GB2608509A

GB2608509A - Asymmetric installation construction method for straddle-type light rail special steel box girder extradosed bridge

Info

Publication number: GB2608509A
Application number: GB2209777.8A
Authority: GB
Inventors: Wei Gan; He Peng; Ge Xingguang; Huan Jianpeng; Du Zhijun; Wu Huibiao; Zhou Guoyou; Liang Nengfeng; Chen Guiyang; Huang Jian
Original assignee: Shanghai Civil Engineering Co Ltd of CREC; Fifth Engineering Co Ltd of Shanghai Civil Engineering Co Ltd of CREC
Current assignee: Shanghai Civil Engineering Co Ltd of CREC; Fifth Engineering Co Ltd of Shanghai Civil Engineering Co Ltd of CREC
Priority date: 2020-05-25
Filing date: 2020-10-16
Publication date: 2023-01-04
Anticipated expiration: 2040-10-16
Also published as: CN111622116B; GB2608509B; CN111622116A; WO2021238024A1; GB2608509A8; GB202209777D0

Abstract

Disclosed in the present invention is an asymmetric installation construction method for a straddle-type light rail special steel box girder extradosed bridge. Steel box girders of the whole bridge are divided into several beam sections, which are then asymmetrically installed according to the hoisting sequence of side span section D1→middle span section C1→side span section D2→middle span C2→...side span section Dn→side span section Dn+2→side span joint section→...middle span section Cn→middle span joint section H. The method of the present invention can meet the waterway requirements to the greatest extent, without the need of providing steel pipe supports at the middle span sections.

Description

ASYMMETRIC INSTALLATION CONSTRUCTION METHOD FOR STRADDLE-TYPE LIGHT RAIL SPECIAL STEEL BOX GIRDER EXTRADOSED BRIDGE

Technical Field

The present invention relates to technical field of bridge construction, in particular to an asymmetric installation and construction method of steel box extradosed cable-stayed bridge for straddle type light rail.

Background Technology

A common practice of erecting bridges on rivers is to divide steel box girders of bridge deck into multiple unit blocks, namely girder sections, and then to splice the multiple unit blocks together through pier shafts and supports on site.

An existing steel box girder of bridge deck is usually divided into smaller sections C\I with a length of one section about 8-10m, side span sections and middle span C\I sections are symmetrically hoisted and installed by a crane on bridge deck, and stay cables are installed at the same time. After the installation is completed, the side span sections and the middle span sections are joined, and cable-stayed force and C\I structural line types are adjusted. The above installation method has problems in that: the box girder has many sections; aerial installation process is complicated; precision control is difficult; and with so many sections, water transportation can become busy which may affect the normal passage of the waterways.

Summary of the Invention

The present invention discloses an asymmetric installation and construction method of steel box extradosed cable-stayed bridge for straddle type light rail without needing to provide steel pipe supports at the middle span sections, thus meeting waterway requirements to the greatest extent.

An asymmetric installation and construction method of steel box extradosed cable-stayed bridge for straddle type light rail, comprising the steps of: Si. dividing a full-bridge steel box girder into several girder sections, comprising a middle span closure section H, and middle span sections C, ..., middle span sections C2, middle span sections Ci, support sections Ao, side span sections Di, side span sections D2..., side span sections Dn, side span closure sections and side span sections D,2 symmetrically arranged relative to the middle span closure section H; S2. completing construction of pile foundations, bearing platforms and pier shafts, wherein the pier shafts are arranged below designed positions of the support sections Ao and the side span sections D,2, and support saddles are arranged on upper portions of the pier shafts; 53. during construction of the bearing platforms and the pier shafts, providing steel pipe support systems in the side span sections according to the divided girder sections, wherein the steel pipe support systems comprise upright posts and transverse connection devices, wherein the upright posts are arranged below the designed positions of the side span sections and the side span closure sections, the transverse connection devices are arranged between the upright posts, and top portions of the upright posts are provided with at least one steel cushion box and at least one jack supporting system; 54. installing the support sections Ao of the steel box girder, and adopting a tower crane to cooperate in lifting a steel shaping mold for construction of at least one cable tower; 55. adopting at least one floating crane to install according to a hoisting sequence of the side span sections Di, the middle span sections Ci, the side span sections D2, ..., the side span sections Dnii, the side span sections D,, the side span sections D,2, the side span closure sections and the middle span sections C2, ..., the middle span sections Cn_i, the middle span section C" and then the middle span closure section H, wherein the side span sections D2, ..., the side span sections Di and the middle span sections C2, ..., the middle span sections Cn_i are installed symmetrically or asymmetrically, during hoisting, according to the hoisting sequence of the corresponding girder sections, tensioning corresponding stay cables of the girder sections, and adjusting line types of the steel box girder and pre-camber thereof; S6. before installing the middle span closure section H, firstly relieving support stress of the steel pipe support systems on the side span sections to ensure that the side span sections of the steel box girder of are in a freely suspended state, counterweighting the middle span sections Cr, on both ends, and finally joining the middle span closure section H; and 57. after closure of the steel box girder, adjusting cable-stayed force and structural line type of the full-bridge steel box girder to complete full-bridge construction.

