双轴压弯作用下RC桥墩矩形空心截面性能评价

BEHAVIOR EVALUATION OF RECTANGULAR HOLLOW CROSS-SECTION OF RC PIERS SUBJECTED TO AXIAL COMPRESSION AND BIAXIAL BENDING

针对双轴压弯作用下钢筋混凝土(RC)空心截面性能评价问题,该文根据双轴压弯作用下RC矩形空心截面中和轴布置的不同形式,推导了双轴压弯作用下其承载力计算公式和曲率计算公式。对双轴压弯作用下轴压比、配筋率和配箍率不同的3个RC矩形空心截面试件体桥墩的墩底控制截面,进行了承载力和转动延性分析,得出其在给定轴力作用下的Mx-My曲线和弯矩-曲率曲线,并通过其双轴压弯循环荷载试验,验证了分析结果的正确性和精确性。在此基础上,对一连续刚构桥梁的RC矩形空心桥墩的承载能力、截面转动延性以及相关参数进行了分析。结果表明,双轴压弯作用下两主轴方向弯矩耦合作用降低了截面的极限承载能力,单轴压弯作用的截面设计对结构是偏于不安全的;随中和轴与某一轴夹角的增大,该轴极限弯矩和曲率逐渐减小,而沿另一主轴方向的极限弯矩和曲率逐渐增大,但均小于其强轴方向的极限弯矩和转动曲率,该文的结论可为RC矩心空心截面桥墩的抗震设计和性能评价提供参考。

In order to evaluate the behavior of reinforced concrete(RC) rectangular hollow cross-section of bridge piers under axial compression and biaxial bending, the paper derives the calculation formula for loading capacity and moment-curvature relationship according to the distribution type of neutral axial. The loading capacity and rotation ductility of the bottom control section of three RC specimen bridge piers with rectangular hollow cross-section under different axial compression ratio, reinforcement ratio and stirrup ratio are analyzed based on these calculation formulas. The Mx-My curves and moment-curvature curves are obtained under a given constant axial force. The theoretical analytical results are proved to be accurate through a comparison with experimental results of cyclic testing of three RC bridge pier specimens under axial compression and biaxial bending. The load capacity and deformation of continuous rigid frame bridge with RC rectangular hollow cross-section columns are analyzed. The results show that the coupling effect between Mx and My reduces the load capacity of bridge piers and the design for hollow cross-section is unsafe considering uniaxial load and bending only. With the increasing of the angle between neutral axial and one principle direction, the ultimate moment andcurvature along that direction increase, while along the perpendicular direction they decrease. The research results can be utilized for seismic design and behavior evaluation of RC bridge columns with rectangular hollow cross-section.