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Fibre reinforced polymers (FRPs) are currently being used in new bridge construction as a feasible alternative material for corroded bridge deck replacements, footbridges, and emergency vehicle bridges. For both military and civilian applications, there exists a need for bridges that are lightweight and inexpensive, that can be readily transported and easily erected. The 10 m glass FRP deployable box beam presented in this thesis was developed to aid cross-country mobility in areas where infrastructure has been damaged by conflict or natural disasters. The box beam represents one trackway of a dual trackway system. The quasi-static and dynamic behaviour of the box beam was investigated under laboratory and field conditions. Quasi-static tests were conducted to ensure the strength of the steel hinge, the hinge connection to the base plate of the box beam, and the overall box beam would support the vehicle loads in field testing. Data from these tests were used to validate the finite element model. Field testing was conducted to investigate the natural frequencies of the box beam, calculate the dynamic increment of the structure, and confirm the validity of the finite element model created in Matlab. Three vehicles were used to evaluate the response of the box beam to different types of suspension, loads, and number of wheels per trackway. A finite element model was developed to predict the displacement of the bridge under various vehicle loads. The analysis resulted in displacement contours within a reasonable amount of error when compared to those measured in field testing. Recommendations for future research and development of the structure are provided based on this research. / Thesis (Master, Civil Engineering) -- Queen's University, 2008-09-26 22:49:59.077

This experimental program was designed to provide increasing evidence that second generation steel-free concrete bridge decks are a practical alternative to conventional steel reinforced concrete bridge decks. The bridge deck in this experiment was cast monolithically with one half consisting of a second generation steel-free concrete bridge deck and the second half a conventional steel reinforced concrete bridge deck. A constant cyclic load was applied to each segment at an identical magnitude to compare the two bridge decks in terms of endurance, durability, deflection, crack width, reinforcement strain, concrete strain, and overall performance. The test results obtained in this experimental program confirm the notion that second generation steel-free concrete bridge decks are a safe and reliable alternative to conventional steel reinforced concrete bridge decks, and furthermore should become more widely accepted and practiced in the field of bridge engineering. The mode of failure for both segments was punching shear failure.

Vibration induced by walking pedestrians has motivated research in the civil engineering community for many years. An area within this broad field that has received particular attention is the dynamic interaction that can occur between pedestrians and laterally flexible bridge structures. Perhaps the most notable example occurring on the opening day of London's Millennium Bridge. The enduring interest in this research problem is fuelled by two of its key features; (i) the sensitivity and adaptability of human balance to lateral motion and (ii) the spatial and temporal variation in flow characteristics exhibited by a pedestrian crowd. Both of these features are addressed herein. In this project an experimental campaign was executed with the aim of identifying the interaction mechanism by which pedestrians produce force harmonics, that resonate with the oscillating structure on which they walk. These so-called self-excited forces have been experimentally identified by others but the underlying reason for their existence has remained an open question. In an effort to address this, human balance behaviour while walking on a laterally oscillating treadmill was recorded using 3-dimensional motion capture equipment. Subsequent analysis revealed that human response to sinusoidal base motion is dominated by periodic alteration of foot placement position. This produces amplitude modulation of the lateral component of the ground reaction force and is ultimately responsible for the self-excited force harmonics. It was further revealed that human centre of mass motion while walking on an oscillating structure is predominantly passive. The passive inverted pendulum model is thus an excellent model of pedestrian frontal plane balance. The second facet of this work is concerned with developing a crowd-structure interaction model that builds upon the current state of the art. The model presented utilises the understanding of human-structure interaction identified above and employs an agent-based modelling approach. Thus, the resulting 'virtual crowd' is capable of simulating key crowd features, such as inter-subject variability and emergent velocity-density flow behaviour. Using this model, it is shown that the experimentally identified human-structure interaction mechanism can lead to large amplitude lateral deck oscillations, consistent with field observations reported in the literature. The model successfully predicts the multi-mode instability of Bristol's Clifton Suspension Bridge in the absence of step frequency tuning among the crowd. This provides supporting evidence for the model's validity. The work described above has resulted in a clearer understanding of the feedback between pedestrian balance behaviour and bridge response. Furthermore, the modelling techniques developed have potential for application in the wider study of crowd-induced vibration of dynamically susceptible structures.

This thesis focuses on the simulation of flow around bluff bodies and bridge deck sections, in which unsteady nature and vortex shedding of flow are commonly found, using computational fluid dynamics (CFD). Various turbulence models have been tested to develop understanding and proper modelling techniques for the flow around such bodies. Throughout the thesis, the turbulence models employed, mainly large eddy simulation (LES) and detached eddy simulation (DES), have been validated through comparative study with experimental work. The major part of the work discusses flow around bluff bodies ranging from a simple circular cylinder, a square cylinder to rectangular sections with various aspect ratios (1:2 to 1:8). The research section concentrates on modelling flow characteristics around bluff bodies to investigate the impact of fluid flow on them. This aids in the understanding of a more complex flow around bridge deck sections. The thesis combines investigation and discussion of the vortex shedding nature on the flow around bluff bodies, in which the simulations are done using advanced modelling techniques on high performance computing system. Work also includes a sectional wind tunnel test of the bridge deck section for the comparative study with the numerical solution. Finally, the conclusions outline the achievements and findings of the work done in this thesis and give recommendations for further research on the topic.