Further, in step 53, the steel pipe support systems are also correspondingly arranged below the designed positions of the middle span sections Ci.

Further, in step 56, closure of the middle span closure section H is carried out at a temperature of 16-22°C.

Further, in step SS, when a floating crane is adopted to hoist side span sections Di, the side span sections D2, ..., the side span sections Dn and the side span closure sections, after aligning accurately a later hoisted girder section with the girder section which has been installed on one side thereof in advance, plugging at least one steel plate and at least one temporary limiting girder section at top portions of the upright posts and welding and fixing with at least one plate.

Further, in step 55, before hoisting the side span sections Dn+2, firstly providing temporary steel support saddles on the pier shafts below the side span sections Dn+2, wherein elevations at top portions of the temporary steel support saddles are controlled by elevations of the side span sections Dn+2, then measuring actual line types of the side span sections Dn, simulating closure states of the side span closure sections according to measured values, when there are deviations between the side span sections Dn and the side span sections Dn+2, adjusting elevations of the side span sections Dn, carrying out jacking adjustments with the at least one jack supporting system arranged on the top portions of the upright posts, and adjusting the values until the side span closure sections can be smoothly installed.

Further, arrangement of the at least one steel cushion box and the at least one jack supporting system is as follows: the at least one steel cushion box comprises at least one type A steel cushion box and/or at least one type B steel cushion box, wherein the at least one type A steel cushion box is mainly supported at a position of a web of the steel box girder, and the at least one type B steel cushion box is mainly supported at a position of a diaphragm plate of the steel box girder; and the at least one type A steel cushion box is arranged in a center of a top surface of each of the upright posts, and two jacks are symmetrically arranged, wherein a midline connecting line of the two jacks coincides with a midline of the top surface of each of the upright posts, and one side of the jacks and the type A steel cushion box is provided with the type B steel cushion box.

Further, length of each of the support sections Ao is 10-14m, and length of each of other standard girder sections is 15.3-26m.

Further, the middle span sections Ci, and the middle span sections C2, the middle span sections Ci and the side span sections Di, the side span sections D2 and the side span sections on are symmetrical relative to vertical center lines of the support sections Ao.

The above-mentioned asymmetric installation and construction method of steel box extradosed cable-stayed bridge for straddle type light rail, wherein during installation, stability of the side span sections of the steel box girder is maintained by the steel pipe support systems, connection of the side girder sections and tension of the stayed cables, and stability of the middle span sections of the steel box girder is maintained by the cable-stayed tension, connection of the side girder sections and the balanced tension of the stay cables on the two ends, which has the following advantages: 1. The steel pipe support systems are arranged below the side span sections, which is convenient for adjusting the lengths of the steel box girder sections and the hoisting sequence, and linetype control precision is high; 2. By combining the steel pipe support systems and the stay cables, quantity of pre-assembled sections is reduced and manufacturing precision of the steel box girder is improved; 3. the steel pipe support systems are arranged only below the designed positions of the middle span sections Ci, which can meet requirements of the daily waterway transportation, but it is only necessary to close the waterway when hoisting the middle span sections, and waterway transportation will not be affected in other times, and the number of the middle span sections is less, which greatly reduces occupation of the waterway; 4. as the quantity of the steel box girder sections is controlled in a certain range, times of hoisting can be reduced and time of occupying the waterway can be greatly shortened; 5. prefabrication of the steel box girder can be carried out in a factory, which reduces hoisting and alignment time, saves construction time of the steel pipe support systems below the middle span sections, and greatly reduces the construction period; and 6. existing pile foundations are effectively used and materials are saved.

