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Displacement measurements can provide valuable insights into structural conditions and in-service behaviour of bridges under operational and environmental loadings. Computer vision systems have been validated as a means of displacement estimation; the research developed here is intended to form the basis of a real-time damage detection system. This paper demonstrates a solution for detecting damage to a bridge from displacement measurements using a roving vision sensor-based approach. Displacements are measured using a synchronised multi-camera vision-based measurement system. The performance of the system is evaluated in a series of controlled laboratory tests. For damage detection, five unsupervised anomaly detection techniques: Autoencoder, K-Nearest Neighbours, Kernel Density, Local Outlier Factor and Isolation Forest, are compared. The results obtained for damage detection and localisation are promising, with an f1-Score of 0.96–0.97 obtained across various analysis scenarios. The approaches proposed in this research provide a means of detecting changes to bridges using low-cost technologies requiring minimal sensor installation and reducing sources of error and allowing for rating of bridge structures.

Cement grouts have many purposes in various civil engineering applications such as precast construction, soil stabilization and structural rehabilitation. Using filler materials as a component in cement grouts has been increasingly implemented. The incorporation of such fillers not only does improve the fresh and hardened properties of grouts but also contributes to the decarbonization of grouts by reducing the amount of Portland cement, thereby lowering the carbon footprint of grouting materials. This study aims at assessing the influence of various filler materials on the properties of cement grouts. Three different fillers were used in this study: commercial limestone, commercial pure dolomite, dolomitic quarry dust. These fillers were assessed in terms of their effect on the spread, flowability, cohesion and compressive strength at 3, 7 and 28 days. The results show that fresh properties of the grout were dependent on the type of fillers. Dolomitic quarry dust improved the workability and flowability more than the commercial limestone and dolomite did. The compressive strengths of cement grouts did not change significantly with the incorporation of the fillers. However, cement grout samples including quarry dust exhibited slightly higher 28-d compressive strength than other samples although the same mix had lower 1-d compressive strength than other mixes. This study highlights the benefits of utilizing quarry dust in cement-based binders without compromising the performance.

The aim of this paper is to investigate two different concrete mixes, one with Limestone Powder (LSP) and the other with Ground Granulated Blast-Furnace Slag (GGBS), both mixes containing superplasticizer, in order to analyse their compressive strengths at 7 and 28 days, their abrasion resistance and slip resistance. The two mixes are treated with two different surface protection finishers, applied on the surface after the concrete has cured and analysis of how these finishers affect the abrasion resistance and slip resistance of the concrete is discussed.

This paper presents observations from an active infrared thermography (IRT) experiment about structural monitoring by taking advantage from solar irradiance as a clean and renewable source of energy for thermal excitation. This contributes to reduction of carbon emissions associated with maintenance of existing concrete infrastructure and ensuring their extended life, and safe operation. The models in these observations were five concrete slabs made from a typical mix used for bridge construction in the UK, with simulated subsurface void (representing the defect) at depths of 5 to 25 mm (5mm increment) at the centre of slabs, and one slab without simulated defect. This study was conducted during a sunny afternoon. A sequence of IR images was collected for each slab (six sequences in total), and these sequences were used to calculate the average thermal contrast on surface of the slabs and evaluate its variation with depth of subsurface defect. Finally, the trend of thermal contrast is compared with the trend of thermal contrast from excitation by IR heater to highlight the limitations and future research needs for subsurface damage detection using solar irradiance.

Inspections of engineered structures below water level are essential to ensure the long-term serviceability of bridge infrastructure and to avoid major damage or failure. This research aimed to investigate integrated geophysical technologies for the underwater inspection of bridge foundation-related scour and erodible scour-based infill. Survey methods focused on Water-Penetrating Radar (WPR), supplemented by sonar. Whilst the survey benefits of the sonar imaging water–sediment interface and structures are well known, those of WPR are not. However, it is ideally suited to the survey of the water base and sub-sediment in shallow (>10 m) freshwater, especially where suspended sediment, weed infestation or methane impede sonar results. Our work produced good WPR imagery acquired from small, manoeuvrable boats that allowed bathymetric profiles to be plotted, as well as the likely locations of soft-sediment scour in future high-water flow events. This study provides clear benefits for integrated sonar and WPR surveys in the quantitative assessment of engineered structures within freshwater.