Bridges are an important part of the infrastructure of both road and rail networks. As bridge stocks age it is becoming increasing important to monitor their health and predict their lifespan. Current health assessment methods of visual inspection have many drawbacks and so non-destructive evaluation methods such as GPS are becoming more important. This study focuses on the use of single frequency GPS for bridge deformation monitoring. Previous studies have focussed on the use of more expensive dual frequency receivers. This thesis has resulted in the development of single frequency processing software that has enabled these receivers to be used in bridge deformation situations. Improvements in integer ambiguity resolution methods mean it is now possible to be resolve ambiguities instantly for small bridges and greatly reduces ambiguity time for long bridges. The development of this software is outlined along with results from bridge trials. The thesis further looks at extensions to the use of single frequency GPS by outlining experiments conducted with Garmin handheld receivers and also with JNS 100 receivers measuring at 50 Hz. The potential to use Garmin receivers in monitoring applications is demonstrated. The use of 50 Hz data enables the identification of higher frequency bridge dynamics than has ever been possible before. The final investigation looks at using pseudolites to augment the current GPS constellation specifically for bridge monitoring applications. The introduction of pseudolites led to improvements in all three coordinate directions, with the most improvement being seen in the vertical direction.

The need for conducting real-time bridge deformation monitoring is addressed in the context of the development of bridge management system (BMS) and land transportation safety in this thesis. Current instruments used for bridge dynamic deformation monitoring are compared in terms of system productivity and reliability. An integrated sensor system of Global Positioning System (GPS) receiver and triaxial accelerometer is then proposed with the capabilities to accurately monitor long-term deformation and short-term dynamics of a bridge. Since the investigation of the bridge dynamic responses is of great importance in research and practice, the emphasis of this thesis is on the monitoring of dynamic bridge deformation. Zero baseline (ZBL) and short baseline (SBL) tests are conducted to evaluate the performance of three types of Leica GPS receivers at 10 Hz sampling rate. Statistic characteristics of positioning solutions and the achievable accuracy of each receiver type are analysed, which are employed to design optimal filters for various GPS error suppressions. By using a moving average (MA) technique, millimetre baseline accuracy can be achieved even with a single frequency receiver. It demonstrates the possibilities to conduct millimetre bridge deformation monitoring if appropriate filtering techniques are applied to the positioning solutions and integer ambiguity has been fixed. A simple but accurate triaxial accelerometer calibration technique is proposed in the thesis with a solid mathematical derivative to evaluate the precisions of estimated parameter offsets. A specially designed cage is used to house a GPS antenna with a triaxial accelerometer to avoid complex sensor alignment and simplify the coordinate transformations between different reference frames. The determination of instantaneous attitude of an accelerometer body frame is realised by three GPS stations on the deck of a bridge at a rate of 10 Hz and the sensed 3D accelerations are then transformed into a bridge coordinate system (BCS) simultaneously. BCS is the computation frame of a hybrid bridge deformation monitoring system (BDMS). Important issues in sensor integration such as local gravity determination, synchronisation of time series from different sensors are addressed. Bridge trials are briefed with the emphasis on the instrument configuration for effective error mitigation and sensor integration. A group of reference stations consisting of two reference stations closely setup near a bridge and the permanent continuous GPS stations are recommended for reducing relative tropospheric delay, multipath, and receiver noise both at reference stations and monitoring sites. GPS satellite sky distribution and its impact on propagating ranging errors in mid latitude areas such as in the UK and high latitude areas are analysed both with analytical and simulation approaches. The error propagation formulae are derived to analyse the defects of current satellite constellation on the GPS positioning solutions in each direction of a BCS. This is further exploited to improve the component accuracy of particular interest through changing the dilution of precision (DOP) values. The degree of positioning improvement is illustrated with GPS/GLONASS positioning. A simulator according to ranging error propagation is used to simulate the achievable accuracy from the best and the worst GPS constellations. Modified precise satellite ephemeris by inserting the positions of pseudolites is employed to investigate the changes of DOP values in each direction of a BCS. The summaries of this simulation have universe significance in guiding the selection of the best locations of pseudolites. Adaptive Finite Impulse Response (FIR) filtering or adaptive filtering (AF) for short and important application issues are addressed in the thesis. Autocorrelation lags of ZBL and SBL tests of each type of receiver are used to determine the filter lengths according to the fundamentals of low pass and high pass filter designs. A real-time AF algorithm is introduced and widely employed as an analytical tool in the error mitigation and real bridge deformation signal extraction. The application defects of MA technique in bridge deformation monitoring are compared with AF approach according to the component analysis of GPS positioning solutions. A recursive AF algorithm is proposed to gradually isolate actual bridge deflection signals from multipath and receiver noise both at reference stations and monitoring sites. Spectral analysis is applied to the input and output signals to investigate the efficiency of the designed filter. In order to effectively isolate actual bridge deformation, misalignment and its consequence are demonstrated with day-to-day shifted time series of bridge deflection. Cross-correlation is also used to analyse the feasibility and efficiency of the proposed AF algorithm. Acceleration aided AF approach is detailed in the thesis. A simple algorithm, based on the principles of digital signal filtering and optimal filter design, is proposed to estimate relative displacements of bridge sensed by a triaxial accelerometer in three dimensions. With the relative displacements, GPS receiver noise has been filtered out and the cleaned displacements are obtained. AS another data fusion approach, a software package based on discrete Fourier transform (DFT) to integrate GPS and accelerometer data with a position output rate up to that of a triaxial accelerometer is introduced. Relative tropospheric delay is another major error source identified in GPS-based bridge deformation monitoring. Methods applied to distinguish the impacts of multipath and tropospheric delay are presented. The cause for relative tropospheric delay is analysed and microclimate effect is recognised as the major impact factor in this particular environment. Numerical calculations also confirm the assumption. The way to effectively remove relative tropospheric delay is recommended. The research emphasis in this thesis is to develop a prototype of a hybrid BDMS to achieve centimetre level positioning accuracy at each epoch in three dimension of a BCS. The findings from this research are summarised and the future work is predicted.

