Seismic Performance Of Bridge Research Articles

An innovative sliding-controllable laminated rubber bearing for enhancing seismic performance of highway bridges

Economical laminated rubber bearings have been widely utilized in highway bridges for their exceptional performance under service conditions. These bearings effectively mitigate seismic responses during earthquakes through shear deformation or sliding, contingent upon their bonding methods, whether bonded or unbonded. Nevertheless, past seismic events have underscored vulnerabilities, with unbonded laminated rubber bearings susceptible to excessive displacement and bonded bearings prone to fracture during large earthquakes. To address these seismic deficiencies and improve bridge seismic performance, a novel controllable sliding laminated rubber bearing (SC-LRB) is proposed in this study. The SC-LRB seamlessly integrates the shear-deforming behavior of bonded laminated rubber bearings (B-LRB) with the frictional sliding behavior of unbonded bearings (U-LRB). A quasi-static experiment was initially conducted to investigate the cyclic behaviors of the SC-LRB, leading to the development and calibration of the numerical model for the bearing. Subsequent nonlinear time history analyses were carried out to evaluate the influence of SC-LRBs on the seismic performance of bridges. Results indicate that, with its three-stage working mechanism (pre-sliding, sliding, and post-sliding), the SC-LRB exhibits a friction-shear collaborative behavior, effectively balancing the energy dissipation and recentering capacities of the bearing during earthquakes. Bridges equipped with the SC-LRB demonstrate an ability to maintain balance between controlling bearing displacements and isolating pier seismic demands. The proposed SC-LRB presents promising potential for enhancing the seismic resilience of highway bridges.

Dynamics and Seismic Performance of Bridges with Rocking Piers of Nonconventional Configuration

Dynamics and Seismic Performance of Bridges with Rocking Piers of Nonconventional Configuration

Bridge Capacity Assessment through LRFR Method and Bridge Seismic Performance Evaluation Using the PBSD Concept: Case Study

In this study, a comprehensive evaluation was conducted of the condition and performance of a concrete arch-type bridge located in close proximity to a fault. Utilizing the LRFR capacity assessment method and seismic performance analysis through the NLTHA process based on the PBSD concept, finite element modeling (FEM) was employed with a focus on construction stage analysis and model updating for calibration to site conditions. The assessment encompassed the determination of the rating factor for structural elements under service and ultimate limit state loading. Performance analysis under seismic loads includes an examination of engineering demand parameters such as concrete and reinforcement strains in columns, subjected to varying seismic hazard levels. Additional scrutiny involves assessing bearing displacement and overturning potential to identify potential damage before column failure. The primary objective of this research was to investigate pertinent and efficient techniques for evaluating bridge capacity and seismic performance. A thorough understanding of these methods is expected to facilitate the identification of suitable solutions to enhance the safety and reliability of bridges in Indonesia.

Review Seismic Analysis of a Composite Bridge Structure and Its Properties

Abstract: The seismic performance of bridges is of paramount importance, particularly in regions prone to seismic activity. This study presents an in-depth analysis of the seismic behavior of a composite bridge structure using the powerful finite element analysis software, ANSYS. The research explores the response of a composite bridge, considering the dynamic forces induced during seismic events. A detailed finite element model is developed, incorporating the various components of the composite bridge, including the superstructure, substructure, and the interaction between different materials such as concrete and steel. The analysis involves subjecting the bridge model to realistic seismic ground motions to simulate real-world conditions. Various parameters are investigated, including the bridge's dynamic response, stresses, deformations, and potential failure modes. Through the utilization of ANSYS, this study provides critical insights into the seismic performance of composite bridges. The findings contribute to enhancing the design and construction of resilient infrastructure capable of withstanding seismic forces, ultimately ensuring the safety and functionality of vital transportation networks.

Study on the seismic characteristics of piers considering site conditions and hydrodynamic effect

Sea-crossing bridges face complex site environments compared to onshore bridges, with the marine environment significantly influencing seismic responses. Despite this, current seismic design for these bridges relies on onshore earthquake records. Therefore, investigating the impact of seawater layers and site conditions on sea-crossing bridge seismic performance is crucial. This paper investigates the influence of characteristics of offshore ground motion, site conditions, and hydrodynamic effect on the seismic performance of piers. Initially, based on the validated finite element model, 5 offshore and onshore strong ground motion records from K-NET were selected for assessing the seismic performance of piers. Subsequently, the effects of the water depth and site conditions on the seismic responses of piers were investigated. Finally, the effects of the section size, section shape, and boundary conditions on the piers were investigated. The result shows that the seismic response of piers under offshore ground motion exceeds that under onshore ground motion. In addition, the seismic response of the pier increases with greater water depth, while they exhibit a slight decrease with increasing soil depth. Notably, the larger the section size, result in higher the hydrodynamic pressure, and square piers experience greater hydrodynamic pressure compared to circular piers.

