CN-118481016-B - Method for improving crack resistance of auxiliary pier and tail cable zone bridge deck of steel-UHPC composite beam cable-stayed bridge

CN118481016BCN 118481016 BCN118481016 BCN 118481016BCN-118481016-B

Abstract

The invention discloses a method for improving crack resistance of bridge decks in auxiliary piers and tail rope areas of a steel-UHPC combined beam cable-stayed bridge, which comprises the steps of determining a steel-UHPC combined beam range with crack resistance which does not meet requirements, determining a compressive stress target value required by a bridge deck in a bridge formation state, obtaining a maximum deflection value of a simply supported combined beam under the action of dead weight and controlling the compressive stress of bridge deck plates in a cross section, obtaining a stress difference value of a control cross section of a simply supported beam in two construction stages after the completion and the bridge formation, obtaining a deflection displacement curve of a single-span simply supported beam under the action of dead weight after the dead weight load coefficient is considered, obtaining the maximum deflection value, reversely weighing an upper arch line shape of the steel main beam by the deflection displacement curve, setting a beam deflection control point, wherein the total displacement of each control point is a vertical displacement value corresponding to the deflection displacement curve, and carrying out grading on the maximum beam deflection total displacement. The invention does not need to arrange a large number of in-vivo or in-vitro prestress steel bundles at the auxiliary pier and the side span tail rope region combined beam, and has better economy.

Inventors

LIU QI
SHU JIANG
FU XIAOFAN
XU LIN
LI ZHIGANG
ZHANG QIAN
WANG XIAONING
DING DEHAO
WU XIAOQIN
YUAN LONGPING
HUANG CONGCONG
YANG XING
LIN XING
DING SHAOLING
PENG YUANCHENG
YAN SHAOBO
NIE SHANGJIE
SUN HAO
LONG XIN
ZHANG ZHUO

Assignees

中交第二公路勘察设计研究院有限公司

Dates

Publication Date: 20260512
Application Date: 20240614

Claims (6)

1. The method for improving the crack resistance of the auxiliary pier and the tail cable zone bridge deck of the steel-UHPC composite beam cable-stayed bridge is characterized by comprising the following steps of: (1) According to the stress distribution of the bridge deck plate under the combination of the least adverse load action of the auxiliary pier area and the side span tail rope area combined beam in the operation period, determining that the range of the steel-UHPC combined beam with the crack resistance not meeting the requirement is L 1 +L 2 ; Wherein L 1 represents the distance from the auxiliary pier to the main tower direction to the beam section with crack resistance meeting the requirement, L 2 represents the distance from the auxiliary pier to the transition pier in the main tower direction, and L 1 +L 2 jointly covers the auxiliary pier region and the side span tail rope region; (2) According to the difference between the stress value of the auxiliary pier area and the stress value which can meet the requirement of the crack resistance and is in the normal use limit state of the bridge deck with the cross section controlled by the side span tail rope area, determining a compressive stress target value sigma t required by the bridge deck in the bridge formation state; the control section is the section with the largest tensile stress of the bridge deck plate of the auxiliary pier area and the side span tail rope area steel-UHPC combined beam in the normal use limit state of the lasting condition; (3) Taking a beam section in the range of L 1 +L 2 of the steel-UHPC combined beam as a single-span simply supported beam, and calculating to obtain the maximum deflection value of the simply supported combined beam under the action of dead weight as delta ZZ and control the compressive stress of the bridge deck slab with a cross section as sigma ZZ ; (4) Correcting a construction step of a positive installation calculation model of the steel-UHPC combined beam cable-stayed bridge, and solving a stress difference value of a control section at two construction stages after beam falling is completed and the bridge is formed, namely a stress correction value sigma △ for system conversion in a construction process of the control section; The construction steps of the correction steel-UHPC combined beam cable-stayed bridge forward installation calculation model comprise the steps of setting a support at a beam falling control point, installing an auxiliary pier region, installing a side span tail rope region combined beam and forming a combined section, synchronously falling beams at all control points, side span closure, symmetrically installing stay cables and a middle span combined beam section by section, mid-span closure, dismantling the beam falling control point support, constructing a bridge deck system and forming a bridge; (5) Adjusting the self-weight load coefficient gamma Y of the single-span simple supporting beam, taking the stress value 'sigma t +σ △ ' as the compressive stress generated by the control section of the falling beam, and solving a down-deflection displacement curve S Y of the single-span simple supporting beam under the self-weight action after the self-weight load coefficient gamma Y is considered, wherein the maximum down-deflection value is delta ZY ; (6) N beam falling control points are arranged in the range of an auxiliary pier area and a side span tail rope area L 1 +L 2 at intervals of 6-9 m, the total beam falling displacement S Z1 to S Zn of each control point is a vertical displacement value corresponding to a downwarping displacement curve S Y , and the maximum total beam falling displacement is delta ZY ; (7) Dividing the synchronous girder falling construction stage in the calculation model of the step (4) into m construction stages which are implemented in a grading manner, and calculating the dead weight load reduction coefficients gamma 1 to gamma m of the main girders of each stage according to the displacement of the girder falling of each stage, wherein the dead weight load reduction coefficient gamma m of the last stage is equal to gamma Y ; (8) In the grading implementation process, the beam falling displacement of each beam falling control point of each stage is reversely calculated according to a simple beam deflection curve corresponding to the dead weight load reduction coefficients gamma 1 to gamma m ; (9) In the grading implementation process, the support counter force of each drop beam control point of each stage is the vertical counter force corresponding to the synchronous occurrence of the current grading drop beam displacement of each drop beam control point when each level of dead weight of the combined beam is loaded, and the value is taken according to the calculation model in the step (7); (10) And implementing the classified beam falling according to the calculation result, and performing double control by using the pivot counter force and the pivot displacement to realize the completion of the classified beam falling implementation.
2. The method for improving the crack resistance of the auxiliary pier and the tail rope area bridge deck of the cable-stayed bridge of the steel-UHPC combined beam according to claim 1, wherein the steel-UHPC combined beam adopts the prefabricated hoisting of the whole section of the UHPC bridge deck and the steel main beam, and the bridge deck between the beam sections is connected through transverse wet joints.
3. The method for improving the crack resistance of the auxiliary pier and the tail rope area bridge deck of the steel-UHPC composite beam cable-stayed bridge according to claim 1, wherein the arrangement position of the beam falling control point is corresponding to the transverse diaphragm of the composite beam.
4. The method for improving the crack resistance of the auxiliary pier and the tail rope area bridge deck of the steel-UHPC composite beam cable-stayed bridge according to claim 1, wherein the compressive stress 'sigma t +σ △ ' generated by the control section when the beam falls is smaller than the compressive stress sigma ZZ of the bridge deck of the control section under the action of dead weight.
5. The method for improving the crack resistance of the auxiliary pier and the tail rope area bridge deck of the steel-UHPC composite beam cable-stayed bridge according to claim 1, wherein the maximum deflection value delta ZY during beam falling is smaller than the maximum deflection value delta ZZ under the action of dead weight.
6. The method for improving the crack resistance of the auxiliary pier and the tail cable zone bridge deck of the steel-UHPC composite beam cable-stayed bridge according to claim 1, wherein the self-weight load coefficient gamma is a coefficient for correspondingly reducing the self-weight load when the compressive stress generated by the control section is sigma t +σ △ .