Brief Description of the Drawings

Figure 1 is a schematic structural diagram of division of a full-bridge steel box girder. Figure 2 is a schematic structural diagram of the present invention when constructed to side span sections D2.

Figure 3 is a schematic structural diagram of the structure of a steel pipe support system and pier shafts.

Figure 4 is a schematic top view of the structure of the steel pipe support system. Figure 5 is a schematic perspective view of a type A steel cushion box.

Figure 6 is a schematic perspective view of a type B steel cushion box.

Figure 7 is a schematic structural diagram of the present invention when constructed to side span sections D5.

Figure 8 is a schematic structural diagram of the present invention when constructed to side span closure sections D5.

Figure 9 is a schematic structural diagram of the present invention when constructed to side span sections C3.

Figure 10 is a schematic structural diagram of completed construction of the present invention.

In the drawings, 1-pier shaft, 2-upright post, 3-transverse connection device, 4-stay cable, 5-steel box girder, 501-support section Ao, 502-side span section Di, 503-middle span section Ci, 504-side span section D2, 505-middle span section C2, 506-side span section D3, 507-side span closure section, 508-side span section D5, 509-middle span section C3, 510-middle span closure section H, 6-riverbed, 7-jack, 8-type A steel cushion box, 801-casing of type A steel cushion box, 802-baffle plate of type A steel cushion box, 9-type B steel cushion box, 901-casing of type B steel cushion box, 902-baffle plate of type B steel cushion box, 10-web of steel box girder, and 11-diaphragm plate of steel box girder.

Specific Embodiments Hereinafter, the present invention will be further illustrated with reference to the following specific embodiments, but protection scope of the present invention is not limited to the following embodiments.

An asymmetric installation and construction method of steel box extradosed cable-stayed bridge for straddle type light rail, comprising the steps of: Si. dividing a full-bridge steel box girder into several girder sections, comprising a middle span closure section H, and middle span sections Cr, . , middle span sections C2, middle span sections Ci, support sections Ao, side span sections Di, side span sections D2..., side span sections Dn, side span closure sections and side span sections Dn+2 symmetrically arranged relative to the middle span closure section H; n can be allocated according to a bridge span; 52. completing construction of pile foundations, bearing platforms and pier shafts, wherein the pier shafts are arranged below designed positions of the support sections Ao and the side span sections D5+2, and support saddles are arranged on upper portions of the pier shafts; 53. during construction of the bearing platforms and the pier shafts, providing steel pipe support systems in the side span sections according to the divided girder sections, wherein the steel pipe support systems comprise upright posts and transverse connection devices, wherein the upright posts are arranged below the designed positions of the side span sections and the side span closure sections, the transverse connection devices are arranged between the upright posts, and top portions of the upright posts are provided with at least one steel cushion box and at least one jack supporting system; 54. installing the support sections Ao of the steel box girder, and adopting a tower crane to cooperate to hoist at least one steel shaping mold for construction of at least one cable tower; SS. using at least one floating crane to install according to a hoisting sequence of the side span sections Di-the middle span sections Ci-the side span sections D2, ... the side span sections Dpi, the side span sections Dn, the side span sections D,2, the side span closure sections and the middle span sections C2, ... the middle span sections Cn_i-the middle span sections Cn-the middle span closure section H, wherein the side span sections D2, ... the side span sections Dn_i and the middle span sections C2, ... the middle span sections Cr_i are installed symmetrically or asymmetrically, according to hoisting orders of the corresponding girder sections, corresponding stay cables of the girder sections are tensioned, and line types of the steel box girder and pre-camber thereof are adjusted; wherein the installation method of the side span sections D2, ... the side span sections Dpi, the side span sections D,2, the side span closure sections and middle span sections C2, ... the middle span sections Cn_i can be as follows: the side span sections D2-,can be as follows: the ss C2-... the side span sections Di (wherein the ellipsis part is installation of the side span sections) --the side span sections Dn-the side span sections Dn+2 --the side span closure sections -,... the middle span sections Cn_i (wherein the ellipsis part is installation of the middle span sections), the installation method can also be as follows: the side span sections D2-"... the side span sections Di (wherein the ellipsis part is installation of the side span sections)-the side span sections Dr-, the side span sections Dn+2 -+the side span closure sections-'-the middle span sections C2-... the middle span sections Cn_i (wherein the ellipsis part is installation of the middle span sections), or the installation method can also be symmetrical installation or asymmetrical installation, such as side span sections D2, ... the side span sections Di and the middle span sections C2, ... the middle span sections Cn_i; In addition, it should be noted that the pier shafts are installed below

