A self-balanced linear control method for separate steel box girder cantilever erection construction

Abstract

The present application relates to the field of steel box girder cantilever erection, and discloses a self-balanced linear control method for separated steel box girder cantilever erection, comprising the following steps: a. setting a group of portal frames on the left and right beam sections of the separated steel box girder section to be erected; b. setting cable anchorage points on both ends of the left and right beam sections; c. tensioning the transverse cable between the two cable anchorage points of the left or right beam section; d. tensioning the cable at the cable anchorage points; e. installing a bridge deck crane on the erected steel box girder to lift the steel box girder to be erected; and actively eliminating the reverse arch deformation of the steel box girder by using the vertical component force generated at the top of the portal frame, so that the linear shape of the steel box girder is adjusted to the sag state consistent with the erected beam section, and the height difference and angular deviation of the butt joint end surface are significantly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steel box girder cantilever erection, and particularly relates to a self-balanced linear control method for cantilever erection of a split steel box girder. BACKGROUND

[0002] In the construction of long-span bridges, split steel box girders are widely used due to their light structure, excellent wind resistance, and convenient construction. However, as the span of the bridge increases and the structure becomes more complex, the split steel box girder segments face many technical challenges during the cantilever erection process.

[0003] In the prior art, a bridge crane is usually used to hoist and connect the split steel box girder segment by segment. However, due to the large self-weight and transverse width of a single segment of the split steel box girder, and the relatively low transverse and vertical stiffness, large transverse deformation and uneven deflection can easily occur during hoisting, especially when the cantilevered state of the single-side segment has not yet formed a complete stress system. The erected segment presents a deflected shape under the action of its own weight and the front-end load, while the to-be-erected segment is often arched in the opposite direction (i.e., reverse arch) due to being supported only by temporary supports or hoisting points, resulting in a significant height difference at the joint surface and making it difficult to achieve precise matching.

[0004] In addition, since there is no transverse rigid connection between the left and right split steel box girders, each segment is independently stressed during hoisting, which can easily cause the linear shapes of the two segments to be out of sync, further exacerbating the misalignment problem at the joint surface. Traditional construction methods rely on the fine-tuning ability of the bridge crane or additional counterweights to adjust the linear shape, but the adjustment range is limited and cannot effectively eliminate the linear deviation caused by differences in structural stiffness and stress state, leading to difficulties in on-site matching, poor welding quality, and even the need for repeated adjustments, which seriously affects construction efficiency and structural safety.

[0005] Therefore, how to effectively control the linear shape of the split steel box girder during cantilever erection, especially to solve the problem of linear mismatch between the to-be-erected segment and the erected segment due to different stress states, has become a key technical problem in the cantilever erection of steel box girders. SUMMARY

[0006] The present application aims to provide a self-balanced linear control method for cantilever erection of a split steel box girder to solve the problem that existing construction methods rely on the fine-tuning ability of the bridge crane or additional counterweights to adjust the linear shape, but the adjustment range is limited and cannot effectively eliminate the linear deviation caused by differences in structural stiffness and stress state, leading to difficulties in on-site matching, poor welding quality, and even the need for repeated adjustments, which seriously affects construction efficiency and structural safety. The specific technical solution is as follows:

[0007] A kind of self-balanced linear control method of separate steel box girder suspension construction, it is applied to bridge deck crane hoisting separate steel box girder, comprising the following steps:

[0008] a. each set of portal is arranged in left beam section and right beam section of the separate steel box girder section to be erected;

[0009] b. each two ends of left beam section and right beam section are provided with cable anchorage point;

[0010] c. transverse cable is tensioned between the two cable anchorage points of left beam section or right beam section, and the cable passes through the top of portal;

[0011] d. cable is tensioned at cable anchorage point, and linear is adjusted to preset form;

[0012] e. bridge deck crane is installed on the erected steel box girder to lift the steel box girder to be erected, and matching connection is carried out.

[0013] As one of the improvements of the above technical solutions, in step a, the portal includes portal leg, middle web plate and transverse partition plate, the portal leg is placed above the middle web plate in the transverse direction, and the portal leg is placed above the transverse partition plate in the longitudinal direction, and the portal height is one third of the transverse width of the steel box girder.

[0014] As one of the improvements of the above technical solutions, in step b, the flange end of left beam section or right beam section is provided with top, and space for tensioning of through-type jack is left when the cable anchorage point is arranged on the top plate.

[0015] As one of the improvements of the above technical solutions, in step c, transverse cable is tensioned between the two cable anchorage points of left beam section or right beam section respectively, and left beam section or right beam section is configured to have outer anchorage point and inner anchorage point, and the specific tensioning route is outer anchorage point, outer portal top, inner portal top and finally connecting inner anchorage point in sequence.

