فهرست مطالب

Scientia Iranica - Volume:27 Issue: 1, 2020
  • Volume:27 Issue: 1, 2020
  • Transactions on Civil Engineering (A)
  • تاریخ انتشار: 1399/01/18
  • تعداد عناوین: 14
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  • Rajat Saxena, Trilok Gupta, Ravi K. Sharma, Sandeep Chaudhary, Abhishek Jain Pages 1-9
    Plastic waste is a silent threat to the environment, and their disposal is a serious issue. To sort out this issue, many efforts were made to reuse the plastic waste, but no significant results were achieved. On the contrary, concrete being the widely used construction material is facing problem due to unavailability of ingredient material (sand and coarse aggregate). In this study PET (polyethylene terephthalate) aggregates manufactured from the waste un-washed PET bottles in shredded form were used to partially replace fine aggregate and coarse aggregate in concrete in various percentages (0%, 5%, 10%, 15% and 20%). Various tests like workability, compressive strength, flexural strength, water permeability, abrasion resistance, dynamic and static modulus of elasticity were performed. The micro-structural analysis of the specimens was carried out using an optical microscope. It was found that the workability, compressive strength, flexural strength, dynamic and static modulus of elasticity decreased with the increasing amount of PET waste in concrete. Water permeability of concrete was found to increase with increasing amount of PET waste. In both the cases, i.e., when fine and coarse aggregates were replaced with PET waste, an improvement in the abrasion resistance of concrete was found.
    Keywords: PET waste, static modulus of elasticity, dynamic modulus of elasticity, abrasion resistance, water permeability, microstructure
  • Nader. K. A. Attari *, Narges Azadvar, Saeid Alizadeh Pages 10-24
    Due to the growing popularity of Reinforced Concrete column with Steel beam (RCS) moment frame system in recent years, there are lots of publications about the performance of this structural system. In this paper, fifteen RCS joints with practical details are studied using a verified finite element method. Joint details of the models include Cover Plate, Additional Bearing Plate, Steel Doubler Plate, and joint stirrups. The results show that Cover Plate can be used instead of a combination of steel doubler plate and joint stirrups; it improves the joint performance by increasing the confinement of joint region and contributing to joint shear strength.
    Keywords: RCS connections, composite structural frames, Finite Element Method, Cover plate, Steel doubler plate
  • Saied Yousefi *, Keith W. Hipel, Tarek Hegazy Pages 25-40
    A strategic negotiation methodology for managing complex water-related conflicts is presented in order to consider the decision makers' attitudes. The developed approach systematically exploits the Graph Model for Conflict Resolution (GMCR) as an analytical and practical technique, and helps decision makers find the most beneficial outcomes for negotiating their disputes, assuming the competing needs, wants, and attitudes of decision makers. A real case study of a water-related dispute in Iran is used to demonstrate the implementation of the developed methodology and to emphasize the significance of decision makers' attitudes in identifying feasible negotiation outcomes for resolving complex disputes. In fact, the developed attitude-oriented methodology proposes an innovative engineering approach to help stakeholders address a wide range of conflicts, especially in complex water disputes in developing countries where human factors such as attitude play a significant role. The research can also help decision makers with the shortcomings of conventional decision making systems, such as original GMCR, through incorporating attitudes into conflict resolution tools in order to better clarify needs and interests, obtain equilibrium results, and generate more equitable solutions
    Keywords: Systems Engineering, Conflict, Management, Methodology, Graph Model
  • S.M. Dehghan *, M.A. Najafgholipour, H. Hooshangi Pages 41-56
    Concentrically braced frames provide ductility and imparted seismic energy dissipation through yielding of tension braces and buckling of compression braces. In braced frames with chevron configuration, difference of actions in tension and buckled brace results in considerable unbalanced force at brace-beam intersection, which is addressed in modern seismic design provisions. In this paper, effect of flexural capacity of beam to carry this unbalanced force and consequently seismic behavior of braced frame is investigated by finite element analysis. Two-story and four-story chevron braced frames were modeled in ABAQUS software and studied by means of nonlinear cyclic pushover and nonlinear response history analysis methods. Results showed that inadequate flexural strength of the beams reduce lateral stiffness and strength of braced frame significantly as lateral drift increases; therefore, concentration of lateral deformation in one story may cause formation of soft and weak story. Furthermore, seismic behavior of chevron braced frame and two-story X braced frames were compared.
    Keywords: Chevron Braced Frame, Finite Element Method, Nonlinear Analysis, Response History Analysis, seismic behavior, Weak Beam
  • Babak Lashkar Ara *, Masumeh Fatahi Pages 57-67

