Failure analysis of flood collapse of the tex wash bridge

Abstract

Located east of City of Palm Springs, the Tex-Wash Bridge is a bridge over the Tex-Wash dry river on Interstate Highway 10. On July 19, 2015, one of the three spans of the Tex-Wash Bridge collapsed due to flooding resulting from heavy rain. This paper summarizes the failure analysis to understand the cause of this collapse, and to learn engineering lessons from this collapse. Using the “As-Built“ drawings of the bridge, a nonlinear FE model of the bridge was created in ANSYS. The model then was subjected to simulated flood waters until the bridge collapsed. By studying the results of FE analysis it was concluded that the collapse occurred due to combination of five factors: (1) the bridge had a length of about half of the width of the flood path, creating a bottle-neck on the path of the flood, (2) flood waters before reaching the bridge made an “S“ curve turning right and then left before going under the bridge, which resulted in washing the soil under the east abutment, (3) the east abutment was supported on fill soil without piles, therefore when the supporting soil under the abutment washed away , it could not be supported and collapsed, (4) the wing walls in the abutment were perpendicular to the flood waters, resulting in flood waters pushing the abutment and collapsing it, (5) when the abutment lost its supporting fill-soil and was pushed by flood and collapsed, the deck slab of the roadway supported on it also collapsed.