Restraint system of inclined single-tower cable-stayed bridge and its design and application method

Abstract

The present application discloses a restraint system for a slanted single-tower cable-stayed bridge and its design and application method, which relates to the field of bridge technology. The restraint system for the slanted single-tower cable-stayed bridge comprises: a cable structure pre-tensioned between the tower-beam consolidation point and the foundation of the main beam main span end, a thrust structure pre-thrusted between the tower-beam consolidation point and the foundation of the main beam side span end, or a longitudinal elastic telescopic device pre-stressed between the main beam side span end and the foundation of the main beam side span end; the above-mentioned cable structure, thrust structure, or longitudinal elastic telescopic device is used to at least partially offset the unbalanced horizontal force of the inclined cable of the slanted single-tower cable-stayed bridge. The restraint system for the slanted single-tower cable-stayed bridge of the present application and its design and application method can at least partially offset the unbalanced horizontal force of the inclined cable, thereby effectively reducing the bending moment of the lower tower column of the main tower and reducing the cross-sectional size of the lower tower column, which can not only optimize the landscape effect of the bridge, but also facilitate bridge design and increase the applicability of this type of bridge.

Description

Technical Field

[0001] The present application relates to the field of bridge technology, and in particular to a restraint system for a single-tower cable-stayed bridge and a design and application method thereof. Background Art

[0002] Currently, cable-stayed bridges use cables to transmit the weight of the main girder and its external loads to the main towers, which then transmit the loads to the foundation. Single-tower cable-stayed bridges are an elegantly designed structure that have been widely used in urban municipal bridges in recent years. Analysis of the force-bearing system of single-tower cable-stayed bridges reveals that the horizontal component of the cable force cannot be balanced within the main girder, regardless of whether side spans are provided. Because the horizontal force is large and the vertical force at the main girder side supports is small, it is impossible to transmit the unbalanced horizontal force by installing fixed supports at the main girder side supports.

[0003] In related technologies, tower-beam consolidation transfers unbalanced horizontal forces to the lower tower column, which then transmits them to the foundation. However, these unbalanced horizontal forces generate significant bending moments within the lower tower column, resulting in a large cross-sectional area. This not only affects the bridge's aesthetics but can even render it impossible to design, compromising the suitability of this type of bridge for large spans and heavy loads. Summary of the Invention

[0004] In response to the defects existing in the existing technology, the purpose of this application is to provide a constraint system for a single-tower cable-stayed bridge and its design and application method, so as to solve the problem in the related technology that the horizontal component of the inclined cable cannot be balanced in the main beam, resulting in a large bending moment in the lower tower column.

[0005] In a first aspect, the present application provides a restraint system for an inclined single-tower cable-stayed bridge, which is used for an inclined single-tower cable-stayed bridge with a tower-beam consolidation system. The restraint system for the inclined single-tower cable-stayed bridge is:

[0006] A cable structure pre-tensioned between the tower-beam consolidation point and the foundation of the main beam main span end; a thrust structure pre-thrusted between the tower-beam consolidation point and the foundation of the main beam side span end; or a longitudinal elastic expansion device pre-stressed between the main beam side span end and the foundation of the main beam side span end;

[0007] The above-mentioned cable structure, thrust structure, or longitudinal elastic expansion and contraction device is used to at least partially offset the unbalanced horizontal force of the inclined cables of the inclined single-tower cable-stayed bridge.

[0008] In some embodiments, the above-mentioned cable structure includes an external cable and a first vertical support part for supporting the external cable. The above-mentioned external cable is located inside the main beam of the inclined single-tower cable-stayed bridge, and its two ends are respectively connected to the tower-beam consolidation point and the foundation of the main span end of the main beam.

[0009] In some embodiments, the thrust structure includes a thrust rod and a second vertical support portion for supporting the thrust rod. The thrust rod is located inside the main beam of the inclined single-tower cable-stayed bridge, and its two ends are respectively connected to the foundation of the tower-beam consolidation point and the side span end of the main beam.

