Bridge Expansion Joints Research Articles

Assessment of bridge expansion joints using long-term displacement measurement under changing environmental conditions

This paper addresses the problem of condition assessment of bridge expansion joints using long-term measurement data under changing environmental conditions. The effects of temperature, traffic loading and wind on the expansion joint displacements are analyzed and interpreted, which reveal that measured displacements are observed to increase with an increase in temperature and to decrease with increased traffic loading, while the correlation between displacement and wind speed is very weak. Two regression models are developed to simulate the varying displacements under the changes in temperature and traffic loadings. Based on these models, the effects of the environmental conditions are removed to obtain the normalized displacement. Statistical process control using mean value control charts is further used to detect damage to the bridge expansion joints. The results reveal that the proposed method had a good capability for detecting the damage-induced 1.0% variances of the annual changes in the expansion joint displacements.

Specialty Appraisal of the Movement of the Expansion Joint of Jiangyin Bridge Based on the Health Monitoring Technology

Aiming at the upgrading project of the structural health monitoring system of Jiangyin Bridge, the moving specialty parameters such as the vertical displacement, corner joints, and the synchronization of the two sides of the bridge expansion joint are monitored and acquired by the means of the long real-time health monitoring technology. Based on a large number of measured data, the temperature-dependent regression equation between the movements and the structure temperatures of the bridge expansion joint is established, which could provide much quantitative support and scientific guidance for the daily management and maintenance of the expansion joints.

Laboratory evaluation of a silicone foam sealant bonded to various header materials used in bridge expansion joints

A silicone foam sealant was developed to provide an easy-to-use and economical joint sealant for small-movement bridge expansion joints. In studies reported previously, various laboratory tests were conducted to evaluate the performance of the sealant using concrete as the bonding substrate. In the present study, laboratory tests on the sealant were conducted using other substrates found in practice, including steel, asphalt, and polymer concrete. Some of the tests conducted included a tension test, repair test, oven-aged bonding test, salt water immersion test, and a cure (modulus over time) test that evaluated the mechanical properties of the sealant as it developed its final state of cure. Through the laboratory tests, it has been observed that the silicone foam has the ability to bond to various substrate materials and can easily accommodate deformation typical of small-movement expansion joints in bridges.

Railway Track Performance Monitoring and Safety Warning System

To install the continuous welded rail (CWR) on the viaduct, it is necessary to consider the accumulated axial force owing to temperature difference and the additional force of the rail exerted by the track-bridge expansion as a result of temperature difference, the so-called track–bridge interaction. This paper used A-thermal fiber bragg grating (FBG) sensors which do not need the temperature compensation, and electronic sensors as monitoring instruments to detect performance changes in CWR axial force. These optical fiber sensors coupled with the developed track axial force calculation software and monitoring platforms calculate the axial force distribution along the track to be monitored. To better understand the influence of the change in the bridge’s structure expansion and the change in concrete slab strain on track axial forces, sensors are set up at bridge expansion joints (EJs), rail ends, and concrete slab beds. Monitoring results show that optic fiber sensors provide sensitive, clear, and stable signals. They are also durable and appropriate for long-term monitoring, providing a complete track safety warning system.

Investigation of Bridge Expansion Joint Failure Using Field Strain Measurement

This study was initiated after the sliding plate expansion joints of Millard E. Tydings Memorial Bridge, a long-span truss bridge, failed prematurely just a few months after their initial installation. The study included field investigation, material testing, analysis, and field testing. Test data records show numerous high spikes, which represent high tensile stresses, within their respective measured periods. By extrapolation, the failure was predicted by applying Miner’s linear cumulative damage rule. The calculation shows that the accumulative value would reach 1.0 when the first and subsequent failures were reported. The unexpected high stresses and poor workmanship caused early crack formation attributable to distress.

