FINITE ELEMENT ANALYSIS FOR ULTIMATE CYCLIC BEHAVIOUR OF CONCRETE-FILLED TUBULAR STEEL PIERS WITH GRADE SM570 HIGH STRENGTH STEEL

Abstract

 Steel piers with grade SM570 high strength steel are normally proportioned in design under a requirement that their seismic responses remain in the elastic range. This is chiefly because the available data about the plastic behavior of SM570 steel is too scarce to be utilized in the damage-controlled seismic design. Recently, a series of cyclic loading tests were conducted to examine the elastic-plastic ultimate behavior of concrete-filled tubular SM 570 steel piers, referred to as SM570 CFT piers. Herein, an advanced analysis method originally presented by authors for normal CFT piers was modified and calibrated based on the cyclic loading test results on the SM570 CFT pier specimens and a newly conducted cyclic loading test results on SM570 steel. This is to provide an analytical tool to assess the hysteretic ultimate behavior of the SM570 CFT piers. The proposed analysis method precisely considers the local buckling of steel plates, nonlinear behavior of confined concrete, and interface action between the steel plate and in-filled concrete. Therefore, the proposed method can be used to predict the seismic ultimate of the SM570 CFT piers in terms of their force-displacement relations and local plastic strains.