Stay-In-Place (SIP) formwork systems are widely used for concrete slabs in industry due to their relative ease and speed of construction. Conventionally, corrugated metal sheets or precast panels are used as formwork. In recent years, the SIP formwork technique has been proposed in conjunction with Fiber Reinforced Polymer (FRP) composites. The resulting system combines the construction advantages of SIP formwork with the durability and corrosion resistance of FRP materials. Bridge decks are a particularly enticing application due to their exposure to harsh environmental conditions and the need for rapid construction to minimize traffic disruptions. This study broadly evaluates FRP SIP formwork for concrete bridge decks both experimentally and numerically. In total, 9 full scale bridge deck sections, 32 small scale decks and more than 40 auxiliary tests were conducted, including the construction and testing of a full bridge at scale. Additionally, a numerical model was developed to predict punching shear failure based on the theory of plates and shells. Experimental testing was conducted on two FRP SIP form configurations, namely flat plates with T-shape stiffeners and corrugated plates, and used a variety of different detailing and geometries. Some of the investigated parameters included the width effect of bridge deck section tests, the effect of deck span, the effect of bond at the FRP-concrete interface, the panel-to-panel splice configuration, concrete strength, and boundary condition at support, including a monolithic connection with precise girders. Results of the study include the determination of a critical aspect ratio for bridge deck sections, optimization of the panel-to-panel splice detail, and an assessment of the in-plane restraint available to interior span bridge decks. The numerical model, based on the Levy solution for loaded plates, produces a flexural response for a variety of bridge deck configurations and geometries. A failure criterion was applied to establish the punching shear capacity. The model was evaluated against experimental results and provided good correlation. It was then used to investigate a variety of FRP plate thicknesses, spans and effective widths for full scale FRP SIP formwork bridge decks. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2013-10-11 15:55:26.546

The buffeting response is a type of vibration caused by wind turbulence. As the bridge span and structural complexity increase, this kind of response is notable. Therefore more accurate analysis simulation methods are needed to investigate this aerodynamic phenomenon. The aim of this thesis is to review, discuss and compare the different bridge buffeting simulation approaches in the frequency domain and find the possibility of Computational Fluid Dynamic (CFD) method application in bridge buffeting prediction. In this thesis, the conventional bridge buffeting statistical analysis methods considering the influence of different parameters such as mode coupling, self-excited forces and aerodynamic admittance on the simulation results are firstly reviewed and compared. Since wind turbulence may not excite all structural vibration modes in some frequency ranges, an alternative approach based on the Proper Orthogonal Decomposition (POD) is proposed to study the effective turbulence contribution to the structural vibration. However due to the complexity of turbulence, quasi-steady theory is widely adopted and some semi-empirical functions such as aerodynamic admittance, joint acceptance are introduced to simplify the simulation. With the development of CFD method, CFD simulation of bridge aerodynamic phenomena has become possible. Since the bridge buffeting response is induced by wind turbulence, it is very important to capture the time varying characteristics of wind turbulence. In CFD technique, to close the Navier-Stokes equations and reflect unsteady characteristics, turbulence modelling is always adopted. At present Direct Numerical Simulation (DNS) is an accurate model to capture the time variation unsteady characteristic of the wind turbulence. However, the problems of civil engineering are always high Reynolds numbers, which make the simulation of aerodynamic phenomena of civil engineering impractical based on DNS method. Therefore an alternative model, known as Large Eddy Simulation (LES), becomes popular. In this thesis an unsteady inlet boundary generation technique based on an Autoregressive Moving Average (ARMA) model is proposed to simulate the unsteady inflow turbulence. 3D LES will be selected to validate the applicability of this model in the prediction of the unsteady characteristic of buffeting simulation by investigating the flow characteristic around a square cylinder under different mesh density and different LES model such as standard LES model, dynamic LES model and WALE model at Reynolds number 13,000. Before comparing the influence of inflow boundary condition with turbulence intensity (5%) on the flow around a square cylinder, an empty domain is selected to validate current inflow turbulence generation technique. Major steps of Fluid Structure Interaction (FSI), suitable for future simulation of bridge structural buffeting response, are proposed to predict the structural buffeting response induced by the inflow turbulence. To test the propose procedure of FSI, a square cylinder will be used, the across-flow oscillation of square cylinder with constant damping ratio will be considered to investigate the influence of steady inlet boundary condition and unsteady one on the response of structure. In addition different LES models are considered to compare their influence on the response of square cylinder.

