Seismic Performance Of Bridge Research Articles

Influence of Tie Beams of Pier on the Seismic Performance of a Continuous Rigid Frame Bridge with Twin-Legged Piers

In this paper, the influence of tie beams for piers is investigated on the dynamic characteristics and the seismic performance of a continuous rigid frame bridge with twin-legged piers. Modal analyses and the linear seismic response analyses are performed on a practical continuous rigid frame bridge with twin-legged piers with no tie beam, one tie beam and three tie beams of pier, using software Midas/civil. The findings indicate that installing tie beams of pier can increase the natural frequencies of this kind of bridge. Setting tie beams of pier is disadvantageous to the seismic performance of the bridge beam, but advantageous to improving the seismic performance of the twin-legged piers. The influence of tie beams of pier on the seismic performance on the whole structure is relevant to the pier height. These analytical results provide a reference for the seismic design and analysis of similar structures.

Seismic performance of bridges with rubber bearings: lessons learnt from the 1999 Chi-Chi Taiwan earthquake

In 1999, the Chi-Chi earthquake caused tremendous loss in infrastructure systems and caused severe damage to bridge structures. However, a large number of bridges experienced only minor damage and there has been little discussion of the performance of those bridges. This study is to discuss the damage to bridge bearing systems based on field investigations and numerical analyses. This article draws a qualitative description of the performance and the failure modes of highway bridges during the Chi-Chi earthquake. It is concluded that the sliding mechanism of rubber bearings played an important role in limiting the seismic load transmitted to the bridge columns. In order to demonstrate this phenomenon, a nonlinear finite element model of the Yen-Feng bridge was developed to simulate its seismic performance during the Chi-Chi earthquake. The analytical results were compared with the observed damage. Parametric studies were then conducted by utilizing two kinds of bearing conditions and three friction coefficients on the rubber bearings to explain why similar bridges experienced different levels of damage during the earthquake.

Managing seismic performance of highway bridges – evolution in experimental research

The utilisation of experimental testing data to understand and improve the seismic performance of bridge structures is relatively new. Fifty-two years ago at a meeting of world experts and researchers of earthquake engineering, field observation was the only assessment technique that was discussed with respect to verification of design in physical structures, and laboratory tests were not included in the article. This article shows the evolution in seismic experimental studies and how it was triggered by the 1971 San Fernando Earthquake. Different aspects and examples of component, subsystem, and system testing are discussed. An overview of the seismic retrofit methods and a few examples of seismic repair methods are presented. A discussion of the utilisation of innovative materials such as shape memory alloys to improve the seismic performance and serviceability of bridges after strong earthquakes is also presented.

Bearing Simulation in Seismic Response Analysis of a Multi-Span Continuous Girder Bridge

The damage of bearing will change the boundary condition for whole bridge, if we do not take account of bearing failure, the error of structural analysis and the unreasonable in design will be made. In this paper, the effect of possible bearing damage to whole bridge during strong ground motion is studied through examining the seismic performance of a multi-span continuous girder bridge which is a real damaged bridge during the Wenchuan earthquake in 2008. Proper analytical restoring force models of bearings are proposed, which can simulate the seismic performance of the bridge before and after the bearing damage suitably.

Parameter Effect of Side Retainers on Seismic Response of Bridges with Flexible Rubber Bearings

This paper studies the parameter effect of side retainers on seismic response of bridges with flexible rubber bearings. The pounding effect between girder and side retainers is analyzed by the nonlinear time-history analysis. The pounding and sliding of bearings are simulated by the nonlinear contact elements. Comparative analysis of seismic performance of bridge with/without retainers is carried out. Furthermore, the seismic performances of ordinary retainers and new retainers are compared. Finally, the effect of side retainer parameters on seismic response of bridge is analyzed. The results indicate that the sliding of elastomeric pad bearing should be considered in seismic design. It is shown that the retainers can effectively restrain the relative displacement between girder and piers, and the new type of retainers can greatly reduce the pounding force. It is also proved that both stiffness and gap of the retainer have significant influences on the pounding force.

Seismic performance of isolated curved steel viaducts under level II earthquakes

This paper investigates the effectiveness of the use of seismic isolation devices on the overall 3D seismic response of curved highway viaducts with an emphasis on expansion joints. Furthermore, an evaluation of the effectiveness of the use of cable restrainers is presented. For this purpose, the bridge seismic performance has been evaluated on four different radii of curvature, considering two cases: restrained and unrestrained curved viaducts. Depending on the radius of curvature, three-dimensional non-linear dynamic analysis shows the vulnerability of curved viaducts to pounding and deck unseating damage. In this study, the efficiency of using LRB supports combined with cable restrainers on curved viaducts is demonstrated, not only by reducing in all cases the possible damage, but also by providing a similar behavior in the viaducts despite of curvature radius.