[0016] As one of the improvements of the above technical solutions, in step d, through-type jack is used at cable anchorage point to tension the cable, so that the steel box girder changes from inverted arch to sagging form as the erected beam section when hoisted.

[0017] As one of the improvements of the above technical solutions, in step e, bridge deck crane is installed on the erected steel box girder to lift the steel box girder to be erected, and temporary matching is completed, then welding is carried out, after completion, portal and cable are disassembled, and are moved to the next beam section to be erected for recycling.

[0018] As one of the improvements of the above technical solutions, in step e, when bridge deck crane is installed on left beam section and right beam section, the working end of bridge deck crane extends to the upper side of the separate steel box girder section to be erected.

[0019] Advantages of the present application:

[0020] By tensioning the transverse cable in the to-be-erected beam segment, the vertical component force generated by the portal top is used to actively eliminate the reverse arch deformation of the steel box girder, so that the linear shape is adjusted to the downward deflection state consistent with the already-erected beam segment, the height difference and the angle deviation of the butt joint surface are significantly reduced, high-precision stress-free forced splicing is realized, and the butt joint quality and welding reliability are greatly improved; the left and right beam segments are respectively provided with independent portal and cable systems, differential tensioning control can be realized, the adaptability is high, and the flexibility is high; the portal, the cable, the anchorage device and the tensioning equipment are all detachable and recyclable structures, and after each segment construction is completed, the whole can be removed and transferred to the next segment for repeated use, so that the material consumption and the construction cost are reduced.

[0021] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description, or can be learned by practice of the application. It is to be understood that not necessarily all objects or advantages described can be achieved in accordance with any particular embodiment of the application. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0023] Fig. 1 is a structural schematic diagram of the present application.

[0024] Fig. 2 is a structural schematic diagram of the cable anchoring point of the present application.

[0025] Fig. 3 is a structural schematic diagram of the bridge deck crane of the present application.

[0026] In the figure: left beam segment 1, right beam segment 2, portal 3, cable anchoring point 4, cable 5, through center jack 6, bridge deck crane 7. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments only constitute some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] In the existing steel box girder hoisting, the erected girder segment presents a deflection shape under the action of self weight and front end load, and the to-be-erected girder segment is often in a reverse arch (i.e. reverse arch) due to being only supported by temporary support or hoisting point, resulting in a significant height difference between the two girder segments at the butt joint end face, and it is difficult to achieve precise matching. Secondly, there is no transverse rigid connection between the separated left and right steel box girders, and each girder segment is independently stressed in the hoisting process, which is easy to cause the linear incoordination of the two side girder segments, further aggravating the butt joint surface misalignment problem, and an active adjustment method for the linear of the to-be-erected girder segment and self-balancing control is urgently needed to ensure the girder butt joint precision and improve the construction efficiency and structural integrity.

[0029] Please refer to Figs. 1-3 The present application provides some embodiments to solve the above problems, a self-balancing linear control method for separated steel box girder suspension construction, applied to the hoisting of separated steel box girder by bridge crane 7, comprising the following steps:

[0030] a. A group of gantries 3 are arranged on the left and right girder segments 1 and 2 of the to-be-erected separated steel box girder segment, and a group of detachable gantries 3 are installed on the left and right girder segments 1 and 2 of the to-be-installed separated steel box girder segment. The gantries 3 serve as the support and steering device of the transverse cable 5, and are arranged on both sides of the steel box girder in the transverse direction to ensure that they have sufficient stiffness and stability to withstand the concentrated load generated during the tensioning of the cable 5. The gantries 3 are preferably made of high-strength steel and are welded into shape, with the characteristics of fast installation and repeated use, suitable for the construction rhythm of segmented construction.

[0031] b. The two ends of the left and right girder segments 1 and 2 are each provided with cable anchoring points 4; special cable anchoring points 4 are arranged at the two ends (i.e. the outer flange end and the inner position close to the center line) of the left and right girder segments 1 and 2 in the transverse direction of the bridge, and the anchoring points 4 are welded to the top plate or web structure using reinforced steel plates and are subjected to local stress calculation to ensure that they have sufficient anchoring capacity. The design of the anchoring points 4 takes into account the structural safety and construction operation space, and specially reserves the installation and tensioning operation space of the through-type jack 6, facilitating the subsequent tensioning operation.

