Retrofit Of Bridges Research Articles

Failure analysis and structural resilience of a masonry arch Bridge subjected to blast loads: The Case study, Halilviran Bridge

This study investigates the dynamic response of masonry bridges under blast-induced shock waves, focusing on the structural integrity and safety of these critical infrastructure components under extreme conditions. The research employs theoretical approaches to analyze the effects of blast-induced shock waves on masonry bridge structures. A comprehensive numerical simulation framework is developed using finite element analysis (FEA) to model the dynamic interactions between blast waves and the masonry materials. Key parameters, including the blast load intensity, duration, and distance from the blast source, are varied to assess their impact on bridge performance. The results reveal significant insights into the deformation patterns, stress distribution, and potential failure modes of masonry bridges under blast loading scenarios. The findings underscore the importance of incorporating blast resistance measures in the design and retrofitting of masonry bridges to enhance their resilience against explosive events. This study contributes to the advancement of safety standards and design guidelines for masonry bridge structures in the context of blast loading, providing valuable information for engineers, policymakers, and infrastructure managers.

A simplified procedure for the seismic retrofit of bridges by seismic isolation: Part 1 - assessment of suitability

The study presents a simplified procedure for the seismic retrofit of bridges by means of isolation, applicable to bridges with an isostatic or continuous deck layout, supported by conventional bearings that can be replaced by seismic isolators. The procedure consists of two steps: (1) the assessment of suitability of the bridge for seismic isolation; (2) the preliminary design of the isolation system. This contribution presents the first step of the procedure. The assessment moves from the geometry of the structure and the site characteristics, performing a sectional analysis of the base section of the piers, and comparing the acceleration related to the collapse mechanism with the limit acceleration that the piers alone could withstand. Then the procedure checks whether the piers can resist the seismic action once the inertial forces of the deck are mitigated by isolation. If the assessment is negative, measures must also be taken to strengthen the pier. The preliminary evaluation can be developed in a spreadsheet, without the need of complex finite element analysis. A parametric application of the procedure on a case study bridge with simply supported spans is finally presented.

A simplified procedure for the seismic retrofit of bridges by seismic isolation: Part 2 - predimensioning of the isolation system

This study presents a simplified procedure for the seismic retrofit of bridges by means of isolation system (IS), applicable to bridges with an isostatic or continuous deck layout, supported by conventional bearings that can be replaced by seismic isolators. The procedure consists of two steps: (1) the assessment of suitability of the bridges for seismic isolation; (2) the preliminary design of the isolation system. The first part of the procedure is presented in a companion paper. This contribution presents the second step of the procedure. A nonlinear static analysis of the existing bridge is performed, and its capacity curve is determined. This curve is then transformed into that of the equivalent SDOF system. Combining the information of the nonlinear static analysis and the bridge characteristics in the ADRS plane, the minimum characteristics of the isolation system to achieve a preset performance point are derived. Two scenarios are considered: in the first one it is sufficient to shift the period of the deck; in the second one, in addition to period shifting, it is necessary to introduce damping to control the displacement of the deck. Once the minimum characteristics of the isolators have been defined, the type and model can be identified through a search into databases of commercial devices. The application of the procedure to a case-study bridge and the validation of the method are finally shown.

Pile Group Effect Modeling and Parametric Sensitivity Analysis of Scoured Pile Group Bridge Foundations in Sandy Soils under Lateral Loads

