Civil Engineering
Jagbir Singh; Amrit Kumar Roy
Abstract
The present study demonstrates the pressure variation due to wind load on a two storey building with a square plan and a pyramidal roof through CFD simulation. Past cyclone reports and other related post-disaster studies have shown loss of lives and extensive property loss mostly in the cyclone-prone ...
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The present study demonstrates the pressure variation due to wind load on a two storey building with a square plan and a pyramidal roof through CFD simulation. Past cyclone reports and other related post-disaster studies have shown loss of lives and extensive property loss mostly in the cyclone-prone regions of India. Post-disaster studies reveal that a pyramidal roof has much better chances of survival in comparison with other roof shapes. ANSYS Fluent has been used for the simulation and ANSYS CFD-Post has been used for observing the wind pressure on building roofs. The simulations are performed using the realizable k-ε turbulent model by considering grid sensitive analysis and validation with previously published wind tunnel experimental measurements. The present study includes wind behavior around the building model with different roof slopes. Comparisons of pressure coefficients are shown for five wind incidence angles to study the effect of wind on the building. Results indicate that both maximum positive and maximum negative wind pressure coefficients increase with increasing roof slopes. The results of the study are helpful in understanding the damage caused on the roof surface during the extreme wind condition.
Civil Engineering
Seyed hamid Baiat Ghiasi; Mohamadamin Oyar Hossein; Mostafa Adineh; Vahid Khiali
Abstract
Breakwater walls are buildings that are built to prevent the collapse of the soil or other granular materials and the safety of the sea. One of the destructive phenomena in these structures is the impact of sea wave forces on the overturning phenomenon and instability of the coastal wall, which has damaged ...
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Breakwater walls are buildings that are built to prevent the collapse of the soil or other granular materials and the safety of the sea. One of the destructive phenomena in these structures is the impact of sea wave forces on the overturning phenomenon and instability of the coastal wall, which has damaged the structures existing on these sites. The pattern of interaction between water and seas is complex in coastal structures. In this research, the influence of the different wall heights and soil type changes on wall stability and water pressure distribution in the coastal wall have been investigated. Also, studies will be done on the investigation and optimization of the wall and Finally, by comparing the results obtain with classical methods, the strengths and weaknesses of the classical methods have been analyzed and the effectiveness of these methods (classical) has been evaluated.These walls are made in two types of weighted and flexible (mainly metal) types, in which flexible performance is considered in this research. The behavior of metal shields in front of the water will be examined using the ANSYS software. Several methods for calculating wave forces on perforated coastal walls are also reviewed. In this study, the behavior of the elastic wall is assumed. Coastal walls have been investigated in different hardships and the distribution of pressure and anchor due to hydrodynamic pressure of water on the wall have been investigated. The walls are different in terms of material and amount of rigidity.
Civil Engineering
Audu Mohammed Taiwo; Raheem Ayinde; Raheem A Ayinde
Abstract
The effects of blocking and water repellant coatings applied on fanpalm specimens on the tensile strength were examined. Fanpalm specimens (coated and uncoated specimens) were soaked in sodium hydroxide solution for specific periods up to 1 year to expose item to alkaline attack. Two groups of coating ...
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The effects of blocking and water repellant coatings applied on fanpalm specimens on the tensile strength were examined. Fanpalm specimens (coated and uncoated specimens) were soaked in sodium hydroxide solution for specific periods up to 1 year to expose item to alkaline attack. Two groups of coating agents (blocking and water repellant agents) were applied as treatment agents. The blocking agents were of three types; sodium sulphate, magnesium sulphate and hydroxylamine, while water repellant agents also were of three types sulphur, bitumen and epoxy. Tensile strength tests were carried out on these specimens and results presented. The result revealed that as the duration of soaking in cement slurry of uncoated fanpalm increases, the nominal ultimate tensile strength of the fanpalm decreases from 107 to 17.50 N/mm2 at 366 days in cement slurry. While the specimens coated with water repellant and blocking agents decreased to 40.67 N/mm2 and 18.33 N/mm2 respectively at 366 days. This shows that coating fanpalm with blocking and water repellants will improved the resistant to chemical attack. up to 270 days. Beyond 270 days the coating specimens with water repellant is more effective. The specimens coated with blocking agents are of lower ultimate strength compared with uncoated specimens within 270 to 366 days in alkaline media.
