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Steel corrosion is by far the biggest durability issue for many reinforced concrete bridge structures worldwide. The columns in these bridges can be critical, especially for seismic resistance. In this study, glass-fibre-reinforced-polymer bars were investigated as an alternative to steel for sustainable and resilient bridge construction. As lateral reinforcement is more susceptible to corrosion, and structures fully reinforced with fibreglass bars display softer responses with lower shear and flexural capacity, fibreglass spirals and longitudinal steel reinforcement were used in the tested columns. The experimental programme included the design, construction and seismic testing of full-scale (508 mm diameter) and half-scale (356 mm diameter) columns. The other variables investigated were the axial load and the amount and spacing of spirals. For both column sizes, fibreglass spirals provided increasing confining pressure to the concrete core with increased deformations. For the full-scale columns, no adverse size effects were observed in comparison to the half-scale columns. The columns produced large ductility and energy dissipation. Results from selected representative specimens are presented here to establish the feasibility of using fibreglass spirals in circular bridge columns. Resilience can thus be built into new columns through innovative durable fibreglass lateral reinforcement, with similar if not superior behaviour to steel-reinforced columns. [ABSTRACT FROM AUTHOR]

The Canadian highway bridge design code (CHBDC) uses the concept of a target reliability index for evaluating the load-carrying capacity of existing bridges. This index, which is based on risk to human life, is related to three aspects of uncertainties inherent in a bridge: element behaviour, system behaviour and inspection level. Analysis is yet another uncertainty in bridge evaluation. It is assumed that all bridge inspections are manual. Citing examples of tests on many instrumented bridges, another level of inspection is proposed, carried out with the help of electronic instruments and tests under controlled vehicle loads. Simple additions to the clauses of the CHBDC are proposed, which can be used to determine the optimum load-carrying capacities of existing bridges where structural monitoring information is available. [ABSTRACT FROM AUTHOR]

In recent years, accelerated bridge construction has led to the substantial application of precast post-tensioned segmental (PPS) bridge piers. However, PPS piers are not widely used in high-seismicity regions due to their low energy-dissipation capacity (EDC). To address this deficiency, a series of shape memory alloy (SMA)–concrete composite PPS piers were examined in this work. Non-linear static and dynamic analyses were performed on experimentally validated finite-element models of the SMA–concrete composite piers and the results were compared with those of piers without SMA bars. It was found that the length, area and post-tensioning ratio of the SMA bars affected the EDC of the piers, and an optimal design of the bars is required to reach the highest EDC possible. The effects of SMA bars on the frequency response functions of piers were investigated for the first time in this study and it was found that, unlike the piers without SMA bars, sub-harmonics and super-harmonics were not seen in the responses of the SMA–concrete composite piers, mainly the drift responses. Furthermore, the SMA–concrete composite piers experienced a significant reduction in drift responses compared with piers without SMA bars. [ABSTRACT FROM AUTHOR]

The safety and serviceability of long-span bridges can be significantly impacted by wind effects and therefore it is crucial to estimate them accurately during bridge design. This study develops full-scale three-dimensional computational fluid dynamics (CFD) simulation models to replicate wind conditions at the Rose Fitzgerald Kennedy Bridge in Ireland. The neglect of bridge geometries and the use of small scales in previous studies are significant limitations, and both the bridge geometry and surrounding terrain are included here at full scale. Input values for wind conditions are mapped from weather simulations that apply the weather research and forecasting model. Wind velocities at four different points calculated by CFD simulations are compared with corresponding data collected from structural health monitoring field measurements. The calculated time-averaged wind velocities at four different locations on the bridge are shown to have relative differences of less than 10% from the wind velocities measured by anemometers 90% of the time. The maximum relative difference among all comparisons was only 15%, shown to be partially due to the inclusion of the full bridge and terrain geometry. [ABSTRACT FROM AUTHOR]

River-crossing bridges in seismically active regions are typically susceptible to two natural hazards – earthquakes and floods. For such bridges, design parameters related to piers may play major roles in bridge multi-hazard performance. In this study, the same was explored for key bridge design parameters – the aspect ratio and longitudinal reinforcement ratio of piers and the differential ground elevation between multiple bents. The multi-hazard condition in the southeast of Nepal was considered as the test-bed hazard condition. The regional seismic hazard was represented using a suite of earthquakes generated based on regional seismic design spectra. Due to the flood hazard in the region, expected pier scour of investigated bridges was estimated from 100-year flood discharge (including climate change projection) in the Koshi River, Nepal. Three-dimensional finite-element models of the chosen bridges, with and without scour and with ±10% variations in the stated design parameters, were developed. Fragility and risk curves of the bridges were developed and compared in order to assess the relative influence of the design parameters on bridge performance. It was found that the aspect ratio and longitudinal reinforcement ratio of piers can significantly influence the multi-hazard performance of riverine bridges. The findings also demonstrate how design parameters may be revised to perform risk-targeted multi-hazard design of bridges. [ABSTRACT FROM AUTHOR]

