Multi-span Bridge Research Articles

Effects of Pounding and Abutment Behavior on Seismic Response of Multi-Span Bridge Considering Abutment-Soil-Foundation-Structure Interactions

This study aims to analyze the longitudinal seismic performance of a typical multi-span continuous girder bridge with seat-type abutments under earthquake excitation, especially accounting for different abutment behaviors. Three-dimensional finite element models of typical multi-span bridges are built considering the nonlinearity of the bridge columns, bearings, abutment-backfill interactions, pile-soil interactions, and the pounding at expansion joints. One of the models adopts a simplified bilinear model to express the force-displacement relationship of the abutment backwall. The other adopts a more practical multi-linear model, and the abutment backwall is used as a sacrificial component to control the damage to the abutment’s foundation by changing the strength of the abutment backwall. Comparisons of the results of the analysis of two bridge models with and without a sacrificial backwall indicate that it is more favorable for bridges with a sacrificial backwall to protect the foundation, but it is likely to arouse a larger displacement response of the main beam and even cause the unseating of girders. The recommendation for a sacrificial abutment in seismic design is that the right yield strength of the backwall should be selected to reach the balance point of force and displacement, and a collapse-proof system could be employed to prevent the beam from unseating.

Influence of vehicular movement on the seismic response and fragility of highway bridge structures

Recognising the criticality of highway bridges for the socio-economic development of a nation, multiple researchers have endeavoured towards quantifying the seismic fragility of these key infrastructure elements. Given the present boom in urbanisation, however, there may also be an appreciable likelihood of vehicle presence on the highway bridge deck during an earthquake event. This study focuses on the impact assessment of vehicle-bridge-interaction (VBI) on the seismic fragility of highway bridges by explicitly accounting for vehicular movement atop the bridge deck during seismic shaking. Addressing existing drawbacks in literature that typically adopts a simplified modelling strategy and static vehicle placement, this paper considers different types of moving vehicles (modelled as mass-spring-dashpot system analogies) for VBI assessment through a novel algorithm. The proposed framework also accounts for uncertainties involved in the moving vehicle analysis, pertaining to vehicle characteristics and driver’s perception of the earthquake. The framework is demonstrated on representative multi-span continuous steel girder bridges located in Central and Southeastern United States. A comparative assessment of hysteretic response of bridge components and seismic fragility curves indicate a considerable influence of vehicular movement on bridge damage, signifying the importance of considering moving VBI effects for thorough seismic assessment of highway bridge structures.

ND testing and establishing models of a multi-span masonry arch bridge

The Olla bridge, built in the second half of the nineteenth century, is an arch bridge consisting of five brick masonry arches with stone masonry piers. The bridge crosses the Stura river along the State Route SS 21, connecting the French border with the South-West part of the Piedmont region, and still represents a crucial node for the local commercial traffic. The paper summarises selected results of the extensive research programme carried out to assess the structural conditions of the historic bridge, which exhibited local damage of the arches and diffused surface decay. After a discussion on the common issues arising in the structural assessment of historical infrastructures, the Olla bridge is described and full details are given on the different steps of the investigation: (a) historical research, geomatic survey, on-site visual inspection and limited local tests on materials; (b) operational modal testing and analysis; (c) development of a FE model based on architectural research and selected modelling assumptions; (d) choice of the uncertain structural parameters and identification of the optimal parameters based on the experimentally obtained data.

Rail Structure Interaction Analysis for Providing CWR on Un-Ballasted Multi-Span Open Web Steel Girder Bridge

Rail structure interaction (RSI) requires thorough study to understand the force transfer mechanism between the track and bridge components due to train vertical live loads, braking/traction loads and thermal loads accordingly. RSI analysis gives us an outline of the axial stress in rail, support reactions transferred to the bridge components and the relative displacement caused between the track and bridge. This paper investigates rail structure interaction analysis of unballasted multi-span steel through girder railway bridge carrying dedicated freight corridor (DFC) of 32.5t axle load. For this purpose, RSI analysis is performed as per the guidelines given in UIC774-3R [7] Code of Practice (International Union of Railways) for two different multi-span bridge with a span configuration of 7x63m and 6x48m respectively and the axial stress in rail, relative displacement between rail and bridge and support reactions transferred to the bridge components are calculated based on the span and stiffnesses of the bridges. From the analysis results, it shall be concluded whether to explore the possibility of providing a provision of continuous welded rail (CWR) on the bridge or to adopt switch expansion joints (SEJ) or other expansion devices accordingly.