Civil Engineering
Iman Faridmehr; Elahe Chabokan
Abstract
Irregularity, consider to be one of the main reasons of buildings collapse in recent earthquakes. Irregularity also effects the seismic behavior and maximum capacity of structures. The effect of mass and stiffness irregularity was carried out in this research using static and dynamic analysis. Three ...
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Irregularity, consider to be one of the main reasons of buildings collapse in recent earthquakes. Irregularity also effects the seismic behavior and maximum capacity of structures. The effect of mass and stiffness irregularity was carried out in this research using static and dynamic analysis. Three frames with 5, 10 and 15 stories with a 20% and 50% increase in mass of the middle stories and a 20% and 50% decrease in the ground level and middle stories were investigated separately. Maximum drift, first mode period, mass participation coefficient, and base shear force were evaluated by using a developed program in MATLAB. The results showed that changes in mass and stiffness causes a maximum increase of shear force by 14% and 5% in short and tall frames respectively. Maximum drift and the longest period in short frame occurred when the stiffness of ground level was decreased by 50 percent. In addition, such irregularity causes around 85% increase in mass participation coefficient in both short and tall frames.
Civil Engineering
Hosein Naderpour; Masoomeh Mirrashid
Abstract
In this paper, a new computational model is presented to estimate the compressive strength of mortars admixed with Microsilica and a mineral material namely Wollastonite. For this purpose, an equation with fourteen unknown parameters was considered based on a large experimental data, which were published ...
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In this paper, a new computational model is presented to estimate the compressive strength of mortars admixed with Microsilica and a mineral material namely Wollastonite. For this purpose, an equation with fourteen unknown parameters was considered based on a large experimental data, which were published in the literature. The model used five independent parameters including the amounts of the Microsilica, cement, Wollastonite, water and also the age of the specimens (day). For calculating the unknown parameters, the author used artificial neural network method and divided the experimental database into three parts for three phases of the train, validate and test to tune the coefficients of the considered equation. After determining the coefficients, the final equation was validated and tested to estimate the compressive strength of the considered mortars. The results indicated that the proposed equation of this research could be able to determine the compressive strength of mortars admixed with Wollastonite.
Civil Engineering
Magdy I Salama
Abstract
Buckling study of single-stepped columns subjected to both intermediate and end axial loads are introduced in this paper. The column understudy is considered as two segments where the upper and the lower parts have different cross-section moment of inertia or different material and subjected to an intermediate ...
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Buckling study of single-stepped columns subjected to both intermediate and end axial loads are introduced in this paper. The column understudy is considered as two segments where the upper and the lower parts have different cross-section moment of inertia or different material and subjected to an intermediate load at the location of the cross-section change beside the end load. All the classical end conditions of the studied column are considered in this paper as pinned ends, clamped ends, clamped-free ends and clamped-pinned ends. The analysis is developed using the finite element method to study the effect of the different parameters in the buckling loads. These parameters are i) ratio of the intermediate axial load to the end axial load, ii) the intermediate load location as a ratio to the column span and, iii) the ratio of flexural rigidity of lower segment to that of the upper one. The obtained numerical results are introduced in many interaction curves to obtain the buckling loads for each end conditions considering the other parameters.A comparison between the obtained results and that of the available theoretical studies shows the accuracy and the simplicity of the present work to get the critical load.
