rss_2.0Modelling in Civil Environmental Engineering FeedSciendo RSS Feed for Modelling in Civil Environmental Engineering in Civil Environmental Engineering 's Cover of Spatially Variable Artificial Earthquake: A Case Study of Different Site Conditions<abstract> <title style='display:none'>Abstract</title> <p>The dynamic analysis of structures under seismic ground motions is a major issue in earthquake engineering. The seismic ground motions observed at the surface are variables in space and time. The main causes of this variability come from seismic waves propagation between the source and the site, and in particular the local geological site conditions. For this purpose, it is essential to consider all these factors of the spatial variability of seismic ground motion when representing seismic loading to be applied to any structure. Given the scarcity of real seismic records, many researchers suggest the use of artificial or synthetic seismic motions. The main objective of this study is the simulation of spatially variable artificial seismic motions by considering all fact of factors of the seismic spatial variability, especially site local conditions. In this sense, a simulation technique of spatially variable seismic motions is developed using the spectral representation method. By adopting the unconditional simulation approach, the target seismic motion in bedrock is defined by the Clough-Penzien spectral model and a specified coherency loss model. Then, the simulated ground motions in the bedrock are projected on the surface by considering amplification site effect. The results showed that the simulated artificial seismic motions are strongly conditioned by the local site conditions.</p> </abstract>ARTICLE2022-07-09T00:00:00.000+00:00Reliability Analysis of Stone Columns Bearing Capacity<abstract> <title style='display:none'>Abstract</title> <p>Reliability analysis and stone columns techniques are widely used, with an increasing trend, in different geotechnical engineering problems. Design methods of stone columns is still based on deterministic approach, in spite some degree of uncertainties is associated with soil and stone column parameters. In the present work, reliability analysis of bearing capacity of stone columns is examined; using three methods of reliability analysis, First Order Second Moment FOSM, Point Estimate Method PEM, and Monte Carlo simulations MCs. Parametric analysis using all variables involved in stone columns design has been conducted. Distributions of random variables involved in stone columns design are considered either as normal or lognormal. The random variables correlation effect is examined. The study has allowed to evaluate parameter uncertainty effect on reliability index of stone columns, and has permitted to figure out reduced set of parameters that must be considered as random in reliability analysis of stone columns beside sensitivity analysis.</p> </abstract>ARTICLE2022-07-09T00:00:00.000+00:00Biological Denitrification of Water Intended for Human Consumption<abstract> <title style='display:none'>Abstract</title> <p>Nitrate is the most common form of nitrogen in water. The presence of nitrates in drinking water can harm human health, this is why the maximum concentration of nitrates in potable water is imposed by law. The main treatment technologies used for treating this kind of water are reverse osmosis, ion exchangers, electrodialysis and biological denitrification. The goal of this paper is to determine the efficiency of biofilters in reducing the ammonium concentrations in water, depending on the carrier/filtration media used in the biofilters, the C:N:P ratio used and contact time between water and the attached biomass. The paper is based on the result obtained during experimental tests in which the concentration of nitrates in the raw water was 150 mg/l.</p> </abstract>ARTICLE2022-07-09T00:00:00.000+00:00General Equations of Non-Degenerate Conics<abstract> <title style='display:none'>Abstract</title> <p>In this article, we present a method to obtain equations of non-degenerate conics in an initial Cartesian frame (<italic>xOy</italic>), starting from their canonical expressions in another Cartesian frame (<italic>x</italic>′′<italic>Cy</italic>′′).</p> </abstract>ARTICLE2022-07-09T00:00:00.000+00:00Partial Experimental Contributions on the Validation of Biomechanical Models of the Human Body Subjected to the Action of Mechanical Vibrations<abstract> <title style='display:none'>Abstract</title> <p>This paper focuses on the field of mechanical vibrations experimental analysis in hand arm vibrations (HAVs) for people who by the nature of their job are subject to the mechanical vibrations.</p> </abstract>ARTICLE2022-07-09T00:00:00.000+00:00A Combined-Index Study on the Influence of Earthquake Incidence Angle on the Seismic Performance of Reinforced Concrete Plan-Asymmetric Buildings<abstract> <title style='display:none'>Abstract</title> <p>A study is performed to estimate the critical seismic incidence angle for a nine-story reinforced concrete dual system building, categorized as plan-asymmetric, by considering a combination of two demand parameters, the Maximum Inter-story Drift (MLID) along the height, and the Seismic Vulnerability Index (SVI). The influence of excitation directionality on the response of the building was investigated by nonlinear dynamic analyses, by applying seven scaled bidirectional ground motion records, oriented in eight incidence angles ranging from 0° to 315°, with a 45° increment. The scaling was made for a peak ground acceleration PGA = 0.30g, according to the elastic response spectrum specified for Bucharest by the Romanian seismic code P100-1/2013. From the results, it was found that the most unfavourable response due to a specific seismic excitation may occur at any angle of incidence, which is not necessarily 0° or 90°, and that the response depends not only on the structural configuration, but also on the excitation characteristics. In addition, the influence of the flexible edge (FE) on the structural demand in terms of SVI was studied. The maximum values for SVI were obtained for the most critical angle of incidence, which is the one that has the higher MLID values in the FE for all accelerograms.