土–上部结构相互作用的实用分析模型研究

 讨论现有土–上部结构相互作用分析模型的优缺点，从工程应用的实际需要出发，建立土–上部结构相互作用的实用分析模型及分析方法：采用三维弹塑性杆系模型模拟上部结构，在基础底面放置水平、竖向及转动的弹簧和阻尼单元来模拟土与基础的接触作用，通过弹簧和阻尼参数的改变来模拟不同的场地等状况。用该种方法计算分析一个10层的独立基础钢筋混凝土框架结构，研究场地土剪切波速、上部结构刚度和地震动强度等因素对相互作用体系地震反应的影响，同时探讨各种情况下的结构地震能量反应规律。研究结果表明，对于独立基础钢筋混凝土框架结构来说，考虑相互作用后场地变软和上部结构刚度增大不一定使楼层顶层位移增大，但是软弱场地对结构起到一定的减震作用，并且增大上部结构刚度会使楼层剪力和弯矩有所增加；地震动作用下，上部结构刚度改变对能量的变化趋势影响很小，但是在不同影响因素下的结构阻尼耗能和结构变形能在体系能量的平衡中的作用都是主要的；改变地震强度时，不同的地震波对相互作用体系的能量的影响是不同的，阻尼耗能和结构变形耗能的作用会有所不同。

STUDY ON PRACTICAL ANALYTIC MODELS FOR SOIL-STRUCTURE INTERACTION

Relative merits and demerits of existing soil-structure interaction analysis models are discussed，and a new analytic model is presented based on practical engineering application. The three-dimensional elastoplastic bar model is used to simulate the upper-structure，and the contact between soil and base is simulated by using horizontal，vertical and rotary springs and dampers below the base，with different field categories being reproduced by changing the spring and damping parameters. Dynamic soil-structure interaction of a ten-story RC frame building is analyzed by utilizing the model established with the new method，through which effects of several factors，such as the foundation soil¢s shear wave speed，the rigidity of upper-structure，and the earthquake magnitude on seismic response of the interaction system are evaluated，and then the pattern of the energy dissipation under different situations is discussed. Analytical results show that roof displacement does not certainly increase when softer site or stronger rigidity of upper-structure with soil-structure interaction being taken into account，but softer site can decrease the seismic response，and augmenting the rigidity of upper-structure may increase the shear force and the bending moment. Although the change of upper-structure¢s rigidity affects little on energy¢s changing trend of interaction system，damping energy and strain energy of the upper-structure are the main dissipated energy of the soil-structure interaction system under different situations. When the earthquake magnitude changes，there are some different influences on the energy dissipation of the interaction system under different earthquake waves，and the function of damping energy and strain energy may be different.