    The laboratory studies have been carried out in this research. Determining the sensitivity analysis of the Preston tube diameter in shear stress, four Preston tubes with external diameters of 3.2, 3.9, 4.7 and 6.3 mm were used. The aspect ratios of 2.86 to 13.95 were examined. For measuring the pressure difference of the Preston tube a 200 millibar differential pressure transducer with 0.01 accuracy of the original scale was used. Laboratory results demonstrated that Preston tubes with a diameter of 3.9 mm present the minimum difference in the average value of the shear stress resulting from the Bechert and Patel calibration equations. Therefore, using the Preston tube with an optimal diameter, transverse distribution of shear stress in channels bed and wall were determined. The outcome of this part of study is two dimensionless relationships for determining the local shear stress both in the bed and wall. These relationships are a function of the aspect ratio B/H and the bed relative coordinates b/B in cross section and Z/H sidewall. The survey showed that the dimensionless bed shear stress distribution is considerably influenced by the aspect ratio. The transverse distribution of wall shear stress is independent from the aspect ratio for B/H>3.

    Keywords: Shear stress, Preston tube, differential pressure, transducer, Aspect ratio
  • R. Rajabpour, N. Talebbeydokhti *, Gh.R. Rakhshandehroo Pages 68-79
    Meta-heuristic methods have been widely used for solving complex problems recently. Among these methods, JPSO is regarded as a promising algorithm. However, in order to achieve more robust performance, the probability to solve the graph-based problems is modified by changing the jumping nature of this algorithm and a new algorithm called G-JPSO is presented which is evaluated by solving Fletcher-Powell function and optimal control of pumps in water distribution network problems. In addition to reduction of electricity cost and the problem limitations such as minimum required pressure in each node, minimum and maximum height of tanks, should also be considered. Moreover, another limitation was performed on the objective function which includes the maximum times of turning the pumps on and off. In order to determine the pumps optimal operation, an optimization-simulation model based on the optimization algorithms G-JPSO and JPSO is developed. This proposed model is used for determination of optimal operation program of Van Zyl distribution network. The comparison carried out between the results of our proposed algorithm and those of the similar algorithms including ant colony, genetic and JPSO shows the high ability of the presented algorithm in finding solutions near the optimal solutions with reasonable computation costs.
    Keywords: optimization, pumping station, operation, water distribution networks, G-JPSO
  • S.A. Abtahi, A. Hajiani Boushehrian * Pages 80-87
    This paper studies the behavior of circular footings placed on the gasoil and kerosene-contaminated soil. The ultimate objective of this study is to determine the effect that oil contamination has on the sand bearing capacity. The contaminated sand layers were mixed with different levels of between 1 and 4 percent of gasoil and kerosene contamination. The influence of the contamination depth and type of contamination was examined in this study. Laboratory tests were conducted on small scale models and performed in load-controlled manner. The results showed that the contamination can influence the load-settlement curves and lead to a reduction in its load-bearing capacity. An increase in the depth and percentage of contamination decreased the bearing capacity. Some formulas have been provided in which by knowing the depth and percentage of contamination one can predict the third bearing capacity factor of a circular foundation
    Keywords: oil contamination, Bearing capacity, Load- settlement curve, Circular footings, Laboratory studies, Numerical analysis
  • Majid Barghian, Saeed Khaki Khatibi *, Masoud Hajialilue Bonab Pages 88-104