Civil Engineering
B. A. Ankidawa; J. M. Ishaku; A. A. Hassan
Abstract
The shallow alluvial aquifers on the floodplain are the major sources of water supply for the dry season farming activities. The research is aimed to estimate the aquifer transmissivity of the alluvial formations on the floodplain using Dar Zarrouk Parameters derived from geoelectric soundings. Ten profiles ...
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The shallow alluvial aquifers on the floodplain are the major sources of water supply for the dry season farming activities. The research is aimed to estimate the aquifer transmissivity of the alluvial formations on the floodplain using Dar Zarrouk Parameters derived from geoelectric soundings. Ten profiles of vertical electric soundings (VES) using schlumberger array method with the aid of a sensitive ABEM Signal Averaging System (SAS) was in the investigation. The results revealed five geoelectric layers on the alluvial formation of the floodplain. There were three, four, five, six and seven layers beneath the alluvial formation. The results were compared with the alluvial floodplain lithologies at each sounding points with resistivity values ranging between 0.98 Ωm to 4,113 Ωm and depths varying from 0.01 to 146 m. The geoelectric sequence of the alluvial formations of the flood plain reveals semi aquifer system. The aquifer hydraulic characteristics indicated that the transverse resistance R ranged between 436.8 Ωm2 to 77,324.40 Ωm2 with a mean value of 11,963.71 Ωm2. The longitudinal conductance S ranged between 0.0026 to 1.792 with an average value of 0.26348. The hydraulic conductivity value across the floodplain ranged between 0.16 m/day to 29.79 m/day with a mean value of 5.597 m/day. The transmissivity values obtained for the various layers range between 1.6 m2/day to 834.1 m2/day with an average value of 128.86 m2/day. The results of the hydraulic head reveal that the floodplain recharges the River. High groundwater potential zone occurs in the southern part of the study area
Civil Engineering
Samson Olalekan Odeyemi; Adeola Abdullahi Adedeji
Abstract
Earthquakes constitute a major problem for mankind resulting in loss of lives and structures. Smart structural materials such as Shape Memory Alloy (SMA) suppress the structural vibration in a structure by adjusting the dynamic performance of the structure. SMA rods are unique for their shape memory ...
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Earthquakes constitute a major problem for mankind resulting in loss of lives and structures. Smart structural materials such as Shape Memory Alloy (SMA) suppress the structural vibration in a structure by adjusting the dynamic performance of the structure. SMA rods are unique for their shape memory effect and super elasticity and have been used as structural reinforcement for earthquake retrofits. This research focused on investigating the appropriate percentage of shape memory alloy and steel reinforcements for the least deflection in the column-capping beam of a 3-span composite Matsurube Bridge in Japan subjected to seismic load. Five different earthquake scenarios were used to obtain the best combination of steel and SMA reinforcement in the columns and capping beam for the best resistance to the earthquake response. Data used for simulations were obtained from the bridge components. It was observed that SMA has a high resistance to seismic loads when combined with steel reinforcement and it is therefore recommended for inclusion in reinforced concrete bridges to serve as means of reducing the effect of earthquakes on structures in earthquake prone areas.
Civil Engineering
Babu Shivaram Chawhan
Abstract
ABSTRACT: This paper presents the results of experimental and numerical analysis of laterally loaded bamboo pipe piles embedded in multilayered cohesionless soil. An experimental investigation on model piles had been carried out using bamboo pipe pile with outer diameter of 24mm and inner diameter of ...
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ABSTRACT: This paper presents the results of experimental and numerical analysis of laterally loaded bamboo pipe piles embedded in multilayered cohesionless soil. An experimental investigation on model piles had been carried out using bamboo pipe pile with outer diameter of 24mm and inner diameter of 20mm in a multilayered cohesionless soil. In first case, a loose layer is maintained between the dense layers with H/D ratio of 0.50 and in second case, only dense sand layer of H/D ratio 0.0 is maintained with the depth of 0.0m. Where, H is the depth of middle soil layer and D is the embedment depth of pile of different slenderness (L/d) ratio of 25, 30 and 38. An experiment was carried out to study the behaviour of lateral load on bamboo pipe piles of different slenderness ratio of 25, 30 and 38. The experimental results of first case and second case show that the lateral load –lateral displacement response depends on the slenderness ratio of the piles. The experimental program was further verified by a two dimensional finite-element technique. The experimental results were compared with numerical analysis and are in a close agreement.