Current vision-based displacement measurement methods have limitations such as being in need of manual targets and parameter adjustment, and significant user involvement to reach the desired result...

This paper aims at investigating the serviceability behaviour of high-volume fly ash-self-compacting concrete (HVFA-SCC) slabs reinforced with basalt fibre reinforced polymer (BFRP) bars through an experimental test and theoretical analysis. Those structural components are suggested to solve problems of corrosion in steel reinforcement and high carbon footprint in cement-based concrete together. A series of full-scale concrete slabs were constructed and tested using a four-point loading in this experimental test. The test variables were concrete material type, percentage of polypropylene fibre in HVFA-SCC, reinforcing material and BFRP reinforcement percentage. This experimental investigation presented the test results on cracking behaviour and deflection of those test slabs. The effect of those variables on serviceability behaviour of the test specimens was analysed and discussed. Subsequently, the representative theoretical methods in the literatures were adopted to predict deflection and crack behaviour of the BFRP reinforced HVFA-SCC slabs. The comparison of the test results and the predicted results were adopted to evaluate the accuracy of the existing deflection, cracking-load, crack-spacing and crack-width theoretical models. The modification of some empirical coefficients was discussed and studied. Finally, an accurate theoretical method for predicting maximum crack width was proposed using the test results of BFRP reinforced HVFA-SCC slabs.

This paper considers the use of Nonlinear Finite Element Analysis (NLFEA) to predict the load capacity of a range of experimentally tested in-plane restrained reinforced concrete slabs which experienced internal arching effects under loading. The slabs were constructed at one third scale and strengthened with basalt fibre reinforced polymer (BFRP) or carbon fibre reinforced polymer (CFRP) bonded in place using the near surface mounted (NSM) technique. As the research was representative of existing floor slabs within reinforced concrete building frames, all test specimens were constructed with normal strength concrete (~40N/mm2) and 0.15% steel reinforcement. One tenth of one percent fibre reinforced polymer (FRP) was used to strengthen samples which were compared with unstrengthened control specimens. The London University Structural Analysis System (LUSAS) finite element analysis software package was used to model all test samples using experimentally derived material test values. Experiments and NLFEA models were compared with the Queen’s University Belfast (QUB) arching theory which showed that LUSAS was slightly more accurate than the QUB arching theory in predicting slab capacity. However, the QUB arching theory was found to be slightly more consistent in estimating slab capacities compared with LUSAS. Yet, both of these methods were significantly better at predicting slab capacities than existing Eurocode and American Concrete Institute codes.

This paper outlines basalt fibre reinforced polymer (BFRP) and carbon fibre reinforced polymer (CFRP) strengthening of laterally restrained concrete floor slabs. In-plane restraint has previously been shown to enhance slab capacity due to the development of internal compressive membrane action (CMA), which is not generally included in codified strength assessments. By installing fibre reinforced polymers (FRPs) using the near surface mounted (NSM) technique, disturbance to the existing structure can be minimised. The span-to-depth ratios of test slabs were 20 and 15 and these were constructed with normal strength concrete (∼40 N/mm2) with 0.15% steel reinforcement. 0.10% FRP (either BFRP or CFRP), was used to strengthen samples which were then compared with control samples. Investigations showed that FRP strengthening and CMA are generally separate, with limited overlap in terms of their contribution to capacity increase. Recommendations are then made for designers to better determine the capacity of FRP strengthened restrained slabs.

This paper describes development of a contactless, low cost vision-based system for displacement measurement of civil structures. Displacement measurements provide a valuable insight into the structural condition and service behaviour of bridges under live loading. Conventional displacement gauges or GPS based systems have limitations in terms of access to the infrastructure and accuracy. The system introduced in this paper provides a low cost durable alternative which is rapidly deployable in the field and does not require direct contact or access to the infrastructure or its vicinity. A commercial action camera was modified to facilitate the use of a telescopic lens and paired with the development of robust displacement identification algorithms based on pattern matching. Performance was evaluated first in a series of controlled laboratory tests and validated against displacement measurements obtained using a fibre optic displacement gauge. The efficiency of the system for field applications was then demonstrated by capturing the validated bridge response of two structures under live loading including the iconic peace bridge. Located in the City of Derry, Northern Ireland, the Peace Bridge is a 310 m curved self-anchored suspension pedestrian bridge structure. The vision-based results of the field experiment were confirmed against displacements calculated from measured accelerations during a dynamic assessment of the structure under crowd loading. In field applications the developed system can achieve a root mean square error (RMSE) of 0.03 mm against verified measurements.