Description

Method for improving crack resistance of auxiliary pier and tail cable zone bridge deck of steel-UHPC composite beam cable-stayed bridge Technical Field The invention relates to the technical field of bridge engineering, in particular to a method for improving crack resistance of auxiliary piers and tail rope area bridge decks of a cable-stayed bridge with steel-UHPC combined beams. Background The ultra-high performance concrete (UHPC) has the advantages of light dead weight, high strength, small later shrinkage, good crack resistance, impermeability and durability indexes, and is gradually applied to various main stress structures in the engineering industry at present along with the continuous deep exploration of UHPC and the gradual maturation of the preparation technology. The main beam in the composite beam cable-stayed bridge is formed by connecting two parts of a concrete bridge deck and a steel main beam through shear keys, the concrete bridge deck adopts UHPC material, so that the thickness of a concrete slab can be greatly reduced, the self weight of the structure is obviously lightened, the stress requirement of the ultra-large span composite beam cable-stayed bridge is met, and the economic and applicable span range of the composite beam cable-stayed bridge is further enlarged. The main span suitable for the steel-UHPC composite beam cable-stayed bridge is large, and the auxiliary piers are arranged on the side spans, so that the overall rigidity and the earthquake resistance of the bridge can be effectively improved, and the overall stress of the bridge can be improved. The support constraint of the auxiliary pier under the load actions of automobiles, temperature, wind and the like in the operation period can enable the combined beam to generate a hogging moment, and the influence range covers the auxiliary pier area and the side span tail rope area. When the negative bending moment is too large, and the tensile stress of the bridge deck is larger than the initial cracking tensile strength of UHPC, the bridge deck is cracked, the normal use and durability of the bridge are affected, and reliable measures are needed to apply compressive stress to improve the cracking resistance of the bridge deck in the auxiliary pier and the side span tail rope area. The common measures for improving the crack resistance of the bridge deck of the auxiliary pier region and the side span tail cable region of the combined beam cable-stayed bridge are that an in-vivo or in-vitro prestress steel beam is arranged, and an auxiliary pier single-pivot displacement method is adopted. The compressive stress applied to the section of the combined beam through stretching the steel beam is partially applied to the steel beam, the application efficiency of the prestress of the bridge deck plate is low, the consumption of the steel beam is large, the economical efficiency is poor, and as the span is increased, the tensile stress of the bridge deck plate in the auxiliary pier and the side span tail rope area is larger, the consumption of the steel beam is suddenly increased in an application mode with low efficiency, but the prestress requirement of the bridge deck plate cannot be met. The fulcrum displacement method adopts the preset upward displacement at the fulcrum of the auxiliary pier, the erection of the combined beam and the installation of the stay cable are completed according to the set line shape, the upward displacement of the fulcrum is removed, the falling beam applies the pre-compression stress to the bridge deck, the combined beam Liang Guasuo is of a continuous structure with a multipoint elastic support after the completion, the falling beam at the fulcrum is restrained by the stay cable, the applied pre-compression stress is small in range and low in efficiency, and the compressive stress can not be effectively applied to the bridge deck outside the auxiliary pier and in the side span tail cable area. The existing measures have larger limitation on improving the crack resistance of the bridge deck plate in the auxiliary pier region and the side span tail cable region of the cable-stayed bridge of the steel-UHPC composite beam. Disclosure of Invention In order to overcome the defects of the background technology, the invention aims to provide a method for improving the crack resistance of the auxiliary pier and the tail rope area bridge deck of the steel-UHPC combined beam cable-stayed bridge, which does not adopt a stretching prestressed steel beam or a single-pivot falling beam, can apply compressive stress to the bridge deck in a large range with high efficiency, high precision and high operability, effectively plays the high compression resistance of UHPC materials, improves the crack resistance of the auxiliary pier and the side span tail rope area bridge deck of the steel-UHPC combined beam cable-stayed bridge, and ensures the durability and the safety of the structure. In order to further achieve the