This thesis reports the findings of an investigation into the feasibility of using vibration characteristics to monitor the structural health of bridges. The study is the second part of a larger project commissioned by the UK Highways Agency into the investigation of possible monitoring methods that can be used in a pass/fail/monitor inspection programme. To this end, ten one-quarter-scale 5m span reinforced concrete bridge decks were fabricated and loaded incrementally to failure in the laboratory. The dynamic properties of the decks were investigated at each of the loading increments to evaluate their sensitivity to structural cracking using both free and forced vibration. The results indicated that, for the specimens tested, natural frequencies were, in general, more sensitive to the damage introduced than mode shapes. It was found that the support conditions affected the dynamic behaviour of the decks, and indeterminate boundary conditions caused significant variation in the vibration characteristics. This presented several problems in the analysis of the modal properties and, when combined with the damage introduced through static loading, caused some modes to disappear and new modes to be measured, whilst a number of modes also displayed an increase in natural frequency. The application of finite element model updating to determine reduction in flexural stiffness in the damaged areas of the deck provided a systematic method to investigate the condition of the deck. Updating was performed based on the natural frequencies of one symmetrically and one asymmetrically loaded deck, and the cracking observed under the loading, and offered results consistent with expectations. In summary, the evidence presented in this thesis suggests that the natural frequencies of the decks are, in general, more sensitive to the damage introduced than the mode shapes and consistent trends can be observed in the natural frequency change as the damage to the deck increases. However, the application of this method to indicate the structural condition of real bridges may be limited without further investigation as the vibration characteristics were affected by a number of factors arising from the realistic nature of the specimen, such as the three-dimensional distribution of the damage and the indeterminate nature of the support conditions.

The UK Department of Transport (DoT) has recently encouraged the use of externally post-tensioned structures for bridge construction. This is due to the durability problems encountered with the conventional internally bonded post-tensioned structures. However, due to the lack of bond between the concrete and the external tendons, the ultimate strength of these structures cannot be determined by just performing a sectional analysis at the section of maximum moment. Although several recommendations have been made for the ultimate analysis of these structures, none were considered satisfactory here. Hence the purpose of this investigation is to study the flexural behaviour of these structures of all stages up to collapse, and to propose a practical methodology for estimating their ultimate strength. The study introduces eight non-linear analytical models developed for the prediction of the moment vs. deflection response of simply supported externally post-tensioned beams (with and without deviators located along their spans) up to ultimate. The models employ an iterative procedure that involves the application of loads to the structure in increments up to the collapse condition, where the curvature distribution predicted at each loading sequence is used to estimate the stress increase and variation in eccentricity in the external tendons. Second-order effects due to variation in eccentricity of external tendons and frictional behaviour of tendons at the deviators are both taken into account in these models. The eight models were then verified by comparing the results derived from them with reported experimental data, whereby good correlation was obtained. An extensive parametric study was subsequently conducted using the proposed models applied to the various parameters that influence the ultimate behaviour of externally prestressed structures Finally, the recommendations in the codes of practice for the ultimate design of these structures were also investigated here.