S

the side span sections Din, which can be hoisted preferentially without considering symmetry problems. In the two ways listed above, hoisting of the side span sections D, can be adjusted arbitrarily, which only needs to be hoisted before hoisting of the side span closure sections; 56. before installing the middle span closure section H, firstly relieving support stress of the steel pipe support systems to the side span sections to ensure that the side span sections of the steel box girder are in a free suspended state, and then counterweighting the middle span sections Cn on both ends, and finally joining the middle span closure section H; and 57. after closure of the steel box girder, adjusting cable-stayed force and a structural line type of the full-bridge steel box girder to complete full-bridge construction.

Hereinafter an embodiment is given in combination with design of the specific girder section, wherein n is designed to be 3, specifically as follows: the asymmetric installation and construction method of steel box extradosed cable-stayed bridge for straddle type light rail, comprising the steps of: Si. with reference to Figure 1, the full-bridge steel box girder is divided into 19 girder sections, comprising: middle span closure sections H 510, middle span sections C3509, middle span sections C2 505, middle span sections C2503, support sections Ao 501, side span sections D1502, side span sections D2504, side span sections D3506, side span closure sections 507 and side span sections D5508 that are symmetrically arranged relative to the middle span closure section H 510; wherein a length of the support sections Ao 501 is 12m, and lengths of other standard sections range from 15.3-26m. In order to keep the balance of both sides when hoisting the middle span sections C2 505, the middle span sections C1503, the side span sections D2502 and the side span sections D2 504, the middle span sections C3 509, the middle span sections C2 505, the middle span sections C1503 and the side span sections D1502, the side span sections D2 504 and the side span sections D3 506 are preferably designed to be symmetrical relative to the vertical center lines of the support sections Ao.

52. with reference to Figure 3, complete the construction of pile foundations, bearing platforms and pier shafts, wherein the pier shafts are arranged below designed positions of the support sections Ao and the side span sections Dn.2, and support saddles are arranged on upper portions of the pier shafts. Specifically, after constructing underwater steel trestles at positions of the piers, setting up a construction platform for construction of the pile foundations, the bearing platforms and the pier shafts; putting a bearing platform of the main pier shaft in a designated position by a double-wall steel box cofferdam, pouring back cover concrete and constructing the pier shafts; and after construction of the bearing platforms, pouring the pier shafts 1 integrally with customized steel films.

53. during construction of the bearing platforms and the pier shafts, providing the steel pipe support systems in the side span sections according to the divided girder sections, wherein the steel pipe support systems comprise upright posts and transverse connection devices, wherein the upright posts are arranged below the designed positions of the side span sections and the side span closure sections, the side span sections Dn+2 with the pier shafts are not provided with upright posts, the upright posts are inserted into the rock surface with 4)1520mmx1Omm steel pipe piles, and 10m reinforced concrete piles are provided at bottom portions of the piles and are anchored into the rock layer by 5m and overfilled for 5m to form a pile foundation anchor system, the transverse connection devices are arranged between the upright posts, and top portions of the upright posts are provided with at least one steel cushion box and at least one jack supporting system; 54. with reference to Figure 2, installing the support sections Ao of the steel box girder, and adopting a tower crane to cooperate to hoist a steel shaping mold for construction of at least one cable tower, and the at least one cable tower is provided on the support sections Ao; 55. with reference to Figures 2, 7, 8, 9 and 10, adopting a floating crane to install according to a hoisting sequence of the side span sections D1502--the middle span sections C2503-the side span sections D2504-the middle span sections C2 505 -the side span sections D3506-the side span sections D5508--the side span closure sections 507-the middle span sections C3509--the middle span closure sections H 510, according to the hoisting order of the corresponding girder sections, corresponding stay cables of girder sections are tensioned, and a line type of the steel box girder and pre-camber thereof are adjusted; 56. before installing the middle span closure section H 510, firstly relieving support stress of the steel pipe support systems on the side span sections to ensure that the side span sections of the steel box girder are in a freely suspended state, and then counterweighting the middle span sections C3 509 on both ends, and finally joining the middle span closure section H; and 57. after closure of the steel box girder, adjusting cable-stayed force and the structural line type of the full-bridge steel box girder, arranging track girders, evacuation platforms and other auxiliary facilities, and finally adjusting full-bridge cable force, to complete full-bridge construction.

