Amirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501A Decision Support Model for Decision Making with the Use of 2-Tuple Linguistic Model in Subcontractor Selection31490710.22060/ceej.2017.11529.5029ENH. R.AbbasianjahromiFaculty of Civil Engineering Department, K. N. Toosi University of Technology, Tehran, IranJournal Article20160410There are various parties in the execution phase of construction projects but contractors have a direct impact on the execution phase. Due to some challenges such as growing complexity, and the need for specific specialties, contractors’ eager to subcontract project’s tasks to other parties is named subcontractors. Regarding the impact of subcontractors on critical success factors of projects, the first step in their management process is the selection of the best subcontractor. The subcontractor selection is a subject, in which uncertainty and vagueness are dealt with in decision-making. In these situations, linguistic terms can help people in expressing their ideas. This paper applied the 2-tuple linguistics computing to work with linguistic terms and use group decision making to mitigate the deviation of<br />experts’ ideas. For further understanding, a numerical example is presented. Also, a consistency test to investigate the accuracy of the model is offered.https://ajce.aut.ac.ir/article_907_621461af90cadfdaf0e8d4cc25129f91.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501Compressive Toughness of Lightweight Aggregate Concrete Containing Different Types of Steel Fiber under Monotonic Loading152297910.22060/ceej.2017.12224.5151ENH.DabbaghUniversity of Kurdistan, Sanandaj, IranK.AmoorezaeiUniversity of Kurdistan, Sanandaj, IranS.AkbarpourUniversity of Kurdistan, Sanandaj, IranK.BabamuradiUniversity of Kurdistan, Sanandaj, IranJournal Article20161205ABSTRACT: The noticeable brittleness of lightweight aggregate concrete limits its vast application. Using steel fibers will improve the disadvantage contrived in this type of concrete. Steel fiber increases the ductility and prevention of brittle failure of the concrete. In this paper, the influence of steel fiber on the ability of lightweight concrete to absorb energy during the response in compression has been investigated. For this purpose, steel fiber ratios of 0, 0.5, 1 and 1.5 percent by the volume of the sample were used. The sample with 0.0 percent steel fiber ratio was used as a reference to be compared with other samples. Two types of steel fibers, including hooked-end and crimped, were used. All of the fine and coarse aggregates were lightweight. The results show that there is no noticeable improvement in the pre-peak energy absorption by adding steel fiber to the composite. The increase of steel fiber ratio changes the shape of the descending branch of the stress-strain curve in compression and increases the<br />compressive toughness of lightweight aggregate concrete. Furthermore, based on the experimental data,<br />the relationship between compressive strength and steel fiber volume fraction was derived.https://ajce.aut.ac.ir/article_979_c32d9bf27a3da7ec8163957080c8628e.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501The Laboratory Study of the Effect of Using Liquid Anti-Stripping Materials on Reducing Moisture Damage of HMA233093310.22060/ceej.2017.12240.5156ENGH. H.HamediFaculty of Engineering, University of Guilan, Rasht, IranJournal Article20161210Liquid anti-stripping materials are the most popular materials used to improve moisture resistance of hot mix asphalt (HMA). In this study, the effect of two types of liquid anti-stripping materials (Wetfix N422 and Wetfix 312) with different percentages on the moisture susceptibility of HMA have been studied. HMA specimens with three types of aggregates (limestone, granite and quartzite) and two types of liquid anti-stripping materials are used in different percentages that are studied by modified Lottman test. In order to evaluate the effect of additive more accurately, 1, 3 and 5 freeze-thaw cycles are applied to the specimens. The results of this study indicate that the impact of additives used leads to the increased proportion of indirect tensile strength (ITS) in dry and wet conditions of HMA. The results of this study indicate that the additives used in this study increase tensile strength ratio (TSR) and the asphalt mixes’ resistance against moisture damage. In this study, the effect of anti-stripping additives in specimens under the wet conditions is more evident at higher freeze-thaw cycles compared to control specimens. In addition, the results show that the specimens prepared with limestone aggregate and Wetfix 312 additives have the highest TSR values.https://ajce.aut.ac.ir/article_933_043c3d7e489c69b48737cc0c92d0f3a2.