Abstract
To study the shear force distribution laws of a box girder with a single-box multichamber (SB-MC) configuration for different supporting conditions, numbers of webs, stiffness of end diaphragm, and web thickness values, a box girder with SB-MC was numerically simulated using three-dimensional finite element model. According to the comparison results of web shear force, the concept of η, a shear-increased coefficient for webs, was introduced. The results show that supporting conditions and chambers have a significant impact on the shear-increased coefficient η, and end diaphragm must be set up in the 3D finite element model when calculating η. Nonlinear analysis shows that in the elastic phase, the shear-increased coefficient η basically does not change, but in the cracking stage, the coefficient η of each web changes with the degree of web cracking, and side-webs (S-Webs) reach the ultimate load first. The variation of the web thickness hardly affects the distribution of the shear force, so the method to adjust the web thickness of S-Web was proposed according to the result of shear-increased coefficient η to improve the shear resistance of the box girder.
Highlights
Box girder is an important type of bridge structure
Twenty groups of cross sections of the box girder were taken at intervals of (1.3 + 18 × 1.0 + 1.3) m from the midpoint of the bridge midspan to both sides of the bearing along the portrait direction of the bridge to analyze the shear distribution of each web in the portrait direction
In the elastic model, the shear distribution of the single-box multichamber (SB-MC) box girder was examined for different support conditions, the number of webs, the stiffness of end diaphragm, and the thickness of the web
Summary
Box girder is an important type of bridge structure. For box girder, many scholars have conducted research on shear lag, effective width [1,2,3,4,5], and live load distribution factors [6,7,8].ere are multiple webs in the cross section of a single-box and multichamber (SB-MC) box girder, and their spatial mechanical behavior is complicated. e laws of their shear distribution have important significance and value to effectively ensure the excellent work of the web.To study the shear resistance, failure modes, and internal force redistribution of box-shaped bridges, the finite element model of the box girder was established and numerically analyzed [9]. is study revealed the effects of factors such as the shear-span ratio, concrete strength, stirrup ratio, and web thickness on the failure modes and shear capacity of the box girder.e shear resistance of the box girder was experimentally analyzed [10]. e results show that it is unsafe to use the equivalent I-beam to calculate the shear capacity of the box girder. en, methods based on the modified pressure field theory were compared with the experimental results, including the double-section method, single-section method, simplified analysis method, and finite element method. e conclusion is that the analysis methods based on the modified pressure field theory could better predict the shear capacity of box beams.A comparative analysis of the shear design codes of various countries was carried out, and the influence of various influencing factors on the calculation of shear capacity of different national codes was analyzed [11].ere were few results on the shear distribution in the webs of the box girder with SB-MC, so the regular processing method [12,13,14] is each web shares the shear force in the shear calculations of the box girder. To study the shear resistance, failure modes, and internal force redistribution of box-shaped bridges, the finite element model of the box girder was established and numerically analyzed [9]. Is study revealed the effects of factors such as the shear-span ratio, concrete strength, stirrup ratio, and web thickness on the failure modes and shear capacity of the box girder. En, methods based on the modified pressure field theory were compared with the experimental results, including the double-section method, single-section method, simplified analysis method, and finite element method. Based on the summary of actual sharing of shear forces of each web, the Advances in Materials Science and Engineering laws of shear distribution of the box girder are obtained, and related design suggestions are proposed
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