نشریه مهندسی عمران مدرس
سال هجدهم شماره 1 (فروردین و اردیبهشت 1397)

Solidification and stabilization of heavy metal contaminants is recognized as the technology to prevent transfer of contaminants to the lower layers of soil and groundwater. A noticeable increase in distribution of heavy metal contaminants in recent years highlights the importance of effective methods for engineering disposal of industrial wastes. The most important challenge ahead of this endeavor is perhaps the determination of right framework and mechanism of action. Precise mechanism of mobility of contaminants can be grasped by gaining accurate and comprehensive understanding about system behavior and evaluating it from the nano- and micro-structure perspectives. Nano- and micro-sized clay particles can be used effectively as adsorbents of many contaminants (e.g. heavy metal ions and organic compounds) in sewage and wastewater. Moreover, as clay soils have high cation exchange capacity (CEC), they provide appropriate conditions for cation exchange and create considerable capacity to retain heavy metal contaminants. In spite of conducting extensive studies on stabilizing contaminants by the use of cement, inadequate attentions have been paid to microstructure study of interaction process of clay particles, heavy metal ions, and cement, specifically in cement hydration process in different time intervals. Based on this, the present research aims to study the interaction process of clay particles, heavy metal contaminants, and cement over time from the perspective of microstructure. This include the investigation of the effect of presence of heavy metal on cement hydration process and formation of nano-structure calcium silicate hydrate (C-S-H).
Material and In this study, the behavioral tests were conducted on natural clay soil collected from the Qazvin Plain, Iran. The purpose of this selection was to determine geotechnical-environmental properties and contaminant adsorption-retention capability of samples of natural clay with average specific surface area and CEC and the effects of natural clay on the solidification and stabilization process. The majority of experiments of this study were conducted based on ASTM standards and geotechnical-environmental test guidelines of McGill University (Canada). Density and pH of clay samples were determined in accordance with ASTM, D854 and ASTM, D4972 standards. Soil carbon content was determined by titration. Specific surface area (SSA) of the soil was measured using EGME solution. The cation exchange capacity (CEC) of the soil was determined using 0.1 M barium chloride solution. Meanwhile, different concentrations of heavy metal contaminant (zinc) and different percentages of Portland cement were added to natural clay. The interaction process was analyzed experimentally by examining pH changes and evaluating microstructure study (XRD).
Result and According to laboratory results obtained in this study, the high specific surface area of C-S-H nanostructure improves the adsorption characteristics and leads to better filling of pores. It also improves the retention capability by decreasing the mobility of heavy metal contaminants via encapsulation of their ions (solidification). The results show that formation of C-S-H nanostructure improves absorption features due to high specific surface area and decreases mobility of the heavy metal ions through their encapsulation (solidification). In addition, the presence of the heavy mental contaminant (zinc) reduces formation of C-S-H nanostructure so that the presence of 25 cmol/kg-soil of heavy metal ion (zinc) decreases peak intensity of C-S-H nanostructure about 160 CpS.

Dual system of. moment frame and steel sheer wall is interesting to researchers for the good performance in absorbing lateral forces such as earthquakes and for this reason used in normal and high-rise buildings in earthquake-prone countries is used. This system, has many advantages in comparison with the conventional lateral load systems. Some advantages of steel plate shear walls rather than the other systems could be mentioned as: High ductility, strength and stiffness. Being new to this system in terms of seismic performance and functional levels and uncertainty in the seismic characteristics of the other side has created dispersion in the results of previous research.
Evaluation and comparison of seismic performance of dual steel plate shear wall system is subject to far-fault ground motions is the aim of this study. To gain the aim, a four story frame with 14m in height is selected in 4-storey building with a height of 3.5 meters per floor. This building loading according to 2800 standard ad seismic design by AISC360-10 cod and AISC Design Guide 20. To verify the finite element model was used to model the driver and co-workers.
The entire infill plate and boundary elements were using shell elements. The fundamental period of the structure T was estimated 0.39 s. Twenty real earthquake records have been used far-fault acceleration with a magnitude 6 to 7.5 on the soil type II for Incremental dynamic analysis with nonlinear behavior in geometry and material specimen. The real earthquake records which represented a scenario of the probable earthquakes have been gradually increased in their intensity and applied to the frame steel plate shear walls to specify the Seismic behavior. An engineering demand parameters which appropriately characterizes the seismic response of the dual steel shear wall system and its related damage is selected. The IDA curves have been drawn for two Intensity measure the 5%-damped first-mode spectral acceleration Sa (T1; 5%) and Peak ground acceleration PGA and max inter-story drift ratio as an engineering demand parameter. each records were applied to the models incrementally by equal steps of 0.1 for IM and max inter-story drift ratio was obtained from the numerical results.The dispersion of the results by the standard deviation obtained for both intensity measured. Two seismic performance level immediate occupancy (IO) and Collapse Prevention (CP) were evaluated by conceptual definitions, Research and von Mises stress. The following dependence results were evaluated on the characteristics of records based on the frequency content of Acceleration and duration of acceleration.The finite element analyses show that the Damage Index in the elastic stage until the Instability a considerable dispersion of the results for different records. Frame at IO performance level show elastic behavior and a quick return to the original state structures and stiff behavior see and there were no fixed displacement but at CP performance level after a few seconds the system into the fixed displacement behavior. In dual steel plate shear wall system the first floor wall plate the most energy absorption through surrender among the other floor.