Temperature Aging, Compression Recovery, Creep, and Weathering of a Foam Silicone Sealant for Bridge Expansion Joints

Silicone foam was investigated as a sealant for small movement expansion joints in bridge decks. This paper presents results from the laboratory assessment of a model foam sealant subjected to thermal aging (exposure to high and low temperatures and temperature cycling), fatigue conditions, and outdoor weathering. Parallel tests were performed on a commercial solid-silicone bridge-joint sealant. Test results showed that the solid sealant recovered faster than the foam sealant after being subjected to prolonged compression at elevated temperature. When subjected to a constant tensile force, both the foam and solid sealants exhibited high initial creep rates (rate of elongation), but appeared to reach an equilibrium level of elongation at longer times. The foam sealant creeps at a slower rate and takes more time to get to the equilibrium elongation, whereas the solid sealant creeps much faster initially and reaches equilibrium faster. Thermal aging was found to have significant effects on the sealant modulus (increases with temperature); however, the effects on ultimate stress and strain were not apparent for both types of sealants. Temperature cycling between 24 and -29°C was observed to diminish the ultimate stress and strain of both the sealants by roughly 25%; however, no significant changes in modulus were found. Results from the tests on a limited number of outdoor-weathered sealant specimens showed that weathering appeared to produce an increase in sealant tensile and shear moduli (i.e., hardening effects because of weathering) and a decrease in ultimate strain. The weathered samples show tension loading-unloading behavior similar to the unaged samples. The tensile stress relaxation rate of the outdoor-weathered sealants could not be distinguished from those laboratory-cured (unweathered) counterparts.

신축이음장치의 앵커 인발성능 평가 및 나사 풀림 방지를 위한 앵커시스템 개발

교량 신축이음장치의 파손 유형은 주로 후타재(무수축 모르타르)와 관련된 부분에서 많이 발생된다. 또 다른 문제는 중차량 통과에 따른 충격과 진동하중으로 인해서 신축이음장치를 후타재에 고정하기 위해서 사용하는 앵커 풀림 현상이다. 본 연구에서는 무수축 모르타르의 파괴에 따른 신축이음장치의 파손을 방지하기 위해 탄성콘크리트를 개발하였다. 개발된 탄성콘크리트와 현재 주로 사용하고 있는 무수축 모르타르의 인발성능을 비교하였다. 또한, 후타재와 신축이음장치를 일체화하여 후타재의 파손을 방지하고 신축이음장치를 쉽게 교체할 수 있는 앵커 시스템을 개발하였다. The failure of expansion joints for bridges generally occurs in non-shrinkage mortar another problem is the release of anchors in expansion joints due to the impact and vibration that occurs when cars are driving over a bridge. In this study, to overcome the failure of expansion joints that is related to the failure of non-shrinkage mortar, an elastomeric mortar has been developed. The elastomeric mortar has a highly developed pull-out capacity compared with that of non-shrinkage mortar. Moreover, an anchor system that can be changed easily and prevent the fracture of expansion joints has been developed.

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.

Performance of Polymer Modified Asphalt Bridge Expansion Joints in Low-Temperature Regions

Conventional asphalt bridge expansion joints used in low-temperature regions generally show cracking within the first 2 years. To improve the low-temperature performance of these joints, the commercial MEIJIA asphalt binder commonly used in bridge expansion joint construction was modified with two polymers: thermoplastic rubber and rubber. The goal is to find an optimum combination of polymers, binders, and aggregates to improve the performance of asphalt expansion joints in low-temperature regions. The polymer modified binders and mixtures were evaluated for their low-temperature properties using ductility, penetration, indirect tension, and bending tests. The study indicates that performance of these joints at low temperature can be enhanced significantly with the right combinations of polymers, binders, and aggregates. Four expansion joints made with the polymer modified asphalt mixtures were installed on two bridges in a cold region. A construction procedure was also developed to install these joints properly to minimize low-temperature cracking along the interface between the joint and bridge deck. After 7 years of service, the four joints show good performance without any visible cracking or rutting.

