Edge Girders Research Articles

Optimal design of piezoelectric energy harvesters for bridge infrastructure: Effects of location and traffic intensity on energy production

Piezoelectric energy harvesters (PEHs) can be used as an additional power supply for a Structural Health Monitoring (SHM) system. Its design can be optimised for the best performance, however, the optimal design depends on the input vibration and locations. In this work, we extend an optimisation framework from our previous studies to include the effect of the PEH’s location, which uses the cantilevered PEH Kirchhoff–Love plate model discretised by IsoGeometric Analysis (IGA) and coupled with Particle Swarm Optimisation (PSO) algorithm to find the designs with maximum energy outputs for a large number of input acceleration histories, extracted from the recorded dynamic response data of a real cable-stayed bridge in Australia. Then, clustering and evaluation under 24-h excitation are performed to find several best PEHs for the entire bridge. By comparing the best PEH at all locations with a typical benchmark device, the substantial performance improvement brought by the optimisation framework of this work is verified. The comparison results show a significant energy harvesting enhancement of 1.6 times at the best locations, 2.4 times at A2 and A3, and 3.6 times at the edge girders, respectively. The results also reveal the variability of the best design at different locations of the same structure to maximise the energy harvesting of the entire bridge, and demonstrate the design rule that the fundamental frequency of the device can be tuned within a certain frequency range to improve the robustness of PEHs design. Additional studies are performed to explore the effect of location and traffic intensity on energy harvesting by analysing the optimal PEH design and location throughout the bridge structure. The results indicate that the key factors of maximising energy harvesting efficiency are related to the input excitation and the mode of vibration being excited. The position of maximum displacement in the vibration mode corresponds to the best location for energy harvesting. Also, the best device has a fundamental frequency close to the frequency of the corresponding vibration mode. In addition, the change of traffic intensity affects the amount of convertible mechanical energy and also directs the tuning of the fundamental frequency of the PEH to achieve the highest energy conversion.

Noncomposite concrete deck bracing effects on continuous steel stringer lateral torsional buckling resistance

Louisiana’s bridges used two-girder or truss systems in the 1950 s and 1960 s, in which floorbeams are carried by main members and continuous stringers are supported by the floorbeams. The main members are either two edge (fascia) girders or trusses. Continuous span stringer bottom flanges are in compression in their negative moment regions, which could result in lateral torsional buckling (LTB). When these stringers are load rated using AASHTOWare Bridge RatingTM analysis software, lateral torsional buckling (LTB) resistance is calculated in accordance with the AASHTO LRFD Bridge Design Specifications, which the authors have determined may not adequately account for bracing effects provided by a noncomposite deck, and therefore could underestimate the flexural strength. Resulting ratings may be low enough to require restrictive, and possibly unnecessary, load postings or even bridge closures. This issue affects more than 20 significant bridges that are key parts of Louisiana’s highway system. To address the challenge of underestimated stringer LTB resistance and assess bracing effects provided by a concrete deck, experimental and analytical studies were performed on a two-span, continuous, steel stringers in a grillage system, which included three stringer lines, an interior transverse support (floorbeam), and transverse diaphragms at the end supports. The tests encompassed a variety of configurations, with and without a concrete deck. This paper describes laboratory testing setups and discusses experimental results, focusing on bracing effects on LTB resistance due to the presence of a noncomposite concrete deck. Finite element models using ANSYS were calibrated, validated using test results and used to simulate stringer behavior in Louisiana’s representative bridges. Finite element analyses of various tests showed generally comparable results to test data, and provided a feasible approach to load rate continuous stringers if a refined analysis is deemed necessary. The studies showed that stringer LTB resistance could possibly be tripled when noncomposite deck bracing effects are considered.