</p> </abstract>ARTICLE2022-02-02T00:00:00.000+00:00Development and Parametric Analysis of Human ‘Outdoor’ Thermal Comfort Index for Public Green Spaces in Bengaluru, India<abstract> <title style='display:none'>Abstract</title> <p>Urban Warming is an increasing problem in the cities, and inadvertently Thermal Comfort has received an increased attention since the last decade. Compared to indoors, the outdoor environment is more complex and there are larger variations in the climatic parameters. The present research is an effort towards evolving “Human ‘Outdoor’ Thermal Comfort Index”, so as to overcome the limitations of prevalent indices such as ‘Physiological Equivalent Temperature’ and ‘Universal Thermal Climate Index’. The present study was carried out at twenty Public Green Spaces, selected on the basis of geographical location, land use pattern, public prominence, topography and physical area; for 12 hours to monitor Climatic Parameters. The Input parameters included Ambient Air Temperature, Relative Humidity, Wind Speed, Intensity of Sunlight, Green-cover Area; and Public Perception which was ascertained at each observatory with the help of a self-designed compact questionnaire survey. Subsequently, this newly designed empirical relationship was employed for establishing the Thermal Comfort Index of various Public Green Spaces of Bengaluru, with ranking.</p> </abstract>ARTICLE2022-02-02T00:00:00.000+00:00Buckling Loads of Fully Embedded Pile in Clayey Soil Based on the Finite Element Method<abstract> <title style='display:none'>Abstract</title> <p>Pile foundations are a well-established means of transferring axial loads applied by a superstructure to rigid soil layers. However, the geometrical characteristics of piles can induce the appearance of the buckling phenomenon when using this type of foundation. Furthermore, buckling is a very important factor in the design of piles, especially when the upper layers are loose or weak soil. Pile buckling is currently one of the more complicated geotechnical problems that engineers and researchers have to deal with. The aim of this work is to analyze the effects of some geometrical, mechanical or geotechnical parameters into the value of critical buckling load of an axially loaded pile totally embedded in a homogeneous soil. In this study, numerical buckling analysis is investigated by using three dimensional finite element analysis. The buckling load was studied for concrete pile. while the modulus of soil reaction is adopted constantly with depth. The Numerical results of the buckling loads of fully embedded pile that obtained by the finite element method and Davisson method are also compared in this paper.</p> </abstract>ARTICLE2022-02-02T00:00:00.000+00:00Kinetics and Chemistry of Nitrification Process – A Review<abstract> <title style='display:none'>Abstract</title> <p>Nitrogen is an important nutrient for the survival of all living organisms, as its chemical binding properties allow to create structures from which proteins are built. In nature, nitrogen is found in many forms and its transformation from one form to another is described by the nitrogen cycle. Ammonium is a form of nitrogen that has no direct effects on human health, but its presence in water supply systems may determine bacterial growth in the distribution networks and ultimately can generate degradation of the water quality. Its concentrations in wastewater and water intended for human consumption can be reduced by the biological process of nitrification. The purpose of this paper is to review the equations and the kinetics of the biological nitrification process.</p> </abstract>ARTICLE2022-02-02T00:00:00.000+00:00New Methods of Teaching Mathematics in High Schools and Universities<abstract> <title style='display:none'>Abstract</title> <p>In this paper, we show a new approach in math teaching. The thing that makes this method different from the older ones is the way the notions are defined. Thus, we start with a practical problem from Physics, Chemistry, Biology, etc. and we try to get a formula to solve that problem. At a moment, we stop the try, because of a lack of theoretical notion. Then, it follows a paragraph in which we define the mathematical notion that we need to solve the given problem. Some properties of the notion and useful formulas are given. After that, we go back to the practical problem and, using the new defined mathematical notion, we solve the problem. We use this technique to define very important mathematical notions, as: derivatives, Riemann integral and differential equations. With these tools, some important problems from the real life can be solved.</p> </abstract>ARTICLE2022-02-02T00:00:00.000+00:00Experimental Test on Square Concrete Columns Strengthened with CFRP Composites in Different Configurations<abstract> <title style='display:none'>Abstract</title> <p>The shape and FRP configuration of the concrete columns can straight forwardly influence the efficiency of the FRP confinement. Most of the columns shape in concrete buildings are non-circular sections, therefore, special attention need to be given to their strengthening and rehabilitation to maintain the safety of buildings infrastructure especially, for rectangular/square sections with section depth ≥ 300mm. This paper is directed towards to this objective through an experimental investigation carried out on 8 square concrete columns having the same dimensions (300 × 300 × 1000) mm (width × depth × height respectively) with low concrete strength confined with different