    The change in the deck length under temperature load affects the upper part of integral bridge abutments and causes abutments rotation. The deck contraction makes the abutment move away from the backfill and causes a failure wedge. To prevent the failure wedge, a new method has been proposed. In this method, the inhibition of integral bridges under contraction is done by cables connected from each abutment to the buried piles outside the bridge along the abutments. In the analysis, the behaviour of soil around the abutment and buried piles is an important parameter which has a great influence on the results. In this paper, the soil behaviour around a laterally loaded stub abutment and buried piles was studied on laboratory stub abutment models using the PIV (particle image velocimetry) method. The PIV analysis was carried out to obtain the deformation pattern and shear strains of the soil around the stub abutment and buried piles. The effects of piles number and soil – pile interaction on the soil deformation pattern were investigated. The results showed that the use of buried piles connected by the cable avoided creating a failure wedge in the backfill.

    Keywords: Soil behaviour, stub abutment, integral bridge, buried piles, Soil-structure interaction
  • M. Hajiazizi *, E. Nemati, M. Nasiri, M. Bavali, M. Sharifipur Pages 105-116
    Utilization of numerical and analytical methods to stabilize earth slopes applying piles or stone columns is subject commonly discussed by numerous researchers. Various researchers have practiced optimization of the location of pile or stone column, to stabilize earth slope through numerical and analytical approaches. Their efforts have led to various results raising the question of what the optimal place for installation of a pile or stone column is. It is look like that no experimental studies are conducted in this regard; the point which is discussed in this article. Experimental study conducted in this article is new topic and it can solve the problem caused by varying and sometimes contradictory results of numerical analyses to find the optimal pile (or stone column) location. In this article, an experimental study is conducted for two-layer sand earth slope, which is saturated through precipitation and failure after saturation over time. Installing stone columns in different locations and saturating the earth slope through precipitation, rational acceptable results were obtained that can appropriately assist designers. All of the experimental models were modeled and compared using the 3D finite difference method (3D FDM), which are compliant with each other.
    Keywords: Stabilization, Sand slope, Stone column, optimal location, Experimental test
  • Ha Sung Kong * Pages 117-121

    Fire alarm systems are essentially installed in specific firefighting equipment and serve as one of important alarm equipments which senses fire early. The main goal of the study is to find methods for improving the structure of fire alarm needs. This study is about false alarms of fire indicating equipment in fire alarm systems. It is found that false alarms false alarms by fire alarm systems are constantly occurring and fire safety manager is neglecting his duty of work by turning alarm bell stop switch on even during usual times. To prevent this, the alarm bell stop switch should be changed into an automatically resettable manual operation type so that it can automatically reset to its original state even though fire safety manager turns the switch on. As a result, aid in correcting fire safety managers' wrongful practices by making the alarm bell ring whenever an actual fire occurs, and ultimately reduce false alarms by eliminating fundamental causes when false alarms occur.

    Keywords: fire indicating equipment, automatically resettable manual operation type, meta-analysis, fluorescence attenuation, false alarms
  • Hosein Naderpour *, Arian Kiani, Ali Kheyroddin Pages 122-133
    To design a proper structure against earthquake in modern systems, control systems are of special importance. Added passive tuned mass damper is one of such systems which will be discussed in this paper. In this regard, the effect of adding this damper to a 10-floor concrete structure under six near-fault earthquakes is investigated. To do this, a code has been written in MATLAB which receives ground motion record of the occurring earthquake as well as the structure specifications such as matrix of mass, stiffness and damping as an input. As output, it presents time-history of responses for top floor, a diagram for the floor displacement and drift of the structure at the time that the top floor has reached the maximum displacement. Also, these diagrams are compared both when the added damper is present and absent. It is observed that the added passive control of TMD is highly effective in the reduction of structure response against earthquake which in turn depends on the properties of the earthquake and therefore should be chosen based on the site seismic conditions.
    Keywords: Structural Control, Tuned Mass Damper, Passive, Near Fault Earthquake
  • SeyedRohollah Hoseini Vaez *, Zahra Minaei Pages 134-158