The Gordie Howe International Bridge project is providing a new modern border crossing between Windsor, ON, Canada and Detroit, MI, USA. The centrepiece of the project is a 2.5 km long cable-stayed bridge with 853 m main span over the Detroit River and 220 m tall towers on both sides of the river. In addition to the bridge, the project includes ports of entry on both sides of the border and a new freeway interchange with Interstate-75 in Detroit. The project was procured as a public–private partnership that allowed the proponents to propose either a suspension or cable-stayed bridge, with the ultimate selection creating the longest cable-stayed bridge in North America. The paper outlines the need for the new border crossing and results of the environmental assessment process, as well as describing the project evolution from planning through procurement and into detailed design. The scoping of the bridge design parameters is discussed, including: comprehensive geotechnical investigation; load study to develop project-specific live loading; the approach for durability requirements to achieve a service life of 125 years; special considerations for security; wind engineering; and compliance with both Canadian and US design codes. The paper also discusses the approach to achieving an aesthetically pleasing bridge design. [ABSTRACT FROM AUTHOR]

The article focuses on the broader impact of bridge failures on transport networks and regional resilience. Topics include the role of soil-structure interactions in seismic bridge design, the development of new strengthening systems for existing bridges, and the use of analytical methods to assess bridge performance under multiple earthquake events.

The Wan Jiang Bridge in China was damaged by ship impact and subsequently restored. This paper presents a detailed evaluation of the residual service life (RSL) of the bridge using the reliability analysis method of the Joint Committee on Structural Safety, based on the structural load-bearing capacity (LBC) of the bridge and the design load. Data were collected from bridge design codes, field loading tests and finite-element (FE) analysis. The LBC was initially calculated and subsequently revised using specific coefficients. Using FE analysis, the bending moment on the control section of the bridge was determined under the most unfavourable loading conditions and the ultimate LBC of the bridge was checked. Subsequently, static and dynamic loading tests on the restored bridge were conducted, with the load and capacity determined for the control section based on FE analysis. The loads considered were dead load, vehicle load and crowd load. A time-dependent reliability index was developed for the restored bridge using the probability distributions of capacity and design load variables, and the RSL was determined. This case study, predicting the RSL of the bridge based on a multitude of data, should be valuable for future bridge maintenance and management. [ABSTRACT FROM AUTHOR]

A finite-element (FE) investigation into the response of integral abutment bridges (IABs) to seismic loading in the longitudinal direction was conducted. An example multi-span reinforced concrete solid-slab bridge was designed and analysed using an elasto-plastic two-dimensional FE model. The bridge abutment was taken as supported on steel H-piles. The proposed FE model was found to have the capability of simulating both the bridge construction and the backfilling process using a multi-step numerical process. The bridge was examined considering various lengths and different backfill materials, and was subjected to earthquake loading. The analyses showed that the seismic response of IABs is notably affected by the bridge length. Longer bridges may be subject to higher pressures on the abutments and internal forces in the bridge structure. The stiffness and strength parameters of the backfill material may also markedly influence dynamic pressures on the abutments and internal forces in the structure. Backfill materials with greater stiffness and strength parameters may cause significant reductions in the seismic flexural stresses in both the abutments and the deck. Coupling seismic and thermal loads could be suggested for the design of IABs. [ABSTRACT FROM AUTHOR]

The A554 Tower Road connects Wallasey and Birkenhead on the Wirral, north west England. The road crosses the entrance to Birkenhead docks from the River Mersey by way of a moveable bridge, which is of major strategic importance in the local highway network. The previous 'A' bridge, built in 1933, was a Scherzer type bascule lifting bridge with 34.4 m main span, one of four similar bridges that once existed along Tower Road. The deteriorating condition of the bridge, the increasing maintenance costs and the consequential impact of maintenance on the local economy resulted in a decision to replace the bridge with a modern, low-maintenance, lifting bridge. This paper provides the background to the bridge replacement project, including the reasons for replacement with a similar Scherzer bascule bridge. The civil, mechanical and electrical design is described and some of the significant issues encountered during implementation and commissioning are discussed. The new bridge has successfully created a local landmark, contributing to the client Wirral Council's vision for the redevelopment of this dockland area as part of the Wirral Waters regeneration project. [ABSTRACT FROM AUTHOR]

The editorial discusses a themed issue on "Multi-Hazard Effects on Engineering Structures" in the Proceedings of the Institution of Civil Engineers journal. The issue aims to showcase recent research developments in understanding the behavior of structures subjected to multiple hazards, the performance of structural response modification devices, developments in codes and standards, probabilistic multi-hazard structural engineering, and measurement and tracking of condition and performance over the lifespan of structures. The editorial emphasizes the importance of studying and addressing the physical and socioeconomic losses caused by multiple hazards and their impact on society. It also highlights the need for scenario-based and site-specific designs and performance assessment for built infrastructure. [Extracted from the article]