Bridges seismically isolated by DCFP devices: a study on how the main parameters of the problem affect the seismic performance of the system

This paper deals with the evaluation of the main relevant properties of the double concave friction pendulum devices, namely DCFP, able to influence the seismic behaviour of infrastructures such as isolated multi-span continuous deck bridges. With this aim, a numerical model has been proposed to simulate the dynamic behaviour of seismically isolated bridges, and so an eight-degree-of-freedom system adopted in order to model the elastic reinforced concrete pier and the isolators devices. Furthermore, the interaction pier-abutment has been taken into account and the former modelled as a fully fixed restrain. The deck has been assumed rigid in its plane and a non-linear velocity dependent law adopted to model the friction along the two surfaces of the pendulum isolators. The equations of motion have been proposed in a non-dimensional form by means of a preliminar dymensional analysis. Finally, a widely parametric analysis has been conducted and record-to-record variability taken into account by using a set of natural records with different characteristics either in terms of epicentral distance and magnitude. The response of the system in terms of pier and deck displacements, is presented in a probabilistic fashion and as independent from the seismic intensity thanks to the abovementioned dimensional analysis. The main evidence of the study is how the main structural parameters involved in the analysis are able to control and influence the seismic response, such that the outcomes of this research could be used to better design or retrofit multispan coninuous deck bridges isolated with DCFP.

Effect of the backfill material in the seismic response of multi-span masonry arch bridges under seismic loading

The present study deals with numerical modelling of multi-span masonry arch bridges under seismic loading. Based on the evidence coming from an experimental program reported in the literature, a reference 3D nonlinear Finite Element model is calibrated. The numerical model is realized in Abaqus software by adopting a macro-modelling strategy for simulating the masonry behavior. To this purpose the Concrete Damage Plasticity material model is used. The backfill material follows a Drucker-Prager behavior, while the interaction between the two materials is simulated by means of an appropriate contact constitutive law. After calibration, the response of the bridge under longitudinal seismic loads is thus investigated. In particular, a mass proportional load distribution is adopted. Then, the effects of the mechanical parameters of the backfill material on the global response of the bridge are investigated by means of a parametric analysis, which is carried out by varying: i. elastic modulus, ii. cohesion, iii. backfill-masonry contact law, and iv. backfill friction angle. The obtained results provide preliminary indications about reliable retrofitting techniques for cases similar to the one under consideration.

Pelješac bridge, Croatia – Part 2: Construction and Assembly/Pelješac-Brücke, Kroatien – Teil 2: Ausführung und Montage

The 2 404 m long Pelješac Bridge, Croatia ranks among the most demanding bridges in the Europe in terms of both the technological complexity of construction and the complexity of the design. The bridge is designed as a multi-span cable-stayed bridge with a semi-integral hybrid structure. While Part 1 (Bauingenieur 5/2023) dealt with the concept and planning of the bridge, the construction and assembly is reported now.

Pelješac bridge, Croatia – Part 1: Concept and Design/Pelješac-Brücke, Kroatien – Teil 1: Konzept und Planung

The 2 404 m long Pelješac Bridge, Croatia, ranks among the most demanding bridges in the Europe in terms of both the technological complexity of construction and the complexity of the design. The bridge is located in an area of very high seismic activity, exposed to strong and gusty north and south winds. The compact bedrock is located at a depth of up to 100 m below the seabed so very demanding foundation on up to 128 m long driven steel piles was required. The bridge is designed as a multi-span cable-stayed bridge with a semi-integral hybrid structure with five 285 m long central spans. Part 2 deals with execution and assembly.

