Modular Expansion Joints Research Articles

More durable modular expansion joint constructions for road bridges

AbstractRelevant aspects in the design of modular expansion joints are the high fatigue stress caused by heavy load traffic and the corrosion protection. Currently, corrosion damage is often not limited to the traversable surface. Therefore, more durable expansion joints are highly desirable to extend their service life. The FOSTA research project P1574 resulted from the need for durable expansion joints and thus is aimed at hot‐dip galvanized structures. In this project about 14.000 individual damages on 6.300 modular expansion joints were evaluated, relevant hot‐dip‐galvanizing parameters were investigated and recommendations for hot‐dip galvanizing‐compatible constructions were made. In addition, the fatigue strength of existing constructions has been evaluated with regard to the current and upcoming version of Eurocode 1993‐1‐9. This evaluation will be verified in the course of cyclic tests and numerical investigations. A monitoring concept is to be designed according to the requirements of the modular expansion joints and the corresponding neuralgic points.

Cost-based optimum design of the earthquake-resistant system for continuous skew overpasses

This study proposes an efficient optimization framework for the earthquake-resistance system of continuous skew overpasses based on a cost-related objective function. The cable-sliding modular expansion joint (CMEJ) was considered to mitigate the rotational response of skew bridges. The BOX-COX regression was used to modify the probabilistic seismic demand model (PSDM) so that assumptions of the cloud method, viz. linearity, normality, and homoscedasticity, can be satisfied. The optimal intensity measure (IM) was selected from ten candidates. Next, the size of laminated rubber bearings (LRBs) and the initial free movement displacement of joints were optimized through the response surface method (RSM) and the Particle Swarm Optimization (PSO). Finally, the proposed framework was demonstrated using a typical three-span skew continuous overpass bridge. The seismic mitigation effectiveness of the CMEJ was discussed, considering the impact of the skew angle. Results indicate that the proposed optimization method can efficiently minimize the cost-related objective function with acceptable accuracy. Additionally, compared to the bridge equipped with modular expansion joints (MEJs), bearings of the bridge equipped with CMEJs have a smaller damage probability while the damage probability of abutments increases, which results in the total expected repair cost decreases obviously. It is also notable that the total expected repair cost of the bridge with MEJs increases as the skew angle becomes more extensive, while the one for the bridge with CMEJs is independent of the skew angle.

Measurement and analysis of bridge expansion joint noise

The structure-borne noise while the vehicle passing across the bridge expansion joint is the main source of urban bridge noise. In order to control this noise pollution, 20 bridges including three types of typical expansion joints in Ningbo City were selected, and the noises were measured while vehicle passed across the bridge expansion joints. The measured results are expressed by the Z-weighted sound pressure level, which kept the effect of the low-frequency noise. Then the influence factors of this noise are discussed. The results show that: (1) The sound pressure while vehicle on the bridge expansion joints is much greater than that on the normal road or mid-span of the bridges, which results in significant environmental noise pollution; (2) The wider the gap of the bridge expansion joints, the greater the noise level; (3) The noises produced by the modular expansion joints and comb-plate expansion joints are greater than that from the single-gap expansion joints.

Influence of the Acoustic Cover of the Modular Expansion Joint on the Acoustic Climate in the Bridge Structure Surroundings.

The noise generated at the interface between the wheels of vehicles and the road surface is well recognized in the literature worldwide. Many publications describe the phenomenon of reducing this kind of impact by silent road surfaces. A specific type of this noise is the sound generated by vehicles passing over the expansion joints of bridge structures. Due to the impulsive nature of this sound, it is very onerous for people living in the close vicinity of bridge structures. The passage of vehicles over expansion joints causes the formation of vibrations that are transmitted to the structural elements of bridge structures, which may cause the formation of the material sounds (especially arduous in the case of bridges with steel elements). An attempt to reduce this impact was made by making a prototype acoustic cover of the expansion joint on the selected bridge. The paper presents the results of research on the “in situ” acoustic effectiveness of this cover. Additionally, the noise was modelled in the object surroundings before and after the cover’s application. The acoustic efficiency of the cover in the whole measured frequency range was 5.3 dBA. In the narrower frequency bands (1/3 octave bands), larger sound level reductions were observed. The maximum sound levels measured under the tested dilatation were less than 10.0 dBA lower than the maximum sound levels measured under the reference dilatation.

