<p>Very little research has been done on the nonlinear response of asymmetric structures although real buildings may undergo plastic deformations in response to strong ground excitation. Also, it is a common design philosophy to permit inelastic behaviour since lower design forces may be, used.</p> <p>In this analysis, the nonlinear response of a torsionally coupled single-story model consisting of a rigid diaghram resting on three equally spaced frames is investigated. The main concern herein is the peak ductility demand especially at edges.</p> <p>A limited parametric study is undertaken to identify trends in peak ductility demand. The effects of torsional coupling in nonlinear systems are also investigated. Real earthquake records as well as an idealized sinusoidal excitation are used as ground motion. Two types of load-deformation relation are used: (1) the simple bilinear type which can adequately simulate the dynamic response of steel structural elements, (ii) the Clough's degrading stiffness model to simulate the hysteretic behaviour of reinforced concrete structural elements. A comparison between both types is made to assess the significance of the type of load-deformation relation.</p> / Master of Engineering (ME)

<p>A research program is presented to analyze the behaviour of rectangular hollow section (RHS) T-joints in the elasto-plastic range of loading. An attempt was made to obtain the joint ultimate and working strengths. The study includes the determination of both rotational and punching shear stiffnesses of the RHS T-joint due to applied moment and branch member axial loads respectively.</p> <p>Two different joint types were analyzed, the unreinforced T-joint and the haunch reinforcement type. In both cases, the chord top flange was considered as a thin plate loaded on the perimeter of the rigid inclusion, and supported by coupled springs along its longitudinal edges, thus simulating the action of the side walls and connecting bottom flanges. Transverse from the joint, were taken as simple supported.</p> <p>The finite element formulation that is proposed incorporates rectangular plate and boundary elements with springs. The model is then used to study elastic connections. The joint stiffness values are shown to be in good agreement with the experimental results available in the literature.</p> <p>Finally, a study of the RHS T-joint behaviour under both axial load and applied moment, in the elastic-plastic range of loading, is presented. The sensitivity of joints to different geometric parameters of width ratio, λ, haunch size, λ₁, and chord thickness, t, for the entire range of loading is included. A prediction of the ultimate and working loads and moments that can be resisted by RHS T-joints, is given.</p> / Master of Engineering (ME)

<p>A standard solubility test can be used to assess the potential hazard associated with a wide variety of industrial wastes. This test will provide regulatory agencies with a more efficient tool with which to protect receiving waters and hence to establish environmental safeguards. Further, data generated by solubility testing will enable engineers to optimize disposal' site selection, criteria and design.</p> <p>A comparison of nineteen leaching tests was performed to determine the features to be incorporated into an ideal solubility test. Most of the procedures reviewed were geared to the specific waste and method of disposal and few provided guidance on how to apply the test data to the field situation. From the comparison, the shake type procedure was found to be superior to column leaching. The attributes of an ideal solubility test incorporating shaking were identified.</p> <p>Legislation, guidelines and objectives respecting disposal must be considered before an assessment is made of the inherent hazard in a waste. A review of these documents revealed that some requirements relate to effluents while other relate to receiving water quality. A comparison is made of the various criteria that require compliance for water quality in the U.S.A. and Canada (Ontario).</p> <p>Developmental laboratory research into solubility testing was performed in the Construction Materials Laboratory at McMaster University. Background data and information are presented and the procedure adopted finally, the McMaster Modified Solubility Test (MMST), is outlined. The major features of this procedure include:</p> <p>- The use of acidic and neutral leaching solutions</p> <p>- Gentle but effective agitation technique</p> <p>-Use of desorption isotherms to specify optimum leaching solution to waste proportions</p> <p>-Use of batch kinetics to specify optimum shaking time</p> <p>-A means of interpreting the data.</p> <p>The MMST is performed with wastes whose physical and chemical nature warrants a detailed investigation into their solubility limits. These wastes include settling basin sludge from a chemical process, municipal incinerator residue, and raw and solidified industrial sludge. Some conclusions regarding leaching patterns are presented.</p> / Master of Engineering (ME)

