MECHANICAL PROPERTIES ANALYSIS OF U-SHAPED STEEL PLATES OF DIFFERENT HARDNESS AND NUMBERS OF LAYERS

U-shaped steel plates (USPs) can be used for displacement restraining devices or dampers. Single push and push-pull static tests of four kinds of USP made by mild steel or hardened steel were completed. The tests show that thick USPs made by hardened steel fracture easily. Hardened steel USPs provide greater yield load and yield displacement and are more suitable for displacement restraining devices than mild steel ones. Hysteresis curves of hardened steel USPs showed typical spindle shape, and the load increased significantly after yielding. Hysteresis curves of mild steel USPs are parallelograms, and the load increased a little after yielding. Formulae of yield load, yield displacement and elastic stiffness for laminated U-shaped steel plates (LUSP) are derived. Four USPs and four LUSPs were designed and analyzed by Abaqus. The calculation of finite element fits the theory well. The ratios of LUSP to USP in terms of elastic stiffness, yield load and yield displacement are 1/n², 1/n and n, respectively.