Reduction of social and financial losses and rehabilitation in important buildings as a result of terrorist attacks and accidental blast is vital. In this regards, using concrete slabs as a protective shield is one of the main methods of protection. Currently, many methods have been used for improve the behavior of this element such as FRP sheets, fibers, high strength concrete and composite concretes. Using these methods is not favorable due to several reasons such as: increase the dead load of structure, increase the cost of project, employ high-tech methodology and needed high skilled worker for implementation. Therefore, for ordinary projects and households, these methods may not cost effective and a simple and more cost effective method needed to be implemented. In this paper, the behavior of RC slabs reinforced with steel wire mesh which is easy to implement and cheap was studied analytically under blast loads. To this goal, effect of different parameters such as number of wire meshes, slab thickness and concrete strength on maximum slab displacement, damage areas and performance of slabs were studied numerically. First the model was built in general FEM software and calibrated to existing experimental and analytical studies. Then numerous slabs with different thickness (40, 60 and 80 mm), concrete strength (30, 40 and 50 MP), different layers of wire mesh (0, 1, 2, 3) where considered and analyzed with a general FEM software. The results have shown that increasing of slab thickness, concrete strength and adding different layers of wire mesh reduces the slab displacement and the damage area. Due to higher damage in thin slabs (4 Cm) and low concrete strength (30 MP), the effect of adding wire were higher. Generally, the slab thickness is the most important parameter in controlling the damage in the salbs under blast load, but increasing the concerete strength and adding different layer of wire mesh, reduced this damages. From the viewpoint of slab performance, which is defined by the amount of displacement and plastic rotation of hinges, it is observed that the performance of thicker slabs (60 and 80 mm) were in the life safety or immediate occupancy state which is quite good for ordinary purposes. Using wire improved the performance of these slabs. In the thinner slab (40 mm) the performance of slab with concerete strength of 30 MP, was not satisfy the life-safety requirement, therefore it is needed to improve this performance. The result of analysis were shown that adding different layer of wire mesh improve the performance of the slab and limits that. Although different layer of wire mesh did not have significant effect on improvement of the slab performance, it limits the performance of slabs to the code’s value in several occations. Generally, it can be concluded that adding the wire mesh could reduce the amount of damage to the slabs under blast loads, which was expected results, but this reduction, is not that much significant for many occations. This method is more effective in thin slabs with lower concerete strnght.

Dams are one of the most important structures which are built to prepare water for different usages such as drinking, agriculture, industrial, flood control and hydro power generation. Due to the importance of dams and increasing number of terrorist attack, Stability of dam structures against blast loading is important. Dam responses depend on magnitude of released energy and if the dam structure could not be able to resist and maintain its stability against this energy, irreparable consequences will happen. Explosion is a sudden release of energy which could be like gases combustion, nuclear explosion or any kind of bombs. TNT unit usually used as reference to determine the explosion power. Some of basic properties of an explosion are random location of explosion, transient loading and short time loading (up to few seconds). When blast loading happened, energy will released suddenly and this released energy include thermal radiation and wave scattering in air and earth. The waves which scattered in the air are the main factor to structural damage. These waves move faster than sound wave velocity and impact the structure. Due to reflex from structure surface, the pressure of these waves increased and also some air waves penetrate to structural elements from openings such as doors and windows. This process continues until all available parts of the structure affected by pressure waves. In this research, the effects of blast loading on Karun 4 dam are investigated. To this purpose, dynamic analysis of dam-reservoir-foundation system is performed by finite element model using ABAQUS software. Dam-reservoir-foundation modeled three dimensional in which reservoir length is three times greater than dam height. The foundation modeled as a hemi-sphere with a radius of three times greater than dam height. Non-linear material behavior also considered by using concrete damage plasticity method. The CONWEP theory is used to model blast loading. To verify the blast modeling theory and software abilities, a steel plate which investigated under blast loading in references has been modeled and the results shows same responses with the paper. The responses of dam are investigated under two different reservoir conditions include full and empty conditions. Analysis also done for three different explosion points in three different elevations. Explosion points are near base, mid height of dam and near dam crest respectively. All these points have 10 m distance from dam structure. TNT mass used in each noticed conditions, is the minimum amount of TNT which cause damage in dam body. The results indicate that the responses of the dam is very sensitive to mesh dimensions. The results also show, water level has not great effect on explosive mass which is needed for structural damage of the dam. In both full and empty reservoir conditions, when explosion happened near the dam crest, the displacement is more than other cases. It is noteworthy that when the explosion happened near the crest, the maximum displacement of the crest and the point in front of the explosion point, occur in same time but when the explosion point is in middle and also near the base, theses displacements are not in same time.