During bridge design and assessment, effects of thermal actions are accounted for by means of a uniform temperature variation and temperature difference components. The uniform temperature variations cause changes in length and width of the structure, whereas the temperature difference components primarily cause curvatures and internal stresses. The effects of these strains on the superstructure depend on the structure's articulation and restraint. Design profiles used to model the temperature difference components vary between design codes, which can have a significant effect on the induced curvatures. Thermal data findings obtained from a comprehensive, year-long monitoring programme on Waterloo Bridge in London are examined, which allows comparison of these various models with performance data. The design thermal model in BS EN 1991-1-5 is examined, supplemented by the models from the Aashto and New Zealand codes. The measured uniform bridge temperature generally fell within the stipulated limits of BS EN 1991-1-5; however, at low temperatures the minimum deck temperature may be lower than the design relationship provided. The resultant moments implied from the measured vertical profiles: significantly exceed the worst-case values predicted by the UK model; exceed the Aashto model at different bridge sections; and do not exceed the New Zealand model. [ABSTRACT FROM AUTHOR]

The Celtic Manor Hotel Bridge crosses the M4 motorway and forms the main access to the largest hotel and leisure resort in Wales. It was also to be the access for the construction of the Wales International Convention Centre (WICC). A load-carrying assessment found the bridge to be unable to carry a 40 t assessment live load in accordance with Highways Agency, UK guidance BD 21/01, with critical sections failing in shear under its own factored self-weight. A BD 79 risk-management approach using reliability analysis techniques combined with load mitigation interim measures was used to assess the bridge's continued satisfactory performance in the short term. This project uncovered valuable research that provides information on reliability analysis techniques and probability density functions which enabled the application of the technique to this bridge assessment. Strengthening works were designed to enable the bridge to remain in service in the longer term while maintaining safety levels. Shear strengthening was installed during night-time bridge and M4 lane closures and allowed for continued hotel use and passage of construction vehicles without causing any delays to the WICC construction. [ABSTRACT FROM AUTHOR]

Interviews were undertaken with expert bridge designers to reveal their opinions on environmental considerations and the possibility of integrating life-cycle assessment into the bridge design process. Bridge designers were generally found to consider that the need for the bridge, access for future maintenance, use of quality materials, longevity, cost savings and sustainability are matters more important than life-cycle environmental emissions. Moreover, the limited awareness of life-cycle assessments among bridge designers along with a keenness to execute clients' requirements, mostly on the basis of cost, has further widened the gap. This gap could be overcome by ensuring that detailed environmental matters such as carbon dioxide, nitrogen dioxide and greenhouse gas emissions are considered as design criteria; encouraging designers to highlight emerging environmental matters in the design brief; heightening awareness of life-cycle assessment among designers to increase its potential usage; and factoring life-cycle assessment damage indicators into the bridge design process. [ABSTRACT FROM AUTHOR]

The Jinsha River rail–road double-deck arch bridge (bridge designed to 250 km/h) of the Chengdu–Guiyang high-speed railway (HSR) (designed to 350 km/h) is a complex system with a novel structure in China. The upper deck carries a four-track railway while the lower deck carries a six-lane urban expressway, with a height difference of 32 m. The bridge is located in the mountainous river reach of the city of Yibin. The 336 m main span adopts a high-pier, rigid steel frame, parallel tied-arch structure, built using cantilevers and temporary stay cables with the cable crane method. The 116 m and 120 m side-arches are reinforced concrete, simply-supported, basket-lifting tied-arches built by the mass cast in situ method. The rare layered structure gathers different arch types (top-bared, bottom-bared and half-through arches) into one bridge, which brought significant challenges to its design and construction. Other innovative solutions included flexible hangers passing through rigid hangers for the layered stiffening decks, ultra-high-performance concrete for the steel orthotropic deck road pavement and the use of boat shipments to overcome the scarce availability of flat land at the site. This paper describes some of the salient design and construction challenges of this landmark structure, the world's first double-deck HSR arch bridge. [ABSTRACT FROM AUTHOR]

The Shangqiu–Hangzhou high-speed railway is 794.55 km long with a design speed of 350 km/h. The third Wuhu Yangtze River Bridge stands out as the key project of the whole railway. Restricted by the site conditions, the bridge is an asymmetrical low-pylon cable-stayed bridge with a main span of 588 m. To overcome the technical challenges of low stiffness and unfavourable axial force induced by the low pylons, a box-truss type composite section with a strong box at the lower deck and a weak truss above was creatively used in the design of the main girder. In addition, parallel steel wire cables coated with a zinc–aluminium alloy and with a tensile strength of over 2000 MPa were developed to withstand the tremendous axial force in the inclined cables. These two innovative solutions were successfully implemented in the construction of the bridge. This paper describes problem solving through creativity by addressing a few key issues faced by the designers. [ABSTRACT FROM AUTHOR]

