有限刚度基础对掉层框架结构受力与变形性能的影响研究

Based on the actual engineering characteristics of step-terrace frame structure that the upper foundation is mostly slope soil, the performance of a 6-story step-terrace frame with fixed-base and flexible-base conditions is evaluated. The characteristics of the flexible-base models cover three types of soils, namely, medium hard soil, medium soft soil and soft soil. The soil spring model from the US technical report NIST 12-917-21 is adopted to represent the soil condition. This study uses SAP2000 finite element software to analyze the response of the structure. The analysis shows that the torsion displacement ratio is significantly reduced when considering the upper foundation stiffness.But the inter-story drift angle increases obviously in the part where the layer is dropped, especially in the upper ground story. Meanwhile, The structural story shearing force increases obviously in the falling part, that is, the falling part bears more horizontal force. The softer the foundation soil, the more obvious the effect of the above results.