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501Cost Overruns and Delay in Municipal Construction Projects in Developing Countries313891810.22060/ceej.2017.12189.5163ENG.HeraviSchool of Civil Engineering, College of Engineering, University of Tehran, Tehran, IranM.MohammadianSchool of Civil Engineering, College of Engineering, University of Tehran, Tehran, IranJournal Article20161222Cost overruns and delay are common issues in the construction industry of developing and developed countries. In this article, compared with construction projects in other developing countries, the common causes of the cost overruns and delay in delivering municipal construction projects are discussed. This case study considers municipal construction projects in the city of Karaj, as one of the fastest developing cities in Iran. To meet the objectives of this research, 72 different types of urban roads and building projects are considered. This study shows that small-budget and short-term municipal projects, generally, experience higher cost and time performance. This paper contributes to the construction project management body of knowledge by a comprehensive analysis of cost overruns and delays in delivering municipal construction projects in developing countries. The findings of this study may be used by municipalities, for the realistic strategic planning of their construction projects, especially in developing countries.https://ajce.aut.ac.ir/article_918_1e056d2b0ebd5c878c550da6ac5d3724.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501Optimal Stiffeners Spacing for Intermediate Link in Eccentrically Braced Frame to Increase Energy Dissipation394493210.22060/ceej.2017.12345.5176ENM.MojaradDepartment of Civil Engineering, University of Isfahan, Isfahan, IranM.DaeiDepartment of Civil Engineering, University of Isfahan, Isfahan, IranM.HejaziDepartment of Civil Engineering, University of Isfahan, Isfahan, IranJournal Article20170104In general, the behavior of an eccentrically braced frames (EBF) is dependent on the link member characteristics. An efficient link is designed ductile enough to dissipate energy and to prevent the collapse of the frame. Since the link member is reinforced with stiffeners, in order to improve its ductility and plastic deformation capacity, the details of stiffeners design shall be considered more precisely. The existing relationships for web stiffeners spacing in the provisions are based on the behavior of short links with pure shear, while these relationships are applied for intermediate links with shear-bending behavior as well, without any modification. Recent studies have shown the non-conservative stiffeners spacing for some intermediate links. In this study, an optimization algorithm is presented to find the best arrangement of the intermediate link stiffeners. The objective function is the plastic dissipated energy by link before failure and the design variables are locations of stiffeners. The link is simulated under static cyclic loads with finite element software ABAQUS. The heuristic optimization algorithm has been coded in the MATLAB software to find the optimum solutions. The results show that the dissipated energy before failure can be improved significantly by modification of stiffeners spacing.https://ajce.aut.ac.ir/article_932_d2ed45a52bc0edfa11c2064e9edee8bf.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501An Experimental and Numerical Study on the Effect of Loading Type and Specimen Geometry on Mode-I Fracture Toughness of Rock455499310.22060/ceej.2017.12347.5177ENA.FahimifarDepartment of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, IranR.Heidari MoghadamDepartment of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, IranJournal Article20170104ABSTRACT: As fracture toughness (KIC) is one of the most practical parameters in fracture mechanics of rock, this article aims to investigate this parameter both experimentally and numerically. In the current research, mode-I fracture toughness of a kind of limestone was investigated by performing Brazilian disc, cylinder direct tension and under bending cubs. Through performing some tests on straight notched Brazilian disc specimen (SNBD), the effect of specimen diameter and crack length on the rock mode-I fracture toughness was investigated. Moreover, in order to determine the effect of the loading type on the mode I fracture toughness; two other tests were conducted on the cylinder direct tension specimens and cubic specimens (DT and SENB). Then, the effect of the crack length and the specimen diameter on the rocks mode-I fracture toughness was investigated through conducting the statistical analysis of variance (ANOVA) on the results obtained in DT and SNBD tests. In order to determine the required<br />parameters of DT and SNBD specimens for fracture toughness, finite-element software was used. The results showed that by increasing the diameter from 75 mm to 95 mm, for Brazilian disc specimens the average fracture toughness increases by 30%. Also it seems that factors such as the test and loading type as well as the crack geometry can affect the fracture roughness parameter.https://ajce.aut.ac.ir/article_993_7b13b2203029ed80337f27127a9f1d28.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501The Effect of Alkaline Activator on Workability and Compressive Strength of Alkali-Activated Slag Concrete5560101810.22060/ceej.2017.12375.5190ENK.BehfarniaDepartment of Civil Engineering, Isfahan University of Technology, Isfahan, IranH.Taghvayi YazeliDepartment of Civil Engineering, Isfahan University of Technology, Isfahan, IranM. B.Khalili KhasraghiDepartment of Civil Engineering, Isfahan University of Technology, Isfahan, IranJournal Article20170106In this study, experimental results on alkali activated slag (AAS) concrete was assessed to achieve the optimum strength and workability. The alkali contents of Na2O to activate slag in concrete were equal to 3.5, 4.5, 5.5, 6.5 and 7.5 % by mass of slag and silicate moduli of alkali solution varied from 0.45, 0.65, 0.85 and 1.05. The compressive strength test of concrete specimens over 7, 28 and 90 days was measured. To evaluate the concrete workability, the slump of fresh concrete and the setting time of paste were also examined. The results showed that in the proposed range of activation, by increasing the amount of alkali concentration as well as silicate modulus in activator solutions, the workability and compressive strength increased but the setting time of paste reduced. Optimum values for the preparation of AAS mixtures with suitable compressive strength and desirable workability are suggested based on the results.https://ajce.aut.ac.ir/article_1018_ef50c335cca9f340bde656363ebd02fd.