Effect of Steel Jacketing Thickness on Seismic Performance of Bridge

The bridges of Nepal are getting older and old bridges were designed without considering the seismic forces, hence have low seismic capacity. The capacity of these bridges needs to be enhanced and should perform well during seismic events. The jacketing technique can be used to upgrade the bridge's structural performance. This research paper mostly focuses on the seismic performance enhancement after the application of steel jacketing on the bridge pier. The variable that has been varied is the thickness of the steel jacket. The capacity of a bridge pier is evaluated using displacement-controlled nonlinear static analysis (Pushover). The time history load is applied to the structure to determine the seismic demand of the bridge. The quantification of the enhancement of the bridge structure after the application of Steel Jacketing is evaluated by plotting the fragility curve. The modeling of the bridge is done in CSI Bridge V20.2.0. The different damage state is defined using the strain values obtained from the pushover analysis. For different damage states, the capacity and demand value are used to obtain the probability of exceeding at different PGA levels. The fragility curve is developed using the First Order Second Order Method (FOSM). From the study, it is found, that the vulnerability of the bridge after the use of jacketing for extensive damage state, the probability of failure reduced from 28.22% to 14.24% at 1.0g PGA. Similarly, the vulnerability of the bridge after the use of jacketing for collapse damage state, the probability of failure decreased from 16.93% to 7.22% at 1.0 PGA

Does vehicle‐bridge interaction resemble the effect of tuned‐mass dampers on bridges during earthquakes?

AbstractIn many seismic studies, the coupled vehicle‐bridge system is treated as a tuned‐mass damper (TMD)‐bridge system, and unsurprisingly, the vehicle usually reduces the seismic bridge response. The current study challenges this common belief. To this end, it investigates the influence of running vehicles on the seismic performance of bridges. Specifically, it compares the effect of vehicle‐bridge interaction (VBI) to that of a TMD on bridges subjected to earthquakes. The discussion explores the underlying physical mechanisms of VBI and TMD, and highlights the superficial similarities and the substantial differences between them. In this context, the study presents pertinent numerical simulations for a set of natural earthquake records.

Displacement-based seismic performance of RC bridge pier

To correctly manage the road infrastructure before and after an earthquake, it is necessary to estimate and even predict the seismic performance of the bridge. The quantification of the bridge's seismic performance response was present in terms of displacement and also based on previous research of reinforced concrete bridge pier models. The displacement did define from a force lateral-displacement response diagram corresponding to the capacity curve, calculated through a non-linear static pushover analysis of the reinforced concrete bridge pier model for each limit state, from intact state to collapse. Thus, six defined displacements correspond to the cracking displacement, the yielding displacement, the spalling displacement, the crushing displacement, the buckling displacement, and the fracturing displacement. The six defined limit states correspond to the cracking limit state, the yielding limit state, the spalling limit state, the crushing limit state, the buckling limit state, and the fracturing limit state. Also, parametric analysis did carry out to evaluate the influence, relative importance, and trend of the input parameters in response to the seismic performance of the reinforced concrete bridge pier model. Eleven input parameters did analyze as the concrete compressive strength, the yield stress of reinforcing steel, the concrete cover thickness, the pier aspect ratio, the configuration of the transverse reinforcement, the spacing of the transverse reinforcing steel, the transversal diameter of the transverse reinforcing steel, the longitudinal reinforcement ratio, the transversal diameter of the longitudinal reinforcing steel, the axial load ratio, and coefficient of subgrade reaction.

Influence of Span Length and Radius on Isolated Steel I-Girder Bridge under Different Ground Motion

Abstract: Bridges are essential for transportation from many years, out of them Steel I-girder bridge is very old and frequently used in many parts of the world. The current practice of bridge required reduction in bridge demand and proper stability of bridge girder specially at horizontally curve bridge, these are more critical during earthquake. Therefore, it is crucial to understand the seismic behaviour of the Steel I- girder bridge under ground motion. This study investigates the effect of different span length and Radius of bridge, under seismic forces. 3D model of three span, two lane steel I-girder bridge having five number of longitudinal girders, which are interconnected by X-bracing used for analysis. Seismic performance of bridge has been improved by using Lead Rubber Bearing (LRB) as isolator. Time history analysis has been performed to carry out seismic analysis under different ground motion. Study compare both isolated and non-isolated bridge performance. Result help to establish relationship between base shear, span of bridge, radius of bridge, transverse displacement and time period with and without isolator. Result shows that base shear is 60-77% reduce by using LRB.