[0010] In some embodiments, the longitudinal elastic expansion device includes a plurality of disc springs in a stacked relationship, and the plurality of disc springs are arranged along the longitudinal bridge direction.

[0011] A second aspect of the present application provides a design and application method for the above-mentioned single-pylon cable-stayed bridge restraint system, which comprises the following steps:

[0012] Obtaining the pre-tension of the cable structure, the pre-thrust of the thrust structure, or the pre-compression force and elastic stiffness of the longitudinal elastic expansion and contraction device;

[0013] A cable structure is tensioned with pre-tension between the tower-beam consolidation point and the foundation of the main beam main span end, a thrust structure is installed with pre-thrust between the tower-beam consolidation point and the foundation of the main beam side span end, or a longitudinal elastic expansion device with pre-stored pre-stress is installed between the main beam side span end and the foundation of the main beam side span end, so as to at least partially offset the unbalanced horizontal force of the inclined cable of the inclined single-tower cable-stayed bridge.

[0014] In some embodiments, obtaining the pre-tension or pre-thrust specifically includes:

[0015] Obtain the maximum in-plane bending moment Mmax and the corresponding axial force N1 at the base of the main tower under the standard combination of a single-tower cable-stayed bridge, as well as the minimum in-plane bending moment Mmin and the corresponding axial force N2 at the base of the main tower; where the bending moment is positive when the main span is in tension, and the axial force is positive when the main span is in compression;

[0016] Obtain the vertical height H1 from the anchor point of the cable structure or the fixed point of the thrust structure at the tower-beam consolidation point to the bottom of the main tower;

[0017] The pretension or prethrust is calculated using the first formula based on the maximum in-plane bending moment Mmax and the corresponding axial force N1 at the main tower base, the minimum in-plane bending moment Mmin and the corresponding axial force N2 at the main tower base, and the vertical height H1.

[0018] The first formula above is:

[0019]

[0020] In some embodiments, the calculated pre-tension or pre-thrust is used as a calculated value. After the pre-tension or pre-thrust is calculated, the following steps are further included:

[0021] Using rod elements or cable elements to simulate a cable structure, or using rod elements to simulate a thrust structure, a finite element model of a cable-stayed bridge provided with the rod elements or cable elements is established, and the calculated pretension or prethrust is applied;

[0022] Performing a structural stress analysis on the finite element model of the cable-stayed bridge to obtain a new Mmax and the corresponding N1, as well as a new Mmin and the corresponding N2, and then calculating the correction difference of the pretension or prethrust according to the first formula;

[0023] The sum of the calculated value and the corrected difference is taken as the corrected pre-tension or pre-thrust.

[0024] In some embodiments, obtaining the preload and elastic stiffness of the longitudinal elastic expansion and contraction device specifically includes:

[0025] In the tower-beam separation state, a dead load is applied to the main tower to obtain the horizontal component difference of the side-mid-span cable force of each inclined cable when the internal bending moment of the main tower bottom surface is zero;

[0026] The sum of the horizontal component force differences of the side and mid-span cable forces of each inclined cable is used as the upper limit value Fmax of the horizontal force provided by the longitudinal elastic expansion and contraction device;

[0027] The value calculated by the second formula is used as the lower limit value Fmin of the horizontal force provided by the longitudinal elastic expansion device;

[0028] Obtain the longitudinal displacement Δ of the side span beam end under the design live load and temperature load;

[0029] Calculate the above-mentioned preload and elastic stiffness based on the upper limit value Fmax of the horizontal force, the lower limit value Fmin of the horizontal force, and the longitudinal displacement Δ;

[0030] The second formula above is:

[0031]

[0032] Among them, Mmax is the maximum in-plane bending moment of the main tower bottom; N1 is the axial force corresponding to Mmax; Mmin is the minimum in-plane bending moment of the main tower bottom; N2 is the axial force corresponding to Mmin; H2 is the vertical height from the longitudinal elastic telescopic device to the main tower bottom.

