Current Issue : October - December Volume : 2018 Issue Number : 4 Articles : 5 Articles
Based on the triaxial test, the elasto-perfectly plastic strain-softening damage model (EPSDM) is proposed as a new four-stage\nconstitutive model. Compared with traditional models, such as the elasto-brittle-plastic model (EBM), elasto-strain-softening model\n(ESM), elasto-perfectly plastic model (EPM), and elasto-peak plastic-brittle plastic model (EPBM), this model incorporates both the\nplastic bearing capacity and strain-softening characteristics of rock mass. Moreover, a new closed-form solution of the circular tunnel\nis presented for the stress and displacement distribution, and a plastic shear strain increment is introduced to define the critical\ncondition where the strain-softening zone begins to occur. The new analysis solution obtained in this paper is a series of results rather\nthan one specific solution; hence, it is suitable for a wide range of rock masses and engineering structures. The numerical simulation\nhas been used to verify the correctness of the EPSDM. The parametric studies are also conducted to investigate the effects of\nsupporting resistance, residual cohesion, dilation angle, strain-softening coefficient, plastic shear strain increment, and yield parameter\non the result. It is shown that when the supporting resistance is fully released, both the post-peak failure radii and surface\ndisplacement could be summarized as EBM>EPBM >ESM>EPSDM> EPM; the dilation angle in the damage zone had the highest\ninfluence on the surface displacement, whereas the dilation angle in the perfectly plastic zone had the lowest influence; the strainsoftening\ncoefficient had the most significant effect on the damage zone radii; the EPSDM is recommended as the optimum model for\nsupport design and stability evaluation of the circular tunnel excavated in the perfectly plastic strain-softening rock mass....
As one of the most important sustainability project management practices, prefabrication\nhas been drawing increasing attention to project construction practitioners. However, due to the\nneeds of high technology and large capital investment, there is a great challenge for suppliers\nto adopt prefabrication in mega project construction. Therefore, designing an adequate incentive\nmechanism has become a daunting task for the project owner, which aims to ensure a socially\nand environmentally friendly project delivery. In this study, an incentive model with reputational\nconcerns from the perspective of the project owner was established and how this incentive affects\nsupplier�s effort and project owner�s profit was investigated. By contrasting to the incentive model\nwithout reputational concerns, when the reputation incentive is considered in the incentive contract,\nboth supplier�s effort and project owner�s profit increase. In addition, adding reputation incentive\nimplies more expenses, thus the project owner may not want to take this strategy due to the potential\nexpense increase. Therefore, the study also considered an incentive mechanism with constant total\nincentive intensity. By comparison, the result shows that this strategy is also useful which can\nimprove supplier�s effort and project owner�s profit....
This study considers structural reanalysis owing to the modification of structural elements including (1) addition of substructures,\n(2) removal of substructures, and (3) changes in design variables. Coupling and decoupling reanalysis methods proposed in the\nstudy are performed by using the concept of compatibility conditions at interface nodes between the substructures or between the\noriginal structure and the substructures. Subsequently, a generalized inverse method to describe constrained responses is modified\nto obtain the reanalysis responses. In this study, constrained equilibrium equations are modified to consider a reanalysis of\na structure with the addition and removal of statically stable or unstable substructures. The proposed reanalysis method is\nexamined by using five examples of handling coupling and decoupling reanalysis of a truss structure....
Way-finding is the ability of people to perceive routes, flow patterns, or passageways inside and/or around a building. In other words,\nit is the capability of a person to know their whereabouts in a space. Modular buildings and complex spatial plan structure, in general,\ncan be very confusing, especially from a way-finding point of view. This research attempts to measure the way-finding performance of\na modular building by assessing the users� experience in finding their way inside the Male Engineering Building at Qatar University.\nThe study involved students, faculty, and staff members that utilize that space daily. The research focused on accessing indoor spaces\nas well as the walkways and spaces connected to the building. Results show that parameters as the use of colours and numbers can\nimprove capability and swiftness in way-finding. In future research, several types of signage and visual elements will be tested, in\norder to understand how they can enhance way-finding efficiency and user performance within indoor spaces....
The rock slopes with tunnels appear widely in the actual project, but there is no executable basis for the seismic stability calculation of the rock slope with tunnel. According to the upper bound theorem of plastic limit analysis and pseudostatic method, the upper bound solution of the safety factor of the rock slope with tunnel was rigorously derived under earthquake loading. This upper solution takes into account the design parameters of the slope and the tunnel, the horizontal and vertical seismic loads, and the physical and mechanical parameters of the rock mass. Comparing the calculated results with the existing results, the validity of the proposed method was verified. The sensitivity and influence of different parameters on the seismic stability of the slope were analyzed. The results show that the three factors such as the horizontal seismic force coefficient, the slope height, and the internal friction angle are the three key factors that influence the sensitivity of the safety factor and have a great effect on it....
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