Damage Mechanism of Control Springs in Modular Expansion Joints of Long-Span Bridges

Damage Mechanism of Control Springs in Modular Expansion Joints of Long-Span Bridges

Seismic fragility analysis of continuous bridges with UDCMEJ under the excitation of seismic sequence

Pounding and unseating have been repeatedly observed during severe earthquakes. Residual displacement between adjacent components may have already existed after the mainshock and it will get further destroyed with series of aftershocks. The uniform drift cable-sliding modular expansion joints (UDCMEJ) are constructed by connecting the supporting bars and the fuse boxes with elastic cables avoiding the excessive relative displacement between girders. The seismic analysis of bridges with UDCMEJ under the excitation of seismic sequence is conducted on a continuous beam bridge and a probabilistic assessment is introduced in this study. Conclusions are drawn from comparing fragility curves with and without UDCMEJ. It reveals that the UDCMEJ can avoid pounding between girders and the relative displacement is limited to cables’ free movement. With the contribution of the expansion joints, all of the girders work together and get a balance between displacement and force causing decreased damage probability.

Fatigue life of the bolted yoke connection in single support beam (SSB) modular bridge expansion joints

The objective of this article is to demonstrate a comprehensive procedure for the estimation of the fatigue life of the component centre-beam-to-support-beam (CB/SB) bolted yoke connection. In this procedure, all the aspects are included such as fatigue vehicle loading, cycles per truck passage, lifetime average daily truck volume, fatigue classification of the detail and determination of fatigue infinite life. A typical single support beam (SSB) steel modular beam expansion joint (MBEJ) was modelled as 3D space frame. Moreover, three F.E. sub-models were created for the simulation of the (CB/SB) bolted yoke connection with preloaded bolts M16, M20 and M22 respectively. The Fatigue Load Model 2 (FLM2), recommended in EN 1991-2:4.6.4 for infinite fatigue life was chosen for the fatigue verification of the bolted yoke connection detail, assumed to be travelling at 90 km/h over the expansion joint. The 3D space frame was analysed by using Time-history dynamic analysis and thereafter, the calculated outputs were introduced in the F.E. sub-models. From the analysis of the sub-models the stress ranges were obtained and the fatigue evaluation of the yoke joint was performed. The investigation shown that poor detailing at the connection between the centre-beam-to-support-beam (CB/SB) bolted yoke connection is susceptible with reference to fatigue. Finally, important conclusions were extracted for both the behaviour of the entire modular joint and the fatigue life of the bolted yoke detail.

Development and experimental study on cable-sliding modular expansion joints

Development and experimental study on cable-sliding modular expansion joints

Effect of dynamic impact at modular bridge expansion joints on bridge design

To analyze the dynamic impact induced by a heavy vehicle crossing a modular type expansion joint and its effect on the bridge response, a numerical method based on a distributed spring-damper element is presented, in which the contact patch between the tire and the road is considered. The dynamic response of the vehicle and bridge can be obtained by dynamic finite element analysis of the vehicle-bridge system taking into account the bumpy ride of vehicle at the expansion joint. The reduced support to the parts of tire structure over the cavities of the modular expansion joint is considered, and the vertical tire load can be obtained by an iteration procedure. To assess the dynamic impact at the expansion joint on bridge design, the impact factors associated with the vehicle tire loads, and the bearing reactions, shear forces and bending moments of the bridge are evaluated. The multi-gap modular expansion joints leads to lower impact factors than single-gap expansion joints. The effects of dynamic impact at expansion joint on the bearing reactions and shear forces are greater than that on the bending moments of the bridge. Numerical results also show that the impact effects of vehicle axle load and internal forces of the bridge may be higher than those recommended by bridge codes, and they may affect the durability of components in the vicinity.