Data showed that by increasing the adsorbent dose, the availability of sorption sites eased resulting in greater percentage removal of the dye. The percent adsorption increased with increased contact time. Maximum quantitative removal of MB from an aqueous solution was obtained in 10 min for GFP contact time. The pH of an aqueous solution is an important factor in dye adsorption, as it affects the surface charge of the sorbent material and the degree of ionization of the dye molecule.The effect of pH on the amount of MB adsorbed onto fruit pulp was investigated over the pH range from 2 to 12. amount of dye adsorbed per unit mass of the adsorbent increased with increase in the initial concentration up to 25 mg/L. The When the of the solution was 2-6, the sorption of methylene blue was slightly weaker than at pH 6-12 due to poor dissociation of carboxyl Groups. The qe was found to increase with increasing pH. Optimal pH was determind 9. This can be on the basis of a decrease in competition between positively charged H and MB for surface sites and also by decrease in positive surface charge on the adsorbent, which results in a lower electrostatic repulsion between the surface and MB. SEM is one of the useful tools to examine the surface morphology of the biosorbent the SEM micrograph shows that the surface of GFP was porous.FTIR analysis showed that the main functional sites taking part in the sorption of MB included carboxyl and hydroxyl groups. Adsorption data are most commonly represented by the equilib-rium isotherm value, which is a plot of the quantity of the sorbate removed per unit sorbent (qeq) as the solid phase concentration of the sorbent against the concentration of the sorbate in the liq-uid phase (Ceq). The equilibrium isotherm value is of fundamental importance for the design and optimization of the adsorption sys-tem for the removal of a dye from an aqueous solution. Therefore, it is necessary to establish the most appropriate correlation for the equilibrium curve. Several isotherm models have been used to predict validity of the experimental data. The Langmuir isotherm is based on the assumption of monolayer adsorption on a structurally homogeneous adsorbent, where all the adsorption sites are identical and energetically equivalent, wherein the adsorption occurs at specific homogeneous sites within the adsorbent, and once a dye molecule occupies a site no further adsorption can take place at that site. The results indicate that the data for adsorption of dye (R2= 0/9738) fitted well with Langmuir isotherm. Studies suggest that GFP can be effectively used as a cost-effective adsorbent for removal of MB from aqueous solution. Batch adsorption studies show that removal is dependent upon process parameters like pH, sorbate and sorbent concentrations and contact time. The experimental equilibrium sorption data obtained from batch studies at optimized conditions fit well to Langmuir adsorption isotherm equation, indicating monolayer adsorption. FTIR analysis showed that the main functional sites taking part in the sorption of CV included carboxyl and hydroxyl groups. The number of experiments decreased of 256 to 64 by Taguchi method. Based on this that many textile industrial waste waters have an alkaline pH(8-12),this adsorbent can be used instead of effective compound. The present work shows that GFP is an efficient sorbents for the removal of methylene blue from aqueous solution and it may be an alternative to more costly sorbents such as activated carbon. The Taguchi method was efficient manner for optimizing process.

The staggered-truss system has been proposed as a lateral load resisting system in the structural steel framing for high-rise buildings, which was developed in Massachusetts Institute of Technology in 1960s. The system consists of a series of storey-high trusses spanning the total width between two rows of exterior columns and arranged in a staggered pattern on adjacent column lines. the system has the columns only on the exterior walls of the building, the usual interior columns are omitted. Thus, the staggered-truss system can provide a full width of column-free area. In the system, the role of energy absorption and endurance of inelastic deformations is responsible for the special segment of truss, so that the ductility of structure is provided by the development of plastic hinges in this region. Although, in the special segment of truss an opening near the center of span must be provided to permit a width and height of sufficient proportions which is used as a corridor. Hence, the effects of this opening must be investigated in the performance of this system. In this study, the effects of the special segment length and its strengthening pattern on the seismic performance of staggered-truss system are investigated. In order to achieve this purpose, an 8-storey steel staggered-truss system with a 1/8-scaled studied in work of Zhou et al. [14] is selected and considered subjected to the low cyclic loading. First, the finite element (FE) model of this structure, in which both the material and geometric nonlinearity, is provided in ABAQUS software, and the validation of the model is controlled by experimental and numerical study and of Zhou et al. [14]. The results of modeling this structure show that the FE model of this structure has appropriately accuracy. Then, the seismic performance of the system is evaluated by considering the various lengths of the special segment and the proposed strengthening patterns in the special segment. The results of the evaluation show that the use of special segments with great length make the entire structural capacity is not fully utilized. Hence, when the large opening is required the regions must be properly strengthened. In this study, different patterns of the special segment, including strengthening of chords, strengthening of vertical members of the special segment and the strengthening pattern proposed by the Manual Number 14 of AISC code are investigated. Since the plastic hinges are usually formed at the chords of the truss, the strengthening of chords has the greatest effect on increasing the initial stiffness and strength of structure. Instead of the strengthening of the total length of the chord, a part of both ends of the special segment is also strengthened, so that its performance is as same as that of the strengthening of the total chord. It is noted that the strengthening of the special segment is one of the ways to increase the initial stiffness and resistance structure, but this strengthening must not omit the performance of the fuse in the truss system, and the conditions of strong beam and weak column are provided. Based on the FE analytical results, the suggestions of this study can be considered for the design of staggered-truss system.

One of the appropriate methods to improve the roadway that is built on the weak subgrade is use of geosynthetic reinforcement that was already highly regarded. Geogrid and geotextiles are commonly used as reinforcements in pavement and unpaved systems. Geogrid is a net-like geosynthetic with apertures of sufficient size to allow interlocking with surrounding unbound materials such as soil, rock, and aggregate, and functions primarily as reinforcement. Geogrids also provide restraint to the aggregate and minimize lateral spreading of the base course aggregate when subjected to vehicular loads. Many field and laboratory test conducted to investigate the behavior of reinforced subgrade and achieve to the suitable design methodology has been implemented. Through both laboratory and field studies, it has been shown that the inclusion of geogrids at the interface between the base course and subgrade in unpaved road can improve the performance road by extending the service life or reducing unpaved structural thickness with equivalent performance.However, due to limitations such as high cost of laboratory or field test, evaluate the performance of reinforced roads under traffic loads by numerical simulation methods have been developed. Numerical analysis helps researcher predict performance of road via simulation and also Numerical analysis are capable that with simulation of paved and unpaved road, develop the parametric studies for complex structures such as reinforced subgrade. Finite element method (FEM), discrete element method (DEM), and finite difference method (FDM) are three types of numerical analysis commonly used by civil engineers.In this study, the finite element method (FEM) is used to investigate the behavior of the geosynthetic reinforced roads. Therefore, the three-dimensional model in ABAQUS that has several advantages compared to the two-dimensional model conducted and the results of the 3d numerical study with field tests results in Montana university - Bazmn, is compared, then the effect of reinforcing mechanical properties, elastic module of base layer and reinforced substrate on settlement was evaluated. The performance of the test sections has been evaluated from measurements of rut depth and the results showed that the simulation by finite element method, according to the assumptions used in three-dimensional modeling includes the quasi-static loading and frictional interaction parameters in terms of the contact surfaces, have a good agreement with the results of field test. The effect of geogrid reinforcement was shown to reduce surface deformation, improve stress distribution on subgrade layer, and reduce strain induced at the bottom of the base layer due to lateral spread. FEM results indicated that geogrid reinforcement can provide lateral confinement at the bottom of the base layer by improving interface shear resistance and increasing mean stress at the bottom of the base layer. The numerical study results also show that the settlement of reinforced road strongly influenced by the mechanical properties of reinforcement.With reduce the elastic module of geogrid(50%) the surface settlement about 61 percent increased and also effect the stiffness of subgrade and base layer in reinforced test section on the surface settlement compared to unreinforced test section about 50% reduced. In general, geogrid with higher tensile modulus enhanced the reinforcement effects.

Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases. Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases. Different methods are being used for monitoring of crack growth and failure mechanism in rock fracture. Acoustic Emission (AE) is one the methods used for micro crack monitoring in samples under pressure. Existence of porosity and humidity in rock and soil structure cause different effects on process of micro cracks and growth of micro cracks and finally their fracture. In this study, effects of porosity and humidity in micro crack growth and rock fracture are being analyzed. Four parameters which are highly effective in AE method namely hit, count, wave durability and fracture energy are used. Mortar (synthetic rock) was used to have a constant porosity ratio in samples. Cylindrical samples with 54 mm diameter and 110 mm length with 5 different porosity ratios ranging from 17 to 35 percent were made using Panplast lubricant. Samples were subjected to uniaxial compression test in two dry and saturated conditions and AE data were recorded. Data analysis showed that the dominant failure mode on samples of dry mortar with increasing porosity, increase toward the tension mode. With increasing of porosity and moisture content the numbers of micro crack decreases.

Due to population growth and land scarcity, especially in big industrial cities, many ground improvement projects are required annually for new developments. Moreover appropriate ground improvement techniques are also required to encounter dust storms and desert expansion which are common environmental problems in many countries. Thus looking for more efficient and comprehensive methods in the field of soil improvement seems to be an essential necessity. Although a lot of improvement techniques are in use around the world, they have their own advantages and disadvantages. Chemical, physical, mechanical, biological and electrical techniques may be named as the common methods of soil improvement. Some of the methods, particularly those using cement and other toxic chemical grout, may cause environmental problems which limit their usage. The biological stabilization seems to be a promising technique to control the expansion of dune sand deserts and in turn encountering the problem of dust storms. This paper reports the likely potentials of application of biological treatment on dune sand samples taken from Kerman deserts. As an environmental friendly method, biological improvement presents an innovative, novel technique in which microorganisms present in the natural soil are employed to initiate biochemical processes leading to deposition of calcium carbonate. This procedure bonds soil particles to each other and improves soil physical and strength properties. Microbial-induced calcite precipitation (MICP) is an innovative technique that harnesses bacterial activities to modify geotechnical properties of soils. In microbial-induced carbonate precipitation method, urea is hydrolyzed by bacteria and calcium carbonate precipitate is formed by a network of biochemical reactions. The bacteria acts as a biochemical reaction network controller and so power supply of bacteria is very important. Nutrients needed by the bacteria are CO_2, N, P, K, Mg, Ca, Fe generally. In this research study a hybrid microorganism was prepared in the laboratory and injected into cylindrical sand samples of 100mm length and 47mm diameter. In this context, mixed culture performance was compared with that of single culture bacteria in terms of the treatment efficiency regarding strength enhancement of dune sand samples. Sporosarcina urea bacteria was used as single culture and Sporosarcina urea֧⊖宬 subtilis were used as hybrid culture. Cementation solution by dissolving 1 mole of urea and 2 moles calcium chloride per liter of distilled water were prepared. Unconfined compression test results as an indicator of the strength properties showed that the microbial-induced carbonate precipitation method increases the unconfied strength of samples. Unconfied strength of the improved samples by single and mixed culture were obtained 527. 7 kPa and 771. 8 kPa, respectively, that these amount is 16. 6 and 23 times of unconfied strength of sandy samples. Falling head test results as an indicator of the physical properties showed that the microbial-induced carbonate precipitation method decreases the permeability factor of samples. Permeability factor of the improved samples by single and mixed culture compared to sandy samples has decreased 50. 5% and 60%, respectively. increasing unconfied strength and decreasing permeability factor of improved samples by mixed culture to single culture is for this reason that Bacillus subtilis increases urea hydrolysis rate and the rate of precipitation of calcite. Finally precipitated calcium carbonate has been shown by SEM.