[0033] In some embodiments, the pre-pressure F 预压力 for:

[0034]

[0035] The above elastic stiffness K is:

[0036]

[0037] In some embodiments, after calculating the preload and elastic stiffness, the method further includes:

[0038] A finite element model of a cable-stayed bridge equipped with a longitudinal elastic expansion and contraction device was established using spring units, and the calculated preload was applied to the side span ends of the main beams.

[0039] The structural stress analysis of the finite element model of the cable-stayed bridge is performed to obtain a new longitudinal displacement Δ, and then the corrected elastic stiffness is calculated.

[0040] The beneficial effects of the technical solution provided by this application include:

[0041] The present application discloses a constraint system for a slanted single-tower cable-stayed bridge and its design and application method. The constraint system for the slanted single-tower cable-stayed bridge comprises: a cable structure pre-tensioned between the pylon-beam consolidation point and the foundation at the end of the main beam's main span; a thrust structure pre-thrusted between the pylon-beam consolidation point and the foundation at the end of the main beam's side span; or a longitudinal elastic expansion and contraction device pre-stressed between the end of the main beam's side span and the foundation at the end of the main beam's side span. The cable structure, thrust structure, or longitudinal elastic expansion and contraction device is used to at least partially offset the unbalanced horizontal force of the slanted single-tower cable-stayed bridge. Therefore, the use of this constraint system for a slanted single-tower cable-stayed bridge can at least partially offset the unbalanced horizontal force of the slanted cables, thereby effectively reducing the bending moment of the lower tower column of the main tower and reducing the cross-sectional size of the lower tower column. This not only optimizes the bridge's landscape effect, but also facilitates bridge design and increases the applicability of this type of bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0043] Figure 1 This is a layout diagram of the restraint system of the first inclined single-tower cable-stayed bridge in the embodiment of this application;

[0044] Figure 2 This is a layout diagram of the restraint system of the second inclined single-tower cable-stayed bridge in the embodiment of this application;

[0045] Figure 3 This is a layout diagram of the restraint system of the third inclined single-tower cable-stayed bridge in the embodiment of this application.

[0046] Reference numerals:

[0047] 1. Main beam; 2. Main tower; 3. Stay cable; 4. Foundation of the main span end of the main beam; 5. Foundation of the side span end of the main beam; 6. External stay cable; 7. Thrust rod; 8. Longitudinal elastic expansion device. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0049] like Figure 1-3 As shown ( Figure 3 (The middle framed portion is an enlarged portion of the longitudinal elastic expansion and contraction device installation location.) This embodiment of the present application provides a slanted single-tower cable-stayed bridge constraint system for a slanted single-tower cable-stayed bridge with a tower-beam consolidation system. In this embodiment, the slanted single-tower cable-stayed bridge includes a main beam 1, a slanted single tower, a stay cable 3, a foundation 4 at the main beam main span end, and a foundation 5 at the main beam side span end. The main beam can be a steel box beam, the slanted single tower is the main tower 2, the foundation at the main beam main span end is the foundation at the end of the main beam main span away from the main tower, and the foundation at the main beam side span end is the foundation at the end of the main beam side span away from the main tower.

[0050] The restraint system of the inclined single-tower cable-stayed bridge is: a cable structure pre-tensioned between the tower-beam consolidation point and the foundation of the main beam main span end, a thrust structure pre-thrusted between the tower-beam consolidation point and the foundation of the main beam side span end, or a longitudinal elastic expansion device pre-stressed between the main beam side span end and the foundation of the main beam side span end.

[0051] The above-mentioned cable structure, thrust structure, or longitudinal elastic expansion and contraction device is used to at least partially offset the unbalanced horizontal force of the inclined cables of the inclined single-tower cable-stayed bridge.

