Volume 3 Issue 4
Authors: Emad Abd-El Hamied El-Maghraby
Abstract: Ready mixed concrete (RMC) placing is an important operation on construction projects in many countries. This is particularly true as in Egypt high- rise buildings construction increased in the building industry, many of these buildings are still constructed using the traditional method of in-site concrete placing. Concrete must be batched remotely and delivered to sites by truck mixers Therefore, the production rate of Pouring Ready Mixed Concrete (PRMC) could be considered as great importance to improve the productivity of the whole construction industry in Egypt. The aim of this paper is to build a new regression model using correlation analysis method for predicting the production rate of PRMC using tower cranes. The model building was based on a close observation of 418 pours cycles from ten different construction building sites for the pouring concrete in columns, slabs, and beams, each from the beginning to end operation. In addition, it studied the factors affecting the production rate of PRMC using tower cranes. The results of the model implementation in concrete placing for columns, slabs and beams presented an average percentage error value of 2.8197%.
Keywords: Multiple Linear Regression; Tower Cranes; Production Rate; Pouring Ready Mixed Concrete (PRMC)
Authors: Hossein Ataei; James C. Anderson
Abstract: Glass fragments are a prime source of injury to the occupants of buildings during an explosion. Therefore, a better understanding of the post-failure response to these glass panels to the various glazing system parameters and blast load characteristics is an important step in mitigating the blast-related glass fragments injuries. A successful blast-resistant glazing design requires balancing of the safety and security of the window panels with physical appearance and cost-effectiveness to provide a reasonable degree of protection against explosive threats. In this paper, the blast-induced properties of glass fragments for the proposed glazing systems are calculated by application of the Simplified Techniques, Empirical Approaches and the Explicit Finite Element Simulations in order to find the post-failure characteristics of the flying glass debris including the fragment flying velocities; number of generated fragments and their flying distances. The results of the hazard level assessment indicate that for conventional glazing systems, the glass debris characteristics (velocities; distances and fragment numbers) will be consistent through the application of the Simplified, Empirical and Finite Element Methods. Although Simplified and Empirical approaches provide faster practical answers, Finite Element solutions render the results that are more accurate and better representative of the glazing system parameters because of taking into account the glass panel characteristics. These results could be used towards the development of more comprehensive blast-resistant glazing injury models to improve the safety provisions for the building occupants during an air blast.
Keywords: Glazing Systems; Air Blast; Security and Safety; Flying Glass Debris; Hazard Assessment
Authors: Xiaomin Wang; Andre J.A. Unger; Beth L. Parker
Abstract: The focus of this paper is to price the guarantee period of a brownfields redevelopment project, which is the present value of the sum of the cost of failure plus the cost of data collection. The cost of failure is essentially a contingency fee that the developers must reserve from the sale of each residential house to cover the risk of repurchasing it and maintaining the development at a future date. Its price is largely dependent on prediction uncertainty associated with three metrics evaluated in a companion paper. Two methods were adapted from Yu et al. (2012) to estimate the risk capital portion of the contingency fee to cover the developers’ preference for risk aversion. These methods were modified to accommodate the worth of hydrogeological data in reducing prediction uncertainty. The first method is denoted as the “actuarial” premium calculation principle because it follows classical P&C insurance policies. This method uses the standard deviation of the cost of failure as a safety loading factor. The second method is denoted as the “financial” premium calculation principle, which expresses the safety loading term as an interest rate surcharge in excess of the risk free (nominal) interest rate. The advantage of this approach is that it provides an unambiguous link between market information and the worth of hydrogeological data in reducing prediction uncertainty.
Keywords: Risk-Cost-Benefit Analysis; Optimization; Probability of Failure; Risk Capital; Real Option
Authors: Amir Soltani; Asadollah Bassam; Hu Jiaxin
Abstract: Determination of optimal parameters of a passive control system device is the primary objective of this study. Expanding upon the use of control devices in wind and earthquake hazard reduction has led to development of various control systems. The advantage of non-linear characteristics in a passive control device and the optimal control method using LQR algorithm are explained in this study. Finally, this paper introduces a simple approach to determine optimum parameters of a nonlinear viscous damper for vibration control of structures. A MATLAB code is developed to produce the dynamic motion of the structure considering the stiffness matrix of an SDOF frame and the non-linear damping effect. This study demonstrates that the proposed system (variable damping system) has better performance in system response control than a linear damping system. Also, according to the energy dissipation graph, the total energy loss is greater in non-linear damping system than linear damping as well as active control systems.
Keywords: Passive Control System; Damping Devices; Viscous Damper; Control Algorithm