Filler beam bridge constructions with hot-rolled steel sections at close centres and filled with concrete meet all the requirements of small- and medium-span railway bridges. Filler beam bridges have thus been used for many years with considerable success, in particular where construction depth restrictions are relevant for the design. Moreover, they are perfectly suitable for use with high-speed railway lines. Since the late 1970s, various railway companies have established standard designs with guidelines, supplemented with calculation tables that correspond to their own rules. Some of these guidelines have become outdated with introduction of the Eurocodes. However, since on one hand there is growing interest in this type of construction and, on the other, a desire to evaluate large amounts of design data economically, there is a need for a calculation tool that enables quick, efficient and reliable designs. For this reason, new design tables for filler beam bridges in the German high-speed railway network up to 350 km/h have been developed, which enable a quick and direct evaluation of all relevant cross-sectional data of single-track single-span bridges in the span range 5–35 m without costly statics. The tables and the software, with which the tables were generated, are shown in this article. [ABSTRACT FROM AUTHOR]

The Heathrow expansion project proposals comprise major works around Heathrow airport to allow the construction of new terminal buildings and the third runway. Owing to the critical nature of uninterrupted operation of both runway and the M25 motorway, the preliminary design had to be developed to minimise maintenance operations. At over 140 m in the total length, the adoption of an integral bridge of this length is in excess of most integral bridges in the UK, particularly where full-height abutments are being utilised. The maximum predicted expansion length also lies outside the limit equilibrium method set out in PD6694-1. As such, it was agreed that a full soil–structure interaction study should be carried out to assess the impacts of the structural behaviour of the bridge and its abutments. This paper looks at the calibration work for that study, the derivation of the earth pressures behind the walls, the behaviour of the abutment and how this compares with the predictions set out in PD 6694-1. [ABSTRACT FROM AUTHOR]

In the 1995 Kobe earthquake, different bearing fractures were observed in isolated bridges. Piers and bearings were the first and second vulnerable structural elements. The estimation load due to far-field earthquakes can be calculated using BS EN 1998-1:2004, but research on this issue for near-field earthquakes is limited. The aim of this study was to verify the effect of the vertical component of near-field earthquakes on structural responses and compare the results with values suggested using BS EN 1998-1:2004. An isolated bridge was designed based on Eurocode standards and modelled in OpenSees. Moreover, since soil–structure interaction (SSI) has an inherent effect on bridge structures, the induced vertical accelerations were compared with and without SSI effects. It was found that vertical acceleration decreased in the model including SSI effects. The shear strain of the elastomers was found to be within the range allowed by BS EN 1998-2:2005. [ABSTRACT FROM AUTHOR]

Pan-girder (PG) bridges became popular in Texas, USA, in the 1950s and 1960s as a viable alternative for short-span bridges due to their speed of construction, low-labour requirements and cost–effectiveness. However, these bridges were designed for lighter live loads than the current AASHTO HL-93 loading, resulting in gradual decline in their usage. Existing PG bridges may have various structural and non-structural deteriorations because they are nearing or have crossed their service lives. In this study, the existing condition of four selected PG bridges in the Dallas–Fort Worth metroplex were visually inspected to assess their current condition. The bridges exhibited significant concrete spalling, cracking and crushing, resulting in exposed and corroded steel rebars. The newest bridge, built in 1992, experienced less severe damage than the other three bridges built in 1955–1971. The bridges' safety could be compromised due to deteriorations and lighter design live loads. Therefore, the following recommendations were made: (a) glue a polyvinyl chloride pipe on the form-lowering holes extending beyond the concrete surface of the arch to minimise water infiltration and related damage; (b) conduct load testing and ratings to verify the structural safety and load-carrying capacity of the deteriorated bridges; and (c) retrofit to upgrade the existing bridge condition and safety and mitigate against further damage. [ABSTRACT FROM AUTHOR]

A 1 : 2 scale fatigue experiment on an orthotropic steel deck was carried out to investigate the fatigue behaviour of the steel decks of a suspension bridge. The experimental model was developed from the orthotropic steel deck of a long-span suspension bridge in the Three Gorges reservoir area. The fatigue experiment involved 2·8 million load cycles. Up to 2 million load cycles, the stress data showed that the fluctuations in stress values were small and, in the loading and unloading processes, the displacements agreed very well and there was no local cracking or damage. The fatigue performance of the orthotropic steel deck thus met the design requirements and had enough safety reserve. After 2 million fatigue load cycles, the load value gradually increased. Cracks did not appear until 2·6 million cycles. Finally, after 2·8 million cycles, crack accumulation caused structural damage to the model. It can thus be concluded that, with good welding and normal maintenance, this orthotropic steel deck will not suffer fatigue cracks during its design working life. This work provides a theoretical and experimental basis for the practical construction of such bridges. [ABSTRACT FROM AUTHOR]

