بررسي اثرات رفتار غيرخطي خاك بر پاسخ ديناميكي سازه هاي بلند

Evaluation Of Soil Nonlinear Behavior Effects On Dynamic Response Of High Rising Structures

There is evidence documented in numerous case histories, which indicate that, when earthquake occurs, presence of soil media underlying the base of structures and corresponding dynamic soil-structure interaction may increase the seismic forces applied on structures, which at many cases may result in the collapse of structures. This paper intends to evaluate and discuss the nonlinear soil behavior effects on dynamic response of high-rise buildings, considering dynamic soil-structure interaction. This evaluation is necessary, because of its effects on the estimation of seismic applied forces on the structure, and consequently on the design of the structural elements. To this end, various models of dynamic soil-structure interaction systems, with different geometrical, behavioral parameters, and seismic environments are assumed and analyzed with the well-known Subtraction Substructure Method. Having performed the mentioned analyses, variation of spectral acceleration response of the structure, versus the dominant parameters of the problem, such as the ratio of structure stiffness to soil stiffness and maximum input acceleration, is evaluated and the obtained results are compared with conventional dynamic response analysis results. The outcome of aforementioned studies quantitatively indicates that dynamic nonlinear behavior of soils underlying the base of structures, particularly for high-rise buildings constructed on soft soils, may considerably increase the dynamic response of structures. At some cases, this increment is so large that for evaluation of seismic applied forces on structures, it is required to perform dynamic soil-structure interaction analysis. in this case, the results obtained from conventional dynamic response analysis approach may lead to unreliable design of structures.