Model calibration of a long-span concrete cable-stayed bridge based on structural health monitoring data: Influence of concrete variability

Structural Health Monitoring (SHM) systems, in combination with controlled load tests, can provide valuable data for calibrating high fidelity bridge models, which can then be used for evaluating the long-term performance of the bridge, improved load ratings, and permit vehicle evaluation. The objective of this research was to calibrate a 3D model of the Indian River Inlet (IRIB) cable-stayed bridge, using strains recorded by the bridge SHM system during a controlled load test. The bridge was modeled in STAAD-Pro and calibrated using a pre-commercialized software platform that uses a Generic Algorithm to minimize the error between the measured and predicted strains. The calibration parameters were the elastic modulus of groups of the main longitudinal edge girder/deck elements, which once calibrated, could be related to the measured concrete strength of the members. Four different models were investigated, using 6, 10, 14, and 18 parameter element groups of the edge girder members. Of the different models, the 14 and 18 parameter models yielded the best results. The “design” model yielded errors as high as 42% when compared to the measured strains; the error was less than 10% for the majority of measurements for the 14-parameter model. Including the effect of the traffic barriers in the model, the weighted average concrete strength of the calibrated model was within 4% of the measured weighted strength. The calibration was shown to be insensitive to measurement noise and was validated using several unique single and multi-vehicle load cases that were heavier and more offset from the centerline of the bridge. The calibration procedure was able to capture the variability in flexural stiffness of the edge girders due to the variability of the concrete, resulting in significantly better agreement between the live load measured strains and the model predicted strains.

Development of a precast prestressed concrete through‐girder system for shallow bridge structures

AbstractThis paper proposes an innovative precast through‐girder system that can be used in shallow bridge structures. It discusses various components of the through‐girder system, including the edge (through) girders, transverse beams, and longitudinal and transverse connections. The through girders are made of precast concrete box beam segments that are spliced longitudinally through posttensioning. The precast prestressed transverse beams span between the through‐girders involving the use of transverse posttensioning. An important feature of this system is to implement ultra‐high performance concrete (UHPC) at the all joints. The use of UHPC allows to minimizing the joint width and achieving superior durability. A numerical example is presented to demonstrate the analysis and design of the through‐girder bridge superstructure accounting for both high‐performance concrete (HPC) and UHPC options. The UHPC superstructure option can reduce the sizes of the structural members and allow to enhancing the structural performance.

Full-Scale Model Test on the Structural Behavior of U-Shaped Composite Bridge Reinforced with Arch Edge Girders

Full-Scale Model Test on the Structural Behavior of U-Shaped Composite Bridge Reinforced with Arch Edge Girders

Control of footstep vertical vibration for Vierendeel truss – supported steel footbridges

In this paper three dimensional static and dynamic analyses for steel pedestrian bridges have been carried out. The footbridges considered are of a total length of (20, 30, 40 and 50m). The bridge is considered to act as continuous of two equal spans or as a two simply supported spans disconnected at the intermediate support. The latter design philosophy is advantageous in case of vehicle accidents so that only one half of the bridge will need maintenance. The bridge skeleton consists of two Vierendeel trusses acting as the main edge girders and the deck consists of parallel transverse sections covered with a steel plate. The BS5400 has been adopted in the present study for the footstep vibration serviceability. The bridge fundamental frequency and deck acceleration have been obtained and compared with the tolerable limits to avoid human discomfort. The analysis parameters were the bridge span, the height of the Vierendeel truss and whether the bridge is simply supported or continuous.Results have shown that for the continuous bridges of spans less than or equal to 15m, the frequency is greater than the minimum limit and the vibration serviceability requirement is satisfied for the height range of the Vierendeel truss. For spans equal to or greater than 20m the frequency is less than the limit and the deck acceleration has been checked. For the simply supported bridges of spans 10m to 25m the frequency is less than the limit and the deck acceleration has been checked. For the same section properties the maximum acceleration has been increased by (10% to 50%) as compared with the continuous cases.Depending on the mass and stiffness for different analysis cases, a regression analysis has been done to develop equations for estimating the fundamental frequency.

Fire Behavior of Continuous Assembled Monolithic Hollow‐Ribbed Slabs

To further understand the fire behavior of assembled monolithic hollow‐ribbed (AMH) slab floor, a fire test was performed on six small‐scale continuous AMH slabs (two by three). In this paper, the special designed furnace and relevant experimental phenomena are briefly introduced. Detailed experimental results in the form of furnace temperatures, temperature distributions, vertical deflections, and failure criteria are presented. The test data indicate that almost all the AMH slabs showed upward displacements during the fire tests, which is very distinct with the isolated AMH slab under fire. As the edge girders transformed into the frame girders gradually, the edge girders would show displacement plateaus. The integrity of the AMH slab under elevated temperature should receive more critical role to serve as its failure criterion compared with the load bearing function. Except fire environment, boundary constraint conditions also have a considerable effect on the elevated temperature deformations of the structural elements. At last, several rational suggestions are provided to improve the fire resistance of the AMH slabs.

