Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1932. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed July 15, 2010) Includes index (p. 29-31).

In January 1999, the maximum axle weight increased from IN to 11.5t for the assessmenot f highway bridges and structures. At the samet ime, the maximum vehicle weight also increased from 38t to 44t. Highway authorities are urgently searching for a more refined assessmenmt ethod to predict the behaviour of masonry arch bridges. LUSAS finite element analysis was used to study the behaviour of masonry arch bridges. Load versus deflection curves and collapse loads are given for some of the full and large scale arches previously tested to collapse. A parametric study was also performed to determine the influence of the arch material properties and the load dispersal angle: the arch tensile strength and the load dispersal angle were found to have the most significant influence on the collapse load predictions. Repeatability tests were carried out by building three nominally identical large scale arch bridges in the laboratory and testing them to collapse. The first, second and third arches collapsed at 2lkNm', 16kNm', and 25kNm 1 respectively. Finite element analysis predicted a range of 18kNm' to 39kNm 1 for the same arches. This led to an examination of a statistical, risk based, approach to bridge assessment. Two novel risk assessment programs were developed by integrating Monte Carlo simulation with the MEXE and the mechanism methods. Statistical information about the predicted collapse load and allowable axle load is given. These risk assessment tools are offered for incorporation within routine assessmenmt ethods. Their principal benefit lies in providing engineers with a feel for the reliability of their analyses. A modification has been made to the mechanism method by considering arch deflection. A mechanism prediction is accurate only when all the forces and their positions are accurately located. The modified mechanism method was used to analyse some of the full scale arch bridges, previously tested to collapse, which revealed that arch deflections had a significant influence on the collapse load prediction.

The dynamic response of highway bridges is a topic that has been thoroughly researched over many years. However, understanding of how the dynamic response of bridges is affected by the performance of their bearings over an extended period of time is, at present, not clearly defined. Although health monitoring of bridge structures is relatively advanced, the scope for further research is wide. The study presented in this thesis contains research on plate structures; ranging from a simple Euler-Bernoulli method to determine natural frequencies; modal analysis of a plate structure in the laboratory; FEA of the plate structure; modal analysis on a full-scale structure subjected to vehicle loading; and FEA of a simplified model representing the full-scale structure. A combination of these methods has allowed the conclusions presented herein to be drawn with respect to the effects of support degradation, and the consequent effect on structural performance. In the laboratory, modal analysis of a small-scale, thin rectangular plate of Perspex' has been completed. A series of boundary conditions have been investigated through altering the support offered to the plate by a series of springs, each with a different stiffness, to simulate bearings with different stiffnesses. Vibrations of varying frequency have also been forced upon the plate, and its response recorded. Displacement values provided the clearest indication of the effect of bearing stiffness, with the least stiff spring resulting in the largest displacement. Alteration of support stiffness in the model can have a marked effect on the resonant frequency of the plate (approx. 23 % frequency change between spring 1 (1.22 Nmm 1) and 5 (15.62 Nmm 1)). Full-scale testing on a highway bridge at Berwick-upon-Tweed on the Al, over the River Tweed, was completed in May 2005. These data form the baseline for future dynamic testing and condition monitoring of the structure. To describe the dynamic properties of the structure, the force generated by each type of vehicle traversing the structure was determined using instrumentation already in place on the bridge. Statistics drawn from the data are presented, which indicate that the bearings are functioning as expected, but are subjected to forces of a much larger magnitude due to overloaded HGVs than in current design specifications. Larger HGVs made up a small percentage of overall vehicles recorded, but contribute a much higher proportion of damage caused to the bridge. Displacement and frequency were both valid measures of bearing performance and therefore state of degradation. The method is offered as a condition monitoring test for bridges and their bearings.

