Relocation of plastic hinge in steel beam using Shape Memory Alloy

Abstract

Steel framed structures with different types of frames are very widely used in low and midrise buildings around the world. Among all the steel frames moment resisting frames (MRF) are most popular ones which can provide large clear spans as bracing systems are absent in these types of frames. The study of past seismic events implies that the connections are vulnerable under lateral seismic loads. As bracings are not provided in moment resisting frames, the main components which support the lateral loads in the frame are the beam column connections. The failure prone critical location in steel frames is the beam column connection having possibility of brittle failure. To avoid this, efforts are being taken to shift the position of plastic hinge from beam column junction. In this research a new composite beam of NiTi and Steel is developed which absorb the dynamic load and develops a pseudo hinge in NTi Material. This avoids the damage at junction under seismic load. On unloading after the seismic event the yielding developed in NiTi in the beam gets recovered and beam regains the original shape. This happens due to the special property of NiTi, which is known as super elasticity. This is a stress induced property in which material sustains the loads because of superelasticity. The performance of this novel connection is compared with steel connection. The NiTi connection shows superior performance showing 80-95 % recovery.