[0052] The restraint system for the inclined single-tower cable-stayed bridge of this embodiment comprises a cable structure pre-tensioned between the tower-beam attachment point and the foundation at the end of the main beam's main span; a thrust structure pre-stressed between the tower-beam attachment point and the foundation at the end of the main beam's side span; or a longitudinal elastic expansion and contraction device pre-stressed between the end of the main beam's side span and the foundation at the end of the main beam's side span. The cable structure, thrust structure, or longitudinal elastic expansion and contraction device is used to at least partially offset the unbalanced horizontal force of the inclined single-tower cable-stayed bridge. This restraint system for the inclined single-tower cable-stayed bridge can at least partially offset the unbalanced horizontal force of the inclined cables, thereby effectively reducing the bending moment of the lower pylon column of the main tower and reducing the cross-sectional size of the lower pylon column. This not only optimizes the bridge's landscape, but also facilitates bridge design and increases the applicability of this type of bridge.

[0053] Furthermore, the above-mentioned cable structure includes an external cable 6 and a first vertical support part for supporting the external cable. The above-mentioned external cable 6 is located inside the main beam 1 of the inclined single-tower cable-stayed bridge, and the two ends of the external cable 6 are respectively connected to the tower-beam consolidation point and the foundation 4 at the main span end of the main beam.

[0054] There are multiple first vertical support parts, which are sequentially arranged inside the main beam. Optionally, the external cable can be a parallel steel cable or a steel strand cable.

[0055] Optionally, the thrust structure includes a thrust rod 7 and a second vertical support portion for supporting the thrust rod. The thrust rod 7 is located inside the main beam 1 of the inclined single-tower cable-stayed bridge, and the two ends of the thrust rod 7 are respectively connected to the foundation 5 at the tower-beam consolidation point and the side span end of the main beam.

[0056] There are multiple second vertical support parts, and the multiple second vertical support parts are sequentially arranged inside the main beam.

[0057] Optionally, the end of the longitudinal elastic telescopic device close to the foundation of the main beam side span end is fixed on the foundation of the main beam side span end, and the end of the longitudinal elastic telescopic device away from the foundation of the main beam side span end is fixed to the bottom of the main beam side span end.

[0058] Preferably, the longitudinal elastic expansion device 8 includes a plurality of disc springs in a stacked relationship, and the plurality of disc springs are arranged in sequence along the longitudinal bridge direction.

[0059] Among them, the disc spring close to the foundation of the side span end of the main beam is fixed to the foundation of the side span end of the main beam through a fixing piece, and the disc spring away from the foundation of the side span end of the main beam is fixed to the bottom of the beam at the side span end of the main beam through a fixing piece.

[0060] Optionally, the longitudinal elastic telescopic device 8 may also be other telescopic structures.

[0061] Preferably, the above-mentioned cable structure is suitable for situations where a foundation with strong bearing capacity can be set at the end of the main span of the main beam, and the thrust structure and the longitudinal elastic telescopic device are suitable for situations where a foundation with strong bearing capacity can be set at the end of the side span of the main beam. In order to maintain its own stability, the thrust rod needs to be provided with a strong vertical support in the beam. When it is inconvenient to set up vertical support, a longitudinal elastic telescopic device is used.

[0062] The present application also provides a method for designing and applying the above-mentioned single-pylon cable-stayed bridge restraint system, the method comprising the steps of:

[0063] S1. Obtain the pre-tension of the cable structure, the pre-thrust of the thrust structure, or the pre-pressure and elastic stiffness of the longitudinal elastic expansion and contraction device.

[0064] S2. Pre-tension the cable structure between the tower-beam consolidation point and the foundation of the main beam main span end, install the thrust structure with pre-thrust between the tower-beam consolidation point and the foundation of the main beam side span end, or install a longitudinal elastic expansion device with pre-stored pre-stress between the main beam side span end and the foundation of the main beam side span end, so as to at least partially offset the unbalanced horizontal force of the inclined cable of the inclined single-tower cable-stayed bridge.

