Seismic performance of highway bridges considering sacrificial abutment: a case study in Afghanistan

Abstract

The effect of skewness on the sacrificial seat-type abutment and abutment interaction with the skew deck is quite well known. Unlike the simplified approach, this study focuses on the effect of skewness on the seating width of seat-type abutment by providing a rigorous deck model in the analysis while the sacrificial seat-type abutment interacts with the straight deck. This effect is investigated by comparing the seismic performance of two case study bridges, the bridge with elastomeric bearing pad as a bearing mechanism, namely the conventional bridge and the bridge with lead rubber bearing, as an isolated bridge. Realistic seismic response behaviors of these bridges were simulated by nonlinear 3D models. The models are capable of simulating the flexural yielding of piers, the bilinear behavior of isolation bearings, the elastic perfect plastic behavior of elastomeric bearings of the conventional bridge and the other important nonlinear behaviors of these structures. The results highlight the effectiveness of isolation bearing on seismic performance of the isolated bridge, and it was revealed that in the early pounding frequencies, passive forces on the sacrificial backwall springs are uniformly distributed. Whereas for the last pounding frequencies, the passive forces on the backwall are not uniform anymore, this implies that the increase in the pounding frequency leads to an increase in the possibility of deck rotation in the straight deck. Moreover, the result confirms that the earthquake energy absorbed by the fusing backwall could significantly lead to a reduction in dissipation energy by the pier. These results suggest recommendations to improve the seismic performance of the conventional bridge system in the country.