Force-displacement behavior of limited ductile high-strength RC columns under bidirectional earthquake actions

Abstract This paper endeavors to enhance the understanding of the non-linear force-displacement hysteretic behavior of reinforced concrete (RC) columns subjected to bidirectional earthquake actions with different loading paths and magnitudes of lateral displacement in the two axes. RC column testing in literature has traditionally been focused towards the unidirectional testing of both normal and high strength concrete columns or the bidirectional testing of normal strength concrete columns only. This study will address this important knowledge gap by experimentally investigating the biaxial lateral capacity of high-strength RC columns with limited ductile detailing. The results of this experimental study and other previous studies are also used to develop a simplified model for predicting the non-linear backbone force-displacement behavior of RC columns. The paper will firstly present the six full-scale column specimens, the test setup, and the loading procedure. The test results will then be presented and analyzed. Three different bidirectional loading protocols were adopted to study the effects of loading history. The important effects of axial load ratio on the collapse behavior (i.e. maximum drift) are also examined in detail. The paper will conclude with an overview of the proposed backbone model for predicting the force-drift behavior of RC columns subjected to bidirectional loading.