Increasing extreme climate events, intensifying traffic patterns and long-term underinvestment have led to the escalated deterioration of bridges within our road and rail transport networks. Structural Health Monitoring (SHM) systems provide a means of objectively capturing and quantifying deterioration under operational conditions. Computer vision technology has gained considerable attention in the field of SHM due to its ability to obtain displacement data using non-contact methods at long distances. Additionally, it provides a low cost, rapid instrumentation solution with low interference to the normal operation of structures. However, even in the case of a medium span bridge, the need for many cameras to capture the global response can be cost-prohibitive. This research proposes a roving camera technique to capture a complete derivation of the response of a laboratory model bridge under live loading, in order to identify bridge damage. Displacement is identified as a suitable damage indicator, and two methods are used to assess the magnitude of the change in global displacement under changing boundary conditions in the laboratory bridge model. From this study, it is established that either approach could detect damage in the simulation model, providing an SHM solution that negates the requirement for complex sensor installations.

Complex regional pain syndrome (CRPS) is a chronic pain condition often involving hyperalgesia and allodynia of the extremities. CRPS is divided into CRPS-I and CRPS-II. Type I occurs when there is no confirmed nerve injury. Type II is when there is known associated nerve injury. Female gender is a risk factor for developing CRPS. Other risk factors include fibromyalgia and rheumatoid arthritis. Unfortunately, the pathogenesis of CRPS is not yet clarified. Some studies have demonstrated different potential pathways. Neuropathic inflammation, specifically activation of peripheral nociceptors of C-fibers, has been shown to play a critical role in developing CRPS. The autonomic nervous system (ANS) is involved. Depending on whether it is acute or chronic CRPS, norepinephrine levels are either decreased or increased, respectively. Some studies have suggested the importance of genetics in developing CRPS. More consideration is being given to the role of psychological factors. Some association between a history of depression and/or post-traumatic stress disorder (PTSD) and the diagnosis of CRPS has been demonstrated. Treatment modalities available range from physical therapy, pharmacotherapy, and interventional techniques. Physical and occupational therapies include mirror therapy and graded motor imagery. Medical management with non-steroidal anti-inflammatory drugs (NSAIDs) has not shown significant improvement. There have been supporting findings in the use of short-course steroids, bisphosphonates, gabapentin, and ketamine. Antioxidant treatment has also shown some promise. Other pharmacotherapies include low-dose naltrexone and Botulinum toxin A (BTX-A). Sympathetic blocks are routinely used, even if their short- and long-term effects are not clear. Finally, spinal cord stimulation (SCS) has been used for decades. In conclusion, CRPS is a multifactorial condition that still requires further studying to better understand its pathogenesis, epidemiology, genetic involvement, psychological implications, and treatment options. Future studies are warranted to better understand this syndrome. This will provide an opportunity for better prevention, diagnosis, and treatment of CRPS.

Unmanned aerial vehicles (UAVs), known as drones, is an advanced remote sensing technology gaining much interest in the field of civil engineering in the last few years. According to the Association of Unmanned Vehicle Systems International, it is estimated that drones have the potential of reaching an economic benefit of US $82 billion by 2025. This paper investigates novel strategies for the visual inspection assessment and damage detection of bridge condition by maximizing the full potential of UAVs remote technology combined with advanced camera vision methods. The investigation starts by assessing the functionality of modern UAVs and matching the capabilities to the requirements of bridge monitoring. This is important as the driving force behind the technology development of drones has not come from bridge maintenance, but it is important that we exploit the new technologies and the same argument is also true for image processing. The paper explores how these assessment techniques can be transferred on to a UAV platform. The paper not only looks at the important technical issues such as camera stabilization both from flight control and image processing but also the use of UAVs as an inspection and measuring device. The investigation makes use of both laboratory experiments and field trials to assess the effectiveness of the proposed schemes.