[0032] c. Tension the transverse cable 5 between the two cable anchoring points 4 of the left or right girder segment 1 or 2, and the cable 5 passes through the top of the gantry 3. For a single steel box girder (left or right), high-strength flexible cable 5 is arranged between the inner and outer cable anchoring points 4, and the cable 5 path is in turn through the outer anchoring point 4→ the top pulley or corner device of the outer gantry 3→ the top of the inner gantry 3→ finally anchored to the inner anchoring point 4, forming a "U" or "inverted V" tensioning path. The cable 5 is made of high-strength steel wire or parallel steel wire bundle, which has good tensile performance and small creep deformation, ensuring stable transmission of tensioning force.

[0033] d. The cable 5 is tensioned at the cable anchorage point 4, and the linear shape is adjusted to the preset shape. The cable 5 is tensioned by using the through-type jack 6 at the cable anchorage point 4, so that the steel box girder changes from the inverted arch shape to the sag shape as the erected girder segment when hoisted. The through-type jack 6 is used to tension the transverse cable 5 at the anchoring end in stages, so that the cable 5 generates a downward vertical component force by applying a pre-tightening force, which acts on the top of the portal 3, thereby exerting a downward equivalent load on the steel box girder. This load can effectively offset the inverted arch deformation of the to-be-erected girder segment caused by insufficient self-weight or support mode, so that the girder segment gradually changes from the original inverted arch state to the sag shape consistent with the erected girder segment, realizes linear pre-matching, and the tensioning process can realize precise control by combining with the real-time feedback of the girder deflection data by the measurement monitoring system.

[0034] e. The bridge crane 7 is installed on the erected steel box girder to lift the to-be-erected steel box girder for matching connection. After the linear shape adjustment is completed, the bridge crane 7 is installed on the erected steel box girder, and the main girder structure thereof extends above the to-be-erected girder segment to ensure that the lifting device can be stably lifted and accurately positioned. After the bridge crane 7 is started, the steel box girder segment is slowly lifted to be suspended and close to the abutted end face of the erected girder segment. Since the linear shape has been adjusted by the cable 5 system in advance, the height difference between the end faces of the two girder segments is significantly reduced, and they are in a similar sag curvature state, so that high-precision matching can be realized, and then temporary positioning and welding fixation are performed to complete the segment connection.

[0035] As one of the improvements of the above technical solutions, in step a, the portal 3 includes portal 3 legs, a middle web plate, and a transverse partition plate. The portal 3 legs are arranged above the middle web plate in the transverse direction, and the portal 3 legs are arranged above the transverse partition plate in the longitudinal direction. The height of the portal 3 is about one-third of the transverse width of the steel box girder. Specifically:

[0036] If the portal 3 is too high, the height of the gravity center of the overall structure will be increased, the stability will be reduced, and the vertical component force will be reduced due to the too large turning angle of the cable 5, thereby affecting the shape adjustment efficiency.

[0037] If the portal 3 is too low, the space for the cable 5 to pass through is insufficient, it is difficult to form an effective vertical force, and it is not conducive to the operation and installation of the tensioning equipment such as the through-type jack 6.

[0038] Controlling the height of the portal 3 to be about one-third of the width of the girder can maximize the downward pressure of the vertical component force of the cable 5 on the girder under the premise of ensuring sufficient sag of the cable 5 and reasonable tensioning angle, thereby efficiently realizing the elimination of the inverted arch and the linear shape adjustment. Meanwhile, the height is also convenient for on-site installation, disassembly, and transportation, and both structural performance and construction convenience are considered.

[0039] Regarding the through-type jack 6, specifically, the through-type jack 6 is used as a common prestressed tensioning equipment, and its working principle requires that the steel strand or cable 5 passes through the center hole of the jack, and is loaded step by step through the rear end tool anchor and the front end tensioning head. Therefore, when designing the anchoring point 4, a straight space not less than the length of the jack body should be left in front of the anchor plate, and it is ensured that there is no structural obstacle around to block the jack from being smoothly positioned and retreating after tensioning is completed. Therefore, in the b step, the flange end of the left beam segment 1 or the right beam segment 2 is provided with a top plate, and a space for tensioning of the through-type jack 6 should be left when the cable anchoring point 4 is arranged on the top plate.

[0040] In the c step, the transverse cable 5 is tensioned between the two cable anchoring points 4 of the left beam segment 1 or the right beam segment 2 respectively, and the left beam segment 1 or the right beam segment 2 is configured to have an outer anchoring point 4 and an inner anchoring point 4. The specific tensioning route is in turn the outer anchoring point 4, the top of the outer portal 3, the top of the inner portal 3, and finally the inner anchoring point 4. Further, the transverse distance between the outer anchoring point 4 and the inner anchoring point 4 is close to the full width of the steel box girder, and in combination with the height of the portal 3 (about 1 / 3 of the beam width), a reasonable cable 5 inclination angle (generally controlled between 25° and 45°) can be formed, so as to ensure that the tensioning force has a sufficient vertical component and improve the efficiency of the shape adjustment; preferably, the transverse cable 5 uses high-strength low-relaxation steel strand bundles or parallel steel wire cables, which have good tensile properties and small creep loss; a wear-resistant sheath or a sliding bearing is arranged at the turning position to reduce friction loss and ensure effective transmission of the tensioning force.