Expansion joints and bearings of conventional bridges are easily damaged and this commonly incurs high maintenance costs. The concept of the integral bridge was to reduce the maintenance costs by removing those joints. However, the thermally induced expansion-contraction of the bridge superstructure is transferred through the integral bridge’s abutments due to lack of expansion joints. Seasonal thermal cyclic displacement of the integral abutment cyclically loads the bridge backfill material. It has been observed that the lateral earth pressure behind an integral abutment increases as a result of the cyclic loading. Previous studies attribute this increase in lateral pressure to the densification of the backfill material. Granular flow was suggested to have occurred displacing the particles to form a denser and therefore stiffer matrix. An alternative suggestion was that the particles reoriented to form a stiffer matrix that wasn’t necessarily denser. The objective of this research is to explore the behaviour of integral abutment backfill at a micromechanical level by utilising the discrete element method (DEM) and possibly verify these suggested causes of earth pressure build-up behind an integral abutment. DEM models of four granular materials consisting of different particle shapes were tested with 100 cycles of strain. The results indicate that densification occurred for all samples, but the build-up of horizontal pressure did not occur for the more rounded samples. It was further suggested that the particle shape in combination with the change in coordination number closely replicate the behaviour of the sample’s horizontal stress. Particle reorientation and displacements were observed to be small for samples of non-circular particles. Particle activity is concentrated in the smallest particles within the material. It is concluded that the build-up of horizontal stress is caused by the increase in particle contacts due to particle reorientation and not densification.

In current bridge engineering an idealized model is used to apply the parapet load to the bearing pads of a bridge. In this idealized model it is assumed that the parapet load is evenly distributed across all of the bridge bearing pads. However, this assumption is incorrect. The purpose of this study is to demonstrate that the parapet load distribution is more complicated than an evenly distributed load. Instead, this study shows that a majority of the parapet load is applied to the exterior bearing pad. This means that the real world exterior bearing pad reactions will be much larger than the reactions found using the idealized, evenly distributed model. This study utilizes the finite element program, NISA, to model and analyze a simple span bridge. The bridge used in this study was developed using a prestressed concrete girder design example from the Texas Department of Transportation. The design example specified the span length, clear roadway width, prestressed girder type, and girder spacing of the bridge. The bridge is modeled under two different loading conditions to ensure a comprehensive array of results is obtained. The two loading conditions were carefully designed to compare the idealized model, utilized by the Federal Highway Administration, to the real world parapet load distribution. The focus of this study is to determine how the parapet load distribution will affect the bearing pad reactions in a simple span bridge. The results of this study are provided in several tables depicting the bearing pad reactions obtained from the finite element models. The results of each parapet load distribution are compared to one another and percent differences are calculated between each condition. This allows for the use of a single number to define the effect the parapet load distribution has on the bearing pad reactions. A secondary focus of this study is to determine how a bearing pad's deformation, and thus its stiffness, will affect the bearing pad reactions of a simple span bridge. The results of this study are provided in several tables depicting the bearing pad reactions obtained from the finite element models. The results of each bearing pad stiffness condition are compared to one another and percent differences are calculated between each configuration. This allows for the use of a single number to define the effect of bearing pad stiffness on the parapet load distribution. This portion was completed first and the best model was chosen to be used in the main part of the study.

Bearing pads undergo deformation while under service loads of any bridge. The pad translates the load to the support structure, and allows for movement of the superstructure. The deformation of bearing pads is an important element to consider when designing both the super and sub structures of the bridge. The Federal Highway Administration provides a guide for the design of steel brigdes, and Step 6 of this guide covers the design of bearing pads. The purpose of this study is to analyze the deformation of bearing pads using a finite element analysis software. This study will analyze two separate models, one ignoring the steel plates in a bearing pad and ignoring friction, while the other will take into account the steel plates as well as friction during the analysis. Once the linear analysis is run the models that are built can be compared with the FHWA design examples to compare and verify the results. This will facilitate the possible improvement of current design examples and allow for a more realistic result for designers to use. This study also looks at the internal testing results provided by a bearing pad manufacturing company. These internal results will provide a real world model for the linear analysis models to be compared to as well. Once all factors are taken into account, the validity of the current standards can be evaluated.