<p>The object of the work investigated in this thesis is to develop an approximate method for static and dynamic analysis of uniform framed-tube structures. The thesis begins with a review of the developments of high-rise constructions and the methods of analysis of high-rise buildings. Then study is carried out to investigate some special structural problems, such as the shear lag effect in the normal frames, which form the flanges of a "perforated tube" structure and the "column shortening effect" of the rectangular frames. Energy approach is used in formulating the problem and approximations are introduced to represent these effects in deriving simple methods of analysis for investigation. The results of the investigation are co-ordinated to develop an approximate method of analysis for tall uniform framed-tube structures subjected to lateral loading. The method is simple enough for computations to be done on a desk calculator or small computer. The theory for static analysis is then extended to determine the dynamic characteristics of such structural system, which are required for seismic analysis based on the response spectrum technique. Experimental work, which includes both static and dynamic testing of a 6 fest plexiglass framed-tube model, is performed for verifying the theory.</p> <p>An addendum is included to discuss the social and economic aspects of high-rise construction for drawing the attention of those high-rise designers to the reactions of the high-rise users and those concerned.</p> / Doctor of Philosophy (PhD)

<p>A review of the literature related to assessing treatment efficiency and head loss build-up using particle count and size distribution indicates some deficiencies and limitations. These deficiencies and limitations indicate several shortcomings in the available head loss models. It was noted that previous research work, which used particle size analyzers, have experienced difficulty and uncertainty in obtaining the true particle count. A procedure to correct the particle count, supported by quantitative and qualitative validation, is provided. Result obtained from past investigations on floc geometry, and its mode of deposition, have also displayed a pronounced disparity. Furthermore, no photographic evidence has been published that shows the particle dendrites in liquid. Most observations of deposition patterns relate to conditions that exhibit a substantially different behaviour from conventional filter media characteristics. The objective of this work was to develop a mathematical model which describes the head loss in deep bed granular filter based on different modes of deposition. The deposition models include parameters that account for the dynamic fraction of particles that contribute to additional surface area and the change in geometry. The dynamic fraction of particles that contribute to smooth coating and dendrite deposition in filter containing deposit are also included in the model. The deposition morphology was validated visually using an optical fibre endoscope and quantitatively using the filtration test. Three mathematical models have been developed for describing the effect of different deposit morphologies on the head loss build-up in sand filters. The models predict the head loss for a specific deposition mode and a combination of (different) modes. The first model is based on the assumption that retained particles form a relatively smooth coating around the filter grains (smooth coating model). The second model is based on the assumption that retained particles can act as additional collectors, forming chain-like depositions (dendrites mode model) as proposed by O'Melia and Ali (1978). A refinement to the O'Melia model is also proposed. In particular, the variation in porosity and the factor which represents the fraction of retained particles that contribute to the additional surface area were considered in the model refinement. The effect of change on the geometry of the filter grains were considered as well. In the third model, adsorption and bridging were proposed as combined mechanisms of polyelectrolyte action during filtration of small silica (5 um) suspension. Therefore, this model is based on the assumption that the deposition takes place in two stages: smooth coating and dendrite deposition (combined mode model). It is also hypothesized that more than one mode of deposition may govern the deposition process during the filter time. Results from the experimental program and analytical modelling were used to validate the proposed deposition morphologies and to map-out the important factors responsible for different geometries and their contribution to head loss build-up. Reasonable agreement was observed between the measured and predicted head loss. The proposed models are general in nature and may be extended to conditions other than those used for validation, provided that the deposit morphology is the same. The accuracy of the proposed combination of different deposit morphologies was confirmed using experimental data. An analysis and possible explanation for the similarity and dissimilarity of the optimum coagulant dosage between the results from a jar test and filtration test are presented.</p> / Doctor of Philosophy (PhD)

