Influence of abutment straight backwall fracture on the seismic response of bridges

Abstract

Field reconnaissance reports reveal the seismic vulnerability of bridge abutment foundations. To reduce the time and cost of postearthquake repair, modern seismic design specifications allow abutment backwalls to fracture before the supporting abutment foundations reach their maximum strength. This design strategy enables abutment backwalls to function as a fuse, thus protecting the abutment foundations from experiencing excessive forces and damage. This paper introduces a new abutment modeling scheme to capture the shear fracture mechanism of straight backwalls in seat abutments. To this end, a backwall connection spring is developed and incorporated into a spring system that simulates the behavior of various abutment components. The importance of considering the backwall fracture is examined by reviewing conventional modeling methodologies for abutments and building companion numerical models. Static pushover and incremental dynamic analyses (IDAs) were conducted for two bridges (single‐ and two‐span) modeled by both the proposed and conventional abutment modeling schemes. Moreover, component‐level fragility curves are developed using IDA results. The comparisons show that the conventional abutment modeling schemes significantly overestimate abutment foundation damage and underestimate the likelihood of deck unseating, column damage, and bearing displacement in the passive direction. Conversely, the proposed modeling scheme is able to capture the essential seismic responses of various components in seat abutment bridges. The consideration of backwall fracture in the modeling of abutment components enables a more rational seismic response assessment of bridges with backwalls, which are likely to be damaged during earthquakes, particularly for bridges which are seismically designed to protect abutment foundations.

Risk-Based Optimal Design of Seismic Protective Devices for a Multicomponent Bridge System Using Parameterized Annual Repair Cost Ratio

“…Although these studies have made promising attempts, some limitations still exist that warrant further research. First, only the bridge column and bearing are considered the vulnerable components, which contradicts the fact that the seismic damage to other bridge components, such as abutment wall (Zheng et al, 2021), pile foundation (Xie et al, 2021), shear key, span unseating, and joint seal , would also inflict substantial seismic losses.…”

“…The vulnerabilities of the remaining bridge components and their design details might be controlled by different hazards other than earthquakes (Petrini et al, 2020). However, recent studies have also examined the seismic vulnerability of other components, including abutment backwall (Zheng et al, 2021), shear key, bearing (Xie and Zhang, 2018), joint seal, and foundation (Xie et al, 2021), etc. Although the damage of these structural components is generally less likely to cause the complete collapse of the bridge, their inclusion in the seismic risk assessment is of significant importance to bear accurate risk quantifications at the bridge system level (Akkari et al, 2015).…”

Enabling efficient regional seismic fragility assessment of multi‐component bridge portfolios through Gaussian process regression and active learning

“…First, conducting numerous NRHAs to generate EDP‐IM data to develop the surrogate models is computationally demanding. The computational cost would increase exponentially for high‐fidelity bridge models with complex component connectivity and sophisticated material constitutive laws 24 . Moreover, it remains unclear how many NRHAs are sufficient for the data and the resulting surrogate model to cover the entire solution space without overfitting.…”

Modelling of the Full-Range Response of Abutment-Backfill Systems

“…However, lots of backwalls worldwide are stronger and have a more ductile behaviour, forming a plastic hinge at their bottom as they collide with the deck. Such behaviour is common in the seismic regions of Europe [10], [11] and also in bridges in seismic regions of the US that were designed before the implementation of the Caltrans guidelines [12]. Therefore, modelling methods that include nonlinear beamcolumn elements and soil springs to represent the structural parts of the abutment and the backfill soil, respectively, have been proposed (e.g.…”