Civil Engineering
Mohammad Hossein Kashefizadeh; Mohammad Azimzadeh Koocheh; Behtash Amiri; Reza Esmaeilabadi
Abstract
The steel plate shear wall (SPSW) system is one of the most common and acceptable lateral-resisting structural systems for steel structures. Although the advantages of SPSW over the other structural systems are somehow well-known, the wall-farm interaction of the system is not comprehensively investigated. ...
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The steel plate shear wall (SPSW) system is one of the most common and acceptable lateral-resisting structural systems for steel structures. Although the advantages of SPSW over the other structural systems are somehow well-known, the wall-farm interaction of the system is not comprehensively investigated. Therefore, the present study aims at investigating the interaction of the infill steel walls and the moment frames with RBS beams, using finite element method. For this purpose, different finite element model of SPSWs with various span lengths and infill steel plates are developed. The models have the low-yield, medium-yield, and high-strength infill steel plates. At first, eigenvalue buckling analysis is accomplished and those buckling mode shapes were used to introduce the initial imperfection for a realistic simulation. In the study, the important seismic parameters−including the lateral stiffness, the ultimate shear capacity, energy absorption, and ductility−are investigated using nonlinear pushover analysis. Finite element results of the study indicate utilizing the low-yield steel plate affects inversely the contribution to the wall-frame interaction and reduces significantly the shear capacity of SPSWs. However, using high-strength structural steel plate enhances the shear capacity. Moreover, using infill steel plates with different properties does not change the initial elastic stiffness of the shear wall. Additionally, increasing the span length of steel plate shear wall, the ultimate shear strength and energy dissipation increase significantly, but the ductility of the system decreases.
Civil Engineering
Ali Ahani; Elshan Ahani; Hadi Abbaszadeh
Abstract
Seismic performance and behavior of super-tall building is one of significant place of doubt while using energy dissipated outriggers. To improve the seismic performance of super-tall building structures using outrigger is one common method; however, the performance and behavior of the outrigger varies ...
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Seismic performance and behavior of super-tall building is one of significant place of doubt while using energy dissipated outriggers. To improve the seismic performance of super-tall building structures using outrigger is one common method; however, the performance and behavior of the outrigger varies based on the outrigger section and more importantly the elevation and multitude of outrigger in structure, that could cause great differences in seismic behavior of outrigger and the compressive force that is going to apply to mega columns. To evaluate the seismic performance of the building, a case study was carried out. The models was provided with two different outrigger and two different outrigger distribution and results was find out for each model to compare and present the best model that has the higher performance in whole building. The numerical models for the structures in different condition were established with the aid of ETABS software. The responses of the modeled buildings were obtained for TSC 2007 and TSC 2017 and compared. The results show that using outrigger at roof level could significantly affect the story displacement; however, it increases the periods at both X and Y directions.
Civil Engineering
Alla Azimi; Reza Farahnaki
Abstract
Application of group method of data handling (GMDH) to predict the capacity of reinforced concrete beams strengthened with CFRP laminate has been investigated in this paper. The proposed model considers nine parameters including concrete compressive strength, width of beam, effective depth, area of tension ...