The historic River Witham Bridge, Lincoln, UK

River Witham Bridge in Lincoln, UK, is an underline railway bridge carrying two tracks over the River Witham and is owned by Network Rail. The bridge was listed in 1999 to recognise the historical significance of the 1848 river span, which comprises very rare tubular edge girders patented by the engineer William Fairbairn. The bridge was found to be in poor condition and have an inadequate assessed capacity for current rail traffic. To address these issues the bridge was successfully reconstructed in 2017, while the historic river span was also repaired and conserved – an essential element of the project. The conserved girders from the original river span were reinstated beneath the reconstructed bridge deck, maintaining the historic fabric and appearance of the original bridge for the benefit of future generations. The asset management, historical significance, maintenance, mitigation, reconstruction and conservation of this historic bridge are described in this paper.

Fatigue reinforcement during repainting for two motorway bridges

A large number of metallic structures have already reached or even exceeded the limit of their initial design fatigue life. All this paper reports and investigates about the various works carried out in order to extend the fatigue life of existing motorway bridges located in the north of France.The studied bridge is composed with two independent decks of a French motorway carrying heavy traffics for 40 years. The slabs of both bridge decks are very fine: steel-concrete composite slabs associating 8 mm steel plate and 100 mm concrete layer according to the original design of Charles Brignon, who was also a pioneer in France of modern fatigue design for bridges, using rounded gussets to attach transverse beams, which reduces the stress concentration factor at the crossing point of the flanges.The structures of the bridges were recently strengthened to extend their fatigue resistance by three different methods which are:Addition of a continuous welded steel plate inclined outside of the edge girders to increase the safety at the Ultimate Limit State (ULS) and the robustness in fatigue of the bottom steel flanges. The inclined additional plate supported by the webs and the free bottom flangesPost weld treatment with Tungsten Inert Gas (TIG) dressing of the welded cross-beams connection gussets were performed.Bonding of CFRP carbon fibres on the bottom steel flanges of the main beams at the extremities of the welded existing cover-plates. These fibres need a high elastic modulus of 400 GPa.The interactions between both fatigue and anticorrosion life extension works are discussed. An innovative option of mixed complete-partial sandblasting methods was proved more economic than the usual complete sandblasting method and performed. The initial conception with two independent decks carrying the highway showed itself particularly relevant for the implementation of heavy repairs. The traffic deviation on the other deck allowed to work on each deck without stopping the traffic.

Second Dolsan Bridge: A Cable-Stayed Bridge with a Concrete Edge Girder

The Second Dolsan Bridge has a total length of 464 m, consisting of a 230 m main span and two 117 m side spans. This is the first time that a cable-stayed bridge with a concrete edge girder has been built in Korea. The main criterion governing the design and construction of the bridge was the control of tensile stress and negative moment—in not only the edge girder but also the slab—due to the traffic load and the wet concrete load of the deck while under construction. It is necessary to exercise tight geometric control of the camber during construction and to carry out thorough checks to minimize cracking in the deck slab. For this reason, a continuous three-span floating deck system with intermediate piers and a form traveler (FT) supported by permanent stays were chosen. This floating system reduces the tensile stress on the pier table and eliminates the cost of constructing cross-beams on the pylons as well as the maintenance cost of the bearings. Using the FT supported by permanent stays, the tensile stress on top of the previous segment is significantly reduced during the pouring of the concrete. The intermediate piers, while preventing significant displacement and cracking due to the traffic load, also increased the stiffness of the side span and enabled the stay cables on the side span to behave as backstays. Thus, this structure represents a viable example of a cable-stayed bridge with concrete edge girders.