Field Tests on Total Gap of Modular Expansion Joints to Avoid Bridge Pounding

Modular expansion joints (MEJs) are used for accommodating large relative displacements of adjacent bridge segments and for completely eliminating pounding. However, the minimum total gap that an MEJ needs to avoid pounding is not well investigated. To provide guidance for the seismic gap of MEJs, the maximum relative displacement of adjacent bridge segments subject to strong earthquakes was studied experimentally. To date, no experimental investigation of excitation spatial variation effect on bridge on natural soil has been reported. This research addressed a bridge with three identical segments of 100 m. A 1:22 scale bridge model founded on compacted beach sand was tested using electro-magnetic inertial exciters. Different ground motions were applied to the model to simulate the effect of spatially varying ground motions. Soil-structure interaction (SSI) was studied by comparing the minimum total gaps with those obtained from the fixed-based experiments in the laboratory. The spatially varying ground motions were simulated based on the New Zealand design spectra for soft soil, shallow soil and strong rock conditions using an empirical coherency loss function. SSI was found to reduce the minimum total gap of an MEJ needed to avoid pounding between adjacent segments. Under spatially varying ground motions designing adjacent bridge segments with identical or similar fundamental frequencies is still recommended even if it does not necessarily preclude an out-of-phase movement of adjacent structures.

Seismic Performance of Cable-sliding Modular Expansion Joints Subject to Near-fault Ground Motion

According to the research fruits of the diverse damages of bridge in the past, bearings' invalidation is the main reason of the damage of isolated bridges and causes oversized relative displacements between pier and girder. Eventually, it may lead to severe collision of superstructure. It is extremely dangerous when near-fault motion occurs, because it has obvious velocity pulse effect and increases the risk of colliding between girders. Aiming at this problem, this paper puts forward a device named cable-sliding modular expansion joints (CMEJs) that can control the relative displacement and avoid collision. The working principle and mechanical model are described, and then based on a triple continuous seismic isolation bridge which has different heights of piers, a 3D model with or without CMEJs is established. The responses of continuous beam bridges using the CMEJs are comprehensively inspected under the consideration of the velocity pulse effect, and then a real simulation of limit performance of CMEJs is made, focused on CMEJs' restraining effect. The calculation shows that velocity pulse effect would magnify the seismic response of isolation bridges. In addition, the device can well control the displacement and prevent collisions. And the isolation technology combined with CMEJs can be more effective to play their respective roles. The advantage in controlling displacement is obvious.

Dynamics of modular expansion joints: The Martinus Nijhoff Bridge

Modular expansion joints are structures that are submitted to severe fatigue load conditions. This may lead to unexpected premature damage of the structure which, besides the economic cost of repair, may limit the regular service of the bridge. To better understand the dynamic behaviour of modular expansion joints, different over rolling tests have been performed at the modular expansion joint of the Martinus Nijhoff Bridge in the Netherlands. The tests were part of a research program for developing an early warning monitoring system for expansion joints. Strain measurements were performed during the passage of a vehicle at different speeds, for two different scenarios regarding the fixations (sliding springs and sliding bearings) of the cross beams. At the same time, a numerical model was developed and validated by means of the experimental data. This article presents and discusses the measurements and the numerical analysis. The results highlight on the effect of the cross beam fixation, and the effect of the vehicle speed on the strain distribution along the centre beam, together with the changes in modal properties of the structure.

Influence of ground motion spatial variation, site condition and SSI on the required separation distances of bridge structures to avoid seismic pounding

AbstractIt is commonly understood that earthquake ground excitations at multiple supports of large dimensional structures are not the same. These ground motion spatial variations may significantly influence the structural responses. Similarly, the interaction between the foundation and the surrounding soil during earthquake shaking also affects the dynamic response of the structure. Most previous studies on ground motion spatial variation effects on structural responses neglected soil–structure interaction (SSI) effect. This paper studies the combined effects of ground motion spatial variation, local site amplification and SSI on bridge responses, and estimates the required separation distances that modular expansion joints must provide to avoid seismic pounding. It is an extension of a previous study (Earthquake Engng Struct. Dyn. 2010; 39(3):303–323), in which combined ground motion spatial variation and local site amplification effects on bridge responses were investigated. The present paper focuses on the simultaneous effect of SSI and ground motion spatial variation on structural responses. The soil surrounding the pile foundation is modelled by frequency‐dependent springs and dashpots in the horizontal and rotational directions. The peak structural responses are estimated by using the standard random vibration method. The minimum total gap between two adjacent bridge decks or between bridge deck and adjacent abutment to prevent seismic pounding is estimated. Numerical results show that SSI significantly affects the structural responses, and cannot be neglected. Copyright © 2010 John Wiley & Sons, Ltd.