[0065] In this embodiment, when the restraint system of the inclined single-tower cable-stayed bridge is a cable structure pre-tensioned between the tower-beam consolidation point and the foundation at the end of the main span of the main beam, the above-mentioned design and application method includes the following steps:

[0066] First, the pre-tension of the cable structure, that is, the pre-tension of the external cable, is obtained.

[0067] Then, a cable structure is tensioned with pre-tension between the tower-beam consolidation point and the foundation of the main beam main span end to at least partially offset the unbalanced horizontal force of the inclined cable of the inclined single-tower cable-stayed bridge.

[0068] Optionally, when it is inconvenient to connect an external cable between the tower-beam consolidation point and the foundation of the main beam main span end, a thrust rod may be provided between the tower-beam consolidation point and the foundation of the main beam side span end.

[0069] Optionally, when the restraint system of the inclined single-tower cable-stayed bridge is a thrust structure installed with pre-thrust force between the tower-beam consolidation point and the foundation at the end of the main beam side span, the above-mentioned design application method includes the steps of:

[0070] First, the pre-thrust of the thrust structure, that is, the pre-thrust of the thrust rod, is obtained.

[0071] Then, a thrust structure is installed between the tower-beam consolidation point and the foundation of the main beam side span end with a pre-thrust force to at least partially offset the unbalanced horizontal force of the inclined cable of the inclined single-tower cable-stayed bridge.

[0072] Based on the above embodiment, in this embodiment, the values ​​of the pre-tension force and the pre-thrust force are the same. Therefore, obtaining the pre-tension force or the pre-thrust force specifically includes:

[0073] First, the maximum in-plane bending moment Mmax and the corresponding axial force N1 at the base of the main tower, as well as the minimum in-plane bending moment Mmin and the corresponding axial force N2 at the base of the main tower under the standard combination of a single-tower cable-stayed bridge are obtained; the bending moment is positive when the main span is in tension, and the axial force is positive when the main span is in compression.

[0074] Then, obtain the vertical height H1 from the anchor point of the cable structure or the fixed point of the thrust structure at the tower-beam consolidation point to the bottom of the main tower.

[0075] Among them, when obtaining pre-tension, it is necessary to calculate the vertical height from the anchor point of the external cable at the intersection of the tower and beam to the bottom of the main tower; when obtaining pre-thrust, it is necessary to calculate the vertical height from the fixing point of the thrust rod at the intersection of the tower and beam to the bottom of the main tower.

[0076] Finally, the pretension or prethrust is calculated using the first formula based on the maximum in-plane bending moment Mmax and the corresponding axial force N1 at the main tower base, the minimum in-plane bending moment Mmin and the corresponding axial force N2 at the main tower base, and the vertical height H1.

[0077] The first formula is:

[0078]

[0079] Optionally, the calculated pre-tension force may be used to directly tension the external cable, or the calculated pre-thrust force may be used to install the thrust rod.

[0080] Optionally, after calculating the pre-tension or pre-thrust, the method further includes updating and correcting the calculated pre-tension or pre-thrust.

[0081] In this embodiment, a finite element method may be used to perform structural stress analysis, and the calculated pre-tension force or pre-thrust force may be used as a calculated value to update and correct the calculated pre-tension force or pre-thrust force, specifically including:

[0082] First, a cable structure is simulated between the tower-beam consolidation point and the foundation at the end of the main span of the main beam using rod elements or cable elements, or a thrust structure is simulated between the tower-beam consolidation point and the foundation at the end of the side span of the main beam using rod elements. A finite element model of a cable-stayed bridge equipped with the above-mentioned rod elements or cable elements is established, and the calculated pretension or prethrust is applied to the rod elements or cable elements.

[0083] Then, a structural stress analysis is performed on the finite element model of the cable-stayed bridge to obtain a new Mmax and the corresponding N1, as well as a new Mmin and the corresponding N2, and then the correction difference of the pretension or prethrust is recalculated according to the first formula.