As a the limit-cycle oscillation, vortex-induced vibration (VIV) does not cause catastrophic failure but it can lead to fatigue in long and slender structures and structural elements, especially for long span bridges. Assessing this behaviour during the design stage is therefore very important to ensure the safety and serviceability of a structure. Currently, this task requires very time-consuming wind tunnel or computational simulation since a reliable mathematical model is not available. Moreover, knowledge of the underlying physical mechanism of the VIV and, particularly, of the turbulence-induced effect on the VIV is insufficient. Turbulence is normally considered to produce suppressing effects on the VIV; however, this influence appears to depend on cross sections and a comprehensive explanation is yet to be found. This issue can be resulted from some limitation that most wind tunnel or computational studies have used sectional models. The flow field is therefore dominated by 2D flow features. In this research study, the 5:1 rectangular cylinder is selected as the case study since it is considered as the generic bride deck geometry. Using the wind tunnel at the University of Nottingham, a series of wind tunnel tests using a static and elastically supported sectional model is conducted in smooth flow. This wind tunnel study is complemented by a computational study of a static and dynamic sectional model; the computational simulations are carried out using the Computational Fluid Dynamics software OpenFOAM and the High Performance Computer system at the University of Nottingham. A Fluid-structure-interaction (FSI) solver is built to model the heaving VIV. By comparing the surface pressure measurement between these two studies, it uncovers the two separate flow mechanisms and associated flow features, which are both responsible for the VIV. The series of wind tunnel static and dynamic tests is also repeated in different turbulent flow regimes. By analysing the forces, moment, surface pressure and structural response, it reveals the mechanism of the turbulence-induced effect on the aerodynamic characteristics as well as on VIV. By improving the proposed FSI solver, a novel computational approach is introduced to simulate the VIV of a flexible 5:1 rectangular cylinder excited at the first bending mode shape. Employing the Proper Orthogonal Decomposition (POD) technique and comparing against results of the sectional model, some emerging span-wise flow features are revealed together with their influences on the mechanism of the bending VIV. The Hartlen and Currie mathematical model for the VIV is generalised so that it is able to simulate the VIV response of a 3D flexible structure. Such modifications and improvements are originated from and assessed by results of the computational simulation of the flexible model. A case study of the Great Belt East bridge is then carried out to verify this modified model.

A detailed investigation was made to study the shear transfer between precast prestressed beams and in-situ concrete in a relatively new method of construction of continuous bridge decks where the ends of precast beams are connected to an integral in-situ crosshead away from the supports. Two series of tests were carried out. In the first series 1/3 scale models of the M. o. T, C&CA M-8 sections were used, and these were modified in the second series to study the effect of the beam's top flanges within the connection. One of the most important mechanisms of shear transfer proved to be the top flanges of the precast beam. For the precast beams with top flanges (first series), and with a 300mm beam embedment length, it was discovered that: a) The shear force is transferred from a small length at the end of the beam. b) The in-situ concrete nibs (concrete surrounding the web) can take this shear force without stirrups. c) There is no need either to project all the bars from the precast into the in-situ concrete or to prestress the connection transversely as a means of improving shear transfer. d) It was possible to transfer the whole shear force at the connection with a reduced embedment length of 100mm with nib stirrups. For the precast beam without top flanges, the transfer of the shear force at the connection required other improving details. In this respect transverse prestressing and web shear connectors were utilized effectively. The effect of projecting bars was also examined. In the general behaviour of composite continuous beams subjected to shear a detailed comparison was made between different Code predictions for the web cracking shear and web crushing strength. A mathematical model is also proposed to predict the stirrup stress according to shear span, effective depth and stirrup ratio when failure is controlled by web crushing. Stirrup stress measurement in the vicinity of continuous support made it possible to predict the enhanced shear strength and a design method is proposed for the continuous beams. A comparion is also made between different Code predictions in this respect. To obtain more information about the strength of web shear connectors used in the secod series, a separate dowel shear specimen was designed. Different interface conditions including bond, dowel bar size and strength and the effect of shrinkage were examined. A design method is proposed together with a comparison with different Code predictions.