Effects of friction pendulum bearing wear on seismic performance of long-span continuous girder bridge

To clear the wear effect of friction pendulum bearings (FPBs) on the seismic performance of multiple long-span continuous girder bridges, the rapid sliding performance test of the FPBs was carried out to get the wear degree of the modified poly tetra fluoroethylene (PTFE) wear plates. Taking a 6×110 m long-span continuous girder bridge as the engineering background, the seismic response of the bridge with different wear degrees of the FPBs was analyzed. The results show that the modified PTFE wear plate of the FPBs was severely worn in the rapid sliding performance test, and the friction coefficient was first increased to 0.09 and then decreased to 0.016. When the maximum displacement was reached, the bearing collided with the limitation block. Moreover, the internal forces of the critical pier were increased, and the bottom of the piers entered plasticity due to the wear of the FPBs. Due to the change in the seismic performance of the bridge, it is suggested that the rapid sliding performance of FPBs should be tested to ensure the structure safety of the long-span continuous girder bridge in rare earthquakes.

Seismic performance analysis of a concrete filled steel tubes arch bridge: A parametric study

AbstractNumerical method is widely used in bridge seismic performance analysis, but the diversity and complexity structures increase trouble in the modeling process. This article presents a systematic, universal, and flexible bridge numerical modeling method, and the seismic performance of a concrete filled steel tubes arch bridge is studied. The geometric/attribute model involves structural/stiffness equivalence, and the bridge parametric modeling strategy combined commercial computer‐aided design language of software MATLAB and ANSYS. Data exchange in different fields and rapid reconstruction of numerical model are realizing. Finally, the vibration mode, deformation and internal force of the bridge under seismic load are studied. The results indicating that the proposed parametric model formed a complete data transfer process, and the bridge model can be rapidly modifying and reconstructing. The numerical calculation efficiency is greatly improved because of the structure element is employed instead of solid element. The displacement and internal force of arch rib are mainly controlling by lateral load under horizontal uni‐input, and the combined horizontal and vertical load should be considering in seismic design. The leaning angle and width‐span ratio of transverse braces are considered to improve the seismic performance of bridges.

Assessment of the seismic behavior of short-to-medium overall length girder bridges under asynchronous ground motions

Proper seismic analysis and design of bridges are critical, especially in locations prone to high seismic activities where critical infrastructure is at a high risk of seismic damage leading to direct and indirect losses. The seismic performance of bridges has been widely investigated in the literature, but the effect of asynchronous ground motions for short-to-medium overall length girder bridges is a phenomenon that has not been adequately addressed by bridge codes and thus it warrants further research. For such bridges, the often-employed envelope response spectrum is not generally applicable for asynchronous ground motions as this is a multiple-support excitation problem where potential local demand concentrations are critical. This study investigates the effects of asynchronous ground motion on the seismic response of short-to-medium overall length girder bridges with reinforced concrete columns considering crustal, subcrustal and subduction earthquakes. The main source of spatial variability of ground motions considered was the variation in the local soil conditions at the foundation of 3-span (short) and 7-span (medium) overall length prototype girder bridges. Soil classes A (rocky soil) and E (softer soil) were considered to establish different combinations of soil distribution in the foundation and then compared to baseline models where site class C was applied to all the supports of the structure to study the effects of asynchronous ground motions. It was found that the variation of site class in the foundations for such structures could produce detrimental effects on the dynamic response of the structure. The presence of softer soil in most of the structure's foundations elongated the vibration period of the structure and resulted in higher displacement demands. Results also showed that critical demands are concentrated at locations where the soil conditions change, indicating increased sensitivity to seismic effects at certain locations, which would not be captured by the typical code-prescribed procedure in the presence of asynchronous ground motion effects.