Machine learning and statistical approaches have transformed the management of infrastructure systems such as water, energy and modern transport networks. Artificial Intelligence-based solutions allow asset owners to predict future performance and optimize maintenance routines through the use of historic performance and real-time sensor data. The industrial adoption of such methods has been limited in the management of bridges within aging transport networks. Predictive maintenance at bridge network level is particularly complex due to the considerable level of heterogeneity encompassed across various bridge types and functions. This paper reviews some of the main approaches in bridge predictive maintenance modeling and outlines the challenges in their adaptation to the future network-wide management of bridges. Survival analysis techniques have been successfully applied to predict outcomes from a homogenous data set, such as bridge deck condition. This paper considers the complexities of European road networks in terms of bridge type, function and age to present a novel application of survival analysis based on sparse data obtained from visual inspections. This research is focused on analyzing existing inspection information to establish data foundations, which will pave the way for big data utilization, and inform on key performance indicators for future network-wide structural health monitoring.

The strain sensitivity coefficient for a surface-mounted fibre optic sensor is strongly affected by the type of adhesive material used for its installation. In the present study, appropriate strain correction factors have been investigated to modify the strain sensitivity coefficient for surface mounted fibre Bragg gratings to achieve accurate strain data. The experimental study adopts a fibre optic sensor (FOS) mounted on a carbon fibre reinforced polyphenylene sulphide specimen using two adhesive types, i.e. a cyanoacrylate and an epoxy-resin. For comparison purposes strain data was also captured using strain gauge, contact extensometer and digital image correlation instrumentation. The experiments reveal that the predicted correction factors vary considerably with the adhesive material used for the mounting of the FOS. Further analysis demonstrates that a 37 % deviation in the value of the correction factor results in a 27 % variation in the strain output. In addition, the microscopic image analysis confirmed that the thickness of the adhesive layer between FOS and the substrate affects the strain sensitivity of FOS and plays a crucial role in transmitting the deformation of the host material to the sensing element.

International audience; in recent decades sustainability, carbon footprint and pollution have become significant issues on a global scale. it is widely recognised that the carbon footprint of the construction industry can be reduced which has led to sustainable materials being used more and more widely to meet emissions targets. two of these materials are hemp concrete and rapeseed-straw concrete which are bio-composites made of a bio-aggregate, water and a lime binder, in this investigation vicat prompt natural cement (pnc). the addition of a viscosity modifying agent (vma) is studied for its effect on the mechanical, thermal and transport properties. it was found that the use of a vma was very effective at countering the two biggest weaknesses of bio-based building materials as it reduced the capillarity absorption of the concrete significantly and also greatly increased the compressive strength and modulus of elasticity of the material.

Housing shortages in least developed countries (LDCs) continue to escalate beyond previous records and based on current projections this trend is set to increase. The resulting homelessness and poverty affect large populations in many LDCs. The main contributing factors are recognised as global population growth and natural disasters, which disproportionally affect LDCs when compared with developed countries. The challenge of how best to address these shortages in a sustainable manner while simultaneously building resilience against future disasters into the communities has been a central debate in many LDCs. Many different actors, such as governments, non-governmental organisations (NGOs) and communities undertake housing provision projects in these contexts. However, the outcomes are often of poor quality, which can be attributed to a lack of a coherent and holistic design and delivery process with the community served and lack of a sustainable design ethos.

In modern times issues such as sustainability and carbon footprint have become subjects of significant interest on a global scale. A leading industry in greenhouse emissions is the construction industry, and the industry’s carbon footprint needs to be reduced in order to meet emissions targets. Hemp concrete and rapeseed concrete are two alternative sustainable building materials that can help the construction sector improve and meet those targets. Because of their relatively recent introduction, limited studies are available on the durability of these materials. This paper investigates the effect of long-term accelerated carbonation on hemp and rapeseed concretes manufactured with a natural cement and, in some cases, a polyacrylic acid viscosity modifying agent (VMA). Natural carbonation in an outdoor environment was also studied. It was found that the mixes carbonated quickly under accelerated conditions, however no impact on mass or specimen dimensions were observed. In the case of the VMA mixes, it was found that the compressive strength of the samples was improved compared to the equivalently aged control samples. However, it was found that compressive strength was actually inhibited in the untreated mixes when compared with the control samples.

