Numerical evaluation of reinforced concrete connections under post-earthquake fire

Reinforced concrete connections are one of critical points in concrete frames due to changing in concrete characteristics in high temperatures and cyclic loads. In present study the residual capacity of concrete connections was evaluated under seismic and fire loads with push-over analysis. The ABAQUS software was used for parametric study and the experimental results were used for verification of numerical study. In present study the compressive strength of concrete and the area of longitudinal reinforcement of column are considered as variable parameters. The modeled connections were loaded under seismic loads at ambient temperature, so, the temperature analysis was done to evaluate the loading capacity, ductility, stiffness and wasted energy of model under fire situation. The results show that by increasing the compressive strength of concrete from 25 to 45 MPa, the wasted energy and stiffness of connection were increase 10% and 35%, respectively, and the ductility was decreases 8%. Also, with increasing the area of longitudinal reinforcement of column from 1% to 8%, the wasted energy and stiffness of connection were increase 190% and 50%, respectively, and the ductility was decreases 290%. The connections were stable up to 200℃, but, the lateral resistance, ductility and stiffness of connections decrease 55%,60% and 60%, respectively, at 600℃ and 80%, 80% and 340%, respectively, at 1000℃.