Seismic reliability analysis of isolated deck bridges using friction pendulum devices

In this study, the seismic reliability of multi-span continuous deck bridges equipped with isolation friction pendulum (FP) devices is investigated. The relevant aleatory uncertainties associated to the sliding friction coefficient of the FP isolators and to the seismic inputs are considered. A six-degree-of-freedom model is established to reproduce the elastic behavior of the reinforced concrete (RC) pier, the stiff response of the deck supported by the isolation devices and the non-linear response of the FPS bearings which depends on the sliding velocity. Moreover, the RC abutment is assumed as infinitely rigid. For what concerns the seismic inputs, a group of natural seismic records having various characteristics is adopted and properly scaled to increasing levels of intensity. The random variability of the friction coefficient is modelled by suitable probabilistic distribution. Then, considering several bridges and isolator configurations, the fragility curves of the RC pier and of the isolator devices (FP) are determined. Finally, in agreement with the hazard curve of the specific site, the convolution integral is adopted to determine the seismic reliability curves in the performance domain.

Modeling a Viscoelastic Support Considering Its Mass-Inertial Characteristics During Non-Stationary Vibrations of the Beam

Non-stationary loading of a mechanical system consisting of a hinged beam and additional support installed in the beam span was studied using a model of the beam deformation based on the Timoshenko hypothesis with considering rotatory inertia and shear. The system of partial differential equations describing the beam deformation was solved by expanding the unknown functions in the Fourier series with subsequent application of the integral Laplace transform. The additional support was assumed to be realistic rather than rigid. Thus it has linearly elastic, viscous, and inertial components. This means that the effect of a part of the support vibrating with the beam was considered such that their displacements coincide. The beam and additional support reaction were replaced by an unknown concentrated external force applied to the beam. This unknown reaction was assumed to be time-dependent. The time law was determined by solving the first kind of Volterra integral equation. The methodology of deriving the integral equation for the unknown reaction was explained. Analytic formulae and results of computations for specific numerical parameters were given. The impact of the mass value on the additional viscoelastic support reaction and the beam deflection at arbitrary points were determined. The research results of this paper can be helpful for engineers in designing multi-span bridges.

Analysis of the Performance of Quasi-zero Stiffness Isolator on the Reduction of Vibration on a Multi-span Continuous Beam Bridge Under Moving Mass

Analysis of the Performance of Quasi-zero Stiffness Isolator on the Reduction of Vibration on a Multi-span Continuous Beam Bridge Under Moving Mass

Seismic vulnerability analysis of irregular multi-span concrete bridges with different corrosion damage scenarios

This paper investigates the seismic performance and vulnerability of multi-span Reinforced Concrete (RC) bridges with unequal height piers exposed to varied corrosion damage scenarios. An advanced three-dimensional nonlinear finite element modelling technique is developed and verified with available experimental results of a reference shake table test on a large-scale RC bridge. In addition to the pristine state of the reference bridge, various hypothetical corrosion scenarios, including the symmetrical and asymmetrical corrosion of piers, are considered. Several nonlinear analyses, including the pushover and Incremental Dynamic Analysis (IDA) approach, are performed to evaluate the seismic behaviour and vulnerability of hypothetical RC bridge specimens. The influence of symmetrical and asymmetrical corrosion of piers on nonlinear dynamic behaviour and failure mechanism (both in the global and local scales) of studied bridges are then discussed. Finally, the IDA results are used to develop time-dependent fragility curves. The analyses show that seismic vulnerability of a deteriorated irregular multi-span RC bridge crucially depends on the corrosion scenario of its piers, where the unbalanced distribution of seismic ductility demand might be regulated/intensified by different corrosion scenarios. Moreover, some corrosion scenarios resulted in near-synchronised failure of unequal height piers.

Long-term continuous seismic monitoring of multi-span highway bridge and evaluation of bearing condition by wireless sensor network

A 45-month continuous seismic monitoring of a multi-span highway bridge by wireless sensor network (WSN) is described in this paper. The WSN monitoring system is developed using a simultaneous high-speed flooding technique and deployed to monitor a continuous 12-span 381.8 m long highway bridge in Katsuta city, Ibaraki prefecture, Japan. The WSN monitoring system consisted of 20 triaxial accelerometers placed on bridge girder, pier caps, abutment, and on the ground. The monitoring system has successfully recorded seismic responses of 63 earthquakes from August 2017 to December 2020. The paper describes the WSN monitoring system, analyses of seismic responses, and structural assessment using the recorded seismic responses. The analyses include investigation on seismic response characteristics of girder, piers, and bearings, system identifications, and seismic performance evaluation of isolation bearings. The WSN monitoring system provides high quality of seismic responses. Evaluations of ground motions recorded by WSN with the existing strong motion KNET seismograph network have demonstrated the accuracy, reliability, and robustness of WSN monitoring system. Using three system identification methods, dominant bridge modal parameters and their variations with respect to earthquake levels were investigated. High-frequency filtering effect was utilized as indicator in assessment of isolation bearing performance. Systematic classification by clustering algorithm was conducted to determine whether the isolation bearings have functioned normally.