Glued-in rods offer an alternative method for creating structural timber connections however despite decades of research they have had limited implementation. The behaviour of glued-in rod connections in a framed structure was investigated. Nine partial frames were constructed of box sections connected with 12 mm diameter BFRP rods. A theoretical design approach was developed based on the optimum observed behaviour, where failure was located in the connection. For specimens with two embedded rods the theory predicted strength within 16% error of the experimental results. For specimens with two rods but gave an over-prediction of strength where three rods were used.

Currently, the majority of studies on vision-based measurement have been conducted under ideal environments so that an adequate measurement performance and accuracy is ensured. However, vision-based systems may face some adverse influencing factors such as illumination change and fog interference, which can affect measurement accuracy. This paper developed a robust vision-based displacement measurement method which can handle the two common and important adverse factors given above and achieve sensitivity at the subpixel level. The proposed method leverages the advantage of high-resolution imaging incorporating spatial and temporal contextual aspects. To validate the feasibility, stability, and robustness of the proposed method, a series of experiments was conducted on a two-span three-lane bridge in the laboratory. The illumination changes and fog interference were simulated experimentally in the laboratory. The results of the proposed method were compared to conventional displacement sensor data and current vision-based method results. It was demonstrated that the proposed method gave better measurement results than the current ones under illumination change and fog interference.

This paper develops a synchronized multi-camera contactless vision based multiple point displacement measurement system using wireless action cameras. Displacement measurements can provide a valuable insight into the structural condition and service behavior of bridges under live loading. Traditional means of obtaining displacement readings include displacement gauges or GPS based systems which can be limited in terms of accuracy and access. Computer Vision systems can provide a promising alternative means of displacement calculation, however existing systems in use are limited in scope by their inability to reliably track multiple points on a long span bridge structure. The system introduced in this paper provides a low-cost durable alternative which is rapidly deployable. Commercial action cameras were paired with an industrially validated solution for synchronization to provide multiple point displacement readings. The performance of the system was evaluated in a series of controlled laboratory tests. This included the development of displacement identification algorithms which were rigorously tested and validated against fiber optic displacement measurements. The results presented in this paper provide the knowledge for a step change in the application current vision based Structural health monitoring (SHM) systems which can be cost prohibitive and provides rapid method of obtaining data which accurately relates to measured bridge deflections.

This article presents the results of a preliminary study assessing the feasibility of using waste ceramic powder as a partial replacement of cement and/or sand in cement pastes and mortars. Two different ceramic powders, featuring different grain-size distributions, have been employed, one from crushed bathroom fixtures and dental prosthesis waste and a second one from foundry industry residuals. With reference to cement pastes and mortars formulated from SCC mixes employed in precast industry, cement replacement volume percentages equal to 10 and 30% have been considered for each powder. The possibility of hybrid cement and sand replacement with either powder has also been addressed. Effects of the replacement on the workability, shrinkage, compressive and flexural strengths have been considered, up to 3 months curing. The results confirmed the possibility of using this kind of waste in concrete, thus reducing the demand for raw cement and the burden on disposal landfills.

International audience; two vegetal aggregate types are studied for their performance regarding immersion and outdoor weathering. the most widely researched bio-aggregate to date is hemp shiv; which is used in this study as well as chopped rapeseed straw which is an alternative bio-aggregate widely available in the uk. in this study the binder used is vicat prompt natural cement as well as a viscosity modifying agent (vma) admixture. it was found that the hemp aggregate produced the most durable concrete when compared to rapeseed, and the addition of a vma resulted in a much more durable material for both aggregate types. organic and inorganic leaching was also investigated, and it was found that the binder and soluble organics were leaching from all of the concrete types.

Bridge Weigh in Motion (B-WIM) uses accurate sensing systems to transform an existing bridge into a mechanism to determine actual traffic loading. This information on traffic loading can enable efficient and economical management of transport networks and is becoming a valuable tool for bridge safety assessment. B-WIM can provide site specific traffic loading on deteriorating bridges, which can be used to determine if the reduced capacity is still sufficient to allow the structure to remain operational and minimise unnecessary replacement or rehabilitation costs and prevent disruption to traffic. There have been numerous reports on the accuracy classifications of existing B-WIM installations and some common issues have emerged. This paper details some of the recent developments in B-WIM which were aimed at overcoming these issues. A new system has been developed at Queens University Belfast using fibre optic sensors to provide accurate axle detection and improved accuracy overall. The results presented in this paper show that the fibre optic system provided much more accurate results than conventional WIM systems, as the FOS provide clearer signals at high scanning rates which require less filtering and less post processing. A major disadvantage of existing B-WIM systems is the inability to deal with more than one vehicle on the bridge at the same time; sensor strips have been proposed to overcome this issue. A bridge can be considered safe if the probability that load exceeds resistance is acceptably low, hence B-WIM information from advanced sensors can provide confidence in our ageing structures. Science Foundation Ireland DEL Invest Northern Ireland US National Science Foundation