Over the past few decades, engineers working in design offices have become much better at designing for constructability. The use of the design and build form of procurement has, in many ways, been instrumental in this change. The use of accelerated bridge construction in the USA, although primarily a method of reducing traffic impact, has also helped engineers become better at designing for constructability. However, it can be argued that engineers have not made the same progress in designing bridges to make future inspections and maintenance easier. In fact, unless an employer's requirements for inspection and maintenance are clearly prescribed in detail in the contract, then the design and build form of procurement is perhaps the least advantageous when considering the service life of a structure. Over the lifespan of a bridge, the service life costs, including inspection and maintenance, can account for a significant percentage of the lifecycle costs of the bridge. Therefore, the importance of not only ensuring that an adequately funded proper inspection and maintenance regime is established but also that sufficient attention is paid to the provision of inspection and maintenance during the design stage cannot be overstated. This paper examines and compares current practice in the UK and USA and considers ways of improving the design process to assist the future inspection and maintenance of bridges. [ABSTRACT FROM AUTHOR]

The aim of this study is to analytically assess the seismic performance of hollow reinforced-concrete bridge columns using a novel damage index, and to provide data for developing next generation design criteria. Hollow reinforced-concrete bridge columns have been used in the past in place of their solid counterparts in the construction of bridges. These hollow columns have several benefits over solid columns, including the reduction of vertical load applied to the foundation as well as the reduction of seismic mass. Two circular and two rectangular hollow reinforced-concrete bridge columns were tested under a constant axial load and a cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), is used to analyse reinforced-concrete structures. Novel damage indices aim to provide a means of quantifying numerically the performance level in cast-in-place and precast hollow reinforced-concrete bridge columns sustained under earthquake loading. The proposed numerical method for the seismic performance assessment of hollow reinforced-concrete bridge columns is verified by comparison with the experimental results. [ABSTRACT FROM AUTHOR]

Launching is a bridge erection method that provides significant advantages when there is difficult underdeck access for falsework, crane and heavy plant. In such cases, assembling the deck in a more accessible position and launching it over the piers may mean a significant saving of resources. In some cases access is simply not possible due to other constraints, for example over environmentally protected areas. This is the case of the north approach viaduct of the new Queensferry Crossing, a major cable-stayed bridge over the Firth of Forth in Scotland, UK. This paper provides a description of the approach viaduct north and its launch process. This viaduct is a single/twin-girder bridge with composite section and two spans of 101·5 m and 104 m. Owing to its particular characteristics and impressive launch weight of 6200 t, the launching process has not been conventional, and particular solutions have been used and combined to ensure full compliance with the strict design constraints. The assembly process was not conventional either, owing to space constraints and the weight and size of the pieces. [ABSTRACT FROM AUTHOR]

The new Queensferry Crossing near Edinburgh in Scotland, UK, is a cable-stayed bridge with a total length of 2637·5 m and three towers up to 210 m high. The two cable-supported main spans are 650 m long, the two back spans are 223 m and there are approach viaducts at each end of the variable spans, up to 104 m long. The two cable planes are arranged centrally between both carriageways and overlap in the centre of the main spans. This special feature is necessary in order to stabilise the deck and, especially, the central tower. Unique design features, such as having the world's longest pair of free-standing cantilevers with an overall length of 644 m, and constructing the works in an exposed location in adverse weather conditions put very high demands on the engineers and workers involved. This paper describes the design and construction of the cable-stayed bridge deck and cables. [ABSTRACT FROM AUTHOR]

The past few decades have witnessed a rapid increase in the role of the architect in the design of the once sacrosanct area of engineering – bridge design. Reasons for this relative decline in the engineer's role are many and varied, but must include the overemphasis on detailed analysis at the expense of understanding and creative design in engineering courses and the alarming reduction in structural education from engineering courses. With software now readily available to perform detailed structural analysis there is an opportunity to rebalance engineering courses towards much greater emphasis on understanding and design involving new approaches to analysis that can directly assist rational decision making. This paper demonstrates how simple, physically based, analyses can aid rational decision making in bridge design and suggests that such approaches could play a wider role in engineering courses. By way of illustration, these approaches are applied to the iconic, much copied, gravity balanced cable-stay Alamillo Bridge designed by Calatrava. This example also demonstrates the inefficiency of this bridge form and shows how such approaches, applied at an early design stage, could help bring rational engineering judgement back into bridge design at a time when the planet can ill afford such unsustainable solutions. [ABSTRACT FROM AUTHOR]

Bridge maintenance activities are important to consider within sustainable development due to the cost and environmental impact associated with various maintenance activities. Comparisons have been made between different bridge structural forms, based on materials, components and construction method, but less information is available on bridge maintenance activities to help decide a sustainable structural form. Typical maintenance aspects of the predominant forms of bridge structure (i.e. concrete, steel and masonry bridges) were considered in this study to reveal their sustainability in terms of materials, energy, transportation, human health and ecosystems. The results indicate that concrete and steel bridge maintenance activities have an average impact of 42% and 46% compared with 12% for masonry bridge maintenance activities. It is concluded that the component parts of concrete and steel bridges should be revised as they play an integral role in the selection of maintenance options. [ABSTRACT FROM AUTHOR]

