Seismic evaluation of BRBF steel structures with L-shaped irregular plan considering soil-structure interaction

Architectural aspects of buildings, such as the shape of the plan, play an important role in defining the seismic behavior of the building and the future damages structural and non-structural elements may go through. Several items, like the aesthetic aspects and limitations in the field under construction, make an irregular plan shape to be selected as a desirable option. Correctly understanding the building’s behavior on the irregular plan is necessary in this case. With that being said, this research aims to evaluate the seismic performance of buckling restrained braced frames (BRBFs) steel structures having an L-shaped irregular plan. An irregular L-shaped plan amplifies the torsional response of the building and causes stress concentration because of the re-entrant corners. Since the lack of a comprehensive study on the L-shaped plan irregularity in buildings equipped with BRBs and the effect of Soil-structure interaction (SSI) would be felt, three types of buildings, low-, mid-, and high-rise, were considered to study the demands of this system on an L-shaped plan. SSI effects were also considered by the cone method in the frequency domain for a more accurate evaluation of the building’s behavior during an earthquake event. Each building is studied having three different base conditions: 1- fixed base, 2- SSI with soil type C, and 3- SSI with soil type D. Structural demands, including base shear, overturning and torsional moment, lateral displacement, inter-story drift, and column capacity were measured for different models with fixed and flexible bases by performing time history analyses. The results signify the significant SSI’s impact on the building’s demands.