Effect of soil on the seismic response of concrete structures with steel X-bracing

In recent years, the use of steel bracing system in reinforced concrete structures has expanded. The bracing system can also be used effectively to improve existing concrete structures. Considering the soil -structure interaction in the analysis of the structure compared to the case where the soil of the substructure is considered rigid causes a change in the behavior of the structure during seismic excitation. The present study is the result of a realistic approach to the problem of soil effects on the seismic behavior of concrete structures with steel bracing. In this research, considering the 6-story concrete structure, improved with X-bracing on three types of soil C, D and E according to ASCE7-16 standard, under appropriate earthquake records, the effect of soil-structure interaction has been investigated. In modeling, nonlinear behavior is assumed for structure and linear and nonlinear behavior is assumed for soil and nonlinear dynamic analysis of soil -structure interaction is performed using direct method and two-dimensional geometric modeling in Opensees software and the response of structure by considering two The rigid base and the flexible base are compared. The results show that considering the soil -structure interaction in models improved by steel bracing according to the type of soil, increases the period in some cases up to about 72% and reduces the base shear to about 49% compared to the rigid bed in the structure.