Scour can increase the earthquake-induced damage in pile group foundations. Quantifying the parameter sensitivity of the seismic performance for scoured pile group foundations is essential for the optimal design and retrofit of bridges located in seismic-prone regions. Such quantification requires numerical models that are computationally efficient and accurate in describing the mechanical behavior associated with the complex soil–foundation–structure interaction of these systems. This study proposes an efficient finite-element model (FEM) of pile groups based on a beam on the nonlinear Winkler foundation approach. This FEM uses asymmetric p-multipliers to describe the different soil resistance exerted on leading and trailing piles when applying cyclic lateral loads. The proposed FEM is validated by comparing the numerical response with the experimental measurements taken from a quasi-static test available in the literature and is used to perform an extensive parametric sensitivity analysis to quantify the response sensitivity to 11 structural and soil parameters. Tornado diagrams are employed to identify an importance ranking of these parameters on the seismic performance of scoured pile groups. The obtained results indicate that the proposed FEM is able to capture both the global and local structural responses of pile group foundations. The parametric sensitivity analysis shows that pile group foundations have considerable ductility capacity. Pile diameter and axial load ratio of piles are the most important parameters for the seismic performance of pile groups. Increasing the pile diameter is the most efficient approach to improve the seismic performance of a pile group when considering scour effects. The seismic performance of a scoured pile group deteriorates with increasing piles’ axial load ratio. For a deep pile group foundation, seismic performance is very little sensitive to pile length and relative density of sand. Based on the results of the parametric analysis, recommendations are proposed for the seismic design of pile group foundations with scour effects.

Modeling and characterization of fiber-reinforced (FRP) plastic honeycomb sandwich panels for bridge deck

Several factors and reasons, including correcting errors in bridge design and construction, preventing damage caused by natural and environmental factors, forces caused by earthquakes, or strengthening the bridge structure to withstand more loads, increase the need to strengthen the bridge. Reinforcement is usually applied to a specific element in the bridge, such as the foundation, column, beam head and deck, each of which may be reinforced. Also, from the economic point of view, retrofitting of bridges is generally preferred compared to the replacement and renovation option. Bridges play an important role in rescue operations after an earthquake. It is necessary that these structures have a higher level of protection against seismic attacks. The earthquake identified the weak points of the structure. Bridges are very vulnerable to these attacks due to their low degree of uncertainty. Seismic displacements based on the principles of elastic design are much less than what the structure experiences in a real earthquake. One of the consequences is the falling of the decks due to the loss of the support surface. The decision to strengthen the bridge was made when many bending and shear cracks were created on the king beams of the bridge. The use of FRP profiles can significantly prevent losses caused by corrosion and is a good alternative to traditional methods of strengthening the structure. In this article, the design for the deck of a sandwich panel bridge reinforced with FRP fibers is presented.

Distortion-Induced Fatigue Cracking after Crack Arrest Hole Retrofit of Steel Girder Bridges

Distortion-Induced Fatigue Cracking after Crack Arrest Hole Retrofit of Steel Girder Bridges

Betweenness Centrality-Based seismic risk management for bridge transportation networks

Although bridges are integral parts of transportation networks, they are vulnerable to natural hazards. The damage incurred during these natural hazards events leads to network disruptions and hinders post-event recovery. Therefore, improving the seismic performance of transportation networks is critical. This paper proposes an origin–destination pair betweenness centrality (BC)-based methodology to rank bridges according to their importance in a complex bridge network. The proposed methodology is an easy-to-use approach that considers user equilibrium and topology and significantly shorten the computational time. In addition, this study proposes two strategies including the retrofit of bridges and construction of new bridges based on the BC importance of bridges to mitigate the seismic risk of bride networks. A well-studied bridge network in California was used to demonstrate the application and the effect of different strategies was compared in this study. Bridges located at the shortest path significantly affect the seismic performance of bridge networks, indicating there is no need to rehabilitate or replace all bridges under budget constraints. Also, constructing five new bridges based on BC importance improved seismic performance of the bridge network much more than retrofitting 21 bridges. Moreover, the proposed methodology presents a significant reduction in computational time (only 1/30 compared with an existing study) in resolving the importance of bridges in a network and can be applied to provide useful information for disaster management teams to mitigate the seismic risk of bridge networks.