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.

Inspection survey of 150 expansion joints in road bridges

Expansion joints are current equipment applied to almost every type of bridge with relatively high maintenance costs. Furthermore, their service life is generally short (often below 10 years) and lower than the bridge expected service life (over 50 years). In this paper, the results of an inspection campaign of 150 expansion joints in road bridges, the first comprehensive survey of the kind, are presented. They allow knowing and characterizing more properly the expansion joints installed in Portuguese roads and highways, namely in terms of their typology, pathology and rehabilitation. It was concluded that: (a) some types of joints have been systematically replaced (open joints, nosing joints with poured sealant, buried joints under continuous surfacing, steel sliding plates); (b) made-to-order joints are no longer prescribed; (c) the transition strip and the anchorage cavities need more maintenance and more frequent rehabilitation than other parts; (d) installment errors and lack of maintenance are the most frequent causes of pathology; (e) direct or indirect visual observation is still the best diagnosis method; and (f) the importance of the defects found depends a lot on the type of joint and of the defect.

Design of bridge expansion joints with perforated dowels under impact loading

The expansion joints are expected to have movement capacity, bearing capacity for static and dynamic loading, water-tightness, low noise emission and traffic safety. In particular, the failure due to impact loading is the main reason for the observed damages. The problem of dynamic behavior of the expansion joints is so complex that we shall focus our attention on the impact factor for vehicle load that is governed by traffic impact. In order to overcome this difficulty, the cantilever-toothed aluminum joint (finger joint) is one of the promising joints under impact loading. In this study, from the viewpoint of design methodology, numerical studies for impact behavior were conducted for aluminum alloy expansion joints with perforated dowels. The design impact factor for the expansion joints with the perforated dowels against traffic impact loading was examined by using numerical simulations.

Management system for expansion joints of road bridges

This paper presents a management system for expansion joints with unique features in the field of road bridge management. The high costs of maintaining equipment, a significant percentage of the conservation budget of the bridges where they are installed, in conjunction with indirect costs and discomfort associated with intervention for their rehabilitation, amply justify the implementation of an autonomous, but integrated, management system, especially for entities responsible for a high number of bridges. The system is based on the classification of types of joints, defects and possible causes, diagnosis methods and maintenance/rehabilitation techniques, inter-correlated by matrices that are duly validated. Based on parameters that define degradation levels, the system also allows the rating of each defect in terms of physical and functional degradation and of detriment to the social envelope of the bridge.

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.

Development and Laboratory Analysis of Silicone Foam Sealant for Bridge Expansion Joints

Sealing of bridge expansion joint systems is important to protect the structural components below the joint. An elastomeric foam-type joint sealant has been developed for sealing small-movement bridge expansion joints. Laboratory tests including tension, compression, shear, bonding, stress relaxation, cure rate, tack-free time, and water tightness were performed on this sealant. In addition, loading-unloading behavior in tension and compression and effects of immersion in saturated saltwater solution on its engineering properties were investigated. The silicone foam sealant showed an increase in volume of ∼70% on curing and attained approximately 80% of the 21-day curing strength in the first 7 days. Tack-free time for the foam sealant was below 1.5h and comparable to that for the solid sealant. The mechanical test results indicated lower stiffness, greater extensibility, and better bonding associated with the foam sealant compared to the solid (unfoamed) sealant. The foam sealant exhibited smaller loss in extensibility at failure due to saltwater immersion compared to the solid sealant. While in tension both sealants exhibited similar rates of stress decay, in compression the foam sealant was found to relax faster than the solid. Neither sealants exhibited any water leakage during a 96-h test period.