P3P: a software suite for autonomous SHM of bridge networks

This paper presents the development of a new software code for the fully autonomous management of permanent integrated Structural Health Monitoring (SHM) systems installed in highway bridge structures. The code was developed within the framework of a research project funded by Anas S.p.A., the largest public infrastructure manager in Italy. The software program includes all the necessary steps to conduct SHM within the statistical pattern recognition paradigm, including automated dynamic identification, modal tracking, filtering of environmental effects, and damage detection through novelty analysis. Additionally, the software suite includes specific modules for processing and analysis of seismic events and structural reliability analysis of bridges, as well as specific functionalities for span-wise identification of long multi-span bridges. Moreover, a novel automated density-based tracking algorithm is developed. The potential of P3P is illustrated through two real application case studies: (i) a long multi-span bridge, the Trigno V Bridge in Italy; and (ii) the Z-24 Bridge benchmark. This work demonstrates the effectiveness of the developed code for handling large monitoring databases within the framework of SHM as a statistical pattern recognition, and currently P3P is in phase of being applied by Anas S.p.A for the management of a large number of bridges of the Italian roadway system.

Effect of Elastomeric Bearing Stiffness on the Dynamic Response of Railway Bridges Considering Vehicle–Bridge Interaction

This article presents a numerical study that aims to explore the impacts of the stiffness of elastomeric bearings on the dynamic behavior of railway bridges under train-induced vibrations. For this purpose, a finite element code that considers vehicle–bridge interaction using a coupled approach was developed. The software was validated by comparing the numerical response to the analytical solution. The numerical analysis of single- and multi-span bridges with varying bearing stiffness values under passenger trains showed the interplay between bearing stiffness, its impact on the natural frequency of the bridge and the loading frequency. It is demonstrated that the amplitude of the maximum acceleration on the bridge depends heavily on the stiffness of the bearings. Furthermore, the bearing stiffness significantly impacts the location of the maximum acceleration on the bridge. The results of the extensive numerical analyses improve the understanding of the impact of the bearing stiffness on the dynamic behavior of bridges and highlight the importance of quantifying the boundary conditions correctly for reliable estimation of dynamic response of railway bridges under train-induced vibrations.

Seismic behaviors of PCIC piers-supported bridge structures to spatially varying ground motions

Damages to bridge piers were repeatedly observed in many previous strong earthquakes, resulting in disruptions to traffic and impairing the functionality of road network. Extensive studies have been carried out to improve the seismic resistance of bridge piers so as to enhance the seismic performances of bridge structures. In a recent study, an innovative pendulum-type column-in-column (PCIC) system was proposed to reduce seismic induced vibrations of bridge piers. This study extends the previous study on investigating the seismic performances of PCIC piers-supported bridge structures subjected to spatially varying ground motions (SVGMs). Three-dimensional (3D) finite element (FE) models of a typical 5-span continuous bridge supported by the conventional piers and PCIC piers are developed in the ABAQUS software in the present study, and numerical simulations are performed to evaluate the dynamic responses of bridges with conventional and PCIC piers. It is demonstrated that the PCIC piers can effectively mitigate the seismic responses of bridge structures. The SVGMs tend to amplify seismic responses of bridges, therefore need be considered when evaluating the seismic responses of multi-span bridges. The results demonstrate the great potentials of the applications of PCIC piers for seismic-resistant design of bridge structures.

