent non-top-edge embedded steel bars 44 are positioned relative to each other. This construction method is specifically designed for the narrow, high-section track beams 3 unique to straddle-type monorail transit. On-site reinforcement connection and concrete pouring can be conveniently completed from the operating space on either side or the top of the track beam 3.

[0104] ② Set the top edge connecting steel bars 43 and the non-top edge connecting steel bars 45, wherein the top edge connecting steel bars 43 and the two oppositely arranged top edge embedded steel bars 42 are fixed by steel wire binding, and the non-top edge connecting steel bars 45 are inserted into the gap between the non-top edge embedded steel bars 44 of the first track beam 1 and the second track beam 2 in a vertical deflection state and then rotated to the horizontal state, and placed in a horizontal state on the adjacent non-top edge embedded steel bars 44 on both sides, and the non-top edge connecting steel bars 45 and the non-top edge embedded steel bars 44 are fixed by steel wire binding; finally, support and fix the formwork at the gap between the first track beam 1 and the second track beam 2 where the post-cast wet joint 4 is to be constructed, set existing tensioned bundle pipes at the corresponding positions of the built-in pipes and short bundle pipes, and pour concrete to form the post-cast wet joint 4. By adopting the construction method of the present invention, the post-cast wet joint 4 is free of welding operations, the dense reinforcement area at the upper edge of the wet joint has a larger construction operation space, and the linear control and adjustment difficulty of the track beam 3 during on-site tensioning of the upper prestressed short bundle component 5 is relatively low. Compared with the continuous beam and continuous rigid frame system in the prior art, the two time-consuming processes of the difficulty of threading the negative bending moment bundle when the existing full-length bundle is used and the large-scale and dense steel bar welding operations in the limited space at the pier top wet joint are omitted, which greatly reduces the construction difficulty, saves construction measures costs, shortens the construction period, and improves the prefabrication and assembly construction efficiency of the track beam 3 of the continuous beam system.

[0105] ③ Set the upper tensioning bundle 51, and insert the first upper tensioning bundle 51 into the built-in pipes of the first track beam 1 and the second track beam 2, as well as the tensioning bundle pipes of the post-cast T-shaped concrete block 41. The two ends of the first upper tensioning bundle 51 are anchored in the transverse through holes 52 of the first track beam 1 and the second track beam 2 respectively; then, set the continuous pier permanent support 121 between the bottom of the post-cast wet joint 4 and the corresponding bridge pier top, and remove the first temporary support 11 and the second temporary support 21; set the lower edge tensioning bundle 61 in the same way as setting the upper tensioning bundle 51, and after the post-cast wet joint 4 is cured, tension the lower edge tensioning bundle 61 in the lower edge notch 62, and then grout and anchor the lower edge tensioning bundle 61, and finally pour the lower edge post-cast concrete 63, so that the two ends of the lower edge tensioning bundle 61 are anchored and fixed in the lower edge notches 62 of the first track beam 1 and the second track beam 2. Before tensioning the lower edge tensioning bundle 61 , the temporary support must be removed to avoid affecting the prestressing effect of the lower edge tensioning bundle 61 and to prevent the track beam 3 from further pressing the temporary support, making the latter difficult to remove.

[0106] ④ Insert the second upper tensioning bundle 51 into the built-in pipes of the first track beam 1 and the second track beam 2, as well as the tensioning bundle pipes at the corresponding positions of the post-cast T-shaped concrete blocks 41, tension the second tensioning bundle in the other pair of transverse through holes 52 of the first track beam 1 and the second track beam 2, and anchor it according to the setting method of the first upper tensioning bundle 51.

