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在假定地基水平抗力系数在地面处为零并随深度线性增加的条件下,将基础——桥墩作为一个结构系统,研究了自振频率、振型函数和用反应谱理论计算地震荷载作用下内力和弹性位移的比较实用的计算方法,在DJS-6机上对一个具体桥墩,对地基系数的比例系数m和其它有关计算参数取不同值的情况,进行了计算,分析了此系统自振频率和地震荷载下的内力、地基抗力,墩顶弹性位移随m值变化的关系。并与沉井顶面近似作为刚性固定端的计算结果作了比较。发现随地基m值的降低,基础——桥墩系统的频率、内力和地基应力亦将降低,但墩顶弹性位移则大幅度增加。指出在软土地基中桥墩墩顶位移是控制抗震设计的因素之一。用Jacobsen附加质量法考虑了液化体的影响,比较计算结果后可看出略去其影响是偏于不安全的。另外在分析了用线弹簧模拟长钢轨的约束作用的计算结果后,讨论了线弹簧刚性固定计算模型所存在的问题。
Under the assumption that the foundation horizontal resistance coefficient is zero at the ground and increases linearly with depth, the foundation-bridge pier is regarded as a structural system. The natural frequency, mode shape function and response spectrum theory are used to calculate the internal forces And the elastic displacement of a more practical method of calculation, on a DJS-6 machine for a specific piers, the coefficient of the foundation coefficient of the coefficient m and other relevant parameters to take different values, the calculation of the system natural frequency and The relationship between the internal forces under earthquake load, the foundation resistance and the elastic displacement at the pier top with the value of m. And compared with the calculation results of caisson top surface approximation as rigid fixed end. It is found that with the decrease of foundation m, the frequency, internal force and foundation stress of foundation-pier system will also decrease, but the elastic displacement of pier top will increase greatly. It is pointed out that displacement of bridge piers in soft ground is one of the factors that control the seismic design. The influence of liquefied material is considered by Jacobsen’s additive mass method. Comparing the calculated results shows that it is insecure to omit its effect. In addition, after analyzing the calculation results of restraining action of the long rail by the wire spring, the existing problems of the rigid fixed calculation model of the wire spring are discussed.