civil engineering
Hossein Khosravi; Atefeh Adelian Haghighi
Abstract
The concrete-filled double skin steel tubular columns (CFDST) are regarded as one of the composite columns consisting of double steel tubes with square or circular hollow sections and the space between two skins is filled with concrete. These columns possess several advantages, including a proper performance ...
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The concrete-filled double skin steel tubular columns (CFDST) are regarded as one of the composite columns consisting of double steel tubes with square or circular hollow sections and the space between two skins is filled with concrete. These columns possess several advantages, including a proper performance during loading, smaller dimensions, cost-effectiveness, protection of the concrete surface against the damage, others compared to conventional columns. In this paper, the buckling of the concrete-filled double skin steel tubular columns subjected to the axial compression was assessed using finite element software, ANSYS. For further investigation of the various types of this novel column system, the nonlinear behaviors of the 3D model of the double skin sections with various cross-section shapes of the section were compared and the influence of the support condition was studied Moreover the buckling of the columns filled with self-compacting concrete, which is required due to the difficulty in the pouring in the confined space, was scrutinized. The results for the short CFDST columns indicate that the column with square-outer-section and circular-inner-section tubes exhibited high buckling critical load and better ductility. Variations in the support conditions do not have significant influence on the columns.
مدیریت ساخت و مدیریت پروژه
Seyed Mahdi Mirkhorsandi; Hossein Khosravi; Alireza Davoodi; Seyed Mojtaba Movahedifar
Abstract
Financially, project portfolios can be completely self-reliant when their required liquidity is merely obtained through reinvesting the profit of the finished projects and the initial capital of the owners. However, the firm can only perform some profitable projects despite maximizing wealth owing to ...
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Financially, project portfolios can be completely self-reliant when their required liquidity is merely obtained through reinvesting the profit of the finished projects and the initial capital of the owners. However, the firm can only perform some profitable projects despite maximizing wealth owing to a shortage of funds. In such cases, projects’ implementation can be phased as a practical solution to satisfy financial deficiencies. Therefore, decision-makers are involved in finding the optimum selection and scheduling of the self-financing phase-able project portfolios. Some projects especially construction projects encompass a multi-stage process of repetitive activities, which pave the way for taking advantage of the economy of scale when organizing for development. This research proposes a mathematical model for the problem of building construction project portfolio with simultaneous consideration of the reinvestment strategy, phasing strategy, and economy of scale at the enterprise level. In this case, an integer programming model to maximize the investment's net present value is presented. The proposed model provides a decition support system for property developers to select and schedule self-financing phase-able building construction project portfolios, in this context, the model's applicability is illustrated in a case example.