Role carbon nanomaterials in reinforcement of concrete and cement; A new perspective in civil engineering

Nanotechnology has resulted in many advantages in different majors of science and created new approaches to them. nanotechnology has more effect on civil engineering such as utilizing nanomaterials as cement reinforcement. The improvement in quality of materials used in civil engineering such as self-cleaning, self-structural health monitoring, self-sensing, self-vibration damping, self- rehabilitation, cement reinforcement, and self-healing created a new revolutionary civil engineering. Concrete is one of the important parts of civil engineering and especially in the discussion of building and bridge retrofitting. Nanotechnology plays an important role in the concrete process such as alkali silicate reactions (ASR), hydration reactions, and fly ash reactivity. Much of the research showed that nanomaterials improved compressive and flexural strength in concrete and created the best situation for building resistant structures such as bridges, towers, and tall buildings. Due to the mechanical behavior and tensile strength of carbon nanotubes (CNTs), these compounds play a special role in improving concrete properties. Prevention of cracking is one of the positive effects of using carbon nanotubes in improving concrete properties, which has increased significant growth in the application of it in the industry. The present review paper focused on the role of nanomaterials in improving and reinforcement of concrete and the advantages of them in civil engineering.

Investigation of different resilience-based optimisation strategies for retrofitting curved bridges

Recent natural or manmade hazards highlighted the pressing need for allocating enough financial resources for the enhancement of the resilience of infrastructure in our society. In this regard, bridges play a pivotal role in transportation networks, where any reduction in their performance can influence the functionality of the whole network. Bridge retrofitting is a common strategy for enhancing transportation network resilience. Composite reinforcement with different thicknesses and concrete seat extenders with different widths have been used to retrofit an existing curved bridge in Iran. A novel hybrid algorithm called NSGAII-SA was proposed and compared against a simple optimisation strategy, a traditional genetic algorithm solver (NSGA-II), and pure simulated annealing (SA). These optimisation strategies identify the optimal retrofit scenarios set in terms of maximum resilience index, minimum recovery time, and minimum retrofitting cost. For this problem, NSGAII-SA outperforms the traditional NSGA-II. The comparison shows that for this particular application, SA has the best overall performance. However, the proposed NSGAII-SA algorithm has satisfactory performance too, it is a clear improvement over NSGAII and it has the potential to be very useful and better suited than SA for problems with large design spaces and many local minima.

Resilience-based multi-objective optimization for determining the optimal sequence of bridge retrofit projects

This study intends to provide a methodology for determination of the optimal sequence of bridge retrofit projects in the pre-disaster phase. A two-stage optimization model is proposed. In the first stage, single-objective optimization is used, and the weighted average number of reliable independent pathways (WIPW) is adopted as the measure of network resilience (MOR) to be maximized. In the second stage, multi-objective optimization is used, and two objective functions are introduced to be maximized: the measure of strategy implementation sequence (MOS) and the measure of strategy implementation time (MOT). The proposed methodology is illustrated using a hypothetical community road system. The results show that there is an inverse relationship between MOS and MOT. By considering these two new objectives in the process of pre-disaster risk mitigation planning, network owners can determine the trade-off between MOS and MOT and select a proper sequence of bridge retrofit projects based on predictability of the examined disruptive events.

Impact of the Implementation of Unbonded Seismic Isolators on the Design and Retrofitting of Bridges

The existence of road infrastructure such as bridges that do not meet current design criteria, the deterioration of these due to use, environmental factors and extraordinary or unforeseen conditions, and the increase in seismic and gravitational design loads due to regulatory updates, generate the need for search of new design and retrofitting alternatives for this type of structure. Thus, the conditions of these structures need to be assessed and corresponding interventions need to be identified. It is important to implement alternatives that are both economically and functionally efficient. For example, base isolation can reduce direct construction costs by using devices designed and built in the country of origin, but the unfamiliarity and importation costs of these devices are the main obstacles to mass use. In this article, a comparative analysis is performed of a conventional design and an integrated design for base isolation using low-cost unbonded fiber-reinforced elastomeric isolators (U-FREIs) made in Colombia. A methodology is proposed for the analysis of new and existing isolated structures, in which the isolators are placed between the substructure and superstructure. This methodology is used to design and strengthen a typical prestressed concrete girder bridge, and the results are compared against those obtained using a conventional scheme. Finally, an existing bridge is analyzed using on-site measurements to determine the dynamic properties and modify the numerical model used for analysis, design, and retrofitting. The effectiveness of the proposed methodology as a tool for the design of new bridges and the retrofitting of existing structures was verified for all cases. Economic and structural benefits were evidenced by reductions in direct costs of up to 15% and the seismic force of up to 20%, respectively.