It has been two decades since Ultra High Performance Fibre Reinforced Concrete (UHPFRC) has come to the market and, so far, it has been used in only a limited number of highway bridge structures. This is due to many unanswered questions related to its structural behaviour for highway bridge structures and its high initial cost. The lack of knowledge regarding the structural behaviour is down to unavailability of appropriate test methods for this special type of concrete which behaves differently compared to normal concrete. Furthermore, the current precast production contributes to its high initial cost significantly. Therefore, this study has investigated various aspects that are restricting the potential use of UHPFRC for highway bridge applications. The investigation included extensive experimental studies and numerical modelling. In the experimental programme, various parameters ranging from material and mechanical properties, potential use of the concrete for cast in-situ applications to ductility behaviour were investigated. Furthermore, the numerical analyses were carried out to identify appropriate finite element models to predict the flexural and shear behaviour of the concrete. In the experimental work, simple and reliable test methods for material characterisation were developed. The validity of two non-destructive testing methods in studying the elastic properties of the concrete was confirmed. From this, the UHPFRC constitutive material model was obtained and used in numerical modelling. The reliability of the test methods were established by performing numerous experimental tests and similar results obtained at all times. Furthermore, the suitability of the concrete for cast in-situ applications at various temperatures by monitoring the strength development from an early age (12 hours) up to 360 days were investigated. The results showed significant strength gain of the concrete in both compression and tension within 7 days when cured at temperatures similar to site conditions (20 and 30 oC). A phenomenon related to the 90 oC curing temperature in precast production was reported and showed to have caused loss of flexural strength and toughness of the concrete. In addition, for the first time, an effective test method for studying the punching shear strength of the concrete with minimal influence of flexural stress was developed and used successfully. The results showed a reduced effective punching shear perimeter of UHPFRC slabs by half compared to normal concrete. The numerical analyses were carried out using the Abaqus finite element software. In this study, the Concrete Damaged Plasticity (CDP) and Concrete Smeared Cracking (CSC) material models with minor modifications were used to simulate the flexural and shear behaviour of UHPFRC beam and slab specimens, respectively. The results obtained here were validated against experimental studies with good agreement. The CDP model was found to replicate the linear and nonlinear structural response of the concrete with better accuracies than the CSC model. This study presents significant findings on the suitability of UHPFRC for structural applications with a lower initial cost compared to its current precast production. Furthermore, results obtained on its excellent structural behaviour in flexure and shear provides structural designers great confidence in using this concrete for highway bridge applications. The findings reported in this study contribute to the literature of UHPFRC significantly.

A number of artificially generated earthquake time-histories (AGETH) fitting to a Eurocode 8 (EC8) response spectrum are randomly generated using SIMQKE software and the average generated spectrum compares well with the EC8 one. Two Finite element (FE) smeared crack models, named Multi-crack and Craft, are well validated against experimental data of concrete and Reinforced concrete (RC) structures under monotonic and cyclic loadings. They are then used in the analysis of RC bridge piers under the AGETH. Several techniques including Fourier analysis, normalised cumulative spectrum, energy dissipation, damage index as well as probability applications are applied to quantify the structural response and damage. Based on the convergence of the representative responses under different numbers of AGETH, a minimum representative number of AGETH from 6 to 11 may be sufficient depending on the confidence band width from the mean of all damage responses. Effects of several parameters of the earthquake and structure to the dynamic response and damage of the bridge pier are investigated. Throughout these parametric studies, several of the common circumstances that structural engineers face are addressed and the proposed number of artificial earthquake time-histories required for non-linear dynamic analysis is thereby validated.

