@article {bnh-7881, title = {Development of fragility functions for rigid-frame bridges subjected to tsunami-induced hydrodynamic forces}, journal = {Structure and Infrastructure Engineering}, year = {2021}, month = {03/2021}, abstract = {

The rigid-frame bridges with a fully continuous moment connection between the superstructure and substructure piers are suitable for high-seismic regions; however, research on the response of these bridge types under tsunami loads is limited. This paper presents a framework for developing fragility functions of coastal rigid-frame bridges, and bridges with strong pier-to-deck connectivity, undergoing tsunami-induced hydrodynamic loads. The fragility analysis is demonstrated on a three-span reinforced concrete (RC) bridge structure with double-column bents. The Monte Carlo simulation is implemented to consider the uncertainties in capacity and demand parameters. The efficiency of single-parameter and two-parameter intensity measures for predicting the response of bridges is examined. The viability of strengthening bridge piers using fiber-reinforced polymer (FRP) is also investigated. The results indicate that the use of two-parameter intensity measures is a better option to estimate the structural response since the hydrodynamic forces are a function of both the flow depth and velocity. This also leads to a significant reduction in the scatter of fragility data. The comparative assessment of the initial and FRP-strengthened bridges highlights that the FRP-jacketing is an effective method in reducing the risk of failure of the rigid-frame bridges.

}, keywords = {Coastal bridges, fiber-reinforced polymers, fragility model, hydrodynamic loads, numerical simulations, strengthening, structural safety, tsunami}, doi = {https://doi.org/10.1080/15732479.2021.1892774}, url = {https://www.tandfonline.com/doi/full/10.1080/15732479.2021.1892774}, author = {Ismail Qeshta and Javad Hashemi and M. Reza Hashemi and Rebecca Gravina and Sujeeva Setunge} } @mastersthesis {bnh-6161, title = {Fragility and resilience of bridges subjected to extreme wave-induced forces}, volume = {Doctor of Philosophy}, year = {2019}, month = {08/2019}, school = {RMIT University}, type = {Doctorate}, address = {Melbourne}, abstract = {

Bridges are susceptible to severe damage due to wave-induced forces during extreme events such as floods, hurricanes, storm surges and tsunamis. As a direct impact of climate change, the frequency and intensity of these events are also expected to increase in the future. The damages to bridges lead to substantial community impact during emergency and post-disaster recovery activities. Hence, viable restoration strategies are needed to enhance the resilience of bridges under extreme wave hazards. The research on the quantification of vulnerability and resilience of bridges under extreme wave forces is limited. In particular, vulnerability and resilience assessment tools for bridges under different hazard intensity levels are required to quantify the resilience. This research addresses these research needs by providing a comprehensive vulnerability assessment framework for bridges subjected to extreme hydrodynamic forces.

A comprehensive literature review is first conducted on the four resilience assessment elements, namely external wave force characterization, structural response, vulnerability assessment and resilience quantification to identify the existing gaps in knowledge, particularly in vulnerability and assessment methods.
Unified resilience indices, based on the {\textquotedblleft}resilience triangle{\textquotedblright} concept, are proposed to take into account the effect of the consideration of resources (cost) and environmental impact and their relative importance to the decision makers in the resilience quantification. Such indices are important for stakeholders as they provide a linkage between the social (time), economic and environmental impacts in the assessment of restoration strategies.

An integrated vulnerability assessment framework for bridges with strong connectivity between super- and sub-structure is proposed. The framework includes both static and time-history analyses to examine the performance of bridges subjected to significant hydrodynamic forces. The uncertainties in force and structural parameters are taken into account and the probability of damage is estimated using six damage states that define the pre- and post-peak response of bridge. The pier drift is taken as the engineering demand parameter. The use of two-parameter intensity measures that can provide an accurate estimation of the response of bridge such as momentum flux (hu2) and moment of momentum flux (h2u2/2) is investigated.

To demonstrate the proposed framework, a numerical model is developed for a case study bridge located in a flood-prone region in Queensland, Australia. The accuracy of the piers model is validated using published works on small-scale pier specimens that have limited ductility. The effect of strengthening of bridge piers using fibre reinforced polymer (FRP) jackets is examined.

The overall fragility functions for all intensity measures (velocity, inundation depth, momentum flux and moment of momentum flux) are obtained for both initial and strengthened bridge. The reduction in scatter of fragility data is examined for the two-parameter intensity measures for all damage states. The viability of the use of FRP jackets for enhancing the resilience of bridges under extreme wave forces is also evaluated. The application of unified resilience indices based on the damage probability data obtained from fragility analysis is discussed for different intensities of the hazard.

The main contribution provided by this research is the comprehensive vulnerability and resilience assessment methods for bridges under extreme wave hazards. Such methodologies can assist in the evaluation of the different pre-disaster strengthening and recovery schemes for bridges. Decision makers (e.g., road authorities) can use the outcome of this research to assess the different retrofitting options for bridges taking into consideration the time, cost and energy consumption associated with each option.

}, keywords = {bridges, Emergency management, engineering, Fragility, Natural disasters, resilience}, author = {Ismail Qeshta} } @article {bnh-5381, title = {Review of resilience assessment of coastal bridges to extreme wave-induced loads}, journal = {Engineering Structures}, volume = {185}, year = {2019}, month = {04/2019}, chapter = {332}, abstract = {

Coastal bridges are susceptible to severe damage due to wave-induced forces during\ extreme events\ such as\ coastal flooding, hurricanes,\ storm surges\ and\ tsunamis. As a direct impact of\ climate change, the frequency and intensity of these events are also expected to increase in the future. This paper presents a comprehensive review of a four-phase resilience assessment of coastal\ bridge structures, namely, (i)\ characterization\ of external wave-induced forces, (ii)\ structural response\ of bridges, (iii) vulnerability assessment of damaged components, and (iv) post-disaster recovery. The four comprehensive modules are adopted from the classic framework of PEER PBEE and constitute the\ integrated knowledgeneeded for the prediction of the resilience of infrastructure under extreme wave-induced loads. The study also presents new expressions for resilience restoration that simultaneously account for the time, resources (cost) and\ environmental impacts\ of different recovery options with variable importance levels to different stakeholders.

}, doi = {10.1016/j.engstruct.2019.01.101}, url = {https://www.sciencedirect.com/science/article/pii/S0141029618318194}, author = {Ismail Qeshta and Javad Hashemi and Rebecca Gravina and Sujeeva Setunge} }