The effects of the duration, intensity and magnitude of far-fault earthquakes on the seismic response of RC bridges retrofitted with seismic bearings

This paper investigates the effects of earthquakes’ duration, intensity, and magnitude on the seismic response of reinforced concrete (RC) bridges retrofitted with seismic bearings, such as elastomeric bearings (EB), lead rubber bearings (LRB), and friction pendulum bearings (FPB). In order to investigate the effects of the seismic isolation, the condition of the deck with a rigid connection on the cap beams and abutments (i.e., without isolation) was investigated as the first model. The EB, LRB and FPB bearings are used between the superstructure and substructure of the studied bridge in the second, third and fourth models, respectively. First, the effects of using seismic bearings on the seismic retrofit of an RC bridge under the Tabas earthquake were investigated. The results of the nonlinear dynamic analysis showed that the use of seismic bearings leads to seismic retrofit of the studied bridge, and FPB and LRB had the best results among the studied isolation equipment, respectively. The same models were also studied subjected to the Landers and Loma Prieta earthquakes. The magnitude of the Landers and Tabas earthquakes is equal to 7.3 Richter, and the magnitude of the Loma Prieta earthquake is equal to 6.7 Richter. However, the duration and intensity of the Landers and Loma Prieta earthquakes are much larger than the Tabas earthquake. The Landers and Loma Prieta earthquakes caused instability in the isolated models due to their significant duration and intensity. This issue shows that using seismic bearings is very useful and practical for seismic retrofitting bridges subjected to far-fault earthquakes. According to most seismic codes, selecting earthquakes in far-region of faults is based on just magnitude criterion. However, this study indicates that there are two main factors in the features of far-fault earthquakes, including duration and intensity. Ignoring these factors in selecting earthquakes may lead to the instability of structures. Considering earthquakes’ duration, intensity, and magnitude are vital for selecting earthquakes in the far region of the fault.

Risk-informed evaluation of tsunami evacuation risk mitigation strategies

ABSTRACT This paper proposes the risk-informed evaluation of different tsunami evacuation risk mitigation strategies to facilitate the identification of effective strategies that are robust to uncertainties. The tsunami evacuation risk (in terms of casualty rate) is used as a quantitative performance measure to compare different mitigation strategies. An improved agent-based model is used to simulate the tsunami evacuation. A simulation-based framework is used to quantify the tsunami evacuation risk, and various uncertainties associated with the evacuation are explicitly considered. Sensitivity analysis is performed to identify critical risk factors and guide the selection of candidate mitigation strategies. The concepts of importance sampling and augmented sample-based approach are used to efficiently evaluate the evacuation risk under different candidate strategies. The risk-informed evaluation of mitigation strategies is illustrated for the tsunami evacuation in Seaside, Oregon, where strategies such as route widening, bridge retrofit, building vertical shelter, preparedness education, and evacuation drill are compared.

Bridge Network Seismic Risk Assessment Using ShakeMap/HAZUS with Dynamic Traffic Modeling

