Date of Award
Doctor of Philosophy
Civil, Construction, and Environmental Engineering
Jeramy C. Ashlock
Using prefabricated components has been continuously gaining momentum in bridge constructions because of its numerous advantages over conventional cast-in-place construction methods. However, there are few, if any, projects that have utilized prefabricated components to construct the entire bridge piers because the seismic sufficiency of such structures has not been adequately addressed. Therefore, the studies in this dissertation were conducted to investigate the prefabricated bridge pier systems suitable for seismic regions. A pier system consisting of precast column, precast pile cap, and pile foundation was developed. For this system, the prefabricated components are integrally connected utilizing column socket connection and pile pocket connections that are preformed in the pile cap with corrugated steel pipes. An experimental study was performed using eight specimens that modeled the full-scaled connection interfaces, demonstrating that side shear strength in the column socket connection is sufficient to transfer large vertical loads from the column to the pile cap. An outdoor test was subsequently conducted on the column-pile cap-pile system at a cohesive soil site. A half-scale test unit was constructed on the foundation consisted of four vertical steel piles and four battered steel piles. To evaluate the system performance as well as the behaviors of various connections and pile foundation, the test unit was subjected to different combinations of vertical and lateral loads. Throughout the test, the socket and pocket connections maintained fixity with the formation of a plastic hinge in the column, evidencing that the system can ensure life safety and collapse prevention during earthquake events. Along with the results of numerical analysis, the battered piles were found to subject to larger axial forces but less bending moments than the vertical piles. Following the successful development and investigation of the prefabricated column-pile cap-pile system, the controlled rocking pile foundation (CRPF) system with replaceable bar fuses was studied through a numerical approach. The CRPF system allows the pile cap to rock on the pile foundation and dissipates seismic energy through the inelastic deformations of the bar fuses connecting the pile cap and piles, thereby achieving additional seismic performance objectives such as immediately openings after an earthquake, shorter repair times, and lower repair costs. Analysis results indicated that, subjected to a severe earthquake, the CRPF system showed negligible residual displacement and maintained elastic behavior except the bar fuses as designed. The damaged fuses can be rapidly replaced to recover the bridge seismic resistance after the earthquake.
Cheng, Zhao, "Seismic performance of prefabricated bridge piers supported on pile foundations" (2019). Graduate Theses and Dissertations. 17423.