Numerical investigation of noise generation and radiation from an existing modular expansion joint between prestressed concrete bridges

Noise generated from modular bridge expansion joints during vehicle pass-bys has caused localized environmental problems in Japan and elsewhere. The objective of this study was to understand the mechanism of noise generation and radiation from a modular expansion joint installed in an expressway bridge. A numerical investigation was conducted in order to understand the dynamic characteristics of the joint and the acoustic characteristics of the sound field around the joint that measurements cannot reveal due to their limitations, such as the number of measurement locations that are required. Vibro-acoustic analysis was conducted by using the finite element method–boundary element method (FEM–BEM) approach: dynamic analysis of the joint was carried out by FEM and the sound fields inside the cavity located beneath the joint and outside of the cavity were analyzed by BEM. It was concluded that dominant frequency components in the sound pressure inside the cavity were due to excitation of the structural modes of the joint and/or acoustic modes of the cavity. For the expansion joint investigated, the sound field farther than about 35 m from the joint–cavity center could be considered as far field in the range of 50–400 Hz.

Required separation distance between decks and at abutments of a bridge crossing a canyon site to avoid seismic pounding

AbstractMajor earthquakes in the past indicated that pounding between bridge decks may result in significant structural damage or even girder unseating. With conventional expansion joints, it is impossible to completely avoid seismic pounding between bridge decks, because the gap size at expansion joints is usually not big enough in order to ensure smooth traffic flow. With a new development of modular expansion joint (MEJ), which allows a large joint movement and at the same time without impeding the smoothness of traffic flow, completely precluding pounding between adjacent bridge decks becomes possible. This paper investigates the minimum total gap that a MEJ must have to avoid pounding at the abutments and between bridge decks. The considered spatial ground excitations are modelled by a filtered Tajimi‐Kanai power spectral density function and an empirical coherency loss function. Site amplification effect is included by a transfer function derived from the one‐dimensional wave propagation theory. Stochastic response equations of the adjacent bridge decks are formulated. The effects of ground motion spatial variations, dynamic characteristics of the bridge and the depth and stiffness of local soil on the required separation distance are analysed. Soil–structure interaction effect is not included in this study. The bridge response behaviour is assumed to be linear elastic. Copyright © 2009 John Wiley & Sons, Ltd.

Seismic design of bridge structures with allowance for large relative girder movements to avoid pounding

Pounding between bridge girders have been observed in almost all previous major earthquakes. This is because the gap size of conventional bridge expansion joint is usually only a few centimetres, which is not sufficient to preclude poundings owing to large relative displacements between bridge girders caused by the effect of varying vibration properties of adjacent bridge spans, varying ground motions at bridge supports and varying soil-structure interaction (SSI). In this work a new design of bridge expansion joint is introduced. Instead of tolerating pounding and providing possible mitigating measures, this new design approach enables large movement between bridge girders which makes a complete pounding preclusion possible. The new expansion joint is called Modular Expansion Joint (MEJ). The large movability is achieved by installing a number of small gaps in the joint. In this study, the MEJ gap size required to completely avoid girder pounding is investigated. The most significant influence factors – the varying vibration properties of adjacent bridge spans, the effect of SSI and ground motion spatial variation on expansion joint size required to preclude pounding- are calculated. Discussions on the relative importance of various structural and ground motion properties in generating relative displacements of adjacent bridge girders are made.

Seismic Design of Bridges for Prevention of Girder Pounding

In design of conventional bridges the gap between bridge spans is usually only a few centimetres. For such an expansion joint poundings between adjacent bridge girders during strong earthquake shaking are usually unavoidable. Pounding often causes damages to girders. In extreme situations it may push one of the bridge decks off the support. In this work a new design philosophy using a modular expansion joint (MEJ) is introduced. So far MEJs have been used mainly to cope with large thermal expansion and contraction of long bridges. For proper design of bridges to avoid the consequence of poundings under strong earthquakes not only a minimum total gap but also the maximum opening movement of the joint are essential. In this study the simultaneous effect of varying vibration properties of adjacent bridge spans, spatially varying ground excitations and soil-structure interaction on the total closing and opening movements of a MEJ, required to eliminate possible pounding and to ensure the join in perfect working order, is estimated, and the main influence factors are discussed.