Aftershock Fragility Assessment of Continuous RC Girder Bridges Using a Modified Damage Index

Aftershock fragility is usually calculated conditioned on a range of potential post-mainshock damage states. The post-mainshock damage can be identified using damage indices, the latter being frequently associated with displacement-based parameters such as the maximum drift ratio or the residual displacement. However, when the reliable simulation of a structural system in a specific post-mainshock damage state is the objective of a numerical study, using such damage indicators may not assure the structure experiencing a homogeneous level of damage due to different mainshocks characteristics, which induce the aftershock fragility results unreliable. Along these lines, the current study presents a damage evaluation methodology mainly used for aftershock fragility assessment. It aims to reduce the variation of damage levels derived by using different mainshock seismic motions. The methodology presented herein includes: (i) the introduction of a damage index defined by comparing the monotonic pushover curve of the intact and post-earthquake damaged structure; (ii) the description of a finite element (FE)-based scheme that enables to quantify of the proposed damage index; and (iii) a deterioration-related modeling technique that can capture both strength and stiffness degrading performance of structural systems exposed to earthquake-induced excitations. The latter is essential to support the FE-based quantification scheme for the damage index. This methodology evaluation methodology can be primarily used for calculating the aftershock fragility assessment for a multi-span RC continuous girder bridge. The back-to-back incremental dynamic analysis framework uses a larger number of mainshock-aftershock artificial sequences to generate the aftershock fragility curves. The AS fragility results obtained via MBDI are compared with that via maximum drift ratio in terms of the ability to reduce the variation of residual capacities obtained using different mainshocks to induce a specific damage state but collapse by the same aftershock. The comparison shows a more robust relationship of MBDI with the residual capacity. It is found that MBDI, as well as its quantification approach proposed in this study, is a more effective damage predictor than the widely used displacement-based indices for AS fragility assessment.

Condition assessment of seismically isolated multi-span highway bridge bearings using recorded and simulated seismic responses

This paper describes a study on the responses analyses of a seismically isolated multi-span highway bridge recorded during the 2011 Great East Japan (Tohoku) earthquake and assessment of isolation bearing condition based on the responses. During the earthquake, lateral pounding and locking between the side-stoppers and the upper steel plate of the isolation bearings were observed of several piers. Finite element model was employed to analyze the problem and scenarios of locked bearing on the piers were simulated. The study also presents a wavelet-based technique to detect the presence and location of locked bearing. Instantaneous frequency of continuous wavelet transform of girder and piers accelerations were employed to evaluate isolation bearing condition by identifying the occurrence of high-frequency filtering effect. Afterwards, bearing condition was characterized via statistical clustering technique. Accuracy and efficacy of the technique were verified in simulations using three-dimensional finite element model of the bridge. Results of simulations demonstrate that wavelet-based features can effectively characterize isolation bearings condition directly from seismic responses of girder and piers.

Dynamic amplification in masonry arch railway bridges

Dynamic amplification of loads in masonry arch railway bridges is not well understood. There is a scarcity of experimental data and previous numerical studies have only addressed a few specific bridge geometries. Despite this, guidance documents provide empirical and unvalidated formulae to calculate dynamic amplification for masonry arch railway bridges. To improve our fundamental understanding of the problem, determine appropriate modelling strategies and evaluate the reliability of guidance documents, simple 2D and 3D models are explored in this paper. The 2D approach idealises key bridge components (pier, arch, fill and backing elements) with straight Timoshenko beams, springs and lumped masses. It uses an analytical dynamic stiffness formulation, which is computationally efficient and well-suited to explore a range of bridge models. The higher fidelity 3D modelling approach uses shell and solid finite elements and is used to evaluate the limitations of 2D models. In both approaches, linear-elastic material behaviour is assumed and train loads are idealised as moving vertical loads distributed over an effective area. The modelling results indicate a complex relationship between train speed and dynamic amplification that depends critically on bridge geometry and axle spacing. In general, the multi-span bridge configurations experienced higher dynamic amplification over operational train speeds. The results also higlight deficiencies in existing code provisions and demonstrates how efficient numerical models may replace these provisions.

Development of natural frequency in multi-span composite bridges with variable cross-section: Analytical and numerical solutions

In this paper, the natural frequency of multi-span I-beam composite bridges with linear haunched cross-sections is studied analytically and numerically. Newton’s eigenvalue iteration method is used in the analytical process to obtain the angular frequency by MATLAB. A variety of parameters affecting the natural frequency are investigated by validated finite element analysis (FEA). Based on the 143 FEA results, an easy-to-use formula is developed. The validity of the analytical method and the developed formula is demonstrated by numerical examples. It is shown that the developed formula can capture the natural frequency with high accuracy. The mean and maximum errors are found as 3.5% and 14%, respectively.