Seismic Performance of Steel Frames with Shape Memory Alloy (SMA) Bracing System

Abstract

Lateral load resisting capacity of the building can be improved by the application of steel braces and are widely using since 1994 Northridge and 1995 Hyogoken–Nanbu Earthquakes. Usage of steel braces reduces the interstory drifts during earthquake excitations. However, severe earthquakes may cause reduced ductility and energy dissipation in braces due to buckling, which results in residual drifts. Excessive residual drifts makes structure retrofit or even render them irreparable. To overcome these limitations, brace equipped with shape memory alloy (SMA) that provides both re-centering and energy-absorbing capabilities is developed. SMA have the potential to recall a preset shape even after severe deformations which make them widely use in various smart material applications. Shape memory alloys are metallic alloy that has the ability to undergo large deformations (strains up to 10%) while reverting back to its original undeformed shape providing re-centering capacity to the brace by significant energy-absorbing capacity with zero residual strain and is called super-elasticity. SMA braces are effective in limiting interstory drifts and residual drifts during an earthquake which improves the seismic stability of structures. This paper presents a study on efficiency and feasibility of enhancing seismic performance of frames by the use of SMA with different configuration of braces.KeywordsSMAShape memory alloySeismic resistant structureBrace system