[0041] The vertical component of the tension of the cable 5 is fully utilized to actively apply a downward pressure, so that the to-be-erected beam segment is gradually adjusted from the inverted arch state to the sagging state consistent with the already-erected beam segment, and the height difference of the abutment end surface is significantly reduced. The left and right beam segments 2 are respectively provided with independent cable 5 systems, which can respectively adjust the tensioning force to realize differential control of the left and right linear shapes, and are particularly suitable for curved bridges, side spans of cable-stayed bridges, or complex bridge structures with asymmetric load conditions.

[0042] In the e step, the bridge deck crane 7 is installed on the erected steel box girder to lift the steel box girder to be erected. Specifically, the working end of the bridge deck crane 7 extends to the upper side of the separated steel box girder section to be erected, and is temporarily matched and welded after completion. After completion, the portal frame 3 and the cable 5 are disassembled, and the portal frame 3 and the cable 5 are moved to the next steel box girder section to be erected for recycling. Specifically, the main load-bearing structure is erected on the top surface of the erected steel box girder along the bridge direction, and is reliably connected with the girder body through the walking mechanism and the anchoring system, to ensure the overall stability and anti-overturning ability during hoisting. The working end (i.e. the cantilever end of the main girder) of the bridge deck crane 7 extends to the upper side of the steel box girder section to be erected, and the lifting tool is connected with the lifting point of the girder section to be lifted through the lifting rod or the lifting cable. After starting the hydraulic lifting system, the bridge deck crane 7 stably lifts the steel box girder section, lifts it to the designed installation elevation, and slowly moves to the splicing position close to the abutted end surface of the erected girder section.

[0043] The portal frame 3 and the cable 5 system can be repeatedly used, which significantly reduces the material consumption and equipment investment cost, improves the construction economy, and is particularly suitable for long-distance, multi-section continuous cantilever splicing operation. The disassembly and assembly process of the auxiliary structure is standardized, and the moving operation of the bridge deck crane 7 is matched to realize the “assembly line type” section splicing and shorten the construction period.

[0044] Reference herein to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of other embodiments. It will be apparent to those skilled in the art that the embodiments described herein can be combined with other embodiments in various ways.

[0045] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the application should be defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and scope of the equivalent elements of the claims.

Claims

1. A self-balancing alignment control method for the cantilever construction of separated steel box girders, applied to the hoisting of separated steel box girders by bridge deck cranes, characterized in that... Includes the following steps: a. Set up one gantry frame for each of the left and right beam sections of the separated steel box girder section to be erected; b. Cable anchorage points are installed at both ends of the left and right beam segments; c. Tension transverse cables between two cable anchorage points on the left or right beam segment, with the cables passing over the top of the gantry. d. Tension the cable at the cable anchorage point and adjust its alignment to the preset shape; e. Install a bridge deck crane on the already erected steel box girder to lift the steel box girder to be erected and perform matching connection; In step a, the gantry includes gantry legs, a web plate, and a diaphragm. The gantry legs are placed above the web plate in the transverse direction and above the diaphragm in the longitudinal direction. The height of the gantry is one-third of the transverse width of the steel box girder. In step b, the flange end of the left or right beam segment is provided with a top, and when setting the cable anchor point on the top plate, space must be left for the tensioning of the through-hole jack; In step c, transverse cables are tensioned between the two cable anchor points of the left or right beam segment respectively. The left or right beam segment is configured to have an outer anchor point and an inner anchor point. The specific tensioning route is as follows: outer anchor point, top of outer gantry, top of inner gantry, and finally connected to the inner anchor point. In step d, a through-hole jack is used to tension the cable at the cable anchorage point, so that the steel box girder changes from an arched shape to a downward deflection shape similar to the already erected girder segment during hoisting. In step e, a bridge deck crane is installed on the erected steel box girder to lift the steel box girder to be erected. After temporary matching is completed, welding is carried out. After completion, the gantry and cables are disassembled and moved to the next girder segment to be erected for recycling.

2. The self-balancing alignment control method for cantilever construction of separated steel box girders according to claim 1, characterized in that: In step e, when installing the bridge deck crane on the left and right beam segments, the working end of the bridge deck crane extends above the segment of the separated steel box girder to be erected.

Images