Centrifuge Modeling of Spread-Base Integral Bridge Abutments

Integral bridge abutments are attracting increasing interest in many countries around the world. Maintenance costs due to damage from assorted agents to bearings and expansion joints can be greatly reduced. However, adverse temperature effects on the performance of these bridges are of concern to many engineers. This paper describes some centrifuge model tests on, and numerical modeling of, spread-base integral bridge abutments subjected to cyclic deformation, which simulated the expansion and contraction of the bridge deck as effective temperature of the bridge deck changed. Significant settlements were observed behind the abutment resulting from soil densification, “strain” ratchetting, horizontal sliding, and the rocking motion of the abutment. The measured lateral earth pressure increased with the amplitude of the passive displacements and the number of cycles, but at a decreasing rate. Under the serviceability and ultimate limit conditions, the measured lateral earth pressure was less than the Kp value, although the measured value was significantly higher than Ko. A triangular failure wedge developed behind the abutment wall under the ultimate limit conditions.