    Considering the devastating effects of near-fault earthquakes, seismologists and engineers have, qualitatively and quantitatively, represented the strong velocity pulse of near-fault ground motions using models including physical parameters associated with the wave propagation process. In some mathematical models, the derivation of physical parameters is required to fit time history and response spectrum of the simulated record to the actual record through trial and error process, which limits the scope of these models. In the current study, the particle swarm optimization (PSO) algorithm is replaced with the trial and error procedure. In this way, an automatic and quantitative process with the minimal judgment of the analyst is prepared to extract a wide range of pulselike records. Then, the proposed approach is applied to simulate and represent mathematically a set of 91 pulselike records from the Next Generation Attenuation (NGA) project ground motion library. The obtained results show that a velocity pulse of each pulselike record could be extracted using the proposed approach, and it can therefore be considered as a powerful tool in pulse parametric studies and the relationship between velocity pulse and structure’s response.

    Keywords: Pulselike records, Mathematical simulation, Velocity pulse, particle swarm optimization, Penalty function
  • Ameen Ameen *, Zainah Ibrahim, Faridah Othman, Zaher Mundher Yaseen Pages 159-176
    In turbine practice engineering, draft tube downstream running under extreme water flow pressure and velocity. This is causing a vibrations and pressure variation during different operation frequencies. The practical challenge of obtaining a stabilized water flow is ongoing domain of research. In this paper, a proposition of initiating submerged weir in the downstream of draft tube reaction turbine is inspected. The main goal of this research is to reduce the water flow pressure variation, velocity and shear distribution in accordance to the upstream water level influence. Two types of turbines including vertical Kaplan and Francis turbine units are examined. ANSYS CFX software tool is used to build three-dimension (3D) numerical models for the Kaplan and Francis turbines with building a submerged weir at the outlet of the draft tubes at three deferent height suggestions. The influence of the proposed submerged weir is studied the flow through these turbines by considering the dimensions of their components including the penstock with inlets, spiral casing, shafts and blades, and the draft tube with outlets. The findings of this research were tremendous proposition to solve the problem of negative pressure pulsation in draft tube of Kaplan and Francis turbines types.
    Keywords: Numerical fluid analysis, hydropower sustainability, water pressure, velocity, submerged weir, reaction turbine
  • A. Kaveh *, Yasin Vazirinia Pages 177-201
    Smart-home energy-management-systems (SHEMSs) are widely used for energy management in smart buildings. Energy management in smart homes is an arduous task and necessitates efficient scheduling of appliances in buildings. Scheduling of smart appliances is usually enmeshed by various and sometimes contradictory criteria which should be considered concurrently in the scheduling process. Multi-criteria decision-making (MCDM) techniques are able to select the most suitable alternative among copious ones. This paper tailors a comprehensive framework which merges MCDM techniques with evolutionary multi-objective optimization (EMOO) techniques for selecting the most proper schedule for appliances by creating a trade-off between optimization criteria. A Multi-Objective Ant Lion Optimizer (MOALO) is tailored and tested on a smart home case study to detect all the Pareto solutions. A benchmark instance of the appliance scheduling is solved employing the proposed methodology, Shannon’s entropy technique is employed to find the objectives’ corresponding weights, and afterward, the acquired Pareto optimal solutions are ranked utilizing the Evidential Reasoning (ER) method. By inspecting the efficiency of every solution considering multiple criteria such as unsafety, electricity cost, delay, Peak Average Ratio, and CO2 emission, the proposed approach confirms its effectiveness in enhancing the method for smart appliance scheduling.
    Keywords: Building energy management system, Multi-objective Ant Lion Optimizer, Demand side scheduling, Multi-criterion decision-making, CO2 emission, Evidential reasoning