Papers in This Issue

The July 2007 issue of the Journal of Bridge Engineering begins with a paper on vibration of stay cables. In “Vibration Control of Stay Cables of Shandong Binzhou Yellow River Highway Bridge Using Magnetorheological Fluid Dampers,” Li, Liu, Li, Guan, and Ou describe the use of an innovative control algorithm for active and semiactive control of mass-distributed dynamic systems. The longest cables of the Shandong Binzhou Yellow River Highway Bridge were stabilized to suppress vibration using 40 magnetorheological fluid dampers. Field tests were carried out and determined that the semiactive magnetorheological dampers can provide greater supplemental damping than “passive-on” or “passive-off” dampers. Next are three papers on bridge desks. In the first one by Oh, Lew, and Choi, the issue of safety of deck slabs and the resulting frequent repair and strengthening is investigated. In “Realistic Assessment for Safety and Service Life of Reinforced Concrete Decks in Girder Bridges,” the development of a realistic assessment system that can estimate the safety and remaining service life of concrete bridge decks is presented. By determining a realistic and accurate assessment of the bridge deck, the cost of repairs can be eliminated and the loss of use to the public during possibly unnecessary repairs can be prevented. The proposed method uses an assessment of corrosion along with analysis of flexture, shear, and fatigue. The second bridge deck paper is titled “Low-Cycle Fatigue Testing of High-Performance Concrete Bonded Overlay-Bridge Deck Slab Systems” and is authored by Issa, Alhassan, and Shabila. This paper describes a field performance evaluation of a full-scale prototype bridge deck using plain and fibrous latex– modified concrete and microsilica concrete overlays. The study found that this overlay provided good results. “Stiffness and Strength of Metal Bridge Deck Forms,” by Egilmez, Helwig, Jetann, and Lowery, is the final paper on bridge decks. This paper presents the results of the first phase of research investigating the bracing behavior of metal bridge deck forms. While the bracing effects of these forms are used in building construction, due to connection details, the bracing effects are normally not considered when these forms are used in bridge construction. Shear diaphragm tests were conducted to determine the shear stiffness and strength of the forms. The experimental results on the diaphragms indicate the potential for the bracing of steel bridge girders using metal deck forms. The fifth paper in this issue of the Journal of Bridge Engineering is about bridge expansion joints. Malla, Shaw, Shrestha, and Brijmohan in “Development and Laboratory Analysis of Silicone Foam Sealant for Bridge Expansion Joints,” present the results of the development of an elastomeric foam-type joint sealant for use in small-movement bridge expansion joints. The paper presents the results of an investigation using both foam and solid sealants. “Deck-Mounted Steel Post Barrier System,” by Reid, Faller, and Hascall, presents the results of an evaluation of an existing mountable safety barrier system on a fiber-reinforced plastic

Assessment of Bridge Expansion Joints Using Long-Term Displacement and Temperature Measurement

A procedure for assessment of bridge expansion joints making use of long-term monitoring data is presented in this paper. Based on the measurement data of expansion joint displacement and bridge temperature, the normal correlation pattern between the effective temperature and thermal movement is first established. Alarms will be raised if a future pattern deviates from this normal pattern. With the established correlation pattern, the expansion joint displacements under the design maximum and minimum temperatures are predicted and compared with the design allowable values for validation. The extreme temperatures for a certain return period are also derived using the measurement data for design verification. Then the annual or daily-average cumulative movements experienced by expansion joints are estimated from the monitoring data for comparison with the expected values in design. Because the service life and interval for replacement of expansion joints rely to a great extent on the cumulative displacements, an accurate prediction of the cumulative displacements will provide a robust basis for determining a reasonable interval for inspection or replacement of expansion joints. The proposed procedure is applied to the assessment of expansion joints in the cable-stayed Ting Kau Bridge with the use of one-year monitoring data.

