<p>The free vibrations of skirt supported pressure vessels are studied in this thesis; both cantilevered and fixed-pinned systems are considered. A hierarchy of models, ranging from a rigid mass (vessel) supported by massless Euler-Bernoulli beam (skirt) to a model in which both components are represented by Timoshenko beams, is subjected to analysis. Several typical numerical examples are considered for both sets of boundary conditions. The results of these calculations indicate that whereas the cantilevered system may be modeled with fair accuracy, compared to the most sophisticated model considered, by a rigid mass supported by a massless beam capable of undergoing shear deformation, it is necessary to model all components of the fixed-pinned system by Timsoshenko beams, i.e. the most sophisticated model considered. The first two mode shapes for all models of a typical case of each configuration are shown. Finally, some comments on the modeling and analysis of specific realistic systems are made.</p> / Master of Engineering (ME)

<p>The design of column cross sections for known axial loads and moments has reached the stage where practical methods give results which agree very closely with tests and with accurate analyses. However considerable uncertainty exists with regard to methods employed to take into account the effects of the additional moments caused by deflection of columns. Theoretical calculations can be used to accurately predict the loads at which material failure or column instability will occur. However designers require simpler techniques which are sufficiently general in nature to be equally applicable to the large variety of design cases.</p> <p>The effect of column slenderness which is further complicated by consideration of creep under sustained load is the main topic of this study. It is suggested that a realistfc appraisal of design methods must be based on the idea of consistent safety factors. Thus slender columns subjected to sustained load must retain sufficient reserve capacity so that failure loads when compared to design loads provide equal safety factors. The National Building Code of Canada is being revised to include tho relevant provisions of tho ACI Standard 318-71(²). Tho columns analysed in this study were designed in accordance with ACI Standard 318-71. Comprehensive evaluation of the design parameters in the ACI method is given in this thesis along with conclusions and comments. It was observed that the ACI method does not yield consistent safety factors for the different values of the design parameters. The analyses and conclusions of this study are given in details in chapters (6) and (7).</p> / Master of Engineering (ME)

<p>W-shaped steel members are widely used in various structural applications, such as buildings, bridges, and industrial complexes. The recent trend is to produce W -shaped sections using higher and higher strength steel as a replacement for mild-carbon steel, such as 300W steel. However, the width-to-thickness ratios (b/t or w/t) specified in the current CSA steel design standard (1995) for local buckling strength and ductility are based on studies using 300W steel. An investigation was carried out to study the local buckling behavior, with an emphasis placed on flange buckling of compression members, of W-shaped sections made of high strength steel. First, stress-strain characteristics of high strength steel of 350W, 480W and 700Q steel, along with the mild-carbon 300W steel, were determined using standard tensile tests. Based on these experimental material properties, analysis material models were derived for the finite element analysis. Analysis material models used in the finite element modeling were the multi-linear, modified tri-linear, and modified bi-linear models. The next part of the investigation included tests on stub columns of these selected steel grades having flanges at Class I limit based on the current design standard (CSA 1995). Based on the experimental results from these stub column lests, the applicability of b/t Class 1 limits for high strength steel sections were assessed. The experimental results showed that the reserve capacity (f_u/fy) of all the stub columns were close to the sanle, regardless of the steel grade. However, the ductility of the W-shaped sections corresponding to each grade differed substantially. The 300W and 350W steel displayed much more ductility than the 480W and 700Q steel. It was concluded that the bIt limits of a Class I section, which was based on studies on the 300W steel, is also applicable to the 350W steel, but are not transferrable to the higher strength steels. The third part of this study used the analysis material models determined from the tensile tests into a finite element modeling, where a 9-node "assumed strain" shell element was employed. Due to the symmetric behavior of a stub column, a quarter of a stub column was used to simulate the W -shaped section subjected to uniform compression. Meanwhile, an idealized residual stress with parabolic distribution across the web and flange of the W-shaped section was assumed and incorporated in the finite element modeling. Comparing the finite element analysis results with the corresponding experimental results from the stub column tests, an appropriate material model was selected to be used for further finite element analysis. It was found that the results obtained from the tri-linear and multi-linear models were similar to each other, and the modified bi-linear material model best represented the experimental results. Using this bi-linear material model in the finite element analysis, strength and ductility of W-shaped sections with varying flange b/t ratios but constant w/t ratio were determined from the finite element analysis. Results showed that the 350W steel demonstrated characteristics similar to the 300W steel. However, the 700Q steel possessed very little ductility and reserve capacity. The 480W steel was excluded in this part of the study due to the uncertain results from its tensile test. In all of these steel grades, it was found that ductility and reserve capacity decreased as the bIt ratio increased. From both the experimental investigation and the finite element analysis, the b/t limits in the current design standards were found to be applicable to both 300W and 350W steel, but not to the 700Q steel.</p> / Master of Engineering (ME)