Hereinafter some steps therein are described in detail: In step S3, construction of the steel pipe support systems specifically comprises: with reference to Figure 3, the steel pipe support systems are respectively arranged under the side span sections at east and west banks, supports of the side spans adopt 4:11520x10mm steel pipes to form the upright posts, and 10m reinforced concrete piles are provided at bottom portions of the upright posts and are anchored into the rock layer by 5m and overfilled by 5m to form a pile foundation anchor system. 43630mm steel pipes and 4)325mm steel pipes are arranged to be the transverse connection devices between the upright posts, the 4)630mm steel pipes are cross rods, the 43325mm steel pipes are diagonal rods and vertical rods, the diagonal rods and the vertical rods form triangular stable supports, top portions of the upright posts are provided with reinforcing plates and capping steel plates, and top portions of the capping steel plates are provided with steel cushion boxes for supporting the steel box girder. Specific structures are as follows: with reference to Figure 4, top structures of the upright posts of the steel box girders adopt 2mm steel plates to form box structures according to a designed elevation of the steel box girder, the steel cushion boxes are divided into type A steel cushion boxes 8 and type B steel cushion boxes 9, wherein the type A steel cushion boxes 8 are mainly supported at positions of a web of the steel box girder 10, and the type B steel cushion boxes 9 are mainly supported at positions of a diaphragm plate of the steel box girder 11, the type A steel cushion boxes 8 should be placed in centers of the upright posts 2, and two jacks 7 are symmetrically arranged on both sides, midline connecting lines of the two jacks 7 coincide with midlines of the top surfaces of the upright posts 2, and one side of the jacks and the type A steel cushion boxes 8 are provided with the type B steel cushion boxes 9. With reference to Figure 5, the type A steel cushion boxes 8 comprise casings of type A steel cushion box 801 and baffle plates of type A steel cushion box 802, wherein the baffle plates of type A steel cushion box 802 are interlocked and arranged in the casings of type A steel cushion box 801, and outer sides of the baffle plates of type A steel cushion box 802 are connected with the casings of type A steel cushion box 801. The type B steel cushion boxes 9 comprise casings of type B steel cushion box 901 and baffle plates of type B steel cushion box 902, wherein the baffle plates of type B steel cushion box 902 are cross-shaped and arranged in the casings of type B steel cushion box 901. However, as the type B steel cushion boxes 9 are longer than the type A steel cushion boxes 8, the baffle plates of type B steel cushion box 902 in the longitudinal direction are provided to be 2-4 according to actual situations.

Hereinafter a detailed process of construction of the support sections Ao until the middle span closure section H is described, wherein the pier shafts are divided into abutment piers and main piers, and the pier shafts 1 arranged below the support sections Ao are the main piers, and the pier shafts 1 arranged below side span sections Dn+2 are the abutment piers; and in step S4, after construction of the supporting sections Ao and the at least one cable tower is completed, the steel trestle is dismantled in time, and meanwhile, materials of the dismantled abutment pier construction platform and the steel trestles are used for manufacturing the steel box girder supports according to construction progress.

