基于软化薄膜元理论的波形钢腹板PC组合箱梁纯扭全过程分析

Full-range analysis of prestressed composite box girders with corrugated steel webs subject to pure torsion based on softened membrane theory

为解决波形钢腹板PC组合箱梁在纯扭作用下的全过程受力问题,基于软化薄膜元模型(SMMT),结合该桥型的结构及受力特点,建立了一组充分满足平衡条件、变形协调条件及材料本构关系的方程组,根据波形钢腹板未屈服与已屈服两种情况,方程中分别以剪力流连续与剪应变连续来描述钢腹板与混凝土翼板之间的协调关系。在此基础上,给出了求解上述方程组的程序框图,由此建立了针对波形钢腹板PC组合箱梁的纯扭全过程分析模型。对8根已有试件进行验证,结果表明:模型预测的全过程扭矩-扭率曲线与试验曲线吻合良好,包括开裂前的上升段及达到极限状态后的下降段,同时二者在开裂和极限状态下的扭矩与扭率值也非常接近,由此证明了该模型的有效性与准确性。

In order to study the full-range mechanical behavior of prestressed composite box girders with corrugated steel webs subject to pure torsion, a series of equations satisfying the equilibrium, compatibility conditions and constitutive laws of materials were established based on the softened membrane model for torsion（SMMT） and the structural features and the mechanical characteristics of the type of bridge. According to the yielding state or the unyielding state of the corrugated steel web, the continuous shear flow and continuous shear strain conditions in the equations shall be employed to describe the relationship between the steel web and the concrete flanges. Furthermore, the flow chart of solving the equations was given, and thus, the full-range analytical model for prestressed composite box girders with corrugated steel webs subject to pure torsion was proposed. Eight specimens from the literatures were selected for verification of the model. The results show that the entire torque-twist curves, including the ascending stage before cracking of concrete and the descending stage after the limit state, agree well with the experimental curves. In addition, the torque and twist values in both cracking and limit states predicted by the model are close to those from tests, validating the effectiveness and accuracy of the proposed model.