Dynamic Anomalies in a Modular Bridge Expansion Joint

Environmental noise complaints from homeowners near bridges with modular bridge expansion joints (MBEJs) led to an engineering investigation into the noise production mechanism. The investigation identified modal vibration frequencies in the MBEJ coupling with acoustic resonances in the chamber cast into the bridge abutment below the MBEJ. This initial acoustic investigation was soon overtaken by observations of fatigue induced cracking in structural beams transverse to the direction of traffic. These beams are, in the English-speaking world, universally referred to as center beams. However, in Europe the term lamellae is equally common. A literature search revealed little to describe the structural dynamics behavior of MBEJs but showed that there was an accepted belief dating from around 1973 that the loading was dynamic. In spite of this knowledge many bridge design codes used throughout the world specify a static or quasi-static load case with no mention of the dynamic behavior. This paper identifies the natural modes and operational response modes of vibration of the MBEJ installed into Sydney’s Anzac Bridge. In addition, the paper will introduce the dynamic range factor (DRF) and report a DRF of 4.6 obtained after extensive static and dynamic strain gage measurements. The studies indicated that the Anzac Bridge MBEJ was very lightly damped (<2% of critical) and a reduction in the measured DRF through the introduction of additional damping was an option.

Fatigue performance of modular expansion joints for bridges

This paper presents results of an experimental investigation on the fatigue performance of the welded multiple support bar modular bridge expansion joint (MBEJ) used for the recent Jacques Cartier Bridge rehabilitation in Montreal. Three identical subassemblies of the modular joint system were tested in fatigue. Both vertical and horizontal load ranges were applied to the test specimen simultaneously in the following proportions: (i) vertical load range = ΔPv and (ii) horizontal load range = 0.2ΔPv. Different loading ranges were applied to each specimen giving a sufficient number of points to define the experimental fatigue stress range versus the number of cycles (S–N) curve. The number of cycles varied between 567 900 and 3 600 000, while the calculated stress range within the welded connection details varied between 81.4 and 166.7 MPa. Static calibration tests were performed prior to the fatigue testing of each specimen. These calibration tests confirmed the validity of the structural three-dimensional analytical models and also established the repeatability of the experimental data, in conformity with the requirements of the NCHRP-402 report. Fatigue cracks of the same type as those reported by the NCHRP-402 report were observed within the welded connection detail. No fatigue cracks were observed elsewhere. The experimental fatigue curve of the welded connection showed that the fatigue resistance of the welded MBEJ is compatible with category C and C' details, as defined by the AASHTO LRFD 1998 bridge design code. This paper is very useful, as it demonstrates the applicability of the complex requirements of the NCHRP-402 report. These requirements are increasingly gaining wide acceptance among bridge engineers and bridge owners.Key words: modular expansion joint, bridge, deck, test, fatigue, stress range, cycles.

Polynomial Interpolated Taylor Series Method for Parameter Identification of Nonlinear Dynamic System

Abstract This research work is in the area of structural health monitoring and structural damage mitigation. It addresses and advances the technique in parameter identification of structures with significant nonlinear response dynamics. The method integrates a nonlinear hybrid parameter multibody dynamic system (HPMBS) modeling technique with a parameter identification scheme based on a polynomial interpolated Taylor series methodology. This work advances the model based structural health monitoring technique, by providing a tool to accurately estimate damaged structure parameters through significant nonlinear damage. The significant nonlinear damage implied includes effects from loose bolted joints, dry frictional damping, large articulated motions, etc. Note that currently most damage detection algorithms in structures are based on finding changed stiffness parameters and generally do not address other parameters such as mass, length, damping, and joint gaps. This work is the extension of damage detection practice from linear structure to nonlinear structures in civil and aerospace applications. To experimentally validate the developed methodology, we have built a nonlinear HPMBS structure. This structure is used as a test bed to fine-tune the modeling and parameter identification algorithms. It can be used to simulate bolted joints in aircraft wings, expansion joints of bridges, or the interlocking structures in a space frame also. The developed technique has the ability to identify unique damages, such as systematic isolated and noise-induced damage in group members and isolated elements. Using this approach, not just the damage parameters, such as Young’s modulus, are identified, but other structural parameters, such as distributed mass, damping, and friction coefficients, can also be identified.