[0084] Finally, the sum of the calculated value and the corrected difference is taken as the corrected pretension or prethrust.

[0085] At this time, the finite element calculation can be performed again using the corrected pre-tension or pre-thrust to obtain the main tower internal force and then proceed with the main tower structure design.

[0086] In this embodiment, the tower-beam connection and the foundation at the main span end of the main beam serve as two fixed points. Displacement under loads such as temperature, wind, and live loads is negligible. Therefore, the external cable tension remains unchanged under these loads, and the displacement and stress of the main beam structure are not affected, making it highly adaptable. The external cables can be either parallel steel cables or stranded steel cables. This solution can be used for single-tower cable-stayed bridges, regardless of whether back cables are installed.

[0087] Optionally, the pre-tension or pre-thrust may be determined in other ways according to actual conditions.

[0088] Preferably, when the restraint system of the inclined single-pylon cable-stayed bridge is a longitudinal elastic expansion device installed with preload between the end of the main beam side span and the foundation of the main beam side span, the above-mentioned design and application method includes the steps of:

[0089] First, the preload and elastic stiffness of the longitudinal elastic expansion and contraction device are obtained.

[0090] Then, a longitudinal elastic expansion device with pre-stored preload is installed between the side span end of the main beam and the foundation of the side span end of the main beam to at least partially offset the unbalanced horizontal force of the inclined cable of the inclined single-tower cable-stayed bridge.

[0091] Optionally, the longitudinal elastic expansion device is a retractable device primarily made of disc springs. After the bridge superstructure is completed, the longitudinal elastic expansion device is installed between the beam bottom and the foundation, and the aforementioned preload is pre-loaded. During bridge operation, the longitudinal pressure of the longitudinal elastic expansion device varies within the range [Fmin, Fmax].

[0092] Furthermore, obtaining the preload and elastic stiffness of the longitudinal elastic expansion device specifically includes:

[0093] A1. With the tower and beam separated, apply a dead load to the main tower and calculate the horizontal component difference of the side-midspan cable force of each inclined cable when the internal bending moment at the main tower base is zero. The horizontal component difference of the side-midspan cable force is the difference between the horizontal component of the side-span cable force and the horizontal component of the midspan cable force.

[0094] A2. The sum of the horizontal component differences of the side-span and mid-span cable forces of each stay cable is used as the upper limit Fmax of the horizontal force provided by the longitudinal elastic expansion and contraction device.

[0095] A3. The value calculated by the second formula is used as the lower limit value Fmin of the horizontal force provided by the longitudinal elastic telescopic device;

[0096] A4. Obtain the longitudinal displacement Δ of the side span beam end under the design live load and temperature load;

[0097] A5. Calculate the above-mentioned preload and elastic stiffness based on the upper limit value Fmax of the horizontal force, the lower limit value Fmin of the horizontal force, and the longitudinal displacement Δ.

[0098] The second formula above is:

[0099]

[0100] Among them, Mmax is the maximum in-plane bending moment at the bottom of the main tower under the standard combination of a skew single-tower cable-stayed bridge; N1 is the axial force corresponding to Mmax; Mmin is the minimum in-plane bending moment at the bottom of the main tower under the standard combination of a skew single-tower cable-stayed bridge; N2 is the axial force corresponding to Mmin; H2 is the vertical height from the longitudinal elastic expansion device to the bottom of the main tower.

[0101] In this embodiment, it is assumed that the main tower and the main beam are in a separated state, and the horizontal component difference of the side-mid-span cable force of each inclined cable is determined with the internal bending moment of the main tower bottom surface under the constant load condition being zero. The sum of the horizontal component difference of the side-mid-span cable force of all inclined cables is the upper limit value Fmax of the horizontal force provided by the longitudinal elastic expansion device.

[0102] Preferably, the dead load, design live load and temperature load are all fixed design values. Alternatively, the dead load, design live load and temperature load can be set according to design specifications.