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Application of group method of data handling (GMDH) to predict the capacity of reinforced concrete beams strengthened with CFRP laminate has been investigated in this paper. The proposed model considers nine parameters including concrete compressive strength, width of beam, effective depth, area of tension reinforcement, area of compression reinforcement, yield strength of steel, modulus of elasticity of steel, width of CFRP sheet, length of CFRP sheet. There are fourteen-second order polynomials in three middle layers and an output layer. The coefficients of these polynomials are determined based on a collection of experimental laboratory tests, which were collected from the literature. Also, 66 datasets were used to estimate unknown coefficients of the polynomials. To validate the model, 17 datasets were considered from the collected database. The results of the proposed GMDH showed that it could use as a predictive model for determining the ultimate flexural capacity of reinforced concrete beams strengthened with CFRP laminates.
Civil Engineering
K.K. H KIRAN; Jagadish G Kori
Abstract
Shelter is one of the main component of the living creature, it should be safe, uneconomical, hygenic and protective. Now a days shelter should be protective from blast load due to terrorist attack, nuclear explosive, chemical reactions occurring inside the building may be internal blast or external ...
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Shelter is one of the main component of the living creature, it should be safe, uneconomical, hygenic and protective. Now a days shelter should be protective from blast load due to terrorist attack, nuclear explosive, chemical reactions occurring inside the building may be internal blast or external blast.A SDOF structural system subjected to blast load on Front wall, rear wall and roof is studied.The response of the structure is determined. The Pressure impulse curve is determined. Pressure impulse curve plays a vital role in determining the damage level of structure subjected to blast load.A LCS model is considered and studied. A LCS model made up of aluminium foam plays a vital role in the protection of structures subjected to blast load. A parameter of non dimensional parameters κ and τ are studied.A non dimensional parameters κ and τ plays a vital role in finding the damage level of the structure.
Civil Engineering
Hadi Abbaszadeh; Ali Ahani; M.Reza Emami Azadi
Abstract
The effects of FRP retrofitted concrete specimens with couple of notches on the fracture behavior have been investigated during an experimental and analytical test program in this study. This paper represents the fracture characteristics and parameters for three point bending tests on two distinguish ...
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The effects of FRP retrofitted concrete specimens with couple of notches on the fracture behavior have been investigated during an experimental and analytical test program in this study. This paper represents the fracture characteristics and parameters for three point bending tests on two distinguish retrofitted and plain condition for both intact and notched (couple notches) specimens. The experimental test results find out in the laboratory tests indicated that for intact concrete specimens, there would be approximately 285% increase in ultimate flexural strength tests. The experimental results also represents that for the tested couple notched concrete specimens, there might be approximately 318% increase in ultimate flexural strength. Based on the analytical study, it is found that the near failure behavior of the notched specimens have been significantly improved using FRP retrofit of such specimens. The system`s global energy balance and failure load prediction of FRP debonding are the couple of consideration by a developed fracture mechanics based model which made by energy dissipation major mechanisms characterizing while debonding. Model verification is provided using previous researches experimental data from literature. In addition, fracture mechanics parameters were found out for three point bending test in this paper for better understanding on fracture behavior and fracture properties of intended specimens.
Civil Engineering
Chandrakant Narhari Thombare; Keshav K Sangle; Vinod M Mohitkar; Swapnil B Kharmale
Abstract
The individual components of cold-formed storage rack system are most vulnerable to local and torsional buckling lateral loads in addition to under gravity. Deterministic allotment of strength and ductility in the structural components and performance evaluation of appropriate techniques is considered ...
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The individual components of cold-formed storage rack system are most vulnerable to local and torsional buckling lateral loads in addition to under gravity. Deterministic allotment of strength and ductility in the structural components and performance evaluation of appropriate techniques is considered in the capacity based design of cold-formed pallet rack system. Nonlinear time history analysis (NTHA) and nonlinear static pushover analysis (NSPA) are most commonly followed techniques for seismic performance evaluation of any structural systems. Although, NTHA is the most correct technique of seismic demand forecasting and performance evaluation, it is computationally heavy and even requires the selection and application of relevant set of ground excitations. A simple method for the nonlinear static analysis of complicated structures subjected to gradually increasing lateral loads (pushover analysis) is presented here. This paper presents investigation of efficient configuration of conventional pallet racking system on the basis of seismic performance by using NSPA. Finite element models of two different configurations of conventional pallet racking system are prepared and analyzed on the general purpose FE platform using ABAQUS 6.12 under monotonic unidirectional lateral loads. Results show that conventional pallet racking system with horizontal and inclined bracing is more efficient as evidenced from a fair judgment of the overall displacement, base shear and yielding demands.
