Volume 14 (2018): Issue 2 (June 2018)

This paper presents a global fire risk assessment by using fire simulation in an existing underground parking. The simulation is conducted with the Fire Dynamics Simulator, a Computational Fluid Dynamics (CFD) tool and the simulations are performed on a threedimensional model of the parking. Multiple parameters and factors are taken into account in this complex assessment, such as geometry data, ventilation openings (both mechanical and natural), fire detection and fire suppression details. The output of the case study is represented by a large array of data: the time for sprinkler activation, maximum temperatures, smoke flow and overall fire evolution. The intention of the authors is to provide a global fire risk assessment of the parking, based on the fire safety engineering principles.

Sedimentation tanks are a major and important component of the wastewater treatment plants, where the cost of construction for traditional tanks may represent up to 30% of the total cost of the plants, as well as sedimentation tanks occupy relatively large areas and often require long retention times to separate the suspended solids from the liquid. High-rate tube settlers are one of the practical solutions for the development of treatment plants, especially sedimentation tanks, lamella systems can be used instead of conventional sedimentation basins or for upgrade and increase their capacity and efficiency. In addition to their high efficiency, they require much less space compared to conventional sedimentation tanks. The current study was developed to evaluate the performance of the tube settler and the effect of the inclination of tube settler on the effluent quality. In the practical experiments, tube settler unit consisting of four separate circular tubes of 27 mm inner diameter, with a length of 150 cm each were used at different inclination angles of 48, 54 and 60 degrees. A pilot scale model of coagulation-flocculation followed by sedimentation unit was prepared & installed at Colentina Laboratory Complex-UTCB for this purpose.

An empirical formula based on evolutionary regression network is proposed in this paper for predicting the equilibrium depth of scour around bridge piers. The formula expresses the equilibrium scour depth as a function of variables including flow depth and mean velocity, critical flow velocity, median grain size and pier diameter. The empirical formula is developed by training and testing an evolutionary network using scour data available in the literature. The use of the evolutionary algorithm in developing the formula is informed by the need to reduce the model complexity while sacrificing its predictive accuracy. The results of performance comparisons with existing models showed that the proposed formula model produces reasonably accurate estimates of equilibrium scour depth with a much smaller number of fitting constants compared with backpropagation neural networks.

In recent years, the pounding effect during earthquake is a subject of high significance for structural engineers. In this paper, a state space formulation of the equation of motion is used in a MATLAB code. The pounding forces are calculated using nonlinear viscoelastic impact element. The numerical study is performed on SDOF structures subjected by 1940 EL-Centro and 1977 Vrancea N-S recording. While most of the studies available in the literature are related to Newmark implicit time integration method, in this study the equations of motion in state space form are direct integrated. The time domain is chosen instead of the complex one in order to catch the nonlinear behavior of the structures. The physical nonlinear behavior of the structures is modeled according to the Force Analogy Method. The coupling of the Force Analogy Method with the state space approach conducts to an explicit time integration method. Consequently, the collision is easily checked and the pounding forces are taken into account into the equation of motion in an easier manner than in an implicit integration method. A comparison with available data in the literature is presented.