L’objectif principal de la thèse a été d’identifié expérimentalement les comportements mécaniques et rhéologiques de milieux granulaires dans un environnement à complexité croissante. En particulier, je me suis intéressé aux phénomènes de fluage sous contrainte en essayant de mieux comprendre l’impact des vibrations et la présence d’une faible quantité d’eau piégée entre les pores. J’ai monté un système cissométrique permettant de réaliser des tests mécaniques de fluage. Une originalité de mon montage a été de mettre au point un système de lit fluidisé qui, en alliant flux d’air et vibration, m’a permis de fabriquer des empilements à compacité initiale contrôlée. J’ai étudié les propriétés fondamentales de fluage sous contrainte d’un empilement granulaire de billes de verre de taille d = 200μm sous le seuil de Coulomb. Cette étude a mis en évidence que les seuils de Coulomb varient fortement avec la compacité, mais en plus, on a mis en évidence une contrainte appelée " contrainte de première rupture " qui traduit des réorganisation internes dans l’empilement et qui est d’environ 1/3 de la contrainte seuil maximale. En outre, grâce à la précision de la mesure de déformation, on a obtenu les réponses élastiques à de petits cycles en contrainte et on a établi que le module cisaillement élastique G augmente linéairement en fonction de la compacité, en accord avec le modèle d’élasticité non-linéaire de Hertz (modèle de champ moyen). Nous avons réalisé aussi une étude paramétrique complète du fluage en variant systématiquement la compacité et la contrainte de cisaillement. Notre étude sur les seuils de contrainte, l’élasticité effective et la dynamique de fluage, a été prolongée pour des empilements sous vibration générés par des transducteurs piézo-électriques enfouis sous la surface. Ce montage permet en outre par injection dans le granulaire d’un gaz saturé en vapeur d’eau, d’imposer sous un faible gradient thermique une condensation et d’obtenir une quantité contrôlée d’eau piégée dans l’empilement. Cette méthode permettra par la suite d’aborder le cas de granulaires cohésifs. / The main objective of the thesis was to identify experimentally the mechanical and rheological behavior of granular media in an environment varying in complexity. In particular, I was interested to creep phenomenon under stress in trying to understand better the impact of vibration and the presence of a small amount of water trapped between the grains. I set up a system to perform mechanical creep tests. Originality of my setup was the fluidized bed which uses air flow and vibration, and thus allows the control of the initial packing fraction. I studied the basic properties of creep strain of a granular resulting from a packing of glass beads of size d = 200 μm under the Coulomb threshold. This study showed that the Coulomb thresholds vary strongly with the packing fraction. In addition, it showed a stress called "the first rupture", that results from internal reorganizations in the granular medium and which is approximately 1/3 of the maximum stress threshold. Moreover, thanks to the precision of measuring deformation, we obtained the elastic response with small stress cycles, and we found that the shear elastic modulus G increases linearly with the packing fraction, in agreement with the model of nonlinear elasticity of Hertz (mean field). We performed a parametric study of creep in varying the packing fraction and shear stress. In all cases, we found the dynamics of logarithmic strain for long times. Our study on stress threshold, the elastic modulus and dynamics of creep, has been extended to granular medium under vibration generated by piezoelectric transducers buried under the surface. A small amount of water can be added and thus modifies the mechanical properties by the presence of capillary bridges. Preliminary experiments show the dependence of the Coulomb threshold of the elastic response and dynamic creep with an amount of water content.

Accurate inspection data is important for efficient bridge management. Visual inspections play a key role in providing this information, but the reliability of such data has limitations. A range of techniques addressing these limitations are used in other sectors, but not to assist routine visual bridge inspection. Work has been undertaken investigating the feasibility of performing routine visual bridge inspections based on systematically collected images alone. The requirements of such a system are considered and defined. The research demonstrates that more detail can be seen in images at 1-pixel-per-mm than can be seen from 3m, and that images at this resolution can be systematically collected, processed, displayed, and inspected to complete General Inspections with results comparable to traditional routine visual inspections. No existing systems were found to be suitable for routinely providing visual inspection data; consequently a prototype was developed demonstrating the feasibility of the image-based inspection approach. The development considered hardware, image collection methodology, processing, alignment, display and interpretation. Inspectors tested and used the system to perform image-based General Inspections on several bridges. It is concluded that an image­based approach can be used to perform routine visual bridge inspections, with no loss of detail compared to traditional inspections.