Development of continuity between precast prestressed bridge girders by post-tensioning the insitu top slab In the regions of hogging moment is a relatively new technique which forms the basis for this research study. Compared to the more conventional method of using reinforcing steel in the slab over the interior supports, prestressed slabs will ensure a crack free more durable bridge deck, and will therefore reduce the maintenance costs. The effect that such a slab has on flexural and shear behaviour of the bridge deck has been studied both analytically and experimentally by considering composite beams based on M-8 standard precast beam section. Comparison of the design of bridge decks with a prestressed slab and a reinforced concrete slab indicated that a partially prestressed slab with a prestress considering up to 50% of the live load will ensure the slab remains crack free under total service load. Although secondary effects and the two stage construction of such a slab tend to increase the prestress requirement for the slab, the same two effects considerably reduce the positive midspan moments, resulting in a decrease in the prestress required in the precast beams (and thus a possible increase in the span range) for given standard precast beam sections. The experimental investigation consisted of testing eleven 1/3-scale M-8 continuous composite beams in two series, Series-A and Series-B. Series A, in which three beams were tested as double cantilevers was planned to study the effects of prestressed slab on overall flexural behaviour. A considerable improvement in crack control under service loads and a higher ratio of measured to calculated ultimate moment capacity was obtained in beams with a prestressed slab. The continuity developed using insitu prestressed slabs was very effective at all levels of loading. Recommendations have been made for the flexural design of continuous bridge decks with this type of prestressed slabs. In Series B, effect of prestressed slabs on shear strength at the continuity connection has been studied. A considerable increase in web shear cracking load was obtained for beams with prestressed slabs, resulting in a decrease In the amount of shear reinforcement required for such beams. The different methods of predicting web shear cracking strength and web crushing strength according to current design codes were compared with experimental values, and based on the results, recommendations for the design for vertical shear of composite beams subjected to hogging moments have been made.

The Bridge River Region is a mining district situated in southern British Columbia on the eastern side of the Coast Range. The boundary of the region is defined by the drainage basin of Bridge River above Moha. The region is isolated. The geology is complex, and highly metamorphosed sedimentary, volcanic and intrusive rocks are present. The rocks range in age from Permian to Recent. Mineralization is thought to be linked with the location of the region on the eastern margin of the Coast Range batholithic intrusions. The topography is mountainous and strongly glaciated. The hanging valley of Bridge River is the deepest erosional feature of the district. Generally, the valley is at an elevation of 2000 feet, and the flanking Bendor and Shulaps ranges rise to 8000 and 9000 feet. The rugged nature of the country makes transportation especially difficult. Towards the Chilcotin Plateau, the mountains are more subdued in character. During the snow-free season, sheep and cattle are pastured in the alpine grazing ranges of this transition belt of mountains. The country is also the habitat of big-game animals which are a resource of the tourist industry. The Bridge River Region has many climates because of great relief. As a whole, the climate is continental, although continentality is modified by proximity to the Pacific Ocean. The annual average temperature in the main area of settlement is forty degrees and the annual average precipitation is twenty-four inches. Four months have average temperatures below freezing. The country is forested but timber is generally of little commercial value. Ponderosa pine, Douglas fir and Lodgepole pine are the basis of a small-scale forest industry. The industry is largely subsidiary to mining. Trapping is a part-time occupation based on the fur-bearers of the region. The many creeks of the district head from snow-fields and glaciers. Hurley River and Cadwallader Creek have been developed for hydro-electric power. Bridge River, which has its source in extensive ice-fields, ultimately will produce 620,000 horse power. Most of this power will be supplied to Vancouver and the Lower Mainland. Rapid run-off makes storage dams necessary. The resultant flooding obviates most agricultural development. Historically, mining has been the dominant industry of the Bridge River Region. Beginning in 1858, miners came into the district seeking placer gold. Their sporadic and desultory activity gave place to the more permanent lode gold mining around 1898. In modern times, Bralorne and Pioneer Gold Mines have developed as successful producers. Efficient transportation has come to the region by the building of the Bridge River highway which provides a link with the Pacific Great Eastern Railway. Bralorne and Pioneer are small-scale, fully mechanized mines. Most of the ore is produced by shrinkage and cut and fill stoping. Bralorne ranks first as a gold producer in British Columbia and Pioneer holds fourth place. The known reserves at both mines will last eight years at present rates of production. Much exploration work is going on in the district to bring other mines into production. The population of about two thousand persons in the Bridge River Region is almost entirely dependant upon mining. Three quarters of the people live in the company towns of Bralorne and Pioneer. The destiny of future settlement rests largely with the mining industry. / Arts, Faculty of / Geography, Department of / Graduate