Innovative Fragility-Based Method for Failure Mechanisms and Damage Extension Analysis of Bridges

Abstract

The seismic assessment of existing bridges is of the utmost importance to characterise the main structural deficiencies, estimate the risk, prioritise retrofit interventions, or estimate losses and repair costs in case of earthquakes. The above tasks require information on the damage mechanisms likely to occur as well as on the damage extent over the structure. Such types of information are generally not provided by classical fragility analysis, which is mainly focused on the evaluation of the global performance of the bridge. In this paper, a systematic probabilistic methodology for the evaluation of bridge fragility is proposed. The methodology aims at offering insight into the failure mechanisms most likely to occur and the evolution and extent of damage within the bridge structure. First, a mathematical description of the proposed analysis methods is given, then an application to a realistic case study—a reinforced concrete multi-span simply supported deck link-slab bridge—is provided to illustrate the applicability of the tool. A nonlinear 3D finite element model is developed, and a multiple-stripe (nonlinear dynamic) analysis is performed by using a stochastic bidirectional seismic input. The results highlight the suitability of the proposed methodology to reveal the main structural deficiencies, the relations among different failure mechanisms (involving piers, bearings, abutments, etc.), and the expected damage extent.

Seismic Risk Analysis of Existing Link Slab Bridges Using Novel Fragility Functions

“…Two novel typologies have recently been proposed [22] to provide a wider spectrum of information on the possible failure mechanisms, their interaction and extent. These are examined in the following subsections.…”

“…A comprehensive probabilistic framework is thus proposed and adopted in this study to perform seismic reliability and risk analysis of these systems. One of the key points of the framework is represented by a novel practical-oriented procedure for fragility analysis recently proposed by Minnucci et al (2022) [22] with the aim of overcoming some limits of classical approaches and providing rapid and useful data to directly support the decision-making process.…”

A case study for the reliability evaluation of an existing prestressed bridge according to current Standard

“…A large part of them, indeed, is designed according to old Codes and it is still in service. Such infrastructures can suffer the effects of both natural hazard (e.g., earthquakes [1], [2] and floods [3]) and anthropic loads. Regarding the latter, it is quite common to find bridges subjected to loads far from the design ones, considering also the steadily increasing of the vehicle traffic, loads and legal load limits.…”

Nonlinear analysis procedures for safety assessment of existing RC bridges under traffic loads

“…In order to properly assess the current capacity of bridges with respect to traffic and seismic loads, to date several studies have been published in the literature. All of them recognize that for detecting structural defects, visual and instrumental in-situ inspections remain an essential point in the assessment procedure, allowing also to program monitoring and right interventions [1][2][3][4].…”