<p>The design of a nuclear power station to resist the effects of a strong motion earthquake represents one of the most significant considerations confronting, the electric power generating industry today. The prevailing view in the nuclear industry is that structures are designed to remain essentially elastic and functionally-important equipment to remain fully functional during and/or after an earthquake.</p> <p>In seismic analysis of reactor buildings it is usual to consider planar models along each of the two principal axes, and to independently analyse the response of each model to the in-plane horizontal component of ground motion. Analysis on this basis is strictly valid only for structures with coincident centers of mass and rigidity. The lateral and torsional motions of the structure are coupled if the centers of mass and rigidity do not coincide.</p> <p>It is the purpose of this thesis to consider the torsional effect in the seismic analysis of Nuclear Power Plant Reactor Systems and to illustrate the effect of the lateral-torsional coupling on the equipment response. The equipment response is represented by floor response spectra. It is usually impractical to include such equipment in the dynamic model representing the building structure because of the large difference between the mass of the equipment and that of the building. Therefore, the equipment and the building are treated separately and the building response are used as inputs for the equipment analysis.</p> <p>A torsionally coupled reactor model is developed considering the effect of eccentricities between the center of mass and the center of rigidity for each floor level of the corresponding uncoupled model, and a detailed coupled analysis is investigated. To consider the effect of torsion, lateral floor spectra are developed for more than one location on each floor level. Uncoupled and coupled lateral floor spectra are presented for excitation due to several different earthquakes with the objective of evaluating the effect of torsional coupling and its influence on the equipment response.</p> <p>The second object of this study is to develop a simple procedure to compute floor response spectra of the torsionally coupled reactor building without a time-history analysis. And finally, the effect of torsional ground motion is investigated, in which, a rotational time-history ground motion is generated in addition to the recorded lateral component and these two time-history excitations are used as input motions applied at the base of the torsionally reactor building. The floor response spectra are determined and analysed with the objective of evaluating the influence of the estimated torsional ground motion on the response parameters.</p> / Doctor of Philosophy (PhD)

<p>This thesis deals with numerical modelling of mechanical behaviour of reinforced concrete structures. The main objective of this study is to establish a rational constitutive model for concrete subjected to monotonic or cyclic loadings and to analyze nonlinear behaviour of reinforced concrete structures by finite element method.</p> <p>The constitutive model described here is built within the framework of rate-independent theory of plasticity. In the present study, the emphasis is placed on an adequate modelling of basic trends in the behaviour of concrete, e.g. compaction-dilatancy transition, sensitivity of material characteristics to confirming pressure, gradual transition in failure mechanisms from a brittle to a ductile mode and phenomenon of cyclic degradation of material stiffness and strength, etc. The proposed model is suitable for describing strain hardening and softening response of concrete under any complex state of stress. In order to describe rigorously the strain softening response, an appropriate criterion for strain localization is derived from considerations of stability of the constitutive relations. The model is verified for a number of loading paths by comparing the numerical results with the experimental data available in the literature.</p> <p>The finite element modelling of reinforced concrete slabs is also presented. In this finite element model, the post-cracking behaviour of concrete and tension stiffening effect are modelling using the proposed constitutive theory. Moreover, some common problems relared to numerical instability are carefully studied. The nummerical results are compared with the experimental data and the results obtained from other analytical models.</p> / Doctor of Philosophy (PhD)

<p>A micro/macro-structural analysis is undertaken to determine the effects of welding thermal cycles on austenitic stainless steel. The analysis is subdivided into three parts; heat flow analysis, micro-structural analysis, and thermal elastic visco-plastic analysis.</p> <p>A three-dimensional, finite element program based on heat conduction equation is developed and also incorporates a model for heat input due to welding to approximate the welding thermal cycles. The program is capable of handling the nonlinear material properties according to the temperature field. A two-point recurrence scheme is employed to obtain the temperature field for every time step. A weighted residual iterative method is employed to minimize drifting.</p> <p>A micro-structural model based on the Avrami Equation and the grain growth law is developed to predict the grain growth due to welding. The heat affected zone is assumed to be composed mainly of the grain growth zone for the austenitic steel and ignores the recrystallization process.</p> <p>A coupled thermo-elastic viso-plastic formulation including the micro-structural changes is developed to predict the overall deformation and residual stresses caused by a welding thermal cycle. The macro-structural behaviour is modelled by using the nine-node isoparametric shell element. A twenty seven integration point scheme per element is used to transfer the temperature and the thermal strain field from the heat flow analysis and the austenite grain size from the micro-structural analysis to the thermal elastic visco-plastic analysis. An incremental load method is used along with the Newton-Raphson iterative method to solve for the incremental displacement and hence obtain the macro-structural response.</p> <p>After the development of all segments of the finite element programs, the accuracy and the stability of the solutions are tested. Various studies are conducted to check the modelling of the heat flow for both low carbon steel and austentic stainless steel, and the results are compared with the experimental data available in the literature. The micro-structural model is also checked with experimental data available in the literature. Moreover, a micro/macro-structural analysis is performed on heat on edge weld and head on edge weld for austenitic stainless steel and the results are compared with the experimental and analytical results available in the literature.</p> / Doctor of Philosophy (PhD)