Aging railroad bridge infrastructure is subject to increasingly higher demands such as heavier loads, increased speed, and increased frequency of traffic. The challenges facing railroad bridge infrastructure provide an opportunity to develop improved systems of monitoring railroad bridges. This dissertation outlines the development and implementation of a Structural Impairment Detection System (SIDS) that incorporates finite element modeling and instrumentation of a testbed structure, neural algorithm development, and the integration of data acquisition and impairment detection tools. Ultimately, data streams from the Salmon Bay Bridge are autonomously recorded and interrogated by competitive arrays of artificial neural networks for patterns indicative of specific structural impairments. Heel trunnion bascule bridges experience significant stress ranges in critical truss members. Finite element modeling of the Salmon Bay Bridge testbed provided an estimate of nominal structural behavior and indicated types and locations of possible impairments. Analytical modeling was initially performed in SAP2000 and then refined with ABAQUS. Modeling results from the Salmon Bay Bridge were used to determine measureable quantities sensitive to modeled impairments. An instrumentation scheme was designed and installed on the testbed to record these diagnostically significant data streams. Analytical results revealed that main chord members and bracing members of the counterweight truss are sensitive to modeled structural impairments. Finite element models and experimental observations indicated maximum stress ranges of approximately 22 ksi on main chord members of the counterweight truss. A competitive neural algorithm was developed to examine analytical and experimental data streams. Analytical data streams served as training vectors for training arrays of competitive neural networks. A quasi static array of neural networks was developed to provide an indication of the operating condition at specific intervals of the bridge's operation. Competitive neural algorithms correctly classified 94% of simulated data streams. Finally, a stand-alone application was integrated with the Salmon Bay Bridge data acquisition system to autonomously analyze recorded data streams and produce bridge condition reports. Based on neural algorithms trained on modeled impairments, the Salmon Bay Bridge operates in a manner most resembling one of two operating conditions: 1) unimpaired, or 2) impaired embedded member at the southeast corner of the counterweight.

The objective of this thesis is to explore the possibility of a non-destructive method of improving the dependability and economy of timber railroad bridges that have been exposed to environmental and service conditions. With railway companies increasing the load of trains in return for larger profit, maintenance and replacement of timber bridges has risen throughout recent years. Once chosen for its low cost and ease of construction, timber bridges are being replaced by more efficient concrete and steel trestles. The load path of a passing train through the elements of a bridge pier can be affected for several reasons. One focus of this report is how the load is distributed among the piles or supporting elements. Through recent research at Texas A&M University (2003), a relationship between the ultimate test load, Pmax, and the strength parameter, Lambda, was derived from 33 destructively tested specimens. Piles used in the testing were accumulated from three different locations in the United States and subjected to uniaxial compression along the length of the pile in a steel test frame. Instrumentation along the length of the piles provided data for plots of load versus deflection. Analysis of the plots showed that the tendency of the strength parameter, Lambda, to predict the ultimate test load was consistent but a computer generated model representing a typical service train revealed significantly lower loads on the piles than those used in the destructive tests. Further analysis of the test specimens at lower load levels led to a service level strength parameter that was derived with levels comparable to typical train loads. Guidelines for the service strength parameter, Beta, were based upon hypothetical loads from the computer generated model and previous test data. Field testing involved consent from a railroad company to install load cells and string potentiometers on an in-situ timber bridge. While simultaneously taking load and deflection measurements for bridges under the dynamic load of a passing train, the axial stiffness of the piles was determined and used in the calculation of the service level strength parameter,Beta. Future research includes removing the piles that were tested in the field and assessing them in the original method of axial compression in the steel test frame. This method can be used universally in the field to examine load path of passing trains and assess the amount of remaining axial strength of in-situ piles without interrupting daily flow and traffic of the railroad bridge. Ultimately, this research could lead to the railroad industry saving money and time due to the quick and convenient installation process.