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501The Effect of Bio-Deposition on Mechanical Performance of Cement-Based Materials616692610.22060/ceej.2017.12378.5192ENA. A.RamezanianpourConcrete Technology and Durability Research Center, Amirkabir University of Technology, Tehran, IranV.BokaeianConcrete Technology and Durability Research Center, Amirkabir University of Technology, Tehran, IranM.BagheriConcrete Technology and Durability Research Center, Amirkabir University of Technology, Tehran, IranM. A.MoeiniConcrete Technology and Durability Research Center, Amirkabir University of Technology, Tehran, IranJournal Article20170107ABSTRACT: Applications of concrete are expanding rapidly all over the world, in a way that approximately<br />7% of the entire CO2 emit into the atmosphere by human pertains to the interventions made to nature in order<br />to produce concrete. Hence, the need for producing types of concrete that are more compatible with sustainable<br />development is felt more than ever. Finding novel methods for making cement-based materials to reduce<br />cement consumption and the resulting pollution are of great importance among researchers. Improving the<br />properties of these materials using microbial calcite sediments is an environment-friendly technique with an<br />acceptable performance. To improve the compressive strength of cement mortar, microbial calcite sediments<br />produced by Bacillus Subtilis and Sporosarcina Ureae bacteria types were used in this study. Recent studies<br />were also investigated in this paper. To examine the effect of the culture environment, two general designs<br />(with and without extra urea) with different concentrations of zero to 106 cells per milliliter were developed.<br />Moreover, to study the effect of the curing method, two processing curing schemes (in distilled water and in<br />a mineral-containing nutrient environment) were considered. The results show the proper effectiveness of this<br />method, in a way that up to 35% increase in the samples’ compressive strength may be observed depending on<br />bacterium type and curing method.https://ajce.aut.ac.ir/article_926_cbb6a3b884f4f88b3a8e3d44c636cbd8.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501Evaluation of Damage Indicators of Weld and Cyclic Response of Steel Moment Frame Connection Using Side Stiffener Plates677694310.22060/ceej.2017.12351.5200ENM.RaftariDepartement Of Civil Engineering, Faculty Of Engineering, Khoramabad Branch, Islamic Azad University, Khoramabad, IranR.MahjoubDepartement Of Civil Engineering, Faculty Of Engineering, Khoramabad Branch, Islamic Azad University, Khoramabad, IranA.HekmatiDepartement Of Civil Engineering, Faculty Of Engineering, Khoramabad Branch, Islamic Azad University, Khoramabad, IranJournal Article20170110ABSTRACT: The beam to column connection with side stiffeners in steel moment frames is a moment resisting connection. This type of connection is able to reduce the damage caused by seismic loads. It also has the capability to increase the rate of energy absorption. Moreover, the plastic joints in the base beam significantly reduce the failure of the connection components, including connection region plates, welding, column, etc. In this paper, after introducing the damage indices, the indices were extracted and compared in the weld of the components of connection under cyclic loading. Then, the hysteresis behavior of the connection was examined. For this purpose, modeling was done using finite element method by considering the effects of large deformations. The effects of changes in the thickness of top flange plate, presence or absence of the stiffener plates inside the column and the column thickness changes on the damage indices of the weld of different parts of the connection were studied. Finally, the effect of variations of aforementioned components on the hysteresis parameters of the connection was examined and compared. The results of the present study showed that the variation of the components of connection leads to dramatic changes of a number of damage indices and thereby hysteresis parameters, including the rate of energy loss. As a result, the potential for damage failure may vary.https://ajce.aut.ac.ir/article_943_2f885d0fbe2e131bfc9d98363e55d1d4.