<p>Most of the design of concrete gravity dams is based on a two dimensional analysis which is suitable for monoliths with smooth, unkeyed, contraction joints. However, when keyed contraction joints are used, it is expected that the dam monoliths will interact in a manner that may affect the overall response of the system. The objective of this study is to investigate the seismic behaviour of concrete gravity dams, built with keyed contraction joints, including the effect of monoliths interaction. The scope of research work included: 1) development of a simplified procedure to investigate the effect of monoliths interaction on the seismic behaviour of the structure, 2) after this was proved to be important, a detailed and comprehensive procedure was developed and 3) investigation of the parameters which affect the response of the structure and significantly influence monoliths interaction.</p> <p>In the simplified procedure, each monolith of the dam is modeled using beam elements which has the advantages of keeping the number of degrees of freedom to a minimum and being available in most of structural engineering computer codes. The approximate added mass technique is used to simulate the hydrodynamic effects when the dam and reservoir are subjected to an earthquake ground motion. The importance of including monoliths interaction is illustrated by analyzing different cross-sections of concrete gravity dams.</p> <p>In the proposed detailed analysis of gravity dams, a substructuring technique is employed to model the structure. The dam is divided into a number of substructures equal to the number of monoliths. Each monolith is then reduced to a few degrees of freedom on the upstream face and Ritz vectors are used to represent internal degrees of freedom. The analysis is carried out in the frequency domain to include the frequency-dependent terms which appear when including reservoir-darn-foundation interactions. The results obtained are compared to typical three-dimensional analysis and a good agreement is obtained. It is noted that the importance of monoliths interaction is dependent on two factors; 1) the type of contraction joints used in construction and 2) the longitudinal profile of the dam.</p> <p>The effect of monoliths interaction is to increase the natural frequencies of the structure and as a result leads to a change in its overall response. It is concluded that in many cases the effect of monoliths interaction is important and should be included in the analysis. The geometry and material properties of contraction joints have a significant effect on the overall response of the dam. Depending on the crack width, the shear behaviour of the joints varies widely. The longitudinal profile of the dam was also found to have a substantial effect on monoliths interaction. Important variations in the response of the dam, from that calculated using typical two-dimensional analysis, is obtained for some cases. This is usually the case for short dams with rigid monoliths at the sides or for dams built in steep canyons.</p> / Doctor of Philosophy (PhD)

<p>Although moment resisting frames (MRFs) are the most widely used structural system for seismic-resistant steel buildings, several important aspects of their behaviour under real earthquake excitation are not well understood. One of these issues that needs to be further studied is the seismic performance of beam-to-column joints. During severe earthquakes, joints can undergo severe inelastic deformations affecting the strength, stiffness and inelastic action distribution throughout the frames. Therefore, the objectives of this study are to investigate the behaviour of beam-to-column joints, to assess the effect of the joints' response on the frame's overall behaviour and to provide guidelines and design rules for detailing the joints. In this thesis, attention was focused on studying the behaviour of bolted extended end-plate joints. This was achieved through an experimental-analytical research program. The experimental work carried out involved two phases. First, cyclic tests on full scale beam-to-column connections was done to examine the behaviour of such a connection type, together with the response of its individual components. Second, cyclic tests on full scale subassemblages were done to study the response of panel zones of this joint type. Based on the observation and results of the experimental program, analytical models to predict the behaviour of both the connection and the panel zone were developed. The sensitivity of these models was checked by comparing their predictions with the experimental results. The models were then incorporated into Drain-2D computer program to be used in analyzing MRFs. Analytical research on the dynamic behaviour of MRFs designed to allow active yielding of panel zone joints and to permit connection deformation was performed. Several steel MRF designs for an eight-storey and twenty-storey office buildings were analyzed using various ground acceleration records. Finally, design criteria for detailing the joints, i.e. the connection and the panel zone, and code recommendations to improve the performance of MRFs subjected to severe earthquakes were introduced.</p> / Doctor of Philosophy (PhD)