A construction process of step 55 specifically comprises: 55.1. the side span sections Di 502 are hoisted by a 400t floating crane. After the side span sections Di 502 are accurately aligned with the support sections Ao 501, each of the side span sections Di 502 is connected to one side of each of the support sections Ao 501 and is fixed by plates, and meanwhile, a top portion of each of the upright posts (4# upright post) below each of the side span sections Di 502 is plugged with steel plates, and vertical force is released by the floating crane, and displacement of the girder sections is observed in real time during releasing process, so as to ensure that the displacement falls in the scope of specification requirements. If the displacement is rather large during releasing, it is required to cut off the plates and readjust the steel box girder. After installation of the side span sections Di 502 is completed, the side span sections Di 502 and the support sections A0501 are girth welded, and when welding is completed, the floating crane is loosened.

55.2. the middle span sections C1503 are hoisted by a 400t floating crane. After the 400t floating crane hoists the middle span sections C1503 to be accurately aligned with the support sections Ao 501, a top portion of each of the upright posts (S# upright post) below each of the middle span sections Ci 503 is plugged with steel plates and temporary limiting girder sections, and meanwhile, each of the middle span sections C1503 and the other side of each of the support sections Ao 501 are welded and fixed by the plates. After fixing by the plates is completed, the temporary stay cables (L1 temporary stay cable) corresponding to the middle span sections Ci 503 are immediately arranged, and the temporary stay cables are pre-tightened according to stretch-draw instructions. At the same time of stretch-draw, part of vertical force is released by the floating crane, and ensures that the steel box girder is free from top portions of the 4# and 5# upright posts. After stretch-draw is completed and the line types of the middle span sections C1503 has been checked to meet the requirements, the middle span sections C1503 and the support sections Ao 501 are girth welded, and when girth welding is completed, the floating crane is loosened. Before hoisting, it is required to go through temporary transportation closure formalities.

55.3. the side span sections D2 504 are hoisted by a 400t floating crane. After the side span sections D2504 are accurately aligned with the side span sections D1502, each of the side span sections D2 504 is welded and fixed with each of the side span sections D3502 by the plates, and meanwhile, a top portion of each of the upright posts (3# upright post) below each of the side span sections D2504 is plugged with steel plates, and vertical force is released by the floating crane, and displacement of the girder sections is observed in real time during releasing process, so as to ensure that the displacement falls in a scope of specification requirements. If the displacement is rather large during releasing process, it is required to cut off the plates and readjust the steel box girder. After installation of the side span sections D2 504 is completed, the side span sections D2504 and the side span sections Di 502 are girth welded, and when welding is completed, the floating crane is loosened.

S5.4. the middle span sections C2505 are hoisted by a 400t floating crane. After the 400t floating crane hoists the middle span sections C2505 to be accurately aligned with the middle span sections C1503, each of the middle span sections C2505 and the middle span sections C1503 are immediately welded and fixed by the plates, and at the same time, the temporary stay cables (M1 and M2 stay cables) corresponding to the middle span sections C2 SOS are immediately arranged, and are pre-tightened according to stretch-draw instructions. At the same time of stretch-draw, part of vertical force is released by the floating crane to have the stay cables bear forces, and top portions of the 34, 4# and 5# upright posts are checked to be free from bottom plates of the steel box girder. During installation, the steel box girder is monitored in real time to ensure stability of the line type of the steel box girder. After stretch-draw is completed and the line type of the middle span sections C2 SOS has been checked to meet the requirements, the middle span sections C2 505 and the middle span sections C1503 are girth welded, and when girth welding is completed, the floating crane is loosened. Before hoisting, it is required to go through temporary transportation closure formalities.

55.5. the side span sections D3506 are hoisted by a 400t floating crane. After the side span sections D3506 are accurately aligned with the side span sections D2504, each of the side span sections D3506 is welded and fixed with each of the side span sections D2504 by the plates, and meanwhile, a top portion of each of the upright posts (2# upright post) below each of the side span sections D3506 is plugged with steel plates, and vertical force is released by the floating crane, and displacement of the girder sections is observed in real time during releasing, so as to ensure that the displacement falls in scope of specification requirements. If the displacement is rather large during releasing process, it is required to cut off the plates and readjust the steel box girder. After installation of the side span sections D3506 is completed, the side span sections D2504 and the side span sections D3506 are girth welded, and when welding is completed, the floating crane is loosened.