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) Contamination in Surface Soil along Tehran-Semnan Road, Iran778691910.22060/ceej.2017.12380.5204ENA.KhoshandFaculty of Civil Engineering, K.N. Toosi University of Technology, Tehran, IranB.TabiatnejadSchool of Engineering, University of British Columbia, Okanagan, British Columbia, CanadaS.SiddiquaSchool of Engineering, University of British Columbia, Okanagan, British Columbia, CanadaH. R.KamalanDepartment of Civil Engineering, Pardis Branch, Islamic Azad University, Pardis, IranA.FathiFaculty of Civil Engineering, K.N. Toosi University of Technology, Tehran, IranJournal Article20170111ABSTRACT: The objective of the current research is carrying out the evaluation of the distribution,source, and environmental health risk of polycyclic aromatic hydrocarbons (PAHs) compounds in soil samples taken from the vicinity of Tehran-Semnan road, Iran. This road is a densely populated one in central northern part of Iran with a heavy load of vehicular traffics and several industrial complexes. Four different sampling sites (S1 to S4) were selected in the studied area and then a concentration of 16 PAHs compounds in taken soil samples were measured by High-Performance Liquid Chromatography (HPLC). Total PAHs concentrations varied significantly from 148.4 ng g-1 to 721 ng g-1. The Siman-e Tehran (S1) site has the highest average total PAHs concentrations (654.55 ng g-1) and Dehenamak (S4) has the lowest average total PAHs concentrations (168.7 ng g-1) among the studied sites. The obtained total PAH concentrations in the studied soil samples are relatively lower than those reported in the literature for similar areas. The diagnostic ratios of fluoranthene to pyrene (Flu/Pyr) and phenanthrene to anthracene (Phe/Ant) were used to determine the petrogenic and pyrogenic sources of PAHs, respectively. The derived results indicated that PAHs contamination in the majority of studied soil samples was caused by both petrogenic and pyrogenic process.https://ajce.aut.ac.ir/article_919_3e89ebdb49f712c7d90d1b39e348bbbf.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501Effect of Rotational Components of Strong Ground Motions on the Response of Cooling Towers Based on Dense Array Data (A Case Study: Kazeron Cooling Tower)8792100910.22060/ceej.2017.12687.5249ENG. R.NouriDepartment of Civil Engineering, Kharazmi University, Tehran, IranS.BararniaDepartment of Civil Engineering, Kharazmi University, Tehran, IranJournal Article20170323ABSTRACT: The effect of earthquake rotational component (torsional and rocking ones) on the structures,<br />has attracted the attention of many researchers in recent years. The impact of the rocking and torsional<br />components of the ground motion, particularly on high-rise and height-wise irregular structures, is significant. In<br />this paper, the rotational components of earthquake record were computed employing the acceleration gradient<br />method, using the data obtained from a dense accelerometer array, and the behavior of the cooling towers under<br />the influence of these rotational components was investigated. To this end, three distinct loading combinations<br />were applied to the tower, and the results were examined and compared. The loading combinations include<br />1) three translational components of earthquake record, 2) applying rotational and translational components<br />of the earthquake simultaneously, and 3) applying translational and rocking components concurrently. The<br />response of the tower under the two latter loading combinations was compared with that of the first one. The<br />results indicate that in the case of simultaneous action of translational and rocking components, displacements<br />and support reactions, on average, increase by 5% in comparison with the case of applying solely translational<br />component. Furthermore, including the torsional component, in addition to the rocking one, leads to a rise of<br />nearly 6% in the displacements and supports reaction in comparison with the first loading combination results.https://ajce.aut.ac.ir/article_1009_31b3b31a1c2f8a370206f111127c0dbd.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-28991120170501An Investigation on Biological Treatment of Sandy Soil93100103710.22060/ceej.2017.12225.5152ENM .KhaleghiDepartment of Civil Engineering, Isfahan University of Technology, Isfahan, IranM . A.RowshanzamirDepartment of Civil Engineering, Isfahan University of Technology, Isfahan, IranJournal Article20161205ABSTRACT: Due to environmental problems of desert expansion as well as dust storms, looking for more<br />efficient and comprehensive methods to stabilize dune sands seems to be an essential necessity. Microbialinduced<br />CaCO3 precipitation (MICP) is an innovative technique that harnesses bacterial activities to modify<br />the physical and mechanical properties of soils. This method produces calcium carbonate precipitation in<br />the soil pores by fracturing urea in the presence of calcium ions. An important factor in achieving uniform<br />calcite deposition (and hence consistent enhancement of geotechnical properties) throughout the treated soil<br />mass is the protocol adopted to inject the reagents of ureolytic bacteria, urea, and calcium. In this study, an<br />urease microorganism was prepared in the laboratory and injected into cylindrical dune sand samples. After<br />required and appropriate curing time, the samples were subjected to unconfined compression and fallinghead<br />permeability tests. The test results showed a significant strength improvement and the reduction of<br />permeability of the treated samples in comparison with those of untreated soil. The research results verified the<br />capability of the biological treatment of dune sand which may be regarded as a potential technique to control<br />desert expansion and dust storms.https://ajce.aut.ac.ir/article_1037_eddb904a6db773755d2857aacadb1cb0.pdf