Rolling Fatigue Test of Large-Sized UHPC Member for Cable Stayed Bridge

Recently, research strives to apply Ultra High Performance Concrete (UHPC) to large-sized structures owing to its remarkable mechanical performance and durability compared to normal concrete. The Korea Institute of Construction Technology proposed SuperBridge800, an edge girder type UHPC cable stayed bridge with central span of 800 m, through its detailed design. The bridge is designed to be erected through the connection of precast UHPC segments. The precast UHPC segment is monolithically composed of one ribbed deck slab and edge girders at each side. The connection between the precast segments is achieved by steel bars at the edge girders and by UHPC cast-in-place wet joint at the slab. Despite of the outstanding mechanical performance of UHPC, the fabrication of large-sized members is a difficult task since UHPC hardens faster than normal concrete and requires a special curing process. Therefore, the constructability of large-sized UHPC segment should be secured to achieve SuperBridge800. Besides, the performance of the connection between segments should also be guaranteed, especially in terms of the fatigue performance of the UHPC cast-in-place joint, which constitutes a weak point. To that goal, two half-scaled UHPC segments are manufactured and the constructability is examined by fabricating a large-sized UHPC member connected with respect to the design conditions. This study conducts rolling fatigue test on the so-fabricated large-sized UHPC member. Rolling fatigue test is carried out up to 2 million cycles considering actual vehicle load at each center and quarter points of the member. The test results confirm that the service limit state is satisfied.

The Design of the River Suir Bridge in Waterford, Ireland

The new cable-stayed bridge across the River Suir in Waterford is 465 m long with a 230 m long main span and a single pylon. It has the longest span and the highest pylon in Ireland. This bridge has a number of characteristics which make it singular. Most of its foundations consist of large-diameter micropiles with a working load of 5000 kN. The pylon is an inverted Y without any intermediate cross beam and with streamlined external surfaces, which was made of reinforced concrete. The deck is a composite structure consisting of a steel grillage with a concrete deck. Specific steel tube and plate assemblies were designed to anchor the cables from outside the edge girders to comply with strict specifications regarding possible impact of vehicles against the cables. The concrete deck is made of ribbed pre-cast slabs. The deck has a variable width, which makes it very singular for a cable-stayed bridge. There is a single dilatation joint along the full bridge. Consequently, the deck is integral with one of the abutments.

UB 30/274 Daer Viaduct replacement

The Saltire Society Design Commendation for the New Daer Viaduct reads ‘It will become the benchmark to which other similar schemes are prepared'. A two-span bridge carrying the West Coast main line over the River Clyde was replaced by a single river span. All construction of the new substructure and superstructure and jacking of the superstructure into its permanent position was carried out below the existing bridge with no disruptive track possession. Only one 42 h possession was utilised to remove the old superstructure and the original central pier and to install minor precast infill units. The superstructure comprised two steel edge through girders supporting a transverse steel composite deck. The edge girders were aligned to pass the ends of the original central pier. When the superstructure was jacked up, the concrete robust kerb and edge girders moved up outboard of the original bridge edge girders. Thus, prior to the possession, the superstructure had all been built except for the portion occupied by the original pier. Following removal of the pier, this portion was completed with a precast concrete unit.

Monte Carlo simulation of cable fatigue stresses in two cable-stayed bridges

Monte Carlo simulation studies were performed to determine fatigue stress distributions due to truck traffic in all stay cables of two existing cable-stayed bridges. One bridge had two planes of stay cables with concrete edge girders, and the other h

剥離干渉法を用いた鋼２主桁斜張橋の耐風安定性に関する検討

Characteristics of wind-induced response of cable-stayed bridges with two steel edge girders were studied experimentally, and the effects of the Separation Interference Method and its applicability regarding the structural rationality were discussed. Two types of edge girders, i.e., I section and box girders, were considered. The vertical wind-induced responses of two I section girders were suppressed by locating the girders at the inner position. However, this requires additional bracket beams that anchor the stay cables, and may not be economical. The wind-induced responses of two box girders were generally suppressed by applying the Separation Interference Method without additional aerodynamic appendages such as fairings. This case does not require additional bracket beams and can possibly be used as an economical choice.

