主次结构相互耦合下楼层反应谱的频域分析

直接从由建筑物和设备组成的主次结构耦合系统各自的动力特性出发,考虑主次结构间调谐、干扰、非经典阻尼等因素的影响,推导出频率传递函数和次结构的加速度均方根响应,并由此进一步得到楼层的加速度均方根反应谱。这一方法避免了求解联合系统的复特征值和动力方程出现病态等问题,大大简化了计算过程。最后在算例中就次结构的阻尼比、质量比、安装楼层及场地土等因素对楼层加速度均方根反应谱的影响进行了讨论,算例表明,质量比是决定能否采用古典谱的关键因素,场地土对反应谱的影响也不容忽视。

THE ANALYSIS OF FLOOR RESPONSE SPECTRUM IN EQUIPMENT-STRUCTURE INTERACTION FORM IN FREQUENCY DOMAIN

Based on the dynamic properties of the primary-secondary coupling structural system composed of an equipment and a structure,the frequency transfer function and the root mean square of acceleration response of the equipment are deduced directly,and the factors including tuning,interaction and non-classical damping have been taken into consideration in the process of deduction.Furthermore,the floor response spectrum of the root mean square of acceleration is obtained.Since the calculation of the complex eigenvalue problem and the ill-conditioned equation of motion of the combined system are avoided in this approach,the procedure of calculation is simplified greatly.In the end,the influencing factors on the floor response spectrum are discussed,including damping ratio,mass ratio,the location of the equipment and the soil of the building site.As shown in the numerical example,the mass ratio is the key factor in deciding whether the classical floor response spectrum may be used or not,and the influence of the soil of the building site should not be ignored.