This paper describes the design and construction of Ohmi–Odori Bridge in Japan, which is the world's first multi-cell extradosed prestressed composite bridge with corrugated steel webs. Structurally, the bridge combines two new technologies: a composite prestressed concrete bridge with a corrugated steel web to reduce the dead weight of the main girder and an extradosed bridge to allow a longer span length. Several innovations were used on this bridge, including a three-cell box cross-section, adopted for the first time for the main girders of a bridge using corrugated steel webs, and a steel–concrete composite structure adopted for the cable anchorages. In 2006, the bridge was honoured with the highest award for a bridge project, the Tanaka Prize awarded by the Japan Society of Civil Engineers. [ABSTRACT FROM AUTHOR]

There is a large number of masonry arch bridges on the rail networks in Europe and other parts of the world. However, the mode of response of masonry arch structures subjected to railway loading is little understood. To address this, an experimental study involving large-scale physical models of backfilled masonry arch bridges subjected to railway loading conditions was conducted. The study explored the influence of the rail track–bed system on bridge behaviour and load-carrying capacity. The tests results indicated that the track–bed system fundamentally alters the mode of response of the bridge system and significantly increases load-carrying capacity. Using the same test facility, load tests were also used to explore and characterise the behaviour and performance of damaged arch bridges. The results obtained suggest that, although there is likely to be a reduction in overall capacity, even a significantly damaged arch bridge can still perform adequately under loading. This has important implications for bridge owners and assessment engineers. [ABSTRACT FROM AUTHOR]

The strategic road network (SRN) in England carries 33% of traffic in England and Highways England's bridge management systems plays a crucial role in the maintenance of infrastructure assets along the SRN. Reinforced concrete half-joint structures are susceptible to deterioration and hard to inspect, hence they require special attention. Inspection data relating to half-joint structures on the SRN was gathered. Within this portfolio, 252 structures with half-joint-related defects were interrogated to classify the most common defects and identify any potential shortcomings in current inspection practice. Clear correlations were shown to exist between defect classes, emphasising the need for quality control and proper workmanship. A revised inspection methodology for half-joint structures that provides more comprehensive information about crack details, and a greater alignment between defect information and indicators of structural measures, is proposed. Concurrently, knowledge of the zonal crack location, crack orientation and crack severity helps inform decision making about the structural condition. There is scope for use of the methodology in conjunction with automated processing procedures to identify half-joint structures with particular defect characteristics and profiles. In this way, asset managers will be better able to allocate resources to structures with an increased risk of failure. [ABSTRACT FROM AUTHOR]

Network Rail (NR) manages over 60 000 bridge spans, many of which are more than 150 years old. Having contemporary capability information for these ageing assets is vital for the safe and effective management of the rail network. NR has never before had comprehensive, contemporary capability information, and has relied on assessments up to 18 years old. In some cases, assets did not have assessments so their ongoing performance alone was relied upon. Without reliable data on the strength of these structures it would be impossible to operate the railway safely, deliver effective maintenance, decide when repair intervention is required or plan future development of the network. This paper describes the current approach to the assessment of bridges on the railway and the innovative work that has been undertaken to improve the efficiency of assessment and deliver the considerable volume of bridge assessments required to bring strength capability information to an acceptable standard. The paper will also explore the potential of consistent data collection and recording for the better management of the asset as it inevitably deteriorates. [ABSTRACT FROM AUTHOR]

Vision-based systems offer a promising way to measure displacement and are receiving increased attention in civil structural monitoring. However, the working performance of vision-based systems, especially their measurement accuracy and robustness to different field conditions, is not fully understood. This study reports three cases studies of vision-based monitoring tests including one in a laboratory, one on a short-span bridge and one on a long-span bridge. The tracking accuracy is quantified in laboratory conditions in the range from 0·02 to 0·20 pixel, depending on the target patterns as well as the tracking method selected. The measurement performance under several field challenges is investigated, including long-range measurement (e.g. camera-to-target distance of 710 m), low-contrast target patterns, changes of target patterns and changes in lighting conditions. Three representative tracking methods for the video processing, namely, correlation-based template matching, Lucas–Kanade optical flow estimation and scale-invariant feature transform were used for the analysis, indicating their advantages and shortcomings for field measurement. One of the main observations in field application is that changes in lighting conditions might cause some low-frequency measurement errors that could be misunderstood without prior knowledge regarding structural loading conditions. [ABSTRACT FROM AUTHOR]