<p>No Abstract available</p> / Master of Applied Science (MASc)

<p> This study is intended to focus on the optimization of offset derrick structures and to present a novel connection details for derrick structures. The overall goal of this study is to improve performance, ease fabrication, and reduce material and labor costs associated with derrick structures, and study the performances of Double Channel Endplate and Single Channel Endplate Connections using Finite Element Method (FEM) analysis. </p><p> Optimization of derrick structure is carried out by modeling different bracing systems with different parameters of design, for example, vertical panel height, bracing type, buckling restraint, and member orientation to come to optimum result in terms of structural weight, lateral stiffness, and number of joints. Eccentric bracing system, 2X-bracing system, X-bracing system, and K-bracing system are studied and comparisons are made among structures with similar vertical panel height to come to efficient geometry of that category. A Double Channel and Single Channel Endplate connection are developed and modeled to see the stress distribution, moments, and rotation capacities. Finally, behavioral plots (moment-rotation) are modeled to rate the performance of connections. </p><p> Structures with relatively shorter force path, uniform internal force distribution, and small internal forces are found to respond well and they are stiff, economical, and elegant as well. For 2X-bracing system, efficiency of offset derrick structure to resist the load is found to decrease for both small and large vertical panel height and optimum height was found in between. For this study, the optimum height was 20 ft. for 2X-bracing system. Thickness, and overlapping length of channel plate is found important for in-plane capacity of connection while stiffeners are more important for out-of-plane capacity. Connection is found to have higher in-plane bending stiffness than for out-of-plane. </p>

<p> LEED-certified green buildings benefit the owner not only in reducing operating costs, but also in improving the wellbeing of the occupants. LEED premium cost is the extra money a project owner invests in order to upgrade a conventional building to a Green Building. From the financial perspective, the amount of the premium cost is the major concern that keeps investors from targeting LEED certified projects. This study presents the development of cost estimation simulation model: LEED Premium Aided Cost Estimation (LEED PACE) for accurate premium cost in order to help the project owner/investor/architect to estimate the premium cost for potential LEED projects. The estimation program is built off on traditional building code (normally referred to as local municipal codes) and LEED system, which provides project based premium cost estimation. LEED PACE provides potential LEED credits acquisition based on existing project design information. Furthermore, PACE lists all targetable LEED credit(s) with corresponding premium cost(s) to inform project owner what LEED credit(s) can be acquired by changing project design elements and contributing extra cost(s). The parameters used to calculate extra construction costs are extracted from Green Building Cost RS MEANS. Although LEED PACE estimates extra construction cost needed for a traditional project in the City of Los Angeles to target LEED certification, the framework of building LEED PACE can be used to make LEED premium cost estimation for traditional project without geographical limitations. This empirical tool is expected to assist building owner/investor/policymaker in making better-informed decisions towards LEED certification from the economic perspective of sustainability. </p>

This study proposes an optimization framework to include different sources of uncertainty in the design of multidisciplinary analysis with feedback coupling. To achieve this goal, four objectives were pursued, two related to multidisciplinary analysis and two related to design optimization. A likelihood-based decoupling approach is first proposed for probabilistic feedback coupled analysis to include both aleatory and epistemic uncertainty, using an auxiliary variable method. No convergence analysis is needed in this approach, so it achieves great computational efficiency. Secondly, A novel uncertainty propagation approach is proposed when individual disciplinary analyses are connected to each other by a large number of coupling variables. The Bayesian network with a copula-based (BNC) sampling strategy is adopted for efficient probabilistic multi-disciplinary analysis that satisfies interdisciplinary compatibility condition. The BNC approach is then exploited as a surrogate model in reliability-based design optimization (RBDO). The joint probability of multiple objectives and constraints is included in the formulation. The Bayesian network along with conditional sampling is also exploited to select training points that enable effective construction of the Pareto front. A comprehensive multidisciplinary optimization under uncertainty framework is finally developed based on the BNC approach. In this fourth objective, the BNC approach is extended for simultaneous interdisciplinary compatibility enforcement and the objectives/constraints evaluation within MDO. The proposed methodology is observed to achieve significant computational efficiency in solving several engineering examples, including an electronic packaging problem, an aeroelastic wing analysis and design problem, and a vehicle side impact problem.

