Introduction and seismic performance investigation of the proposed lateral bracing system called “OGrid”

In this paper proposed bracing systems for earthquake resistant steel structures are introduced and studied through an experimental program and FEM (finite element method) numerical analysis. These proposed bracing systems called OGrid, by two types as the OGrid-I and the OGrid-H, are braced frames with circular braces connected to MRF (moment resisting frame) with joint connections. Linear and nonlinear behavior of the new OGrid bracing systems are studied and compared with X-bracing system, and MRF in one story base models. To achieve the linear and nonlinear behavior of models, response spectrum analysis and nonlinear static (pushover) analysis are used by FEM. Results showed that new OGrid bracing systems have appropriate vibration period, elastic stiffness and displacement. Absorbed energy of the proposed OGrid-I and OGrid-H bracing systems in comparison with MRF is 1.74 times and in comparison with X-bracing system is 34.8 times. The OGrid-I and OGrid-H bracing systems have more ductility and have great distance between relative deformation of the structure in yield strength level and the maximum relative deformation of structure after entering the plastic region, which cause to dissipate much lateral loads, and there is a great distance between first hinge formation and the moment that structure collapses.