The fundamental frequency of vibration of a bridge deck is a key parameter that represents the dynamic characteristics and the condition of the superstructure. This paper reviews the different empirical and/or theoretical formulae that have been proposed in the past. The classical vibration theory of beams and plates was simplified in order to clarify and review the general philosophy behind the previously proposed formulae. On the basis of the results obtained from limited dynamic tests performed by the authors on a number of reinforced concrete bridges and the results of limited tests conducted by other researchers, a formula for the first bending natural frequency of a bridge deck was derived. Moreover, as new applications, new practical formulae are introduced that can be used for estimating the initial dimensions of a deck cross-section for simple span bridges, which are particularly suited to bridge-widening projects. The first bending natural frequency/period of the bridge deck and its corresponding cross-sectional properties are considered here as functions of the bridge main span length. [ABSTRACT FROM AUTHOR]

The Van Zylspruit River Bridge is a 90 m long, fully integral bridge located on the South African National Roads Agency SOC Ltd national N1 route. It is a situated in central South Africa, an area known for its harsh climate, with both high and low temperatures. The bridge has been extensively instrumented to measure environmental and material property effects on the structural behaviour. The instrumentation was installed during construction and data have been logged continually from the construction phase onwards. In this paper, the results from the first phase of the monitoring project with regard to the measured effects of temperature variation and concrete shrinkage are outlined and the effects of these environmental effects on the structure are discussed. The results of the research should help to quantify the effect of temperature and shrinkage on the behaviour of the bridge and point towards how future designs should be approached, in particular how environmental and material property factors should be taken into account in the design and construction of longer integral bridges with specific reference to South African conditions. [ABSTRACT FROM AUTHOR]

The Highways England A14 Cambridge to Huntingdon Improvement Scheme consists of both online improvements to existing sections of the A14 and a new offline section constructed on a green field site bypassing Huntingdon, UK. The scheme includes the design and construction of 22 integral bridges in varying forms typically found across the wider highway network. This paper outlines the different structural forms used on the A14 including 'bankseat' abutments on discrete columns, half-height abutments on a single row of piles and full-height abutments. The design challenges encountered for each type of structure are discussed, including the methods of modelling adopted for the soil–structure interaction. Primarily, it will highlight areas where the current codes of practice and design guidance (such as 'PD 6694-1:2011: Recommendations for the design of structures subject to traffic loading to BS EN 1997 1:2004') could be developed to reflect the specific requirements of modelling these types of structures, now commonly in use, and how the requirements varied depending on the type of abutment/foundation considered. [ABSTRACT FROM AUTHOR]

The design and implementation of integral and semi-integral bridges has grown in prominence in New Zealand practice over the last two decades, and bridge designers in the country refer to the New Zealand Transport Agency (NZTA) Bridge Manual for design guidance. However, several issues related to the design and construction of integral bridges were identified as requiring either further investigation or clearer guidance for local design practice. These included non-seismic effects such as concrete creep, shrinkage and temperature, seismic effects and geotechnical issues including soil–structure interaction. Particularly, it was noted that there are no well-established earthquake design procedures for bridges with integral abutments and that the topic of soil–structure interaction required further guidance. NZTA research report 577, published in November 2015, was developed to sit alongside the Bridge Manual and provide local engineers with the necessary guidance for the design of integral bridges, including a description of the issues that need consideration to ensure excellent long-term performance. Report 577 also contains details of a review of the performance of numerous existing integral bridges in both New Zealand and California that have been subject to strong seismic events. This paper discusses the key issues for consideration in the design of integral bridges in non-seismic and seismic regions and the key recommendations for addressing these issues, and also provides examples of documented performance of some integral bridges in New Zealand. [ABSTRACT FROM AUTHOR]

This paper presents the design and construction of an integral bridge that provides road access over the River Nene in Northampton (UK), to the new university campus. The client's aspirations and planning requirements mandated retention of the existing landscape character while also creating an appropriate landmark. This resulted in an elegant 50 m span flat arch structure with only 3·6 m rise. The awarded tender design proposed an alternative steel–concrete composite solution that is integral with its abutments and includes stiffened counterfort walls. A comparison between several alternative articulations arrangements considered for the rigid frame structure is presented. Sensitivity-based analysis between geotechnical and structural models for the derivation of support stiffness and resulting global load distribution between deck and piled foundations relating specifically to the flat arch arrangement is also described. Finally, a discussion of construction sequence, tolerance considerations, and temporary works for stability in the temporary condition is also presented. [ABSTRACT FROM AUTHOR]

Interest in integral abutment bridges (IABs) from the industry has increased in recent years. IABs are robust bridges without joints and bearings and hence they are durable and virtually maintenance free; moreover, the resulting cost-saving associated with their construction is significant, a fact that makes IABs appealing to agencies, contractors and consultants. However, their use in long-span bridges is limited by the complex soil–structure interaction. Thermal movements, horizontal loads and dynamic actions are transferred directly to the backfill soil, leading to settlements, ratcheting effects, high earth pressures and deterioration of the backfill soil. The longer the integral bridge the greater the challenge, as movements are increased. This paper provides an extended review of the techniques used in the international literature and in practice to alleviate the interaction between a bridge abutment and the backfill. Subsequently, the performance of an innovative isolation system for IABs using recycled tyres as a compressible inclusion is studied using detailed numerical models of a representative three-span IAB. The proposed isolation scheme was found to be an effective and sustainable method to isolate the structure from the backfill soil, reducing the pressures experienced by the abutments and the residual vertical displacements of the backfill soil. [ABSTRACT FROM AUTHOR]

