effect of different abutment modeling strategies on the seismic response of irregular reinforced concrete bridges

In this study, the sensitivity of the seismic response of irregular bridges to the abutment modeling assumptions has been investigated using inelastic time history analyses and recommendations are provided in this regard. the bridges were modeled using different abutment modeling assumptions, including fixed, roller, simplified, and spring abutment models. in the spring abutment model, the effects of all of the important abutment components, including the gap, bearing pads, shear keys, and backfill soil were considered. including the abutment modeling for some cases increased the maximum seismic demands in the short columns and made their condition even more critical. the results also showed that using the simplified models in some irregular bridges could lead to an underprediction of the maximum seismic response in the critical columns by up to 30% that could result in an unsafe design. it was shown that the accuracy of the predictions from different models also depends on the bridge configuration and the location of the critical columns in the irregular bridges. a study of the influence of different abutment parameters such as gap length, abutment stiffness and strength, and bearing pad dimensions indicated that the variation of these parameters can change the predictions by up to around 15%, 30%, and 50%, respectively. the assumption of the fixed abutment condition resulted in up to 70% error in some bridges. a simple abutment modeling strategy was proposed to predict the maximum seismic demands in bridges with medium to high column stiffness using the fixed and roller abutment conditions.