| Corrugated steel webs is a new steel-concrete composite structure to its light weight, high prestressing effect, high material use efficiency, structure is beautiful and reasonable stress and other advantages, more and more be applied in practical engineering. For the large span cross-section of corrugated steel webs PC composite box girder bridge, how to solve the high web buckling bearing capacity problem is the primary issue to improve the span. In this paper, based on the the Lanzhou Yanbai Yellow River bridge, starting with the shear stress of the steel plate with variable cross-section, research on shear buckling bearing capacity of corrugated steel webs, The main research contents are as follows:1. The structure and stress characteristics of PC composite box girder bridge with corrugated steel webs and the research status of buckling stability at home and abroad are summarized. The main content, purpose and significance of this paper are introduced;2. From the means of the elastic force balance of combined with variable cross-section structure and stress characteristics,derived variable cross-section girder shear stress calculation formula, respectively on cantilever beam calculation cases and real bridge with steel web plate shearing stress theory and finite element method, due to the variable cross-section effect of the existence of bending moment at the variable section beam segment of additional shear stress makes its computation result is less than the shear stress calculation formula in material mechanics. The calculated two calculation cases of steel webs along the height direction of the web, the maximum shear forces are not in the center section of the shaft, cantilever beam count cases in the numerical along the span direction distribution with the distance from the root section distance reduce and gradually downward from the upper edge position, and continuous box girder with corrugated steel webs on the side span side the value with the distance from the support root section distance decreases gradually downward movement, in the cross side the numerical with distance in bearing the cross section of the root distance increases at first and then upward and downward after.3. Calculation of beam section parameter values of variable cross section webs shear stress effect, root section beam and the thickness of the web plate of variable cross section webs shear the greatest impact, the cross section of the root and cross section of the beam height and span length ratio on the edge, in the span of the largest shear should influence of the force position is high;4. Summed up the part of the scientific research test and specification of buckling strength calculation formula, on the selection of real bridge calculation cases of steel web buckling strength calculation, to achieve the plate buckling strength value as the critical value of the buckling strength of the steel webs. This numerical calculation steel webs shear stress reaches a critical flexion bending strength values uniformly distributed load size, the load value is the maximum shear buckling bearing capacity, combined with ANSYS analysis of linear elastic buckling bearing capacity calculation result is theoretical calculation value of 4.9 times, indicating that the specification of the buckling strength calculation formula of safety and reliable.5. Buckling strength of the steel webs combined with variable cross-section beam shear force and buckling bearing capacity calculation are lined with concrete pouring length and thickness values by calculation results get lining concrete pouring length should according to reach the buckling strength of steel webs of critical steel webs height value is determined and the thickness of the lining concrete values should not be set more than 50 cm, 20~35cm for Lanzhou Yanbai Yellow River Bridge of lining thickness of concrete proposals. |