55.6. before the side span sections D3508 are hoisted, temporary steel support saddles are firstly arranged on the abutment piers, elevations at top portions of the temporary steel support saddles and the top steel cushion boxes of the 1 # upright posts (the upright posts below the side span closure sections 507) are controlled by designed elevations of bottom portions of the side span sections D3508, and permanent bearings are placed on sides of cushion stones, and the permanent bearings can be installed after line type adjustment of the side span sections of the steel box girder is completed. The side span sections D5 are hoisted by a 400t floating crane. Before hoisting, actual line types of the side span sections D3506 should be measured, a closure state of the side span closure sections 507 is simulated according to measured values, when there is a deviation between the side span sections D3506 and the side span sections D5508, when to adjust elevation of the side span sections D3506, 100tx2 sets of hydraulic jacks are arranged on top portions of the 2# and 3# upright posts to carry out jacking adjustment to the side span sections D3 506, and adjust the values until the side span closure sections 507 are smoothly installed.

55.7. the side span closure sections 507 are hoisted by a 400t floating crane. When the side span closure sections 507 are processed in a processing factory, 100mm matching cutting lengths are reserved, before installing the side span closure sections 507, it is required to continuously observe the side span sections D3506 and the side span sections D5 508 for 48 hours to determine the optimal closure time and matching cutting lengths, after the side span closure sections 507 are hoisted in place, plates are welded on the girder sections at two sides to fix the side span closure sections 507, and then vertical force is released by the floating crane, and whether the line types of the three girder sections, namely, the side span sections D3 506, the side span closure sections 507 and the side span sections D5508 meet the design requirements is monitored.

55.8. the middle span sections C3509 are hoisted by a 400t floating crane. After the 400t floating crane hoists the middle span sections C3509 to be accurately aligned with the middle span sections C2 505, each of the middle span sections C3 509 and the middle span sections C2505 are immediately welded and fixed by the plates, and at the same time, the stay cables (M3, M4 and M52 stay cables) corresponding to the middle span sections C3 509 are arranged, and are pre-tightened according to stretch-draw instructions. At the same time of stretch-draw, part of vertical force is released by the floating crane to force the stay cables, and the top portions of the 1#, 2#, 3#, 4# and 5# upright posts are checked to be free from bottom plates of the steel box girder. During process, the steel box girders are monitored in real time to ensure stability of the line type of the steel box girder. After stretch-draw is completed and the line type of the middle span sections C3 509 has been checked to meet the requirements, the middle span sections C2 505 and the middle span sections C3509 are girth welded, and when girth welding is completed, the floating crane is loosened. Before hoisting, it is required to go through temporary closure formalities.

S5.9. the middle span closure section H 510 is lifted with a 400t floating crane. Before hoisting the middle span closure section H 510, counterweight the middle span sections C3 509 of the east and west banks respectively, observe closure openings of the middle span closure section H 510 for 48h, and select the best time period to adjust and close; after the 400t floating crane hoists and installs the middle span closure section H 510 and linetype adjustment are completed, the middle span closure section H 510 is temporarily welded and fixed by the plates. After the middle span closure section H 510 is fixed, counterweight of the girder sections is released; after linetype adjustment is completed, the middle span closure section H 510 is girth welded; and test the full bridge, adjust cable-stayed force according to instructions, and sections of the full bridge are joined.

In above embodiments, n is designed to be 3, and n can be designed to be other values and n 5, preferably n is not greater than 5, which can reduce times of hoisting and the time of occupying the waterway, and meanwhile, it is also beneficial to full-bridge linear control because of reduction of sections assembled in the air.