CFRP configurations. Two of the columns left without CFRP strengthening to be as a control specimens, two specimens were strengthened with two-layers of CFRP sheets (full confinement), two specimens were strengthened with two-layers of CFRP sheets and CFRP strips combined with CFRP anchors, in addition, one specimen was strengthened with one-layer of CFRP and CFRP strips combined with CFRP anchors, finally, the last specimen was strengthened with CFRP strips combined with CFRP anchors (partial confinement). The results revealed that CFRP composite wrapping in different confinement procedures can enhance the ultimate load capacity and ultimate compressive strength of square concrete columns having low compressive strength subjected to axial load, and the anchorage system improved based on the final failure mode of confined columns where the failure didn’t happen in the anchors zones, which was an aim of the research.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00The Fundamental Vibration Period Determination for an Existent Historical Monument Building, by Using Numerical Modelling, Empirical and Experimental (AVT) Methods<abstract> <title style='display:none'>Abstract</title> <p>One of the most important parameters necessary in the seismic force determination is the building’s fundamental vibration period, which is also useful in “health monitoring” procedure for the existent buildings, during their exploitation. The fundamental vibration period can be determined by theoretical, empirical or experimental methods. In particular, the experimental method it is known as AVT (Ambiental Vibrations Tests) procedure, which intensively studied today. In this paper it was performed a comparative analysis between fundamental vibration periods values, determined for an existent building, by using a numerical method (finite elements program - ETABS), some direct methods (empirical formulas), and an experimental method (dynamic recordings, based on AVT), using special devices as accelerometers from KINEMETRICS brad. The existent building has “house flats” destination, and it is historic monument, located in Bucharest city, which it was built in ~1930 period, and it has basement and 4 floors. The building’s structure is done half by masonry walls with concrete slabs and half by RC frames (columns and beams), with concrete slabs. The main goal of the analysis is to emphasize the advantages and disadvantages of each studied method.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00Investigation of RC Beams Rehabilitated with Angle-Ply Composite Laminate Plate<abstract> <title style='display:none'>Abstract</title> <p>This parametric study investigates the RC Beams Rehabilitated with angle-ply composite laminate plate [θn/90m]<sub>s</sub>. This work is based on a simple theoretical model to estimate the interfacial stresses developed between the concrete beam and the composite with taking into account the hygrothermal effect. Fibre orientation angle, effects of number of 90° layers and effects of plate thickness and length on the distributions of interfacial stress in the concrete beams reinforced with composite plates have also been studied.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00Experimental and Numerical Study on the Influence of Mechanical Ventilation on the Survival Conditions in a Room Set on Fire<abstract> <title style='display:none'>Abstract</title> <p>Statistics show that most fires occur in civil residential buildings. Most casualties are caused by the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aims to determine the physical and chemical parameters essential for the survival of persons in the early stages of a fire in different ventilation situations: with and without a mechanical ventilation system for the extraction of hot air.</p> <p>These essential parameters are indoor air temperature, visibility, oxygen concentration, and carbon dioxide concentration. Three full-scale experiments were carried out to study the burning behaviour. The experiments were used to calibrate and validate a numerical model with respect to the temperature variation at a specific control point inside the experimental stand. The model was further employed in order to understand the influence of the operations of the ventilation system on other active firefighting systems, fire evolution, and people evacuation. We found the ventilation system has mixed influences; we present here a detailed conclusion on its influence.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00Probabilistic Approach Applied for Brezina Concrete Weight Arch Dam<abstract> <title style='display:none'>Abstract</title> <p>This article target is to perform a probabilistic analysis of a concrete dam.Brezina weight arch dam situated at El Bayedh in Algeria is chosen as a case study. Ansys code is used for three-dimensional finite element modeling of the dam. Input variables are generated arbitrary by Monte Carlo (MCS) method which is more precise but costly in terms of computing time. Simulation number privileged in this method (MCS method) is in order of 500 simulations chosen based on convergence of results (of responses). Normal and Log-Normal distributions laws are used to generate random variables; young Modulus (E) and density (ρ).</p> <p>The bandwidth limits are 38.14Hz and 42.15Hz. It represent frequency margin whose resonance risk is very high. This bandwidth has been determined from a determinist study which is a numerical modal analysis using Ansys code.</p> <p>The obtained results show that the variation coefficient of E and ρ for Brezina concrete weight arch dam hasn’t an impact on the dam security whose resonance risk is almost neglected. Results also confirm that the mean frequency value for the two distribution laws cases (Normal and Log-Normal) stay practically stable. So, we can conclude that the concrete weight arch dam object of the present study is safe for different values of E and ρ.