Wind-induced characteristics of two-edge girders for the bending degree-of-freedom

Two-edge girder bridge deck sections are investigated by wind tunnel tests. Aerodynamic force coefficients (drag, lift, and moment coefficients) varying the angle of attack from −5° to +5° are measured. Moreover, vibration tests due to wind loads are performed for the bending degree-of-freedom. The steady mean drag coefficient decreases as the edge girders are extended. In addition, the flexural vibrations are reduced by attaching appendages: flanges, extended plates, and cross beams. The reduced velocity inducing a flexural vortex-shedding vibration is predicted using the result of the FFT analysis for the steady aerodynamic lift force time history and is in good agreement with the vibration test result.

Recent topics on bridge aerodynamics

This paper aims to describe the aerodynamic vibrations of various structural elements of bridges, which are particular issues at present. The aerodynamic countermeasures for those vibrations are also discussed considering the generation mechanisms of the aerodynamic instabilities. In this paper, an example of vortex-induced oscillation of bridge deck and its lesson are discussed. Next, the wind-induced cable vibration and its aerodynamic countermeasures are reviewed. Then, the aerodynamic characteristics on two edge girders and their feasibility for application to long span cable-stayed bridges are considered. Furthermore, the bridge decks for future long span bridges are proposed and their aerodynamic characteristics are also discussed.

Seohae Grand Bridge

The Seohae Grand Bridge, located about 65 km south of Seoul, Korea, is currently under construction and, when complete, will be the longest bridge in Korea. The total length of the bridge is 9.4 km from Pyongtaek on the north to Dangjin on the south, carrying three lanes of traffic in each direction across the Asan Bay. The center span provides a 62-m-high navigation clearance above the high sea level of +4.65 m. The main bridge is composed of three cable-stayed spans of 200, 470, and 200 m and two 60-m-long side spans, one at each end. The center span will form the entrance to the harbor and will be built in the future. The bridge deck is supported by two longitudinal steel edge girders that are spaced 34 m apart and by transverse steel floor beams at 4.10 m on centers. The majority of the bridge deck is composed of precast panels and cast-in-place joints. The bridge superstructure is restrained in the transverse direction at the two pylons and end piers. The bridge longitudinal displacement due to live load, temperature variation, and creepshrinkage is restrained at one pylon with longitudinal shear keys. Lockup devices are installed on the other pylon and are mobilized only for longitudinal earthquake loading.

Sidney Lanier Bridge, Georgia

The existing Sidney Lanier Bridge crossing the Brunswick River near Brunswick, Georgia, has a lift span of 76.25 m (250 ft), which is deemed too small for the ships that visit the harbor today. The new Sidney Lanier Bridge is a replacement for the existing structure to ensure navigational safety. It will be 2372.9 m (7,780 ft) long with a 381.25-m (1,250-ft) cable-stayed center span, which has a vertical clearance of 56.425 m (185 ft) above the mean high water level. The new bridge will permit the passage of any ship known to exist in the world today. The total width of the bridge deck is 24.71 m (81 ft), which will accommodate two traffic lanes in each direction. The concrete deck girder consists of a concrete slab 27.94 cm (11 in.) thick supported by 1.525-m (5-ft) by 1.45-m (4.75-ft) concrete longitudinal girders at each edge and by transverse floor beams spaced at 8.29 m (27.17 ft). At the two pylons, the superstructure is free to move in the longitudinal direction and restrained in the vertical and transverse directions. The concrete deck is cast monolithically with the two end piers. Each concrete pylon carries two vertical planes of fan-shaped cables anchored to the edge girders.

An experimental study on aerodynamic improvements for edge girder bridges

This study aimed to develop simple, economical and effective aerodynamic attachments for edge girder bridges. In the study, wind tunnel tests and computational flow analyses were combined in order to more efficiently explore the effects of different attachments. As basic cross sections of edge girders, B′=4D type and B′=8D type (B': length between two I-beams, D:deck depth) were used in wind tunnel tests.As a result of the studies, we successfully developed a simple, economical and effective aerodynamic attachment called a “Tip Plate”. The tip plate makes remarkable aerodynamic improvements for edge girders. Especially, this aerodynamic attachment stabilizes torsional flutter and vortex-induced vibration by suppressing flow separation from the leading edge of the deck.