A.H.M. Muntasir Billah

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

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...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 methods and applications rather than penetrating down to a critique of the associated analysis procedure or mathematical framework. It synthesises the existing information on fragility analysis, presents it in concise and useful tables, and explains different applications for different purposes, which would motivate decision-makers and stake holders to extend the application of fragility curves for more informed decision-making.

Fragility Analysis of Retrofitted Multicolumn Bridge Bent Subjected to Near-Fault and Far-Field Ground Motion

AbstractThis paper focuses on the fragility-based seismic vulnerability assessment of retrofitted multicolumn bridge bents. Fragility curves are developed to assess the relative performance of various retrofit methods under both near-fault and far-field ground motions. A probabilistic seismic demand model (PSDM) is used in generating the fragility functions. Through nonlinear dynamic analysis, fragility curves are developed for multicolumn bridge bents retrofitted with four different retrofit techniques, specifically carbon fiber–reinforced polymer (CFRP) jacketing, steel jacketing, concrete jacketing, and engineered cementitious composite (ECC) jacketing. Following the performance-based evaluation approach, this study aims to investigate the effectiveness of different retrofitting methods to minimize the overall seismic vulnerability of deficient bridge bents. To investigate the seismic responses of the retrofitted bridge bents, a total of 40 earthquake excitations, of which 20 are near-fault and 20 are ...

Seismic Fragility Assessment of Concrete Bridge Pier Reinforced with Superelastic Shape Memory Alloy

In an attempt to reduce permanent displacement and damage, a hybrid reinforced concrete (RC) bridge pier configuration is considered in the present study. The plastic hinge region of the bridge pier is reinforced with superelastic shape memory alloy (SMA) and the remaining portion with regular steel. This paper focuses on fragility-based seismic vulnerability assessment for a SMA-RC bridge pier considering residual displacement, displacement ductility, and performance criteria as the demand parameters. Fragility curves are developed to assess the relative vulnerability of a SMA-RC bridge pier and a conventional steel-RC bridge pier using probabilistic seismic demand model (PSDM). The fragility curves are developed with a suite of 20 near-fault ground motions using incremental dynamic analysis. The fragility curves provide insight into the failure probability of the bridge piers and aid in expressing the impact of SMA on the bridge pier vulnerability.

Erratum to: Seismic fragility assessment of SMA-bar restrained multi-span continuous highway bridge isolated by different laminated rubber bearings in medium to strong seismic risk zones

This study analytically determines the seismic fragility of a three-span continuous highway bridge fitted with laminated rubber bearings and shape memory alloy (SMA) restrainers. Fragility function, which expresses the likelihood of exceeding a damage state conditioned at a given earthquake intensity, has been derived based on SeismoStruct’s nonlinear incremental dynamic analysis results of the bridge subjected to medium to strong earthquake excitation records. A total of 20 excitation records with peak ground acceleration values ranging from 0.45 to 1.07 g, are used in the nonlinear dynamic analysis of the bridge. A 2-D finite element model scheme is used in this study considering nonlinearity in the bridge piers and the isolation bearings. Two types of laminated rubber bearings are used in the bridge system in addition to the SMA restrainers: high damping rubber bearings and lead rubber bearings. The fragility curves are constructed for two bridge components (i.e. piers and isolation bearings), and the system as well. The component fragility curves are combined to evaluate the fragility curves for the entire bridge system at different damage states. The bridge system, for simplicity, considers the bridge deck, isolation bearings with SMA restrainer and bridge piers but excluding the bridge foundations and the abutments. The numerical results show that the failure probability of the bridge system is dominated by the bridge piers over the isolation bearings. Moreover, the inclusion of SMA restrainers in the bridge system exhibits high probability of failure, especially, when the system is isolated with lead rubber bearings.

Green Concrete Made with RCA and FRP Scrap Aggregate: Fresh and Hardened Properties

AbstractBecause global landfills are filling at a fast rate with waste that can potentially be recycled, it is now time for the development and implementation of sustainable materials in construction. This article investigates the properties of a new generation concrete containing fiber reinforced polymer (FRP), fiber scrap aggregate (FSA), and recycled concrete aggregate (RCA). Although previous research has been undertaken for the use of RCA in concrete, the use of FSA is a new research area and has been found in this study to have exciting potential. Through different replacements of these aggregates in the concrete, both individually and in combination, conclusive test results were produced. The results indicate that both the fresh and hardened RCA concrete properties were similar to those of the control concrete containing only natural aggregate. In the case of fresh properties, the RCA concrete experienced slightly lower slump than the control concrete. The FSA concrete had a lower compressive stren...