Civil Engineering
Magdy I. Salama
Abstract
This paper is concerned with the elastic stability of slender tapered columns of regular polygon cross-section with constant volume is presented. Various end conditions of the tapered columns such as pinned ends, clamped -pinned ends and clamped ends are considered in this paper. The analysis is developed ...
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This paper is concerned with the elastic stability of slender tapered columns of regular polygon cross-section with constant volume is presented. Various end conditions of the tapered columns such as pinned ends, clamped -pinned ends and clamped ends are considered in this paper. The analysis is developed using finite element method for linear, parabolic and sinusoidal tapers assuming firstly circular cross-section. The polygon cross-sections other the circular one are studied by investigating a direct relation between the side number of the polygon cross-section and the critical load parameter. The main parameter in this study is the section ratio that defined as the ratio between the section depths at the mid-span of the considered column to that at the column ends. The obtained numerical results are introduced in many curves to describe the relation between the buckling load and the section ratio considering linear, parabolic and sinusoidal tapers and various side number of the polygon cross-section for each end conditions. The obtained results of the buckling factor are simple with satisfactory accuracy compared with results that obtained in other theoretical studies.
Civil Engineering
Mehdi Babaei; Alireza Moniri
Abstract
One of the common methods of the inactively controlling structures subject to earthquakes is the use of Tuned Mass Damping (TMD) systems. These dampers consist of three major parameters, namely mass, damping and stiffness. TMDs generally reduce the response domain by influencing a mode, which is most ...
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One of the common methods of the inactively controlling structures subject to earthquakes is the use of Tuned Mass Damping (TMD) systems. These dampers consist of three major parameters, namely mass, damping and stiffness. TMDs generally reduce the response domain by influencing a mode, which is most often the first mode of the structure. Since the TMD parameters remain constant during vibrations, it is very important to tune them correctly and optimally. In this study, a ten-story structural model with mass irregularities has been investigated. The mass ratio for the mass damper is assumed to be at 2%. Considering a nonlinear structure, to tune the frequency of the mass damper to its optimum value, proposed experimental relationships have been used.Both regular and irregular structures have been subjected to seven near-field and far-field earthquakes and amplified dynamic analysis from 0.1g to 1.0g with 0.1g steps and mass dampers has been used to evaluate the structural behavior. Based on the analyses outcomes, it can be seen that the TMD in structures with mass irregularities shows a better performance in the first 5 floors compared to the absence of dampers. In addition, by creating mass irregularities in the floor levels, the structure becomes more prone to damages in near-field earthquakes and the performance of the TMDs is better in earthquakes of far-field nature.
Civil Engineering
Salahudeen Bunyamin; Saideh Aghayan
Abstract
In engineering practice, settlement of foundations are experimentally determined or numerically modelled based on conventional saturated soil mechanics principles. The study area, Oferekpe in Abakaliki LGA of Ebonyi State, South Eastern Region of Nigeria is characterised with sedimentary formations highly ...