Bridge weigh-in-motion (B-WIM) systems provide a non-destructive means of gathering traffic loading information by using an existing bridge as a weighing scale to determine the weights of vehicles passing over. In this research critical locations for sensors for the next-generation B-WIM were determined from a full 3D explicit finite element analysis (FEA) model. Although fiber optic sensors (FOS) have become increasingly popular in SHM systems there are currently no commercially available fiber optic WIM systems available. The FEA in this research facilitated the development of the first ever full fiber optic B-WIM and its potential has been demonstrated with the site installation of this system. The system combined nothing-on-the-road axle detection and alternative methods of measuring strain at the supports. The system was installed on a 20-m span beam and slab RC bridge in Northern Ireland and the results presented in this paper confirm the suitability of FOS in providing the clear defined peaks required for accurate axle detection in B-WIM.

In this paper, the level of dynamics, as described by the Assessment Dynamic Ratio (ADR), is measured directly through a field test on a bridge in the United Kingdom. The bridge was instrumented using fiber optic strain sensors and piezo-polymer weigh-in-motion sensors were installed in the pavement on the approach road. Field measurements of static and static-plus-dynamic strains were taken over 45 days. The results show that, while dynamic amplification is large for many loading events, these tend not to be the critical events. ADR, the allowance that should be made for dynamics in an assessment of safety, is small. Irish Research Council Science Foundation Ireland Transport Infrastructure Ireland (TII)

Bridge weigh-in-motion systems were introduced in the 1970s as a structural health monitoring tool for road bridges. They help bridge operators determine the cause of induced strain in bridges and collect statistics on vehicle weight, class and frequency. There have been over 3000 installations in 25 countries worldwide, which has led to vast improvements in data post-processing. However, existing systems are based on electrical resistance strain gauges, which can be prohibitive in achieving data for long-term monitoring of rural bridges due to power consumption. This paper introduces a new low-power system using fibre optic sensors, which has been pioneered in Northern Ireland. A series of fibre optic sensors were attached to the soffit of an existing integral bridge with a single span of 19 m. The site selection criteria and full installation process are described in this paper. A method of calibration was adopted using live traffic at the bridge site, based on which the accuracy of the system was determined. New methods of axle detection for bridge weigh-in-motion were investigated and verified in the field.

In this study, fibre optic sensors (FOS) were used to investigate the interfacial stress-strain behaviour of bonded-in basalt fibre reinforced polymer (BFRP) rods loaded into glulam members. Pull-out tests were conducted to examine the effect of bonded length and load-to-grain direction on the distribution of stress at the BFRP rod/adhesive zone. It was observed that the stress concentration at the loaded end of the BFRP rod of the samples was significantly the highest while the unloaded end showed the lowest. Increasing the bonded length at the same loading configuration resulted in a decrease in stress concentration at the loaded end. The stress concentration at the loaded end of the perpendicular to the grain samples was relatively higher than that of the corresponding parallel to the grain samples.

This paper is an overview of the development and application of Computer Vision for the Structural HealthMonitoring (SHM) of Bridges. A brief explanation of SHM is provided, followed by a breakdown of the stages of computervision techniques separated into laboratory and field trials. Qualitative evaluations and comparison of these methods have beenprovided along with the proposal of guidelines for new vision-based SHM systems.

