钢筋混凝土箱梁横向受力有效分布宽度的非线性分析

NONLINEAR ANALYSIS OF THE EFFECTIVE DISTRIBUTION WIDTH OF TRANSVERSE INTERNAL FORCE IN REINFORCED CONCRETE BOX GIRDER

对钢筋混凝土单箱单室箱梁顶板、翼缘板开裂进入非线性阶段后横向受力特点及横向受力有效分布宽度的发展规律进行了详细的论述;对两种典型边界条件下翼缘板的横向受力有效分布宽度的发展进行了比较。数值计算结果表明:考虑结构开裂后的材料非线性影响后,横向受力有效分布宽度的发展和相应的弹性值之间存在较大差异,从应力水平来看采用钢筋屈服前的最大横向受力有效分布宽度进行设计是合理的,顶板及翼缘板的横向受力有效分布宽度可在我国现行规范JTG D62的基础上提高40%。对于翼缘板而言,支承边界的改变也同样影响横向内力的分布,横隔板附近的翼缘板由于受刚性约束的影响其横向受力有效分布宽度按规范的50%设计比较合理。根据有限元参数分析结果,提出了钢筋混凝土箱梁顶板在混凝土开裂后弹塑性阶段的横向受力有效分布宽度的概念及以其进行设计的新方法,并与国内外相关桥梁规范进行了比较。

The transverse internal force in the flanged top panel of single-box and single-cell reinforced concrete box girders after concrete cracking is discussed, and the nonlinear behavior of the effective distribution width in the panel is presented. The effective distribution widths in the flanges under two different boundary conditions are also analyzed. The numerical result shows that, in contrast to the case of linear-elastic solution, there existed a significant difference when the material non-linearity effect and boundary condition were considered. The numerical result also shows that, based on the stress level of the concrete and reinforcement, it is rational to increase the effective width obtained from the present bridge code JTG D62 up to 40 percent for the design of the top panel, while in another case, because of the rigid restriction of the diaphragm, it is reasonable to decrease the effective width of the present bridge code to an extent of 50 percent for the design of flange near the diaphragm. Based on the parametric study, the elastic-plastic effective distribution width concept is proposed, and a revised method of evaluating box panel＇s effective transverse width considering concrete cracking is presented and compared with those bridge codes at home and abroad.