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In engineering practice, settlement of foundations are experimentally determined or numerically modelled based on conventional saturated soil mechanics principles. The study area, Oferekpe in Abakaliki LGA of Ebonyi State, South Eastern Region of Nigeria is characterised with sedimentary formations highly susceptible to compression under applied load. The study was aimed at evaluating raft footing settlement by both analytical and numerical modelling methods and determine the effect of raft thickness on settlement. Standard penetration test (SPT) data was used to correlate soil properties that were used together with laboratory results to obtain the input parameters used for the prediction of settlement. Four footing embedment depths of 1.5, 3.0, 4.5 and 6.0 m with applied foundation pressures of 50, 100, 200, 300, 400 and 500kN/m2 were considered using a raft footing dimension of 20 x 20 m2 at varying thickness of 0.5, 0.75 and 1.0 m. The numerical modelling finite element application package used was Plaxis 3D. For applied pressure of 100 kN/m2 and at footing embedment depths of 1.5, 3.0, 4.5 and 6.0 m, settlement values of (21.89, 11.51, 9.04 and 6.52), (19.70, 8.60, 6.41 and 4.39), (25.62, 14.88, 12.05 and 9.27) and (25.20, 11.59, 5.57 and 2.58) were respectively predicted by the elastic, semi-empirical, empirical and finite element methods. The elastic method of predicting foundation settlement proposed by Steinbrenner yielded a very close range results generally to those predicted by finite element method. It was generally observed that thickness of raft footing has no significant effect on the predicted settlement.
Civil Engineering
Hojjatollah Torkian; Zahra Keshavarz
Abstract
Earthquakes are considered as one of the most significant natural disasters that can potentially cause significant damages to structures. Displacement of buildings’ floors is one of the serious failures in structures caused by earthquakes. In this paper, the drift of a concrete frame with the shear ...
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Earthquakes are considered as one of the most significant natural disasters that can potentially cause significant damages to structures. Displacement of buildings’ floors is one of the serious failures in structures caused by earthquakes. In this paper, the drift of a concrete frame with the shear wall is estimated using ANFIS modeling. A dataset of 300 measured data points was used herein as the inputs for the ANFIS model. The dataset has totally six input parameters including frequency, magnitude, peak ground acceleration (PGA), and shear wave velocity (Vs) of an earthquake and the distance from the earthquake epicenter to use in the ANFIS model, while the model has just one output. Moreover, a sensitivity analysis was performed on the dataset in order to determine the efficiency of the individual input variables on the accuracy of the results. The results demonstrate that the ANFIS model is an effective model for predicting the drift in reinforced concrete structures. Finally, according to sensitivity analysis, the acceleration and shear wave velocity of an earthquake have the highest and lowers impacts on the accuracy of the results, respectively.
Civil Engineering
Zahra Jandaghian
Abstract
A two-dimensional model is used to simulate temperature distribution, wind speed and pollutants dispersion within an isolated two-dimensional street canyon using SIMPLE algorithm in ANSYS Fluent version 16.2. The simulation is based on the Reynolds-averaged Navier–Stokes equations coupled with ...
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A two-dimensional model is used to simulate temperature distribution, wind speed and pollutants dispersion within an isolated two-dimensional street canyon using SIMPLE algorithm in ANSYS Fluent version 16.2. The simulation is based on the Reynolds-averaged Navier–Stokes equations coupled with a series of standard, RNG and realizable k-ε turbulence models. Simulation domain consisted of a street canyon with two buildings enclosing a street with the aspect ratio of 1. The wind is assumed to be perpendicular to the direction of the street and the source of the pollution is assumed to be liner. The results showed that the RNG k-ε turbulence model is the most optimum model by comparing with the calculated data under different wind speed patterns and pollutant dispersion model. The improvement of turbulent viscosity term of the RNG k-ε turbulence model provides a more accurate and reliable numerical solution for the present study regarding to the pollution dispersion in a street canyon. The simulation results also showed that the dimensionless pollutant concentrations, P, is larger on the leeward side of the buildings and decrease exponentially from floor to top of the upstream buildings. Furthermore, the results showed that the pollutant concentrations on the leeward side of building are more than that on the windward side due to the pollutant transportation of vortex circulation.
