中文摘要：

根据简支体系的受力特点，提出采用刚度折减法快速计算非线性动力分析中二阶效应的方法，通过解析法推导出考虑P-δ效应的Euler-Bemoulli梁刚度修正系数，且给出了Timoshenko梁的P-δ效应刚度修正系数。编制相应计算程序，将所得修正系数引入结构Pushover计算和直接积分的非线性动力时程计算，并将该法应用在实际桥梁抗震计算中。各种计算结果与采用增量迭代法的高精度实体单元结果进行了对比分析，结果表明，采折减刚度系数法能够有效、准确地计算结构动态二阶效应；Timoshenko理论中的二阶效应计算要比Euler-Bernoulli理论的更为准确；在地震作用下梁结构中二阶效应会被放大，必须考虑其对结构的影响。

英文摘要：

Based on mechanical characters of the simply supported bridges, the method with stiffness correction coefficient for quick calculating the P-δ effect in nonlinear seismic analysis was presented.The stiffness correction coefficient which fits to Euler-Bemoulli beam theory considering the P-δ effect was derived in analytic method. On this basis the stiffness correction coefficient for Timoshenko beam theory was also derived. The stiffness correction coefficient was introduced to the Pushover analysis and the direct integration method of nonlinear dynamic timehistory calculation with the compiled program, and the method was applied to the calculation of the bridge seismic resistance. Compared with results using the high precision solid element analysis with increment iteration, it is concluded that （ 1 ） the method with tangent stiffness correction coefficient is a simple, effective method to solve the problem with second-order effect; （2） the results in Timoshenko beam theory is more accurate than results in Euler -Bernoulli beam theory; （3） during earthquake, second-order effect of the structure can be magnified, its role should not be neglected.