In this study, a baffled photocatalytic reactor was used to treat wastewater containing azo dye. The baffles made of Plexiglas covered by TiO2 nanomaterials placed vertical in the reactor, were used. Using this reactor could enhance in the wastewater passage time, decrease in contact distance due to existence of the colored wastewater and the effect of preventing the passage of UV ray, bring about turbulence in the current, prevent from short circuit phenomenon, increase at the current length, and cause enhancement in effective surface against the relatively low occupancy level that make it possible to construct this kind of reactors in larger scales. The dimensions of the Reactor were 20 cm*25 cm*50 cm and the baffle dimensions used in the reactor were selected 20 cm*12 cm. The photocatalyst particles were fixed on baffles and then the experiments were conducted based on the experimental design by Design Expert software. In order to ensure adequate waste water to pass from the photoreactor, the rotary flow regime was used in the original design. In the research, Methyl orange one of the anionic dyes with the chemical formula C14H14N3NaO3S was used. This azo dye was the kind of amino benzene and has a functional azoic group (-N = N-) and cofactors NaSO3 and now widely used in dyeing textile, wood, paper, leather and printing applications. In order to investigate the effect of the main factors and optimizing colored wastewater treatment process by using TiO2 nanoparticles in the baffled reactor Response Surface Methodology, central composite design (CCD), was used. Based on the results, reducing the pH and initial dye concentration had synergetic effect on color and COD removal simultaneously. The effect of pH less than 5 and less than 75 mg/L concentrations are more rapidly. This phenomenon was a result of amphoteric behavior of TiO2 and the weakening of oxidation ability of the produced holes in alkaline conditions. The pH of the solution influence on how the TiO2 surface is ionized and leads to amphoteric behavior the TiO2 nanoparticles under different conditions and this behavior changes the oxidation ability of the process. Another reason for this phenomenon could be described as the reduction in light penetration due to increased dye concentration in the solution and the more dye adsorption on the surface of TiO2 causes a part of UV energy is absorbed by the molecules of the dye. Although Methyl orange is an anionic dye with the negatively charged sulfonic group thus in high pH, hydroxyl radicals lose the chances of reaction with the trapped dye quickly. At the same time reducing the pH and increasing the reaction time also increases the efficiency of COD and color removal and enhanced for the pH below 4 and after 6.5 hours for dye removal and at pH below 5 and after 8 hours for COD removal. This was due to increased opportunities for photocatalytic activity in acidic pHs reduce the initial dye concentration and increase the reaction time had amplified effect in efficiency of decolorization and reduction of COD. The rate of the phenomena was more obvious for the dye concentration less than 50 mg/L and after 8.5 hours. The results showed that the color removal efficiency was more than COD removal efficiency. The most noticeable reason for this phenomenon is the breaking of the colored azoic bond and producing colorless intermediate products that decrease removal efficiency during tests. The maximum amount of COD and color removal when the 50 mg /L initial dye concentration and at the pH= 5 were 98.81 and 69.7 percent, respectively, after 9.5 hours. The results data comply with reduced quadratic model with a correlation coefficient (R2) 94.95 and 95.30 percent for color and COD removal respectively that validate the model results. Laboratory assessment also indicated that due to the very small difference between the results of the represented model and the experimental data, the model was consistent with acceptable confidence level.

Disposal of Waste materials is a major challenge in each country and the use of plastics materials is increasing every day. A large part of the plastic wastes are bottles of drinks which are made of Polyethylene terephthalate (PET). The reuse of plastic wastes plays an important role in sustainable solid waste management. Plastic waste management helps to save natural resources that cannot be replenished, decreases pollution of the environment and also helps to save and recycle energy production processes. Now a days , PET has been widely used to produce fibers, particles, or lakes to obtain cement-based products with improved properties One transcendental alternative to recycling PET materials consists of using them as substitute of concrete aggregates. Due to demands of technological development in the construction area, the possibility for generating alternative materials that can be applied with increasing functionality, low costs, and better physical, chemical, and mechanical properties than conventional materials is being explored Fiber-reinforced concrete is a composite material resulting from the addition of reinforcing fibers to the brittle matrix of ordinary concrete. The idea of using fiber reinforcement comes from the need to find a remedy to the phenomena of cracking, such as produced by shrinkage, which inevitably affects the service life of concrete buildings. Concrete is a material that is well resistant to compression, but has low tensile strength. The low level of tensile strength is caused by phenomena such as plastic and/or hydraulic shrinkage with the formation of unwanted micro and macro cracks Fiber-reinforced concrete represents the current tendency to apply more eficient crack-resistant concrete. The ability to enhance flexural and tensile performance of the concrete matrix, together with the opportunity for improving its durability, pushed boundaries in developing new materials to be used as fibres. Several studies using reinforced concrete with polymer fibers like polypropylene, polystyrene, polyethylene terephthalate, and polyethylene have evidenced variation of concrete properties according to the nature and size of the aggregate . The level of fibre performance depends strongly on the quality and amount of the employed fibres applied, on their shape and dimensions as well as on their bond to the concrete matrix . One way for recycling and efficient use of PET is adding to the concrete as fibers. Use of PET fibers in concrete will solve environmental problem of this waste material in addition to improvement of mechanical properties of concrete. Research on the use of PET fibres as dispersed reinforcement in concrete and mortars has been ongoing for about a decade with sporadic studies. In this research physical and mechanical behavior of concrete containing recycled PET fiber has been studies. For this purpose 10 concrete mixture, including 1control mixture and 9 pet fiber concrete mixtures were made. Fibers in volume percentage of 0.15%, 0.30% and 0.45% with the length of 1, 2 and 3 cm were used separately. Compressive strength, tensile strength and flexural strength tests were done on the samples. Fibers deformed with deforming machine to improve the adhesion of fiber with concrete. Compressive strength were performed ater 7 and 28 days. The results show that PET fibers increase. Compressive strength and flexural strength of concrete between 5-18% and 6%- 30% respectively. No significant efects on tensile strength were observed with the addition of fibers.

