EXPERIMENTAL AND ANALYTICAL EVALUATION OF SEISMIC RESPONSE OF A STEEL STRUCTURE WITH AND WITHOUT SHAPE MEMORY ALLOY DAMPERS

摘要

Recently, there has been increasing interest in using super-elastic shape memory alloys for applications in seismic resistant design. Shape memory alloys (SMAs) have a unique property by which they can recover their original shape after experiencing large strain upto 8 % either by heating (shape memory effect) or removing stress (Pseudo-elastic effect). In the present study a new device is made with austenitic SMA wires which dissipate energy when axially stressed in tension. This device uses collets which tightens the grip on the wire. Extensive tests are done on the wires and device at various frequencies and amplitudes of loading. Since this device represents a nonlinear hysterical dynamic system a physically based simplified SMA model considering the residual martensite strain effect is developed. An experimental program of shaking table tests on reduced scale model of a steel structure supporting a tank, is carried out for assessing the capability of SMA wires in dissipating energy. This paper presents a comprehensive overview of the main results of the shaking table tests performed on the steel structure without SMA Dampers and the analysis results for the frame with SMA wires. Initially sine sweep tests are carried out and then the frame is subjected to spectrum compatible earthquake loading with increasing peak base excitation from 0.05 to 0.2 g. Lastly a comparison is made between experimental and analytical response. The addition of dampers in the braces of steel framed structure resulted in significant benefits on its overall seismic behaviour.