土—端承桩—结构相互作用对连续梁桥自振特性的影响

THE INFLUENCES OF INTERACTION BETWEEN SOIL, END BEARING PILE AND STRUCTURE ON THE FREE VIBRATION BEHAVIOR OF CONTINUOUS BRIDGE

本文根据连续介质力学理论,用传递矩阵法求得分层土端承桩的阻抗函数。由于桩基础的阻抗函数随频率变化,所以结构的刚度矩阵也是频率的函数。为求解非线性特征值问题,采用了逐步逼近的方法,反复调用广义雅克比程序,直到求得真实的自振频率和振型为止。将本文的计算结果和刚性地基的计算结果作了比较表明:考虑桩基础参与振动时求得的自振频率和振型变化较大,还没有达到可以忽略的程度。

The impedance function of the end bearing pile in stratified soil has been obtained by the method of transfer matrix according to the theory of continuous medium mechanics. The structural stiffness matrix is the function of frequency because that the impedance function of the pile foundation changes with its frequency. In order to solve the value of nonlinear characteristic, an asymptotic method is adopted and the Jaeobi's program is carried out repeatedly until the real frequency of free vibration and its model arc obtained. After the comparison between the results calculated by the method presented in this paper and that of a stiff foundation, it has been found that the frequency of free vibration and vibration model calculated in consideration of that the pile foundation participates in the vibration were changed significantly. Such differences could not reach the extent to be negleted.