Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnologico / Made available in DSpace on 2016-01-08T18:15:51Z (GMT). No. of bitstreams: 1 96047.pdf: 3520588 bytes, checksum: d3771efa18a7a4e78a4abeae5d8e8ce9 (MD5) Previous issue date: 1993 / Este trabalho apresenta um sistema computacional que foi desenvolvido com o objetivo de auxiliar na tarefa de planejamento e programação de projetos lineares de Construção Civil. Motivado pelas mudanças mercadológicas observadas neste setor industrial, o método proposto incorpora aspectos externos ao canteiro de obras à medida que procura compatibilizar os fluxos de recursos financeiros necessários e disponíveis do projeto. Para melhor compreender o método de programação desenvolvido, é apresentado e discutido o modelo matemático que lhe dá suporte. Por fim, o trabalho apresenta uma série de simulações realizadas com o sistema, procurando evidênciar, através dos resultados, a aderência do modelo à realidade da tarefa de programação de obras.

<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>

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<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>

<p> The premature deterioration of RC structures is a major concern for infrastructure owners. Cracks accelerate the deterioration processes by providing preferential flow paths for water and aggressive agents. Therefore, to accurately estimate the degradation rate, methodologies to account for the effect of discrete and distributed cracks in service life prediction tools need to be developed. To account for the effect of cracks, their effect on moisture transport in concrete needs to be fully understood and quantified. </p><p> The research reported in this dissertation provides more insight to the effect of damage induced by freeze-thaw loading on moisture transport. This study includes an extensive experimental program on moisture transport in saturated and unsaturated damaged cement-based materials. Analytical study and numerical modeling are also used to determine the parameters that have significant effect on the mass transport. Furthermore, new nonlinear parameters are proposed to estimate the freeze-thaw damage in concrete using acoustic spectroscopy technique. Therefore, this study consists of four phases. </p><p> In the first phase, three objectives are studied: (i) how damage affects the saturated and unsaturated moisture transport as well as electrical resistivity of concrete. Conceptual models are developed based on the fundamentals of damage mechanics and fluid transport to analytically describe the effect of damage, (ii) whether one-dimensional analyses based on the Sharp Front Theory can explain the relationship between the saturated and unsaturated moisture transport in damaged concrete, and (iii) which transport property and therefore which measurement method is more sensitive to damage. The results show that damage differently affects each of the transport mechanisms, and saturated hydraulic conductivity is more sensitive to damage as compared to sorptivity and electrical resistivity. The 1D analysis, based on the sharp front theory, does not adequately describe the effect of damage on unsaturated transport. </p><p> In the second phase, damage was induced by freeze-thaw in mortar specimens. Mass transport properties were measured using electrical resistivity, rapid chloride permeability, sorptivity, drying, air permeability, water permeability, and desorption isotherm. The results indicate that the measured effect of damage depends on the mechanisms of transport used in the measurement technique and different techniques provide a different measure of the effect of damage. The water and air permeability are comparatively more sensitive to the presence of damage. </p><p> In the third phase, it is investigated whether classical isothermal unsaturated moisture transport can be used to simulate moisture ingress in damaged mortar and concrete. The results indicate that the unsaturated moisture transport model well simulates early stages of moisture ingress, where capillary suction is the prominent mechanism, for all damage levels. At later stages of moisture transport, where air diffusion and dissolution have significant contribution, simulation results diverge from the experimental results. In the fourth phase, it is investigated whether Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS) technique can be provided a method, using nonlinear parameter and nonlinear quality factor (Qfactor) parameter, to estimate the damage in the absence of prior knowledge of intact material? </p><p> The outcomes of this work can be used to develop methodologies to integrate the degree of damage measured on concrete structures using non-destructive testing into service life prediction models and therefore more accurately predict the service life of reinforced concrete structures. More accurate service life prediction models can help operators of infrastructure in scheduling the repair and maintenance activities. Service life prediction is a main deriver in life cycle costing and life cycle assessment analyses and therefore developing more accurate service life prediction models can help to more accurately quantify life cycle cost and environmental emissions and implications of concrete infrastructure. </p>

<p>This thesis addresses the difference between design camber predictions using the Precast/Prestressed Concrete Institute (PCI) methodology and constructed camber predictions for precast prestressed box girders. Existing bridges constructed with box girders with a range of spans, depths, sections, and fabricators are field measured for camber. A statistical analysis of the field data is preformed to compare design versus constructed camber. Revised multipliers for design are calculated based on statistical distributions of the field data. Additionally, girders are selected from various bridges and analyzed theoretically for camber using the Tadros equation. The girders are also analyzed for consideration of the two-stage pour sequence that is common in the construction of box girders in Colorado. The field data cambers and theoretical cambers are compared and analyzed. Recommended multipliers and high and low multipliers are found. The multipliers are found to be lower than the PCI and Martin multipliers and are recommended to be 1.65 for the prestress camber and 1.70 for the self-weight deflection. </p>

<p> Shear beams and shear walls were constructed using varying amounts of steel fibers and rubber to determine the effect of these constituents on concrete when subject to shear loads and reversed cyclic loadings. 22 concrete beams were tested using mixes with differing amounts of fibers and rubber. The beams were designed to fail in shear by applying a single downward point load at midspan using a MTS Universal Testing Machine. Using the recorded load and displacement data the behavior of each beam and the shear strength contribution for each mix were determined. For all mixes that included fibers and/or rubber the shear strengths increased 12% to 56% in comparison to the plain concrete mixes. Four concrete walls were also tested using four of the 22 beam mixes. The four selected mixes were chosen based on the comparable compressive strengths and mix constituents. The walls were designed to fail in shear by applying a lateral load to a top block cast on top of the shear wall. The walls were tested on a modular strong-block test system within a rigid steel frame so that the load could be applied by a hydraulic actuator. During testing, the displacement at 10 selected locations, the loads placed on the walls at each displacement, and the behavior were recorded and analyzed. The walls containing rubber experienced lower strengths, a brittle failure with severe spalling and damage, and dissipated a low amount of energy. The walls containing fibers exhibited strain hardening characteristics leading to a ductile failure mode, higher strengths, and little web damage. Using the findings from this study, it can be concluded that both fibers and rubber can be used to increase shear strength but only fibers were found to be a viable option for application in walls subject to reverse cyclic loadings.</p>