Performance-based prioritisation for seismic retrofitting of reinforced concrete bridge bent

In this study, a seismically deficient three-column reinforced concrete bridge bent has been considered which was designed in the pre-1965. Several retrofitting provisions, namely carbon-fibre-reinforced plastics jacketing, steel jacketing, concrete jacketing, and engineered cementitious composites jacketing, have been considered in this study to enhance the seismic resistance and the performance of a gravity load-designed bridge bent under seismic forces. Performance evaluation and optimal selection of retrofit techniques have multi-level and multi-factor features and, therefore, are regarded as multiple criteria decision-making (MCDM) problem. MCDM methods are decision-support procedures, which are used when there are multiple decision-makers involved in the evaluation and comparison of a set of alternatives involving different evaluation criteria. This paper shows the application of such methodological framework for a performance-based seismic retrofit selection of a multi-column bridge bent. Here, different seismic retrofit strategies, reflecting common as well as innovative approaches, are adopted, and their seismic performances are compared by using the technique for order preference by similarity to ideal solution MCDM algorithm. Through rigorous analyses, a decision-making tool has been developed to identify the most effective retrofitting scheme considering its seismic performance alone.

Performance-Based Seismic Design of Shape Memory Alloy–Reinforced Concrete Bridge Piers. I: Development of Performance-Based Damage States

AbstractPerformance-based seismic design aims to dictate the structural performance in a predetermined fashion given the possible seismic hazard scenarios the structure is likely to experience. Identifying and assessing the probable performance is an integral part of performance-based design. Before implementation, accurate and practical definitions of different performance levels and corresponding limit states must be determined. This study aims to develop performance-based damage states for shape memory alloy (SMA)–reinforced concrete (RC) bridge piers considering different types of SMAs and seismic hazard scenarios. Using incremental dynamic analysis (IDA), this study develops quantitative damage states corresponding to different performance levels (cracking, yielding, and strength degradation) and specific probabilistic distributions for RC bridge piers reinforced with different types of SMAs. Based on an extensive numerical study, this study also proposes residual drift–based damage states for SMA-RC...

Seismic fragility assessment of concrete bridge pier reinforced with shape memory alloy considering residual displacement

Post-earthquake rapid recovery of bridge is one of the prime objectives for performance based design. Shape Memory Alloy (SMA) has the unique ability to undergo large deformation, but can regain its undeformed shape through stress removal (i.e. superelasticity), which brings about an added advantage in seismic regions. In an attempt to reduce permanent damage of concrete bridges, a hybrid RC bridge pier configuration is presented here. In the proposed configurations of bridge piers, the plastic hinge region is reinforced with SMA and the remaining portion with regular steel. Residual displacement is a critical parameter for performance based earthquake engineering as it dictates the functionality of a member after an earthquake. This paper evaluates fragility-based seismic vulnerability of SMA reinforced concrete bridge pier considering residual displacement. Fragility curves have also been used to assess the relative performance of SMA with conventional steel RC bridge pier. Probabilistic Seismic Demand Model (PSDM) has been used in generating the fragility functions. The development of these fragility curves for bridge piers aid in expressing the potential impact of SMA on the bridge pier vulnerability.

Performance-Based Seismic Design of Shape Memory Alloy–Reinforced Concrete Bridge Piers. II: Methodology and Design Example

AbstractHere, a performance-based seismic design method is presented for shape memory alloy (SMA)-reinforced concrete (RC) bridge piers. The proposed design method is developed based on the existing displacement-based procedure where the expected performance is quantified by linking material strains and deformations to damage states, as well as to the probable postearthquake functionality of a bridge. Based on the performance-based damage states developed in a companion paper, this study presents the sequential procedure for the performance-based design of SMA-RC bridge piers using a combination of residual and maximum drift.

Statistical distribution of seismic performance criteria of retrofitted multi-column bridge bents using incremental dynamic analysis: a case study

Probabilistic performance assessment requires the development of probability distributions that can predict different performance levels of structures with reasonable accuracy. This study evaluates the performance of a non-seismically designed multi-column bridge bent retrofitted with four different alternatives, and based on their performance under an ensemble of earthquake records it proposes accurate prediction models and distribution fits for different performance criteria as a case study. Here, finite element methods have been implemented where each retrofitting technique has been modeled and numerically validated with the experimental results. Different statistical distributions are employed to represent the variation in the considered performance criteria for the retrofitted bridge bents. The Kolmogorov-Smirnov goodness-of-fit test was carried out to compare different distributions and find the suitable distribution for each performance criteria. An important conclusion drawn here is that the yield displacement of CFRP, steel, and ECC jacketed bridge bents are best described by a gamma distribution. The crushing displacement and crushing base shear of all four retrofitted bent follow a normal and Weibull distribution, respectively. A probabilistic model is developed to approximate the seismic performance of retrofitted bridge bents. These probabilistic models and response functions developed in this study allow for the performance prediction of retrofitted bridge bents.