Sensitivity analysis of seismic performance of portfolio of bridge supports for multiple qualitative limit states

The seismic performance of bridges is of primary importance for the durability and functionality of these structures. Several numerical methods have arisen in order to evaluate this performance and one is generally led to define the most significant input parameters in the seismic response. Thus, the sensitivity analyses are practical tools to achieve this objective. In this study, a sensitivity study was carried out on the seismic performance of 88 supports of a road network located in a low to moderate seismic zone. A preliminary visual inspection of these structures was carried out and showed the degree of advanced degradation that the structure had undergone during its lifetime. This visual inspection was completed by a set of non-destructive and destructive tests in order to characterize the geometric and mechanical parameters of the materials that compose these supports. The data collected is directly inserted into the finite element model on OpenSees, which describes the nonlinear fibered behavior with distributed plasticity of these supports. The seismic capacity is thus described through the nonlinear static analysis which provides the shear force curves at the base as a function of the displacement at the head of the pile. This curve will be idealized into a bilinear curve in order to integrate it into the equivalent linear system composed of both the supports and the elastomers that serve as seismic isolators. The sensitivity study is carried out on the basis of the analysis of variance, which evaluates the part of the variance of the input parameters in the output responses that characterize the seismic behavior of these structures. The input parameters are vertical loads, geometric and material properties, and output responses are the deck and top pier displacements, in addition to the shear force at the base of the supports and the distortion of the elastomers. The results of the sensitivity study allowed to prioritize the most significant parameters in the seismic responses for different limit states. The most significant parameters are the ratio of longitudinal and transverse reinforcement, followed by the diameter of the piles and the applied vertical loads.

Seismic performance of bridges with novel SMA cable‐restrained high damping rubber bearings against near‐fault ground motions

AbstractThis study presents a novel type of shape memory alloy (SMA) cable‐restrained high damping rubber (SMA‐HDR) bearing, which is particularly suited to near‐fault (NF) regions where the pulsing effect potentially exists in the ground motions. The working mechanism of the bearing is first described, followed by an experimental investigation on a full‐scale SMA‐HDR bearing specimen. The test results confirm the efficient restraining effect offered by the SMA cables, which contribute to 65% and 24.4% of the lateral load resistance and total energy dissipation, respectively, prior to the initial fracture of the SMA cables. The failure of the cables is initiated near the end grip where moderate stress concentration exists at this region. Following the experimental study, the numerical modeling strategy for the bearing is discussed, and a case study is then presented, demonstrating the application of the SMA‐HDR bearings in the Datianba #2 highway bridge, a real project that first adopts the proposed bearings in the world. A simplified design process is introduced for the bridge with novel SMA‐HDR bearings to mitigate the potential damage during strong earthquakes especially the NF ones. The system‐level analysis on the prototype bridge shows that the novel SMA‐HDR bearings equipped with ten 7×7×1.2 SMA cables in each bearing could reduce the average maximum bearing displacement (MBD) by nearly 30% compared with the conventional bridge with HDR bearings. The application of the novel SMA‐HDR bearing can significantly alleviate the pounding effect, especially under the NF earthquakes. The presence of the SMA cables tends to increase the maximum force response of the piers, but this effect is minor and under control.

Seismic Response of a Cable-Stayed Bridge considering Non-uniform Excitation Effect: Model Design and Shake Table Testing

In the absence of intensive tests on the cable-stayed bridges under non-uniform excitation, this study provides a practical and accurate approach to investigate the seismic response of cable-stayed bridges considering spatially varying earthquake inputs. The cable-stayed bridge model with a scale ratio of 1:120 was designed and tested on a newly-developed dual shake table system. Firstly, the modal test was conducted to evaluate the accuracy of the designed specimen. Secondly, both the same input cases and the different inputs cases were executed to study the wave passage effects on bridge specimen's dynamic response. Lastly, the effects of non-uniform excitation and site classification on the experimental bridge's seismic performance were studied with test results of various soil condition cases. The test results showed that the bending of the girder was magnified, while the swing of the tower was subdued when the effect of wave propagation was considered. Moreover, compared with the same input cases, the different inputs cases reported a larger response to the extent of 80%. Regarding the effects of site conditions, it was concluded that the site of soft soil had more influence on the dynamic responses of such bridge structures than that of the firm soil site.

Influence of Restrainer Piers on the Seismic Performance of Long Bridges with Equal-Height Piers

Pounding may occur between the main girders under the action of strong earthquakes, so as between main girders and abutments. This causes excessive longitudinal displacement of the main girder and unseating damage to bridges. Because long bridges in mountainous areas with high intensity are easy to unseat, the authors studied the influence of restrainer piers, expansion joint spacings (EJSs), and the span on the seismic performance of long bridges. The ABAQUS finite element software was used to simulate a bridge dynamic analysis model considering the elastoplasticity of the pounding effect of the pier and the beam. By inputting El-Centro, Northbridge, and Taft seismic waves, the time-history analysis of the seismic response of long bridges was carried out. The results indicated that a reasonable number of restrainer piers, an appropriate EJS, and a span could effectively reduce the maximum relative displacement of pier-beams. This behavior will improve the seismic performance of bridge structures. Moreover, for a 24-span equal-height beam bridge, the optimum seismic effect was obtained when 3 restrainer piers, an EJS of 70 mm, and a 50 m span were used.