[0107] ⑤ A side formwork 521 is set on the outside of the upper post-cast concrete 53. The side formwork 521 plays a supporting role for the upper post-cast concrete 53, which facilitates the molding and anchoring construction of the upper post-cast concrete 53. The upper post-cast concrete 53 and the lower edge post-cast concrete 63 are poured into the two pairs of horizontal through holes 52 and the lower edge notch 62 respectively. After the upper post-cast concrete 53 solidifies, the side formwork 521 is removed.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A simply supported to continuous track beam bridge, characterized in that: It includes a track beam, a bridge pier, a permanent support for a continuous pier, a post-cast wet joint, and an upper prestressed short beam assembly. The track beam width B is ≤ 100 cm. The adjacent track beams erected at the continuous pier in the bridge pier are respectively the first track beam and the second track beam. The opposite butt ends of the first track beam and the second track beam are connected by the post-cast wet joint. The top and bottom surfaces of the post-cast wet joint are flush with the top and bottom surfaces of the first track beam and the second track beam respectively. The post-cast wet joint is supported on the top of the continuous pier through the permanent support of the continuous pier. The post-cast wet joint is provided with a tensioned beam pipe running through both ends. The post-cast wet joint includes a post-cast T-shaped concrete block, wherein the longitudinal section of the post-cast T-shaped concrete block along the bridge direction is T-shaped, the first track beam and the second track beam are respectively provided with a notch at the top of the butt end, the transverse portion of the post-cast T-shaped concrete block matches the notch, and the vertical portion of the post-cast T-shaped concrete block is butt-jointed between the first track beam and the second track beam; The opposite butt ends of the first track beam and the second track beam are provided with built-in pipes connected to the tensioning beam pipe, the upper prestressed short beam assembly includes an upper tensioning beam, a transverse through hole and an upper post-cast concrete, the first track beam and the second track beam are respectively provided with a transverse through hole on the same side, the transverse through hole is a hole that passes through along the transverse bridge direction, and the top surface of the transverse through hole is located below the top surface of the track beam, the built-in pipe is connected to the transverse through hole, the upper tensioning beam is arranged in the tensioning beam pipe and the built-in pipe, the two ends of the upper tensioning beam are respectively tensioned into the corresponding transverse through holes of the first track beam and the second track beam, and are anchored in the corresponding transverse through holes through the upper post-cast concrete, and the length L1 of a single upper tensioning beam in the bridge direction is ≤ half of the sum of the spans of the adjacent track beams; The post-cast wet joint also includes top edge embedded steel bars, top edge connecting steel bars, non-top edge embedded steel bars, non-top edge connecting steel bars, and vertical connecting bars; the top edge embedded steel bars are L-shaped, and the first track beam and the second track beam respectively correspond to the horizontal sections of the top edge embedded steel bars, the vertical sections of the top edge embedded steel bars are located in the post-cast T-shaped concrete blocks and are arranged vertically, the top edge connecting steel bars are in an inverted U-shape and are placed in the post-cast wet joint, the top edge embedded steel bars embedded in the first track beam and the second track beam are respectively tied and fixed with the top edge connecting steel bars, the non-top edge embedded steel bars are U-shaped, and a single non-top edge embedded steel bar is placed horizontally, and multiple non-top edge embedded steel bars are arranged vertically in an array. Arrangement, the open ends of the non-top edge embedded steel bars are embedded in the first track beam and the second track beam, the closed ends of the non-top edge embedded steel bars extend into the post-cast T-shaped concrete blocks, the non-top edge connecting steel bars are annular and horizontally placed on the horizontally adjacent non-top edge embedded steel bars, the non-top edge connecting steel bars are tied and fixed to the non-top edge embedded steel bars, a plurality of the vertical connecting bars are arranged alternately and vertically, the lower ends of the vertical connecting bars are embedded in the first track beam and the second track beam at the notch, and the upper ends of the vertical connecting bars extend into the post-cast T-shaped concrete blocks, and the post-cast T-shaped concrete blocks are respectively connected to the first track beam and the second track beam as a whole through the vertical connecting bars.

2. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The width L3 of the vertical part of the post-cast T-shaped concrete block along the bridge direction is ≥30cm, the width L2 of the transverse part of the post-cast T-shaped concrete block along the bridge direction is >L3, and the thickness H2 of the transverse part of the post-cast T-shaped concrete block is ≥max(10cm, H0 / 20), where H0 is the height of the post-cast T-shaped concrete block.

3. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The vertical length H of the top edge embedded steel bar 42 ≥0.6H0.

4. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The minimum horizontal clearance L between the top edge embedded steel bars embedded in the first track beam and the second track beam 42 ≥4cm.

5. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The vertical dimension H of the top edge connecting steel bar 43 ≥0.6H0, H0 is the height of the post-cast T-shaped concrete block, and the longitudinal dimension L of the top edge connecting steel bar 43 >L 42 +4*max(d 42 ,d 43 ), d 42 and d 43 They are the nominal diameters of the top edge embedded steel bars and the top edge connecting steel bars respectively.

6. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The minimum horizontal clearance L between the non-top edge embedded steel bars of the first track beam and the second track beam 44 >L 43 +4*max(d 43 ,d 45 ), d 45 is the maximum nominal diameter of the non-top edge connecting steel bar, and the longitudinal dimension L of the non-top edge connecting steel bar is 45 >L 44 +4*max(d 44 ,d 45 ), d 44 It is the maximum nominal diameter of the non-top edge embedded steel bars.

7. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The length L of the non-top-edge connecting steel bars within the transverse part of the post-cast T-shaped concrete block 45 > L3, and the length L of the non-top-edge connecting steel bars within the vertical part of the post-cast T-shaped concrete block 45 < L3, where L3 is the width of the vertical part of the post-cast T-shaped concrete block along the bridge direction.

8. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The minimum vertical distance H1 between the top surface of the transverse through hole and the top surface of the first track beam or the second track beam is ≥ the single wheel width of the straddle-type monorail vehicle guide wheel, and the upper tension beam extends into the transverse through hole and bends vertically.

9. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The upper prestressed short bundle assembly also includes a side template, which is provided with a grouting hole. The upper post-cast concrete is made by pressing high-strength grouting material into the transverse through hole through the grouting hole.

10. The simply supported to continuous track beam bridge according to claim 1, characterized in that: Several transverse through holes are provided on the same side of the first track beam and the second track beam, and the transverse through holes are arranged at different positions in the horizontal direction. The upper tensioning bundle includes a first upper tensioning bundle and a second upper tensioning bundle. The length of the first upper tensioning bundle is greater than that of the second upper tensioning bundle. The first upper tensioning bundle passes over the transverse through hole at the anchorage of the second upper tensioning bundle, and the first upper tensioning bundle is tensioned and anchored before the second upper tensioning bundle. The transverse through hole corresponding to the first upper tensioning bundle is arranged in the beam section of the first track beam or the second track beam whose upper edge is under pressure under the action of the live load of the train.

11. The simply supported to continuous track beam bridge according to claim 1, characterized in that: A lower edge prestressed short bundle component is also provided at the bottom end of the post-poured wet joint, and the lower edge prestressed short bundle component includes a lower edge tensioned bundle, a lower edge notch and a lower edge post-poured concrete. After the first track beam and the second track beam are erected, the lower edge tensioned bundle is inserted into the pre-buried pipes in the first track beam and the second track beam, and into the short bundle pipes provided in the post-poured T-shaped concrete blocks. The two ends of the lower edge tensioned bundle extend into the lower edge notch respectively. The lower edge notch is provided at the bottom surface of the end of the first track beam and the second track beam. The lower edge post-poured concrete is provided in the lower edge notch. The length of a single lower edge tensioned bundle along the bridge direction is L4≤L1.

12. The simply supported to continuous track beam bridge according to claim 1, characterized in that: The simply supported to continuous track beam bridge also includes a prefabricated prestressed beam. The first track beam or the second track beam is respectively provided with a prefabricated prestressed beam along the bridge direction. The two ends of the prefabricated prestressed beam respectively pass through the two ends of the first track beam or the second track beam and are anchored.