Bridge infrastructures are critical nodes in a transportation network. In earthquake-prone areas, seismic performance assessment of infrastructure is essential to identify, retrofit, reconstruct, or, if necessary, demolish the infrastructure systems based on optimal decision-making processes. As one of the crucial components of the transportation network, any bridge failure would impede the post-earthquake rescue operation. Not only the failure of such high-risk critical components during an extreme event can lead to significant direct damages, but it also affects the transportation road network. The consequences of these secondary effects can easily lead to congestion and long queues if the performance of the transportation system before or after an event was not analyzed. These indirect losses can be more prominent compared to the actual damage to bridges. This paper brings about seismic performance assessment for the Cyprus transportation network from which the decision-making platform can be modeled and implemented. This study employs a seismic hazard analysis based on generated USGS ShakeMap scenarios for the risk assessment of the transportation network. Furthermore, identification of the resiliency and vulnerability of the transportation road network is carried out by utilizing the graph theory concept at the network level. Moreover, link performance measures, i.e., traffic modeling of the study region is simulated in a dynamic traffic assignment (DTA) simulation environment. Finally, for earthquake loss analysis of the bridges, the HAZUS loss estimation tool is used. The results of our investigations for three different earthquake scenarios have shown that seismic retrofitting of bridges is a cost-effective measure to reduce the structural and operational losses in the region.

Commuter welfare-based probabilistic seismic risk assessment of regional road networks

This study integrates welfare, a measure of the impact of road network disruption on individual commuters’ well-being, with a probabilistic seismic risk assessment framework in a computationally tractable way. Welfare is a network performance measure that reflects the differential impacts of changes in commute time on various groups. For a case study of the San Francisco Bay Area, welfare loss is computed by augmenting an origin–destination matrix with publicly available information about commuters’ income levels, residences, and workplaces. While commuters from all income groups have similar risk of drivers’ delay due to road network disruption, commuters with low incomes have a substantially higher risk of welfare loss than those with high incomes. A comparison of bridge retrofit policies shows that disaggregation of welfare loss by income group is necessary to examine whether such policies reduce risk equitably. While a retrofit policy determined using drivers’ delay reduces the expected drivers’ delay, it increases the disparity in the per-capita welfare loss of commuters with low and high incomes relative to the network’s baseline state. In contrast, a retrofit policy that prioritizes low-income commuters reduces the difference in welfare loss of commuters with low and high incomes compared to the baseline network state.

Life Cycle Assessment of Waste Glass Powder Incorporation on Concrete: A Bridge Retrofit Study Case

The construction sector is responsible for some of the highest energy and natural resources consumption. In this context, new materials and solutions are created aimed at developing sustainable alternatives. While the literature presents papers that evaluate the mechanical and durability properties of concrete with glass waste powder and account for its environmental impact, no papers have executed the evaluation considering the retrofit of bridges. Furthermore, no papers evaluating the materials, construction, and maintenance could be found. Hence, this study proposes a technical and sustainable solution for the retrofit of the Third Bridge of Vitoria, an important intercity urban connector. This study evaluates both the technical and the environmental performance of structural concrete elements, considering the partial substitution of cement with glass waste powder and a baseline scenario with conventional concrete. The environmental impacts were evaluated through the life cycle assessment tool. The results indicate that incorporating waste glass powder in the prestressed hollow-core slabs as a partial cement replacement can improve the durability-related properties and mitigate environmental impact. It also shows that the manufacturing phase is the most impactful and that glass powder can significantly reduce the impact of maintenance.

Shear Characteristic Changes in Blended Rubber of Elastomeric Bearings due to Aging

Rubber bearings are widely used for seismic retrofit of bridges because they reduce the seismic force by making the vibration period of the bridge longer and distributing the seismic force to all the piers. However, they have the disadvantage of being easily aged compared to steel bearings as well as having variations in the shear stiffness. The shear characteristic changes in the blended rubber for the rubber bearings were analyzed, specifically, the aging accelerated by heat. The higher the aging temperature and longer the exposure time, the greater is the maximum stress and strain at that time, and the greater is the shear stiffness. This implies that the seismic performance gradually deteriorates due to aging as the service period becomes longer. This can provide the basis for the mechanical model of the aging bearing.