Civil Engineering
Mohammad Reza Azadi Kakavand; Mohammad Khanmohammadi
Abstract
The brittle behavior of older non-ductile reinforced concrete buildings such as shear-axial failure in columns can cause lateral instability or gravity collapse. Hence, the attempt is to assess the collapse potential through fragility curves. Current research focuses on fragility assessment of these ...
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The brittle behavior of older non-ductile reinforced concrete buildings such as shear-axial failure in columns can cause lateral instability or gravity collapse. Hence, the attempt is to assess the collapse potential through fragility curves. Current research focuses on fragility assessment of these buildings emphasizing on shear-axial failure using two well-established methods; empirical limit state material versus ASCE/SEI 41-13 recommendations. To this aim, two 2D reinforced concrete models (3 and 5-story) according to typical detail of existing buildings in Iran were modeled using two aforementioned modeling approaches and analyzed under monotonic analysis and incremental dynamic analysis (IDA). In the following, seismic fragility assessment were carried out by means of obtained results from IDA. The results of fragility curves showed that, collapse capacity of buildings modelled by ASCE/SEI 41-13 are more than empirical method and fewer cases can pass the level of safety probability of failure suggested by ASCE/SEI-41.
Civil Engineering
Abdullahi Alao Jimoh; Rauf Rahmon; Sofiyyat O. Ajide
Abstract
This research work examined the reliability of the Nigerian grown Iroko and Mahogany timber species as column materials. The strength and physical properties of these timber species were determined to predict the suitability of the species as structural material. Forty lengths of timber species of 50mm ...
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This research work examined the reliability of the Nigerian grown Iroko and Mahogany timber species as column materials. The strength and physical properties of these timber species were determined to predict the suitability of the species as structural material. Forty lengths of timber species of 50mm x 50mm cross-section were purchased from timber market in Ilorin, Nigeria. The prevailing environmental conditions during the test were 31oC and 64% relative humidity. The properties tested included; air dry density, moisture content and compressive strength parallel to grain of forty test specimens each of lengths, 200, 400, 600 and 800mm done in accordance with the British Standard BS 373(1957). Mean air-dried moisture content for Iroko and Mahogany were 12.09 and 14.81% respectively. Mean density of Iroko and Mahogany were 500.8 and 830.1kg/m3 respectively. The derived continuous equations for design of Iroko column and Mahogany column are σ=〖37.552e〗^(-0.005λ) and σ=〖37.125e〗^(-0.007λ) respectively. The results of the reliability analysis show that Iroko and Mahogany timber species have reliability index of 0.64 and 0.65 for a service life of 50 years, assuming other serviceability conditions are met. This design procedure is distinct and more effective than the usual procedure of classifying compression members as short, intermediate and long using their slenderness ratios.
Civil Engineering
Behtash Amiri; Hamed AghaRezaei; Reza Esmaeilabadi
Abstract
In the current study, the nonlinear behavior of the stiffened steel plate shear wall with diagonal stiffeners is numerically studied. After nonlinear pushover analysis, the finite element modeling results are compared with un-stiffened and stiffened steel plate shear walls, with the horizontal and vertical ...
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In the current study, the nonlinear behavior of the stiffened steel plate shear wall with diagonal stiffeners is numerically studied. After nonlinear pushover analysis, the finite element modeling results are compared with un-stiffened and stiffened steel plate shear walls, with the horizontal and vertical stiffeners. First, a finite element model of steel plate shear wall is developed and validated by using Abaqus software. After assuring the behavior of the boundary elements (beams and columns) and the infill steel plate, the finite element models of the steel shear walls are developed and analyzed using nonlinear pushover method. Steel plate shear wall models are designed according to AISC 341-10 Seismic Provisions. Finally, the obtained results and the behavior of finite element models are compared with each other. The important seismic parameters (initial elastic stiffness, ultimate shear strength, and ductility) are calculated and percentage of changes are discussed. Based on the results, the performance of steel plate shear walls with diagonal stiffeners enhances as compared with unstiffened steel plate shear walls.