Pattern Recognition of the Seismic Demands for Tall Pier Bridge Systems

ABSTRACT An essential and emerging task in the area of performance-based seismic assessment of bridges is to improve the estimation of the seismic demands. Existing research proved that the bridge column is one of the dominant components in estimating the bridge system vulnerability. However, the seismic performance of bridges with tall piers is not deeply investigated yet. This study aims to address this problem through analysis of multi-span concrete box-girder bridges with tall piers. This study implements a clustering algorithm that identifies optimized groupings which can set up the basis to establish the best choice for generating MLPSDMs. The evaluation results implicate better performance of cluster-wise multiple models than a single model to represent the variation in the bridge demands. The insights gained from the findings of this study can pave the way toward a better realization of the seismic performance of bridges having tall piers.

Seismic performance of bridges with ECC-reinforced piers

Engineered cementitious composite (ECC) material, which is characterized by satisfactory resilience, moderate energy dissipation capacity as well as superhigh compressive and tensile strengths, has been widely applied to civil infrastructures (e.g., bridges, buildings, and coastal structures). To identify sensitive parameters, enhance resilience, and reduce cost of the ECC-reinforced structures effectively, a sensitivity analysis framework for the ECC-reinforced structures is necessary. In this regard, a uniaxial material model for the ECC material is firstly introduced and implemented in an open system for earthquake engineering simulation platform (OpenSees). A sensitivity analysis approach for the ECC material is proposed by deriving a series of sensitivity analysis equations at structure, element, and material levels based on direct differentiation method (DDM). The sensitivity analysis approach is integrated into the OpenSees and could be used directly for the ECC-reinforced structures. At last, the proposed ECC constitutive model are validated by three benchmark examples. The performance assessment and sensitivity analysis are conducted on a prototype bridge. The analyses results indicate that: (1) the earthquake-resistant and damage-control capacities of the ECC material are better than those of the normal concrete; (2) the DDM-based sensitivity analysis method is more efficient and accurate than the FDM-based one.

Influence of time-varying attenuation effect of damage index on seismic fragility of bridge

Fragility as one of the most effective methods to evaluate seismic performance, which is greatly affected by damage index. Taking a multi span continuous rigid frame offshore bridge as an example. Based on fragility and reliability theory, considering coupling effect of time-varying durability damage of materials and time-varying attenuation effect of damage index to analyze seismic performance of offshore bridges. Results show that IDA curve considering time-varying damage index is obviously below that without considering; area enclosed by IDA of 1# pier and X-axis under No.1 earthquake considering this effect is 96% of that without considering. Area enclosed by damage index of 1# pier and X-axis under serious damage with considering time-varying damage index is 90% of that without considering in service period. Time-varying damage index has a greater impact on short pier when ground motion intensity is small, while it has a great impact on high pier when the intensity is large. The area enclosed by fragility of bridge system and X-axis under complete destruction considering time-varying damage index is 165% of that without considering when reach designed service life. Therefore, time-varying attenuation effect of damage index has a great impact on seismic performance of bridge in service period.

Residual drift spectra for RC bridge columns subjected to near-fault earthquakes

Permanent displacement of a bridge column can be directly measured during the inspection after near-fault earthquakes. However, the engineer needs to estimate the expected residual drift at the design stage to determine if the bridge seismic performance is satisfactory. The most direct method to estimate the residual displacement is nonlinear response history analysis, which is time consuming and cumbersome. Alternatively, an attractive but indirect method is generating estimated residual displacement spectra that depend on displacement ductility demand, column period, site conditions, and earthquake characteristics. Given the period and the expected displacement ductility demand for the column, the residual drift response spectra curves can be utilized to estimate the residual drift demand. Residual drift spectra that are applicable to RC bridge columns in different parts of the United States were developed based on nonlinear response history analyses using a comprehensive collection of recorded and synthetic near-fault ground motions and were linked to one-second spectral acceleration (S1) of the AASHTO maps. It was also found that the residual drift ratio is below one percent when S1 is less than 0.6 g.