Claims

Claims 1. An asymmetric installation and construction method of steel box extradosed cable-stayed bridge for straddle type light rail, comprising the steps of: Si. dividing a full-bridge steel box girder into several girder sections, comprising a middle span closure section H, and middle span sections Cri... middle span sections C2, middle span sections Ci, support sections Ao, side span sections Di, side span sections D2... side span sections Dn, side span closure sections and side span sections Dn+2 symmetrically arranged relative to the middle span closure sections H; 52. completing construction of pile foundations, bearing platforms and pier shafts, wherein the pier shafts are arranged below designed positions of the support sections Ao and the side span sections Dn+2, and support saddles are arranged on upper portions of the pier shafts; S3. during construction of the bearing platforms and the pier shafts, providing steel pipe support systems underneath the side span sections according to the divided girder sections, wherein the steel pipe support systems comprise upright posts and transverse connection devices, wherein the upright posts are arranged below the designed positions of the side span sections and the side span closure sections, the transverse connection devices are arranged between the upright posts, and top portions of the upright posts are provided with steel cushion boxes and jack supporting systems; S4. installing the support sections Ao of the steel box girder, and adopting a tower crane to cooperate in lifting steel shaping molds for construction of at least one cable tower; 55. adopting a floating crane to install according to a hoisting sequence of the side span sections Di, the middle span sections Ci, the side span sections D2, ..., the side span sections Dn_i, the side span sections Dn, the side span sections D1+2, the side span closure sections and the middle span sections C2, ..., the middle span sections Cn_i, the middle span section Cn, then the middle span closure section H, wherein the side span sections D2, ..., the side span sections Di and the middle span sections C2, ..., the middle span sections Cn_i are installed symmetrically or asymmetrically, according to the hoisting sequence of the corresponding girder sections, tensioning corresponding stay cables of girder sections, and adjusting a line type of the steel box girder and pre-camber thereof; 56. before installing the middle span closure section H, firstly relieving support stress of the steel pipe support systems on the side span sections to ensure that the side span sections of the steel box girder are in a freely suspended state, and then counterweighting the middle span sections Cr, on both ends, and finally joining the middle span closure section H; and 57. after closure of the steel box girder, adjusting cable-stayed force and the structural line type of the full-bridge steel box girder to complete full-bridge construction.
2. The construction method according to claim 1, wherein: in step 53, the steel pipe support systems are also correspondingly arranged below the design positions of the middle span sections
3. The construction method according to claim 1, wherein: in step S6, closure of the middle span closure section H is carried out at a temperature of 16-22 °C.
4. The construction method according to claim 1, wherein: in step SS, when a floating crane is adopted to hoist side span sections D1, the side span sections D2, ..., the side span sections Dn and the side span closure sections, after a later hoisted girder section is accurately aligned with the girder section which has been installed on one side thereof in advance, plugging steel plates and temporary limiting girder sections at top portions of the upright posts and welding and fixing by welding plates.
S. The construction method according to claim 4, wherein: in step SS, before lifting the side span sections Dn+2, arranging temporary steel support saddles on the pier shafts below the side span sections Dn+2, elevations at top portions of the temporary steel support saddles are controlled by elevations of the side span sections Dn+2, measuring actual line types of the side span sections Dn, simulating closure states of the side span closure sections according to measured values, when there are deviations between the side span sections Dn and the side span sections Dri+2, adjusting elevations of the side span sections D, carrying out jacking adjustment by the jack supporting systems arranged on top portions of supports, and adjusting the values until the side span closure sections are smoothly installed.
6. The construction method according to claim 1, wherein: arrangement of the steel cushion boxes and the jack supporting system is as follows: the steel cushion boxes comprise type A steel cushion boxes and type B steel cushion boxes, wherein the type A steel cushion boxes are mainly supported at positions of a web of the steel box girder, and the type B steel cushion boxes are mainly supported at positions of a diaphragm plate of the steel box girder; and the type A steel cushion boxes are arranged in centers of top surfaces of the upright posts, and jacks are symmetrically arranged, wherein midline connecting lines of the two jacks coincide with midlines of the top surfaces of the upright posts, and one side of the jacks and the type A steel cushion boxes are provided with the type B steel cushion boxes.
7. The construction method according to claim 1, wherein: a length of each of the support sections Ao is 10-14m, and a length of each of other standard girder sections falls in a range of 15.3-26m.
8. The construction method according to claim 1, wherein: the middle span sections Co and the middle span sections C2, the middle span sections Ci and the side span sections Di, the side span sections D2 and the side span sections Dn are symmetrical relative to vertical center lines of the support sections Ao.
9. The construction method according to claim 1 or claim 7, wherein: n < 5.