No description available.

Historic bridges are an important part of the nation's infrastructure. However, many historic bridges are not being maintained to a level that will ensure their continued use. In 2007, the I-35 W Mississippi River Bridge collapsed demonstrating significant issues with the safety of older bridges in service. Currently there are so many bridges that are considered structurally deficient that transportation authorities are continuously faced with the dilemma of distributing limited bridge funds. This situation underscores a need for cost effective and reliable maintenance and rehabilitation strategies. This thesis promotes historic preservation in two main tasks: (1) rehabilitation and repair methods are determined to guide engineers, preservationists, and other stakeholders and (2) an assessment is performed for a prototype historic bridge. More specifically, the assessment is performed in three tasks: (1) modeling of the historic bridge, (2) evaluation of the bridge using load rating procedures, and (3) rehabilitation strategies are recommended based on the results of the assessment. The prototype bridge is a 1930s variable depth T-beam bridge. The bridge did not meet requirements for flexural capacity at the mid-sections of the approach and main span interior girders. Three rehabilitation methods considered were support modification at the cantilever ends, external fiber reinforced polymer (FRP) plies, and external post-tensioning. The support modification raised the bridge to a 75-year exposure period, the highest level of evaluation, without disrupting the historical integrity of the bridge. The FRP plies raised the positive moment capacity of the bridge to legal load standards, a 5-year exposure period. The FRP retrofit was limited by de-bonding issues. The external post-tensioning raised the positive capacity to design load standards at the inventory level, a 75-year exposure period. The external post-tensioning was limited by the use of a straight tendon, but is less visible than a draped tendon. From the information in the assessment, support modification is more effective than the other methods and will not negatively affect the bridge’s historic integrity. Other factors such as the projected effects on other bridge elements including the substructure, cost, installation procedures, and durability should be considered and might lower the benefits of the considered methods.

The purpose of this study was to determine the effectiveness of early diagnosis and a summer program to strengthen precalculus skills before students enrolled in Engineering Calculus I. A meta-synthesis of interventions to increase success in college calculus was conducted, with a meta-analysis of studies that contained sufficient quantitative data to calculate Hedge's g effect sizes. Content validity for a mathematics placement exam was confirmed by an expert panel, and internal consistency of scores from 2008-2011 was verified using Cronbach's alpha. Effectiveness of a summer program to strengthen precalculus skills was measured by Hedge's g effect size. Results of content analysis of surveys given to tutors and students in the summer program were presented. ANOVA was used to compare mean GPA's of participants and nonparticipants of the summer program. The meta-synthesis revealed that numerous strategies, some in precalculus and some in calculus, were successful for increasing success in college calculus. For the studies in the meta-analysis, the highest effect sizes were found in studies that used a more comprehensive approach (e.g., collaborative groups and projects) rather than a single strategy (e.g., computer skills practice). An expert panel determined that the exam was a good measure of requisite knowledge for calculus. One question was considered unnecessary for calculus and was not of a type addressed in precalculus and was eliminated from further analysis. Cronbach's alpha was consistently above .8 for each year's scores 2008-2011 and for each subset of scores by gender, ethnicity, and selected majors for 2008-2011. The 122 students who participated in the summer program increased the average score by 6.45 points (total of 33), with 81% of the students raising their scores above the cut score to take Engineering Calculus I. Results of ANOVA to compare mean GPA's for students in the summer program and students who did not participate, both with placement exam scores in the range 16 to 21, inclusive, showed no significant difference. The summer program was successful in allowing some students the opportunity to strengthen their precalculus skills and take Engineering Calculus I a semester earlier than the control group.