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2 Archives of Civil and Mechanical Engineering

2 2018

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Shear strength degradation of steel plate shear walls with optional located opening

Afshari M. J., Gholhaki M.

Archives of Civil and Mechanical Engineering

2018

Vol. 18, no. 4

1547--1561

Regarding high ductility and potential of steel plate shear walls in energy absorption, they are required to be very thin in thickness especially in upper floors of the building in order to resist lateral loads and sometimes it will reach to a fraction of millimeter in calculations. Since preparation of such thin steel plates is not simply possible, a thicker plate with an opening can be used to reduce stiffness. On the other hand, the existence of opening is inevitable due to architectural considerations such as lighting. In the present paper, shear strength of steel plate shear wall with openings in different zones has been studied by finite element method. As a result, an empirical simple dimensionless equation has been presented to estimate accurately the amount of decrease of shear strength of the wall with an arbitrary opening position in any zone of the plate. To validate the accuracy of suggested relation, numerous finite element models have been simulated with different geometric properties such as shape, diameter, location of opening, thickness and span to height ratio of plate. Comparing results with that of suggested relation and corresponding values of theoretic relations shows the accuracy of the proposed relation for applying in a wide range of steel plate shear walls with different geometric specifications.

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

Boostani M., Rezaifar O., Gholhaki M.

Archives of Civil and Mechanical Engineering

2018

Vol. 18, no. 4

1024--1041

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.