[0103] Preferably, the pre-pressure F 预压力 for:

[0104]

[0105] The above elastic stiffness K is:

[0106]

[0107] Optionally, the longitudinal elastic expansion and contraction device may be installed directly using the calculated preload and elastic stiffness.

[0108] Optionally, after calculating the above-mentioned preload and elastic stiffness, the calculated elastic stiffness is also updated and corrected.

[0109] In this embodiment, a finite element method may be used to perform structural stress analysis to update and correct the calculated elastic stiffness, specifically including the following steps:

[0110] First, a finite element model of a cable-stayed bridge equipped with a longitudinal elastic expansion device was constructed, using spring elements between the tower-beam connection and the foundation at the side span end of the main girder. A longitudinal concentrated force, equal to the preload force, was applied to the side span end of the main girder. The spring stiffness of the spring element was the elastic stiffness calculated above.

[0111] Then, the structural stress analysis of the finite element model of the cable-stayed bridge is performed to obtain a new longitudinal displacement Δ, and then the corrected elastic stiffness is recalculated according to the formula.

[0112] At this time, finite element calculation can be performed again using preload and modified elastic stiffness to obtain the main tower internal force and then proceed with the main tower structure design.

[0113] In this embodiment, the longitudinal elastic expansion device is subject to compression, but its length is relatively short, eliminating compressive stability issues. The longitudinal elastic expansion device can adapt to longitudinal displacement of the beam end, allowing the longitudinal pressure to vary within the range [Fmin, Fmax]. By setting the aforementioned elastic stiffness, the main tower's load safety requirements are met when the longitudinal pressure of the elastic expansion device varies within this range. This solution can be used for inclined single-tower cable-stayed structures, regardless of whether or not back cables are installed.

[0114] Optionally, the above-mentioned preload and elastic stiffness can also be determined by other methods according to actual conditions, on the premise of ensuring the safety of the main tower under stress.

[0115] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0116] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0117] The above are merely specific embodiments of the present application to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but rather is intended to conform to the widest scope consistent with the principles and novel features of the present application.

