SIMULATION METHOD OF LOW CYCLE RECIPROCATING LOADING OF PIER COLUMN CONSIDERING BOND-SLIP EFFECT

Based on the stress-slip model of concrete proposed by fib Model Code, the slip of rebar was derived and formulated to consider the bond-slip phenomenon occurring both in the column and in the footing. Furthermore, the stress-strain constitutive model of the tensile rebars located within the plastic zone of the column was modified to incorporate the rebar slips in the column and in the footing. In this way, the effect of bond-slip on the seismic responses of the column can be equivalently considered. The feasibility of this method was verified by experimental results. Besides, the comparison was made of the results between the proposed method and the Zero-Length Section Element (ZLSE) method. It can be concluded that the lateral stiffness, the cumulative hysteretic energy, and the residual displacement are all overestimated without considering the bond-slip phenomenon. Apart from that, the strength degradation of the column is unable to reflect objectively. Both the ZLSE method and the proposed equivalent method have the capability to resolve the issue of strength degradation. However, the former method yields the numerical results prominently susceptible to the rebar diameter, while the latter one can efficaciously capture the reciprocating loading process of the column affected by the bond-slip phenomenon.