APPLICATION OF THE DISCRETE ELEMENT METHOD ON THE STUDY OF THE CYCLIC RESPONSE OF A SEMI-INTEGRAL BRIDGE ABUTMENT
Discrete element method (DEM); Semi-integral bridge; Earth pressure; Cyclic behavior.
Integral and semi-integral bridges are alternatives for conventional bridges, which routinely present problems associated with expansion joints and bearings. However, the cyclic lateral displacements of the superstructure, induced by temperature variations, lead to a complex interaction between the backfill and the abutment of an integral or semi-integral bridge, which requires in-depth assessment of the behavior of these bridges. In this research, ISSS’s Rocky software was used to build a computational model based on the discrete element method (DEM) for investigating the response of a granular backfill to the cyclic displacements a semi-integral bridge abutment located in Texas, USA. In order to bring the stresses and strains in the numerical model to the same level of the stresses and strains developed in the bridge abutment in the field, the numerical simulations were carried out with a gravitational acceleration equal to 3 g. The cyclic sequence of imposed lateral displacements was chosen to simulate the completion of the bridge in the summer. The prescribed lateral displacement magnitude of ± 5 mm was selected to represent the annual cyclic response of the bridge. Results indicated an increase in the lateral earth pressure coefficient on the abutment’s face and an increase in settlements on the backfill surface with the cycles. A good agreement was found between the results obtained in the present work and results obtained from simulations performed for the same bridge using the finite element method (FEM). Additional DEM simulations were performed to investigate the influence of the lateral displacement amplitude, the completion season of the bridge construction and the type of abutment movement. Variations of the lateral displacement amplitude and variations of the abutment movement type were found to play a significant influence on lateral earth pressures on the abutment wall and on vertical displacements of the backfill soil, while variations of the completion season of the bridge construction had little influence on the results.