Comparison on Force-Based and Displacement-Based Approaches for Evaluation of Bridge Reliability under Multiple Hazards

The Strength I Limit State of American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) specification deals with the failure probabilities of the combination of non-extreme loads. This design limit state equation (DLSE) has been fully calibrated for dead load and live load by using the reliability-based approach in previous research. However, most of other DLSEs, including the extreme event I and II, with certain probability-based concepts considered, have not yet been fully calibrated by using the reliability-based approach. This paper presents an evaluation of the bridge reliabilities under the limit state of Extreme Event I combination of dead load, live load and earthquake load, by using a force-based and a displacement-based approach on a set of nine simplified bridge models. Results show that the displacement-based approach came up with more convergent and accurate reliabilities for selected models.