Assessment and modeling of embankment participation in the seismic response of integral abutment bridges

The dynamic response and seismic performance of bridges may be appreciably affected by numerous contributing factors, with soil–structure interaction being the dominant exogenous influence. The most familiar form is the so-called soil–pile interaction, but embankment–abutment interaction is also documented through field observations and analytical investigations, particularly evident in integral R.C. bridges. Recent studies have shown that this form of interaction may significantly alter the bridge response and should be taken into account during design and assessment, especially in the case of typical highway overcrossings that have abutments supported on earth embankments. In light of this emerging problem and in order to facilitate quantitative estimates of the interaction effects, the question of appropriate modeling and seismic assessment of R.C. integral bridges is the main object of the present paper. Based on already established procedures to account for soil–structure interaction, a new approach is proposed to model the contribution of the embankment, the bent and the abutments to the overall bridge response. Furthermore, the capacity curve of the entire bridge system is evaluated through the implementation of Incremental Dynamic Analysis (IDA), therefore allowing for seismic assessment of the complex superstructure–foundation system with well established displacement based procedures. Using as a benchmark case two typical instrumented U.S. highway bridges located in California, the proposed method is implemented and provided results from this analysis are correlated successfully with available field data. Results obtained from the analysis indicate excessive displacement demands for the entire bridge–embankment system owing to the embankment contribution and the soil degradation under increasing shear strains. Furthermore, seismic performance is strongly related to the central bent deformation capacity, with soil–pile interaction effects being of critical importance.

Curvature effect on seismic response of curved highway viaducts equipped with unseating cable restrainers

This paper investigates the possibility of pounding, deck unseating and tangential joint residual damage depending on the curvature radius. Furthermore, an evaluation of the effectiveness of the use of cable restrainers on the overall 3D seismic response of highway viaducts is presented. For this purpose, the bridge seismic performance has been evaluated on four different radii of curvature, considering two cases: restrained and unrestrained curved viaducts. Depending on the radius of curvature, three-dimensional non-linear dynamic analysis shows the vulnerability of curved viaducts to pounding and deck unseating damage. In this study, the efficiency of using cable restrainers on curved viaducts is demonstrated, not only by reducing in all cases the possible damage, but also by providing a similar behavior in the viaducts despite of curvature radius.

Effect of torsional stiffness of prestressed concrete box girders and uplift of abutment bearings on seismic performance of bridges

Uplift of certain abutment bearings during earthquake may be utilized as a safety mechanism for the protection of the bridge against excessive stress. For this reason design codes such as Eurocode 8 permit the uplift of such bearings under certain conditions. Uplift of an abutment bearing occurs when the torque at the deck end exceeds a critical value. Therefore the torsional stiffness of the deck, before or after concrete cracking, is an important factor. In this work realistic values for the cracked torsional stiffness of the bridge deck are estimated from a parametric study of typical thin-walled prestressed box girders, based on non-linear analysis of softened space truss models proposed in the literature. Moreover the interaction between bearing uplift and pier flexural response is investigated and recommendations for the seismic design of bridges are proposed, taking into account the possibility of uplift of abutment bearings before or after yielding of the piers.

Full-scale pseudo-dynamic test for bridge retrofitted with seismic isolations

The authors examine retrofitted bridge pier performance with a seismic isolation present. Retrofitted bridge seismic performance experimental validation was done through fabrication and testing of four full-scale reinforced concrete bridge piers with fixed support conditions. To simulate the superstructure dead load, a static vertical load was applied to the bearing top and several different bearing systems were installed. Conventional pot bearing was also considered in addition to lead rubber bearing (LRB) and rubber bearing (RB) systems. To simulate earthquake loading, a horizontal loading was applied to the specimen using a pseudo-dynamic testing method. Isolated RB and LRB system specimen seismic response was compared to that of the conventional pot bearing specimen. That the seismic isolation system this study considers is effective in magnitude reduction of transferred substructure forces and period bridge shifting is shown in the results. The peak acceleration transmitted to the structure can be effectively reduced by the LRB structure, which under earthquake loading is less than those with RB system. That the proposed seismic retrofit method was found to be valid can be concluded through the test results.

Research on seismic safety, retrofit, and design of a steel cable-stayed bridge

After the 1995 Great Hanshin Earthquake, Japanese design specification of highway bridges was revised and many piers and bearing supports have been retrofitted. Large span bridges such as arch, truss, and cable-stayed bridges located in bay area of Kobe city also suffered damages from this earthquake. Therefore the investigation of seismic performance of long span bridges has been conducted for large earthquake. The Aratsu bridge constructed in 1987 is a steel cable-stayed bridge of 345m length, continuous three spans, and single plane of stay cables. The seismic performance of this bridge was examined by nonlinear time history analyses using tri-linear back bone and hysterecis loops. Furthermore fiber model analysis and FE analysis are successfully used to check the behaviors of this bridge. According to the analysis of the target bridge, weak members for large earthquake have been clarified. Install of damper and displacement restrainer, and strengthening of components of bearing supports are proposed retrofit countermeasures. The behavior of retrofitted bridge satisfies the criteria of design specification of highway bridges.

Faulting and Fault-induced Damages and Disasters:DAMAGE OF BRIDGES RESULTING FROM FAULT RUPTURE IN THE 1999 KOCAELI AND DUZCE, TURKEY EARTHQUAKES AND THE 1999 CHI-CHI, TAIWAN EARTHQUAKE

This paper describes the damage of bridges resulting from the fault movements in the 1999 Kocaeli and Duzce, Turkey, Earthquakes and the 1999 Chi-Chi, Taiwan, Earthquake. Effect of the fault displacement on the seismic performance of bridges is presented with an emphasis on the mechanism of failure.