A significant number of concrete structures have been suffered extensive damages during past earthquakes. Since the Northridge (1994) and Kobe (1995) earthquakes, numerous analytical and experimental researches have been undertaken to employ new methods for design and retrofit the seismic resisting concrete structures. Stiffness, strength and ductility are the main parameters in seismic performance of any structure. In general, stiffness and strength are the factors that control structural and non-structural damages; and ductility is a structural characteristic that provides the structure to withstand the inelastic deformations and controls the structural members’ failure. Ductility is the key parameter for earthquake energy dissipation rather than the other effective parameters. It depends on the formation of plastic hinges at the beam ends in concrete structures during an earthquake. Formation of plastic hinges at the beam ends arising from the large displacements causes an increase in the ductility and energy dissipation in moment resisting frames. Although, formation of plastic hinges leads to energy dissipation, but large inelastic deformation results in an increase in the residual displacement of structures. In common reinforced concrete structures, post-earthquake residual strains and displacements play an important role. Therefore, the serviceability of structures may be disrupted after an earthquake and in few cases they need to be re-built. Using Shape Memory Alloy (SMA) materials with the ability of super-elasticity in large strains at beam plastic hinges instead of reinforcing bars reduce residual displacements and deformations. High fatigue and corrosion resistance, ability to regain the original shape after a heat treatment, and high energy dissipation capacity are the advantages of using these material. Also there is no need to replace SMA members after an earthquake. Using shape memory alloy materials in the critical zones of structures such as plastic hinge zones decreases post-earthquake residual displacement, provides serviceability, and prevents the need for destruct or retrofit the structures. One of the most important features of the shape memory alloy materials is the ability to regain their original shape in strains less than 8%. In this paper five concrete moment resisting frames with 3, 5, 7 and 9 stories are modeled and subjected to near-field earthquakes. The amount of damages in the structures that are subjected to near-field ground motions due to the presence of the long-period pulse at the beginning of the record, is more extensive than far-field earthquakes. The non-linear time history analyses have been performed by “SeismoStruct” finite element software. Relative lateral displacement of stories (drift angle), residual relative lateral displacement of stories, lateral displacement of roofs and base shears are investigated. Results showed that using shape memory alloy (SMA) materials instead of steel reinforcing bars at beam plastic hinges reduces the residual displacement of the structure and relative repair cost after earthquake. The relative lateral displacement of stories is increased in the RC frames with SMA. Also residual roof displacements and base shear of SMA RC frames are decreased. In general, the SMA RC frames that are subjected to near-field earthquakes showed desirable performance. It can be deduced that using shape memory materials (SMA) instead of steel reinforcing bars at the beam plastic hinges reduce structural damages.

In signalized intersections and at the onset of the yellow phase, drivers often come across a dilemma situation where they are unable to stop comfortably before the stop line or clear the intersection (without excessive acceleration) prior to the onset of the red signal phase. yellow time is designed to inform drivers about passing time and preventing extreme changes in car's speed in timing of intersections with traffic lights. However, studies have confirmed that drivers face high level of uncertainty during yellow time. drivers visually sample their surroundings while driving so they are able to change their behavior based on other vehicles’ movements, the roadway environment and traffic signal data. This implies that drivers’ behaviors are affected by surrounding factors such as other vehicles’ headway or intersection conditions. In the dilemma zone, drivers’ decisions are influenced not only by their own condition (e.g., distance to the stop line, speed, red time)but also by the surrounding environment at an intersection. The primary goal of the research described here was to develop a comprehensive knowledge of the stopping characteristics of dilemma zone drivers at signalized intersections. Physical, traffic, timing and phasing of intersections and weather conditions are assessed factors. The research performed here involved macroscopic evaluation of driver behavior; thus, characteristics of individual drivers were not investigated as it was not feasible to determine information such as age, experience, route familiarity, and sex of each driver. This study investigates actual data of traffic cameras and central smart program in four intersections in Qazvin in which traffic lights are set up. Peak, normal sunny and rainy conditions and driver's behavior in yellow and red times are studied using binary logit model. A field study was performed using a video-based data collection system to record several attributes related to the behavior of the last vehicle to go through and the first vehicle to stop in each lane during each yellow interval. The researchers concluded that a driver’s decision to stop or go through when presented with a yellow indication is complex but can be predicted reasonably well based on several factors. Pedestrians in streets(Coef.=-0,61241; p-value=0,0177), time passed in red phase(Coef.=-0.53836; p-value=0,0177), and headway(Coef.=-1,89062; p-value=0,0854) are the most effective factors on driver's pauses in yellow or red phase. High speed of cars(Coef.=,172; p-value=0,0087) and also waiting time (red phase) (Coef.=,864; p-value=0,0095) are the most influential factors on drivers motion in yellow or red phases. I addition, in the situations in which drivers distance to intersection is less than one meter at the beginning of yellow phase and speed is higher than 20 m/s, passing probabilities are 74 and 90%, respectively. One of the innovations of this study is evaluating the effect of rain on the behavior of drivers. The results of model show the possibility that the drivers pass the traffic light in yellow or red phase will be increased by rising the amount of rainfall. Our results are able to inform officials about driver's behavior at intersections with traffic lights and facilitate their control and surveillance.

