Typescript (photocopy). / Digitized by Kansas Correctional Industries

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Digitized by Kansas Correctional Industries

This research focuses on developing a Construction Supply Chain Risk Management (CSCRM) framework that can be adapted by developing countries to help construction projects make better use of materials procurement in their organisations, and to improve construction project management by effectively controlling the project to avoid project cost overruns. The research is conducted in Myanmar and all the companies studied, including the case-studies, are operating in Myanmar. The proposed CSCRM framework includes the plan, resources, process and control model part. The model suggests the development of close relationships with various stakeholders of the project for better use of the Risk Management Model. Without a proper CSCRM framework, a construction company in Myanmar can encounter a cost overrun of about three times the estimated total cost. However, the use of the proposed CSCRM framework can minimize the cost overrun by amounts of two times the total project cost. The results of case studies in three construction companies in Myanmar confirm that the proposed model is effective in managing the supply chain of construction projects in Myanmar, with effective mitigation of cost overrun risks and maximization of competitive advantages of the company.

This thesis provides an investigation into the structural behaviour of cold-formed steel zed- and channel-section purlins when subjected to uplift loading in purlin-sheeting systems. In pre-buckling, an analytical model is presented to describe the bending and twisting behaviour of partially restrained zed- and channel-section purlins when subjected to uplift loading. Formulae used to calculate the bending stresses of the roof purlins are derived by using the classical bending theory of thin-walled beams. Detailed comparisons are made between the present model and the simplified model proposed in Eurocode EN1993-1-3. In buckling, a numerical investigation is presented on the buckling behaviour of partially restrained cold formed steel zed- and channel-section purlins when subject to transverse distributed uplift loading. The buckling behaviour of zed- and channel-section purlins of different dimensions subjected to uplift loading under the influence of rotational spring stiffness applied on the middle line of the upper flange is examined. In the post-buckling, nonlinear finite element analysis models are created for the partially restrained cold-formed steel zed- and channel-section purlins subjected to transverse uniformly distributed uplift loading. The analyses are performed by considering both geometric and material nonlinearities, and corresponding design curves of zed- and channel-section purlins are established.

The aim of this research is to develop a coupled thermo-mechanical damage model for implementation in finite element software in support of fire-induced collapse assessment of steel structures. The need for properly modelling steel deterioration behaviour remains a challenging task in structural fire engineering because of the complexity inherent in the damage states of steel at large strains and high temperatures. A fully three-dimensional damage-coupled constitutive model is developed based on the hypothesis of effective space elastoplasticity and isotropic damage theory. The coupled damage is simulated by a coupling formulation between a mechanical damage component and a thermal damage component in attempt to capture the coupled damage growth under combined actions of mechanical loading and fire loading. The proposed damage model comprises a limited number of parameters that could be identified at unloading slopes of stress-strain relationships through tensile coupon tests. Alternatively, an inverse analysis type of calibration procedure could be adopted when coupon test data is unavailable. The proposed damage model is successfully implemented in the finite element software ABAQUS and calibrated with a comprehensive range of experimental results and established numerical results. The damage-affected structural response is accurately reproduced under various loading conditions and a wide temperature range, demonstrating that the proposed damage model is a useful tool in giving a realistic representation of steel deterioration behaviour under combined actions of fire and mechanical loads. Three-dimensional FE models of a five-storey and a ten-storey steel-framed office building are developed in ABAQUS and the proposed damage model is adopted in assessing their susceptibility to progressive collapse. Three types of accidental scenarios are investigated : (i) fire only scenario, (ii) post-blast fire scenario, and (iii) fire-triggered explosion scenario. The location of the compartment where triggering loads occur is varied and the most vulnerable location is at the mid-height of both building systems. Estimation of ultimate failure time by incorporating damage model with the suggested damage parameter set has the potential to be utilized as a useful tool in helping designers to determine how much time is realistically available for evacuation before progressive collapse occurs in this type of buildings. Results show that the proposed damage model significantly affects the limit state of steel buildings under fire, and especially under combined actions of blast and fire. Compared to conventional numerical approaches, the consideration of coupled thermo-mechanical damage accumulation results in an 8.25% ∼ 23.47% decrease of collapse resisting time. A key finding from this study is that the alternative load path, which is a crucial factor in deciding the survival of buildings upon local column failure, may be severely compromised due to the coupled thermo-mechanical damage propagation in surrounding columns. Based on the identified collapse mechanisms, effective strategies are suggested to improve the survivability of buildings under blast and fire.

Deflection is usually controlled by limiting the span/depth ratio. One aspect of this research is to document the deflection of a concrete slab in a large residential block. The other part of the research is to look at current design limits. Limits on deformation were set many decades ago, when the forms of construction, partitions, finishing, cladding and service were very different from what they are now. Part of that is to review the span-to-depth method of design. Site investigation and testing theory through observation and data collection was the main deductive approach of this research. A quantitative method was used to calculate and determine the deflection on concrete slabs, the research is attempted to identify target companies and projects to participate in the research. The data indicate that the slab has not sagged significantly due to the back propping for 30 days. However, it does seem that the slab was sloping down from the corner by 6 mm diagonally across the 12m bay. A margin of deflection around 2mm occurred especially in the mid-span of the slab 12 x 7 m corner bay. The 2 mm deflection occurred at the beginning of the investigation after back propping reinforced concrete corner bay slab. The back propping applied after 7 days of pouring slab.

Thesis (M.S.) Massachusetts Institute of Technology. Dept. of Building Engineering and Construction, 1956. / Bibliography: leaf [62]. / by George C. Tso. / M.S.

Thesis (M.S.) Massachusetts Institute of Technology. Dept. of Building Engineering and Construction, 1956. / Bibliography: leaf [51]. / by Isaac Tiles. / M.S.

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