13. A bearing design method for a simply supported to continuous track beam bridge, applied to the simply supported to continuous track beam bridge according to any one of claims 1 to 12, characterized in that: The simply supported to continuous track beam bridge has N span track beams and N+1 bridge piers, wherein one fixed pier and N movable piers are provided among the bridge piers. Assume that the fixed piers are numbered M, a fixed hinge support is provided on the top of each fixed pier, and a movable hinge support is provided on the top of each movable pier. The process of determining the friction coefficient μ of the movable hinge support is as follows: S1. Calculate the total support reaction force at the top of each pier under all dead loads. Number the total support reaction force at the fixed pier as R along the bridge direction. g 1 ,…,R g M ,…,R g N+1 , R g M ; Align the midpoint of the straddle-type monorail train load with the centerline of the fixed pier, and solve the total reaction force of the pier top under the live load of the train, and number them in sequence along the bridge direction as R q 1 ,…,R q M ,…,R q N+1 , R q M is the total live load reaction force of the train at the fixed pier; S2. Under the action of the maximum traction and braking force Q of the running wheels of the straddle-type monorail train, assuming that the fixed pier is regarded as a special movable pier with a support friction coefficient of ∞, when the supports at the top of all the movable piers are in a critical state of stillness and sliding, and the static friction resistance F of the special movable pier is M The situation where the maximum static friction resistance of all movable piers is equal is the most uniform distribution of force Q on each pier. For safety reasons, the maximum static friction resistance of the bearing is calculated based on its sliding friction resistance. μ is defined as the friction coefficient of the movable hinge bearing. The force balance equations corresponding to the most uniform distribution of force Q on each pier are: The above two equations can be combined to solve the value of μ.

14. The bearing design method for a simply supported to continuous track beam bridge according to claim 13, characterized in that: Before determining the friction coefficient of the movable hinge support, it also includes: S11, N+1 piers include N-1 continuous piers and 2 branch piers, and the piers are numbered 1, 2, 3, ..., N, N+1 in the longitudinal direction of the bridge; S12. When the simply supported to continuous track beam bridge has no longitudinal slope, the fixed hinge support is set on the continuous pier closest to the midpoint of the entire bridge along the bridge direction. When the simply supported to continuous track beam bridge has a longitudinal slope, the fixed hinge support is set on the continuous pier with the lowest pier top elevation.

15. The bearing design method for a simply supported to continuous track beam bridge according to claim 13, characterized in that: After determining the friction coefficient of the movable hinge support, it also includes: S3. To ensure that the track beam does not slide under the action of traction and braking forces, γμ is taken as the optimal design parameter of the movable hinge support, γ is the safety factor, γ∈[1.0,1.3].

16. A construction method for a simply supported to continuous track beam bridge, using the simply supported to continuous track beam bridge according to any one of claims 1 to 12, characterized in that: The construction method includes the following steps: A1. Install prefabricated prestressed tendons through the prefabricated pipes of the first and second track beams. Anchor the ends of the prefabricated prestressed tendons to the ends of the track beams. Attach the first and second track beams to the piers, placing their butt ends on the first and second temporary supports of the piers, respectively. Ensure that adjacent top-edge embedded steel bars are positioned opposite each other, and adjacent non-top-edge embedded steel bars are positioned opposite each other. A2. Install top edge connecting steel bars and non-top edge connecting steel bars. Tie and secure the top edge connecting steel bars to the two oppositely positioned top edge embedded steel bars. The non-top edge connecting steel bars are inserted vertically through the gap between the non-top edge embedded steel bars of the first and second track beams, then rotated to a horizontal position. They are then placed horizontally on the adjacent non-top edge embedded steel bars on both sides and tied and secured. Finally, formwork is supported and secured at the post-wet joint, and concrete is poured to form the joint. A3. Install the upper tensioning bundle. Pass the first upper tensioning bundle through the built-in pipes of the first and second track beams, as well as the tensioning bundle pipes of the post-cast T-shaped concrete blocks. Anchor the ends of the first upper tensioning bundle in the transverse through-holes of the first and second track beams, respectively. Subsequently, install the permanent support for the continuous pier and remove the first and second temporary supports. Install the lower edge tensioning bundle in the same manner as the upper tensioning bundle. Anchor the ends of the lower edge tensioning bundle in the lower edge notches of the first and second track beams. A4. Insert the second upper tensioning bundle into the built-in pipes of the first and second track beams, as well as the tensioning bundle pipes of the post-cast T-shaped concrete blocks. Tension the second tensioning bundle in the other pair of transverse through holes in the first and second track beams, and anchor it. A5. Set up side formwork on the outside of the upper post-poured concrete, and pour the upper post-poured concrete and the lower edge post-poured concrete in the two pairs of horizontal through holes and the lower edge notch respectively. Remove the side formwork after the upper post-poured concrete solidifies.

Images