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00Influence of the Soil-Structure Interaction on Free Vibrations of Beam by the Spectral Element Method<abstract> <title style='display:none'>Abstract</title> <p>In this investigation, the dynamics of soil-structure interaction (SSI) in frequency domain is investigated. The spectral element method is devoted to study free vibrations of Euler-Bernoulli beam resting on general elastic restraint at the ends and continuous springs against rotation and translation. Thus, partial differential equation of the motion is derived and upon solving the eigenvalue problem, natural frequencies are tabulated for the first three modes of vibration. Obtained results are regrouped in (1) the modal analysis of beams on elastic transversal or rotational rigidities of the continuum under foundation, (2) the influence of properties of elastic medium on the beam dynamic response (3), and the influence of non classical boundary conditions. In consequence, various results of above phenomena are described and commented.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:002D Hydrodynamic Model Development for a Critical Sector of the Danube River<abstract> <title style='display:none'>Abstract</title> <p>This paper aims to develop a high-precision two-dimensional hydrodinamic model of the Danube critical sector extended between Bechet and Corabia (from rkm 678 to rkm 625), using Danish Hydraulic Institute (DHI) Mike 21 software. The Digital Terrain Model (DTM) of the study area was obtained based on LiDAR (Light Detection and Ranging) data, combined with topogeodetic and bathymetric data collected during two field campaigns within the FAST DANUBE Project. Hydrodynamic modeling is mandatory in order to identify environmentally friendly technical solutions to solve the navigability issues on each critical area and to ensure safe conditions for the freight transport along the entire length of the Romanian-Bulgarian common sector of the Danube River.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00A Comparative Study on Soils Degree of Swelling Using New Correlations Formulas<abstract> <title style='display:none'>Abstract</title> <p>The main objective of this paper is to apply the correlations to evaluate the risk of soil swelling in the area of the north-west part of Algeria. On this basis, 84 soil samples were collected from laboratories in the region, plus a reading of the main publications on swelling soils in the area of the north-west part of Algeria, and then different types of regressions were applied to this data. The results show that the plasticity index has a high degree of influence on the swelling pressure; the swelling potential and the swelling coefficient compared to the clay content. New empirical relationships were found between the swelling pressure and swelling potential; these correlations are good concordances with the literature. Cubic; quadratic and multiple models of regression seem are in good concordances better adapted compared to simple linear regression models in the presented study.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00Concrete Columns Strengthened with Fibre Reinforced Cementitious Matrix (FRCM)<abstract> <title style='display:none'>Abstract</title> <p>Since concrete structures are subjected to degradation, one of the newly retrofitting system used to increase both the strength and the overall ductility is based on the Fibre Reinforced Cementitious Matrix (FRCM) composite material. FRCM system was proposed as an enhanced alternative to the traditional fibre reinforced polymer (FRP) jacketing, overcoming the limitations related with the use of organic adhesives. After a brief state of art about the FRCM system, the paper presents an analytical study on the confinement of plain concrete columns with FRCM composites. Representative analytical models are selected from the technical literature, and the predictions of the maximum compressive strength are compared with respect to the reference experimental results. Four plain concrete columns strengthened with FRCM system, which were previously tested by the authors, were used for this analytical study. Slightly different strength of concrete materials and different number of FRCM layers (one-layer and two-layer) differentiate the reference specimens. Therefore, the capability of the selected analytical models to make close predictions when changing the base material and the number of FRCM layers was evaluated. Recommendations are made based on the comparative results.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00Modeling and Analyzing Dissolved Oxygen Concentrations in Lacul Morii Using Mike Zero Software<abstract> <title style='display:none'>Abstract</title> <p>Reservoir modeling involves the construction of a computer model for prediction purposes and making decisions regarding the best operation of the reservoir. The environmental consequences of dams and reservoirs are numerous and varied, and includes direct impacts to the physical, chemical and biological properties of reservoirs and environments. This paper dealt with the study of the dissolved oxygen and the BOD concentrations in the inflow streams as well as those in Lake Morii, as well as the effects of phytoplankton, chlorophyll and reaeration rate using simulations in Mike Zero software. The main objectives of this research are to investigate the concentration of dissolved oxygen if they are among the required of water quality standards and how they are dispersed in the lake during a specific time period, as well as reducing concentration the BOD when it reached highest level, especially in summer time The simulations obtained gave us very good results about the dissolved oxygen and BOD concentrations in the reservoir.</p> </abstract>ARTICLE2021-10-26T00:00:00.000+00:00en-us-1