Ageing and deterioration of infrastructure is a challenge facing transport authorities. Inparticular, there is a need for increased bridge monitoring in order to provide adequatemaintenance and to guarantee acceptable levels of transport safety. The IntelligentInfrastructure group at Queens University Belfast (QUB) are working on a number of aspectsof infrastructure monitoring and this paper presents summarised results from three distinctmonitoring projects carried out by this group. Firstly the findings from a project on nextgeneration Bridge Weight in Motion (B-WIM) are reported, this includes full scale field testingusing fibre optic strain sensors. Secondly, results from early phase testing of a computervision system for bridge deflection monitoring are reported on. This research seeks to exploitrecent advances in image processing technology with a view to developing contactlessbridge monitoring approaches. Considering the logistical difficulty of installing sensors on a‘live’ bridge, contactless monitoring has some inherent advantages over conventionalcontact based sensing systems. Finally the last section of the paper presents some recentfindings on drive by bridge monitoring. In practice a drive-by monitoring system will likelyrequire GPS to allow the response of a given bridge to be identified; this study looks at thefeasibility of using low-cost GPS sensors for this purpose, via field trials. The three topicsoutlined above cover a spectrum of SHM approaches namely, wired monitoring, contactlessmonitoring and drive by monitoring

The aim of this research was to study the impact that different mineral powders have on the properties of self-compacting concrete (SCC) in order to obtain relations that make it possible to optimize their dosages for being used in precast concrete applications. Different combinations and contents of cement, mineral additions (active and inert), superplasticizers, and aggregates are considered. A new approach for determining the saturation point of superplasticizers is introduced. The fresh state performance was assessed by means of the following tests: slump flow, V-funnel, and J-ring. Concrete compressive strength values at different ages up to 56 days have been retained as representative of the materials’ performance in its hardened state. All these properties have been correlated with SCC proportioning. As a result, a number of recommendations for the precast concrete industry arise to design more stable SCC mixes with a reduced carbon footprint.

This paper presents an experimental programme conducted to investigate the structural capacity of bonded-in steel bars loaded parallel to the grain in standard straight elements of natural timber. Tensile pull-out tests were conducted to examine the effect of bar diameter, bonded length and bar type (deformed and threaded steel bars) on the structural capacity of the connection. Pull-out tests on timber blocks in which the bars were deliberately misaligned in the holes were also tested to account for the fact that in real situations bars may not be perfectly centralised in the holes. The pull-out test results showed that bar diameter, bonded length and bar type considerably affected the structural capacities of the bonded-in steel joints. The results were compared with some established design equations.

Improvements in the structural performance of glulam timber beams by the inclusion of reinforcing materials can increase both the service performance and ultimate capacity. This paper describes a series of four-point bending tests conducted, under service loads and to failure, on unreinforced, reinforced and post-tensioned glulam timber beams, where the reinforcing tendon used is 12 mm dia. basalt fibre-reinforced polymer. The research is designed to evaluate the benefits offered by including an active reinforcement in contrast to the passive reinforcement typically used within timber strengthening works, in addition to establishing the effect that bonding the reinforcing tendon has on the material's performance. Further experimental tests have also been developed to investigate the long-term implications of this research, with emphasis placed upon creep and loss of post-tensioning; however, this is ongoing and is not presented in this paper. The laboratory investigations establish that the flexural strength and stiffness increase for both the unbonded and bonded post-tensioned timbers compared to the unreinforced and reinforced beams. Timber that is post-tensioned with an unbonded basalt fibre-reinforced polymer tendon shows a flexural strength increase of 2·8% and an increase in stiffness of 8·7%. Post-tensioned beams with a bonded basalt fibre-reinforced polymer tendon show increases in flexural strength and stiffness of 15·4% and 11·5% respectively.

The behaviour of Basalt Fibre Reinforced Polymer (BFRP) loaded perpendicular to glulam timber elements was investigated. It was found that pull-out load increased approximately linearly with the bonded length up to maximum which occurred at a bonded length of 250 mm (∼15 times the hole diameter) and did not increase beyond this bonded length. Failure mode of the samples was mostly shear fracture which was located at the cylindrical zone at the timber/adhesive interface. Increased bonded lengths resulted in corresponding decrease in interfacial bond stress. At 250 mm bonded length, the pull-out capacity of the proposed design model was about 2% lower than that of the tests. The results also showed that the bond stress of the theoretical model (at the ascending and descending branches) of the stress–slip curve was approximately 5–10% of that of the experiment.

This paper presents an efficient non-linear finite element (NLFEA) model using the commercial FE package ABAQUS to predict the ultimate load behaviour of deck slabs in concrete bridge deck slabs. In order to overcome the instability problems, stabilization methods were adopted and failure criteria were established to capture the ultimate loads. The proposed NLFEA predictions showed a good correlation with experimental tests.