Rainfall Runoff modeling especially in ungauged watersheds is almost dependent on hydro-geomorphologic data. In this regard, the effects of data and DEM resolution on deriving watershed’s geomorphologic data such as subbasins area, channels and subbasins’ slope should be well realized in modeling. In this research, HEC-HMS as the rainfall runoff model and two subbasins with different areas, geomorphologic properties and climate were selected for studying. By reducing the cell size of the DEM derived from a topo map, simulated peaks increased. For DEM cell sizes less than 100 m, the differences in simulated peak were limited to 2 to 5%. Using SRTM DEMs against the topo DEM at the scale of 1:25000, representing the effects of data resolution in rainfall runoff modeling, led to obtaining higher flood peaks at the two watersheds. Such an outcome was obtained for time to peak, hydrograph base time, and the slope of hydrograph rising limb. Change of SRTM DEM resolution affected the model output more than the case of using topo DEM. Decreasing DEMs resolution by decreasing information content of the topo DEM reduced differences in the model output when using two different sources of DEM. Furthermore, it is concluded that the extent of scale effect in modeling could not be inferred by watershed size. It was illustrated that HEC-HMS application in a watershed of more diversity was more sensitive to data resolution. Using cell size of 100 m and less could guaranty the result of the HEC-HMS application regardless of DEM origin and size of watersheds. Rainfall Runoff modeling especially in ungauged watersheds is almost dependent on hydro-geomorphologic data. In this regard, the effects of data and DEM resolution on deriving watershed’s geomorphologic data such as subbasins area, channels and subbasins’ slope should be well realized in modeling. In this research, HEC-HMS as the rainfall runoff model and two subbasins with different areas, geomorphologic properties and climate were selected for studying. By reducing the cell size of the DEM derived from a topo map, simulated peaks increased. For DEM cell sizes less than 100 m, the differences in simulated peak were limited to 2 to 5%. Using SRTM DEMs against the topo DEM at the scale of 1:25000, representing the effects of data resolution in rainfall runoff modeling, led to obtaining higher flood peaks at the two watersheds. Such an outcome was obtained for time to peak, hydrograph base time, and the slope of hydrograph rising limb. Change of SRTM DEM resolution affected the model output more than the case of using topo DEM. Decreasing DEMs resolution by decreasing information content of the topo DEM reduced differences in the model output when using two different sources of DEM. Furthermore, it is concluded that the extent of scale effect in modeling could not be inferred by watershed size. It was illustrated that HEC-HMS application in a watershed of more diversity was more sensitive to data resolution. Using cell size of 100 m and less could guaranty the result of the HEC-HMS application regardless of DEM origin and size of watersheds.

As a result of penetration of water in landfills through precipitations and or by conducting some processes such as size reduction of waste materials as well as biodegradation of materials in composting process, leachate may be produced. High organic loading and containing complex and various compounds introduce leachate as a toxic wastewater and a risk for the environment. With respect to relatively high organic load and existing refractory organic compounds, a single process cannot remove all of the organic matters from leachate. Therefore, to meet discharge standards, additional treatment is required to remove the remaining materials from treated leachate. In addition, Sequencing Batch Reactor (SBR) is a reliable biological treatment applied to eliminate pollutant from leachate and spread in the worldwide. As a result post-treatment of composting leachate via SBR was chosen as the main objective of this study. This study was conducted in laboratory scale and in batch mode. The working volume of SBR reactor was 1.3 L. A complete cycle of SBR is divided into five stages, include to fill, react (mixing & aeration), settle, draw, and idle. The SBR system and duration of five stages were automatically controlled. Sludge bulking is a common problem in biological treatment. For controlling of sludge bulking different parameters such as DO, pH and temperature were adjusted in a fixed range. Furthermore, due to better control of sludge bulking, sometimes H2O2 solution was injected to the reactor. In this study, performance of the SBR system were analyzed according to sludge retention time (SRT) and hydraulic retention time changes. SRT was adjusted to 3, 5 and 7 days and hydraulic retention time was increased from 4 hr. to 6,8,10 and 12 hr., respectively. The leachate samples were collected from the effluent of anaerobic biological reactor of a composting leachate treatment facility in north of Iran. The seed samples were supplied from a wastewater treatment plant in Tehran and acclimatized with diluted leachate. The SBR reactor operated with 1L of leachate and 300 ml of acclimatization seed. The mean initial COD and color were 2000 mg/L and 5.7 Gardner, respectively. Performance of the SBR system was monitored by analyzing the COD and color removal efficiency, determining of MLSS and MLVSS changes and estimating the waste sludge production. In this research, optimum SRT and hydraulic retention time for SBR system were estimated to be 5 days and 12 hours, respectively. Based on the results, the maximum removal efficiency of COD and color in SBR process were estimated to be 90% and 44% respectively, that reduced the initial COD from 2184 mg/L to 215 mg/L and closed to the Iranian standard discharge limits for agricultural purpose. In this process, values of waste sludge production were also analysed respected different hydraulic retention times. The results revealed that by increasing the hydraulic retention time, waste sludge production was decreased. Finally, different kinetic models such as first order, Grau and Stover-Kincannon were examined for the optimal condition. The kinetics studies showed that post-treatment of leachate by SBR processes were in good agreement with the Grau and Stover-Kincannon kinetic models by a correlation coefficient of more than 97%.

Steel-concrete composite beams have been widely used in building and bridge construction since about a century ago. Construction with composite system provides some advantages including: reduction in the weight of steel (saving of 20 to 30%), increasing floor stiffness and increasing span length.In order to analyze such composite beams using the ordinary beam theory, the concept of effective width is used instead of their actual width. Effective width is one of the most influencing factors which plays an important role in determining the ultimate load bearing capacity of steel-concrete composite beams. There are a number of influencing parameters which affect the value of composite beams’ effective width including the ratio between the half width of the slab and the beam length (S/L), the number and rigidity of the shear connectors, the steel section yield strength and the concerte slab strength. There are numerous studies in the literature which have been conducted on the effective width of composite I-beams. However, the steel-concrete composite girders are generally analyzed and designed in current practice (on the safe side) as non-composite steel girders without taking into account the effect of concrete slab, yet. This procedure may lead to an uneconomic design. Although such girders have been widely used in the construction of residential steel building frames, however, their effective with has not been investigated, yet. This paper develops a three dimensional finite-element model using ABAQUS for the elastic and inelastic nonlinear static analysis of steel-concret copmposite girders and uses it to investigate the real effective width of concret slab in these kinds of girders under two types of loadings (a concentrated point load and a uniform distributed load) on their moment gradient factor in different behavioral zones. The concrete slab and steel section were modeled using the three-dimensional eight-node solid element (C3D8). However, the reinforcements were modeled using the Truss one-dimensional elements. To simulate the shear connectors implicitly, the concrete slab and steel girder were joined together with the Tie command available in ABAQUS. To achieve this end, some simply-supported with differet ratios of S/L, and symmetric/unsymmetric adjacent concrete panels were designed first taking into account the effects of secondary perpendicular composite I-beams. Then, considering the actual distribution curve of axial elastic compressive stress within the concrete slab in each model and estimating the area under the curves, their effective width was calculated in different locations along the girders lengths. Furthermore, in order to investigate the effects of concrete slab cracking and damage on the effective width of such composite girders, some of the above mentioned girders were analyzed nonlinearly and their effective widths were recalculated. Comparison of the calculated effective width values with the corresponding values proposed in the Iranian National Building Codes (INBC- Part 10) showed that such composite girders are capable of providing the effective width given in INBC. This indicates that despite the effects of perpendicular composite I-beams as well as bi-directional action of concret slab, the investigated steel-concrete composite girders can be analyzed and designed as common composite beams.