<p> A feature detection algorithm is developed to determine which type of vehicle crosses a mobile bridge using acceleration responses. The purpose of this thesis is to examine the results sensitivity of the algorithm to various parameters that influence the ability to correctly classify vehicles. Each of these results will play a role in developing the most suitable procedure. </p><p> Using numerical and experimental results, the parameters studied are: bridge length, vehicle speed, noise, sensor filtering, and soil conditions. Each parameter is varied individually to determine how much it affects the ability of the method to classify vehicles traversing the bridge. Consideration is given to how parameters could be controlled under real world conditions to yield reliable results. The investigations demonstrate that results vary slightly to noise levels, the length of the bridge is constant once emplaced, sensor filtering setting can be fixed, soil condition impacts are minimum, and the vehicle speed can be controlled if a ground guide is used. </p><p> Based on the observations, a generalized procedure is prepared which consists of: creating a database with multiples parameters, controlling the parameters within realistic constraints, and grouping similar vehicle responses. The procedure aims to provide the best environment to produce reliable detection rates.</p>

No description available.

<p> The crews/actors/subs during a construction project make relationship and communicate with each other on the jobsite primarily when they work in a task sequence or when they work in the same working area at the same time. These interdependencies can have various impacts on their performance, the decisions their supervisor make and their action from both engineering and social aspects. The main focus of the past research is on the project parties&rsquo; relationship based on the information exchange and formal communication, while the research pertaining to the interpretation and investigation of the construction crews/trades&rsquo; interdependencies during the construction project is very limited. How are the construction jobsite actors connected in a construction jobsite? How do the existing interdependencies among them affect their performance? And how can understanding these interdependencies be beneficial for construction site managers? The primary goal of this research is to better understand the existing interdependencies among the construction crews/trades/subs and its impact. Particularly, the objectives of this research are to: 1) develop the jobsite social network of construction crews/trades and quantify its impact, 2) investigate the impact of social conformity on the performance of construction crews/trades, 3) identify the improvement direction (benchmarks) for inefficient construction crews/trades, and 4) investigate the cost/benefit of low or high reliable construction crews/trades and to develop a new educational version of Parade Game. </p><p> First, social network analysis (SNA) is implemented to develop a technique to construct the dynamic jobsite social network of crews/trades in a project and quantify its impact through the network centrality analysis. The results of a case study are presented. Then, SNA and social norm analysis are combined as a method to measure conformity, one of the main social network influences types that results in a change of performance/behavior in order to fit in a group, at construction crew/trade level and demonstrate how it can play role in the performance of crews/trades/subs particularly in their work plan reliability through two case studies. Then, inspired by social learning phenomenon, data envelopment analysis and SNA is combined to develop a procedure that can identify the improvement direction for the inefficient crews/trades/subs in a construction project. At the end, the research concentrates on the engineering aspects of the jobsite interdependencies by developing a simulation model, as a new educational version of Parade Game, that uses different variability levels and the corresponding costs at different work stations to investigate the relationship between the interdependencies and crews/trades&rsquo; variability/reliability. </p><p> Results demonstrate that the performance of construction crews/trades is under the influence of the social aspect of the interdependencies as well as the engineering aspect. They show that there is an association between influences a crew/trade/sub receives from the network and his/her performance. Results of case studies show that the subcontractors follow the performance norm in the project and their tendency to follow the norms of their neighborhood is higher than their willingness to follow the project norm. Parade Game simulation results also show that the production will enhance if the reliability increases and the investment made to improve reliability will return in most of the scenarios. </p><p> This research is significant and valuable as it looks at construction jobsite interdependencies from an exclusively analytical perspective, which has not been done previously. Previous research also did not investigate the social aspects of the construction crews/trades/subs interdependencies. Construction personnel at every level of management are constantly planning and trying to figure out how best to manage and coordinate the construction crews/trades/subs. A better understanding of the existing jobsite interdependencies will help project managers to control it through better planning and leadership, consequently increasing jobsite productivity.</p>