Seismic Design and Retrofit of Bridges

This paper provides a comprehensive overview of the literature on transportation infrastructure system performance in disasters Specifically, it reviews those articles appearing in refereed journals, conference proceedings, and technical reports since the late 1990s that provide insights and tools for the assessment of anticipated transportation system performance, along with its management, given the possibility of physical damage resulting from a future hazard event In the considered literature, performance may be gauged under characteristics of risk, vulnerability, reliability, robustness, flexibility, survivability, and resilience, the most common concepts or measures in the literature In addition to providing an archive and synthesis of recent literature on this topic, the approximately 200 articles are classified based on a host of criteria, including applied measure (qualitative or quantitative), conceptual approach, and methodology

Measuring the performance of transportation infrastructure systems in disasters: a comprehensive review

Structural systems are under deterioration due to ageing, mechanical stressors, and harsh environment, among other threats Corrosion and fatigue can cause gradual structural deterioration Moreover, natural and man-made hazards may lead to a sudden drop in the structural performance Inspection and maintenance actions are performed to monitor the structural safety and maintain the performance over certain thresholds However, these actions must be effectively planned throughout the life-cycle of a system to ensure the optimum budget allocation and maximum possible service life without adverse effects on the structural system safety Life-cycle engineering provides rational means to optimise life-cycle aspects, starting from the initial design and construction to dismantling and replacing the system at the end of its service life This paper presents a brief overview of the recent research achievements in the field of life-cycle engineering for civil and marine structural systems and indicates future dire

Life-cycle of structural systems: recent achievements and future directions

Safety and serviceability of highway bridges, during and after an earthquake, is a prerequisite to ensure continuous transport facilities, emergency and evacuation routes. Recently, fragility curves have emerged as important decision support tools to identify the potential seismic risk and consequences during and after an earthquake. There has been a substantial increase in interest among researchers in the topic of seismic fragility assessment of highway bridges as evidenced by the growing number of published literature. Advanced computational techniques and available resources have led to the development of different methodologies for fragility assessment. This study presents a review of the different methodologies developed for seismic fragility assessment of highway bridges along with their features, limitations and applications. This study presents a review of available methodologies and identifies opportunities for future development. This study mainly focuses on the key features of different method...

Seismic fragility assessment of highway bridges: a state-of-the-art review

Resilience in transportation systems: a systematic review and future directions

This paper presents the results of an experimental investigation on shear strength enhancement of reinforced concrete beams externally reinforced with fiber-reinforced polymer (FRP) composites. A total of nine full-scale beam specimens of three different classes, as-built (unstrengthened), repaired and retrofitted were tested in the experimental evaluation program. Three composite systems namely carbon/epoxy wet layup, E-glass/epoxy wet layup and carbon/epoxy precured strips were used for retrofit and repair evaluation. Experimental results indicated that the composite systems provided substantial increase in ultimate strength of repaired and strengthened beams as compared to the pre-cracked and as-built beam specimens. A comparative study of the experimental results with published analytical models, including the ACI 440 model, was also conducted in order to evaluate the different analytical models and identify the influencing factors on the shear behavior of FRP strengthened reinforced concrete beams. Comparison indicated that the shear span-to-depth ratio (a/d) is an important factor that actively controls the shear failure mode of beam and consequently influences on the shear strength enhancement.

Shear enhancement of reinforced concrete beams strengthened with FRP composite laminates

A simulation-based study is performed to evaluate the socio-economic effect of seismic retrofit of bridges using the California Department of Transportation (Caltrans) Los Angeles area highway network as the testbed. 47 scenario earthquakes that represent the regional seismic hazard, consistent with the US Geological Survey (USGS) hazard map, are considered. Two sets of bridge fragility curves, before and after seismic retrofit, are used to simulate the seismic performance of the network in both cases. Analysis estimates the total social cost arising from driver delay and loss of opportunity in the degraded network. The benefit of seismic retrofitting is computed in present values as equal to the total future economic losses avoided from social cost and repair/restoration cost over the remaining bridge service lives. Estimated benefit is compared with the retrofit cost to investigate the benefit-cost ratio. Study shows that from the Caltrans point of interest, bridge seismic retrofit is cost-effective whe...

Socio-economic effect of seismic retrofit of bridges for highway transportation networks: a pilot study

The impact of an earthquake event on the performance of a highway transportation network depends on the extent of damage sustained by its individual components, particularly bridges. Seismic damageability of bridges expressed in the form of fragility curves can easily be incorporated into the scheme of risk analysis of a highway network under the seismic hazard. In this context, this article focuses on a nonlinear static method of developing fragility curves for a typical type of concrete bridge in California. The method makes use of the capacity spectrum method (CSM) for identification of spectral displacement, which is converted to rotations at bridge column ends. To check the reliability of this current analytical procedure, developed fragility curves are compared with those obtained by nonlinear time history analysis. Results indicate that analytically developed fragility curves obtained from nonlinear static and time history analyses are consistent.

Nonlinear static procedure for seismic vulnerability assessment of bridges

Earthquake in the presence of flood-induced scour is a critical multihazard scenario for bridges located in seismically-active, flood-prone regions. The present article evaluates seismic performance of four example reinforced concrete bridges when they are pre-exposed to regional flood hazards. Nonlinear time history analyses of the example bridges are performed for a suite of ground motion time histories in the presence and absence of scour expected from different intensity flood events. Fragility analysis is performed to develop seismic fragility curves of the example bridges for various scour depths. Results show nonlinear increase in bridge seismic fragility with increase in scour depth.

Swagata Banerjee

Papers

Shear enhancement of reinforced concrete beams strengthened with FRP composite laminates

Socio-economic effect of seismic retrofit of bridges for highway transportation networks: a pilot study

Nonlinear static procedure for seismic vulnerability assessment of bridges

The Impact of Flood-Induced Scour on Seismic Fragility Characteristics of Bridges

Mechanistic quantification of RC bridge damage states under earthquake through fragility analysis