Vibro-acoustic analysis of noise generation from a full scale model of modular bridge expansion joint

Noises generated from modular bridge expansion joints during vehicle pass-byshavebeencausinglocalenvironmentalproblemsrecently.Previousexperimentalstudies showed that possible causes of dominant noise components generatedfromthebottomsideofthejointmightbedifferentfromthosefromthetopside.The objective of this study was to obtain theoretical insights into the mechanismof noise generation from the bottom side of the joint for which a main noisesource might be structural vibration of the joint. Vibro-acoustic analysis wasconducted based on the information from a full-scale model of modularexpansion joint obtained in previous experimental studies. The dynamicbehavior of the joint model was investigated by using the finite element method(FEM) and the sound field inside the cavity located beneath the joint model wasanalyzed by using the boundary element method (BEM). Indirect BEM wasused to calculate the sound pressure inside the cavity with the velocity responseobtained by the FE analysis as a boundary condition. The frequency rangeconsidered in the analysis was 20–400 Hz where dominant frequencycomponents were observed in the noise measured in the cavity beneath the jointin the previous experiment. It was intended to interpret numerical resultsobtained by a model developed with available mechanical properties of the jointcomponents to seek a general understanding of the noise generation mechanismof the modular expansion joint. It was observed that the peaks in the spectrumofnoiseinsidethecavitywereduetoresonancesofstructuralvibrationmodesofthe joint and/or resonances of acoustic modes of the cavity.There was evidencethat showed possible interaction between structural modes of the joint and theacoustic modes of the cavity.

Significance of SSI and non-uniform near-fault ground motions in bridge response II: Effect on response with modular expansion joint

This is the second part of the study of soil–structure interaction (SSI) and ground motion spatial variation effects on bridge pounding responses. The first part [Chouw N, Hao H. Significance of SSI and non-uniform near-fault ground motions in bridge response I: Effect on response with conventional girder gap. J Eng Struct. [in press]] concentrated on studying the responses of bridges with a traditional expansion joint between adjacent girders. The main objective of this second paper is to investigate the influence of spatial variation of ground motions and SSI on the minimum total gap that a modular expansion joint system (MEJS) between two bridge frames must have to prevent any pounding between the adjoined girders. This minimum total gap is critical in a MEJS design because it ensures intact expansion joint and adjacent girders. Additional investigations of pounding response with a large total gap of a MEJS are performed to study the characteristics of pounding responses when collision does occur e.g. due to unintended underestimation of the ground excitation magnitude, which may be different from the pounding responses between bridge girders with a small gap of a conventional expansion joint. The spatially varying ground excitations are simulated stochastically based on an empirical near-source response spectrum and an empirical coherency loss function. The investigation reveals that neglecting spatial variation of ground motions and SSI can significantly underestimate the total gap of a MEJS required to avoid pounding between the adjacent bridge girders. The results also show that pounding between girders with a large gap of a MEJS in general causes stronger impact forces. Compared with the results reported in the first part of this study, using a MEJS with a large gap is likely to completely preclude bridge girder pounding, and consequently to prevent local damage at the girder ends. However, a large girder movement results in large bending moment in bridge piers, which compensates the advantages of using MEJS in bridges to resist earthquake loading.

Mechanism of noise generation from a modular expansion joint under vehicle passage

The mechanism for the generation of noise from a modular expansion joint in a bridge under vehicle passage, which can cause an environmental problem, is investigated in experiments on a full-scale model of the joint. Noise and vibration characteristics of the joint model in the near field are identified by a series of car-running experiments associated with separate tests of the acoustic and dynamic characteristics of the joint. A modal analysis based on finite element modelling of the joint is also conducted and structure-borne noise radiation is discussed by correlating the dominant frequency components of the noise with the modal parameters. It is concluded that the noise from the top of the joint, dominant in the frequency range from 500 to 800 Hz, is caused by a sudden change in the pressure of air within the gap formed by the rubber sealing with two adjacent middle beams, and that the noise from the bottom, dominant in the frequency range below 200 Hz, is attributed mainly to sound radiation from the vibration of the middle beams.