Aerial Thermographic Image-Based Assessment of Thermal Bridges Using Representative Classifications and Calculations

Since the middle of the 20th century many any buildings were built without any energy standards and still have a comparably poor energy quality. To obtain an overview of the current thermal quality of buildings in a whole city district, it may be promising to work with thermographic images obtained by unmanned aerial vehicles (UAV). Aerial thermography represents a fast and cost-efficient approach compared to traditional terrestrial thermography. In this paper, we describe an approach to finding thermal bridges on aerial thermographic images and characterizing them in terms of their risk of mold formation, energy losses, retrofit costs, and retrofit benefits. To identify thermal bridge types that can be detected reliably on aerial thermographic images, we use a dataset collected with a UAV in an urban district of the German city of Karlsruhe. We classify and characterize 14 relevant thermal bridge types for the German building cohorts of the 1950s and 1960s. Concerning the criterion of mold formation, thermal bridges of window components, basement ceiling slabs, balcony slabs, floor slabs, and attics are found to be particularly relevant to retrofit projects. Regarding energy savings, the retrofit of thermal bridges of window sills, window lintels, and attics shows high potential. The retrofit of attics seems to be less attractive, when also taking into account the necessary retrofit costs.

New technique for self-centering shear keys in highway bridges

Shear keys are elements in bridges designed to prevent or limit transverse unseating, rotation, and/or collapse of the superstructure responding to strong-intensity earthquake input ground motion, as well as to absorb breaking and various self equilibrating forces. During the 2010 Maule earthquake, Chile's highway infrastructure was seriously impacted. Shear key failures were endemic and did not function as intended. As a result, some bridges experienced partial or complete collapse. Even when the shear keys appeared to have worked, the superstructure exhibited large offsets, which required expensive repairs. An expensive retrofit of undamaged bridges was also carried out as a result of the inadequate response of the bridge infrastructure. This paper addresses the behavioral issues of bridges designed incorporating conventional shear keys and proposes an innovative self-centering concept that eliminates residual displacements in the superstructure. The self-centering shear key concept, as it will be termed here, makes use of the bridge self-weight as a restoring force to ensure self-centering. This concept proposal takes advantage of the kinematics of the bridge. The self-centering shear key concept was validated for a typical Chilean bridge via an extensive study that made use of nonlinear time history analyses. The results indicate that the increase in seismic demand on the substructure is small enough to maintain the bridge base structure in the elastic range while eliminating any residual displacements in the superstructure.

Traffic efficiency of post-earthquake road network in fault region retrofitted by friction core rubber bearing

The post-earthquake emergency response depends on the traffic efficiency of the transportation network system. The bridge is the key factor affecting the reliability of the transportation network. Due to factors such as low design standards and performance degradation, the bridges built in the early days had low seismic performance. In fault regions, the pulse effect will also increase the seismic demand of the structure. In this paper, a friction core rubber bearing (FCRB) is proposed for seismic retrofit of road network bridge. Then calculate the fragility of bridges with and without retrofit under pulse and non-pulse effect, and the bridge traffic capacity under several road network conditions. The total travel time of the road network is used as a quantitative index of the reliability of the transportation network, and the prioritization of bridge retrofit under the limited budget and the assessment method of road network seismic risk are proposed. By comparing the difference of total travel time of road networks under different working conditions, the influence of pulse effect and the effect of FCRB are analyzed. Finally, a case is given to illustrate the effectiveness of FCRB in retrofitting the road network bridge and the necessity of considering the pulse effect. The results show that: it is necessary to consider the influence of pulse effect in road network risk assessment with high earthquake magnitude; the bridge retrofit prioritization takes into account the bridge traffic flow and the bridge traffic capacity, which is easy to calculate and can identify the critical bridges that have an important influence on traffic efficiency; with the increase of earthquake magnitude, the seismic risk of road network presents a geometric increase trend; FCRB can significantly reduce the road network seismic risk, and the seismic risk can be reduced by more than 50% if 20 bridges are retrofitted; with the increase in the number of retrofitted bridges, the decreasing trend of the annual seismic risk changes from fast to slow, and finally tends to be flat, which verifies the effectiveness of the retrofit prioritization.