Claims

1. A design and application method for a restraint system of a single-pylon cable-stayed bridge, characterized in that: The restraint system of the inclined single-tower cable-stayed bridge is used for an inclined single-tower cable-stayed bridge with a tower-beam consolidation system. The restraint system is: A cable structure pre-tensioned between the tower-beam consolidation point and the foundation of the main beam main span end; a thrust structure pre-thrusted between the tower-beam consolidation point and the foundation of the main beam side span end; or a longitudinal elastic expansion device pre-stressed between the main beam side span end and the foundation of the main beam side span end; The cable structure, thrust structure, or longitudinal elastic expansion device is used to at least partially offset the unbalanced horizontal force of the inclined cables of the inclined single-tower cable-stayed bridge; The method comprises the steps of: Obtaining the pre-tension of the cable structure, the pre-thrust of the thrust structure, or the pre-compression force and elastic stiffness of the longitudinal elastic expansion and contraction device; A cable structure is tensioned with pre-tension between the tower-beam consolidation point and the foundation of the main beam main span end, a thrust structure is installed with pre-thrust between the tower-beam consolidation point and the foundation of the main beam side span end, or a longitudinal elastic expansion device with pre-stored pre-stress is installed between the main beam side span end and the foundation of the main beam side span end, so as to at least partially offset the unbalanced horizontal force of the inclined cables of the inclined single-tower cable-stayed bridge; Obtaining pre-tension or pre-thrust, specifically including: Obtain the maximum in-plane bending moment Mmax and the corresponding axial force N1 at the base of the main tower under the standard combination of a single-tower cable-stayed bridge, as well as the minimum in-plane bending moment Mmin and the corresponding axial force N2 at the base of the main tower; where the bending moment is positive when the main span is in tension, and the axial force is positive when the main span is in compression; Obtain the vertical height H1 from the anchor point of the cable structure or the fixed point of the thrust structure at the tower-beam consolidation point to the bottom of the main tower; The pretension or prethrust is calculated using the first formula based on the maximum in-plane bending moment Mmax and the corresponding axial force N1 at the main tower base, the minimum in-plane bending moment Mmin and the corresponding axial force N2 at the main tower base, and the vertical height H1. The first formula is: ； Obtaining the preload and elastic stiffness of the longitudinal elastic expansion and contraction device includes: In the tower-beam separation state, a dead load is applied to the main tower to obtain the horizontal component difference of the side-mid-span cable force of each inclined cable when the internal bending moment of the main tower bottom surface is zero; The sum of the horizontal component force differences of the side-mid-span cable forces of each inclined cable is used as the upper limit value Fmax of the horizontal force provided by the longitudinal elastic expansion and contraction device; The value calculated by the second formula is used as the lower limit value Fmin of the horizontal force provided by the longitudinal elastic expansion device; Obtain the longitudinal displacement Δ of the side span beam end under the design live load and temperature load; Calculating the preload and elastic stiffness based on the horizontal force upper limit Fmax, the horizontal force lower limit Fmin, and the longitudinal displacement Δ; The second formula is: Wherein, Mmax is the maximum in-plane bending moment at the bottom of the main tower; N1 is the axial force corresponding to Mmax; Mmin is the minimum in-plane bending moment at the bottom of the main tower; N2 is the axial force corresponding to Mmin; H2 is the vertical height from the longitudinal elastic expansion device to the bottom of the main tower; The pre-pressure for: The elastic stiffness K is: 。 2. The design and application method of the restraint system of the inclined single-pylon cable-stayed bridge according to claim 1 is characterized in that: The calculated pretension or prethrust is used as the calculated value. After the pretension or prethrust is calculated, the following is also included: Simulating a cable structure with rod elements or cable elements, or simulating a thrust structure with rod elements, establishing a finite element model of a cable-stayed bridge provided with the rod elements or cable elements, and applying the calculated pretension or prethrust; Performing a structural stress analysis on the finite element model of the cable-stayed bridge to obtain a new Mmax and a corresponding N1, as well as a new Mmin and a corresponding N2, and then calculating a correction difference in pretension or prethrust according to the first formula; The sum of the calculated value and the corrected difference is taken as the corrected pre-tension or pre-thrust.

3. The design and application method of the restraint system of the inclined single-pylon cable-stayed bridge according to claim 1 is characterized in that: After calculating the preload and elastic stiffness, the following steps are also included: A finite element model of a cable-stayed bridge equipped with a longitudinal elastic expansion and contraction device is established by simulating the longitudinal elastic expansion and contraction device with a spring unit, and a calculated preload is applied to the side span end of the main beam; A structural stress analysis is performed on the finite element model of the cable-stayed bridge to obtain a new longitudinal displacement Δ, and then the corrected elastic stiffness is calculated.

4. The design and application method for the restraint system of a single-pylon cable-stayed bridge according to claim 1 is characterized by: The cable structure includes an external cable and a first vertical support part for supporting the external cable. The external cable is located inside the main beam of the inclined single-tower cable-stayed bridge, and its two ends are respectively connected to the tower-beam consolidation point and the foundation of the main span end of the main beam.

5. The design and application method of the restraint system for a single-pylon cable-stayed bridge according to claim 1 is characterized by: The thrust structure includes a thrust rod and a second vertical support portion for supporting the thrust rod. The thrust rod is located inside the main beam of the inclined single-tower cable-stayed bridge, and its two ends are respectively connected to the foundation of the tower-beam consolidation point and the main beam side span end.

6. The design and application method of the restraint system for a single-pylon cable-stayed bridge according to claim 1 is characterized by: The longitudinal elastic expansion and contraction device includes a plurality of disc springs in a stacked relationship, and the plurality of disc springs are arranged along the longitudinal bridge direction.

Images