Integral bridges have become established as a viable structural form in many countries for reducing maintenance liability and increasing the robustness of structures. The advent of new design guidance associated with the Eurocodes provides an opportunity to review the design of these structures. Research indicates that peak stresses due to bridge expansion continually increase with cycles and in theory may reach a fully passive state. However, this may not happen in practice during a bridge's life. A numerical model has been developed and calibrated against test data, enabling predictions of the development of lateral stresses acting on a full-height frame integral abutment during its life, both in terms of magnitude and distribution down the wall. Design guidance is shown to be appropriate for bridges up to 60 m long, but to be unconservative for longer bridges. The effect of applying daily cycles of movement rather than just annual cycles has also been investigated. [ABSTRACT FROM AUTHOR]

Electrification of the Great Western Railway Route being undertaken requires the alteration of existing infrastructure. Farm Road Bridge is a railway overbridge located adjacent to the Severn tunnel in the UK. The original masonry arch arrangement was foul of the electrification gauge. The bridge was reconstructed in 2015 with the innovative use of an integral form. The bridge was constructed in an unconventional manner with the deck and piled walls built on top and beyond the existing arch span. Once the new bridge was completed, the arch structure was demolished from below. The bridge was designed to act as an 'aqueduct' in extreme flood events. The monolithic nature of the integral structure ensures the bridge is watertight and prevents flooding of the Severn tunnel. As the bridge was designed to fit over the existing arch, the deck has varying depths, slimming down from 1 m at the abutments to 0·5 m thick at the centre of the 20 m span. The increase in road level is thus minimised. The change in relative stiffness of the deck means internal forces are redistributed towards the ends of the span. This paper outlines the design and construction of the permanent and temporary works for this structure. [ABSTRACT FROM AUTHOR]

This paper presents the state-of-the-practice of constructed bridges in Korea, focusing on historical development, performance and recent achievements in rehabilitation technologies. The most commonly erected bridge types and trends over the last 100 years are identified. Dramatic changes occurred in the 1960s, when significant economic development in Korea began, evidenced by the replacement of traditional reinforced concrete T-girder bridges with prestressed concrete I-girder bridges. High-performance systems, such as preflex bridges, were introduced in the 1990s. The evolution of rehabilitation techniques indicates that engineers have sought more durable materials for more functional structural systems and have employed these to extend the longevity of constructed bridges. State-of-the-art strengthening techniques are discussed, with potential applications, and a case study is detailed. Suggestions are provided to advance bridge technologies. [ABSTRACT FROM AUTHOR]

Many factors affect the safety of a reinforced concrete river bridge, and some of these factors might have significant uncertainty that should be evaluated. This study focuses on a system reliability analysis of a reinforced concrete bridge, which is the most common type of river bridge in Taiwan. Specifically, non-linear behaviours of core/cover concrete and steel reinforcement in the substructure of a bridge are considered. Uncertainties of stream surface elevation, water velocity, local scour depth, soil property and record-to-record variations are included in the probabilistic model. The aforementioned parameters of six river geometries are incorporated into a Hydrologic Engineering Center-river analysis system (HEC-RAS) model to assess their impacts on the bridge safety. The effect of river geometry has not been studied thoroughly. Results shown here indicate that it plays an important role. Adopting Bayesian theory to consider the record-to-record uncertainty by combining historic and HEC simulation data is another innovative aspect of this study. Monte Carlo simulation is used to conduct the reliability analysis. The results obtained indicate that the proposed procedure for the bridge reliability analysis is consistent with expert engineering judgement and that the variation in scouring depth and river geometry are pertinent to bridge safety. [ABSTRACT FROM AUTHOR]

The Ordsall Chord rail link project in Manchester, UK was designed using building information modelling. Federated three-dimensional models produced by all design disciplines were held in a common data environment, with modelling developed down to the level of individual reinforcement bars. Early involvement of both the main contractor and its steel fabrication subcontractor allowed conventional roles and processes to be challenged. The design models and drawings were produced on the designer's behalf by the steelwork subcontractor, although these models and drawings were still owned by the structural designer. In some cases, drawings were dispensed with entirely, and key structures were built directly from the digital model, prepared in collaboration between fabricator and designer, and taking advantage of the fabricator's highly automated working method. This paper explains the contractual arrangements and collaborative behaviours that allowed conventional roles to be challenged, and discusses the efficiencies that resulted. [ABSTRACT FROM AUTHOR]