The experience of Northridge and Kobe earthquakes have demonstrated poor behavior of welded beam-column connections due to deficiency of welds. After numerous studies, proper method for welding of connection has been proposed. Yet, the proper procedure and detailing of welding usually do not follow due to insufficient supervision of welding process, therefore deficiency in the connection of a real steel structures is expected. One of the most common moment resisting connections in the steel structures is connection with top and bottom plates which is the subject of study in this paper. Among the possible deficiency in the welds, lack of penetration (LOP) and the lack of fusion (LOF) are two main deficiencies in these connections. In this study, the cyclic behavior of three steel moment resistant connection with LOP deficiency in the weld have been studied by analytical method. The deficiency was considered on the top, bottom and both top and bottom plates and results are compared with the original connection. The connections are selected from three different size (small, medium and large) to evaluate the size effect on the results. The connections are modeled by ABAQUS finite element software. The molding of the initiation and growing of cracks in the connections was conducted by the extended finite element technique (XFEM). In the beginning, to examine the efficiency and accuracy of modeling, an experimental study was used for verification. The hysteretic behavior of specimens was studied under the typical loading protocol of SAC and based on that, the constitutional behavior of connections was developed. The backbone curve of each connection was obtained and the curve of each deficiency was compared with each other and the original connection. Results show that in LOP deficiency, the crack is formed and grow in the welds which ultimately lead to rupture in the welds. In general, the deficiency reduces energy absorption, moment and ductility capacity of connections. The result in different beams size are very close which suggest that the size of the beam has not effect on the reduction of the capacity. To estimate the reduced capacity of connections with deficiency in the real cases, reduction coefficient is introduced and presented for yield and ultimate moment and yield and ultimate rotation. In general, it can be concluded that LOP cause 30% reduction in the yielding and ultimate moment capacity of connections and 20% reduction in the yielding and ultimate rotation of connection. In addition, to study the effect of different deficiencies on the reduction of absorbed energy, the area under the hysteresis curve are calculated and compared. The results indicated that the connection with LOP in both plate have the highest reduction in observed energy which follows by the LOP in top and then bottom plate. This results in addition to the value of reduction in capacity and ductility of connections indicated that LOP in the top plate cause the connection to fail in shorter cycles compare to other cases. Therefore, it is better to have not the LOP in top plate which needs special attention in welding of that plate which usually conducted in the workshop with the least possible of supervision.

Large-scale spatial skeletal structures belong to a special kind of 3D structures widely used in exhibition centers, supermarkets, sport stadiums, airports, etc., to cover large surfaces without intermediate columns. Space structures are often categorized as grids, domes and barrel vaults. Double layer grid structures are classical instances of prefabricated space structures and also the most popular forms which are frequently used nowadays.Topology optimization of large-scale skeletal structures has been recognized as one of the most challenging tasks in structural design. In topology optimization of these structures with discrete cross-sectional areas, the performance of meta-heuristic optimization algorithms can be increased if they are combined with continuous-based topology optimization methods. In this article, a hybrid methodology combining evolutionary structural optimization (ESO) and harmony search algorithm (HSA) methods is proposed for topologyoptimization of double layer grid structures subject to vertical load. In the present methodology, which is called ESO-HSA method, the size optimization of double layer grid structures is first performed by the ESO. Then, the outcomes of the ESO are used to improve the HSA. In fact, a sensitivity analysis is carried out using an optimization method (ESO) to determine more important members based on the cross-sectional areas of members. Then, the obtained optimum cross-sectional areas of members are used to enhance the HSA through two modifications. Structural weight is minimized against constraints on the displacements of nodes, internal stresses and element slenderness ratio. In topology optimization of double layer grid structures, the geometry of the structure, support locations and coordinates of nodes are fixed and this structure is assumed as a ground structure. Presence/absence of bottom nodes, and element cross-sectional areas are selected as design variables. In topology optimization of the ground structure, tabulating of nodes is carried out based on structural symmetry: this leads to reduce complexity of design space and nodes are removed in groups of 8, 4 or 1. The presence or absence of each node group is determined by a variable (topology variable) which takes the value of 1 and 0 for the two cases, respectively. The ground structure is assumed to be supported at the perimeter nodes of the bottom grid. Therefore, these supported nodes will not be removed from the ground structure. In order to achieve a practical structure, the existence of nodes in the top grid will not be considered as a variable. This causes the load bearing areas of top layer nodes to remain constant. Also, discrete variables are used to optimize the cross-sectional area of structural members. These variables are selected from pipe sections with specified thickness and outer diameter. Therefore, in topology optimization problem, the number of design variables is the summation of the number of compressive and tensile element types and the number of topology variables. The proposed approach is successfully tested in topology optimization problem of double layer grid structure. In particular, ESO-HSA is very competitive with other metaheuristic methods recently published in literature and can always find the best design overall. Also, it is determined that HSA method can find better answer in the topology optimization of large-scale skeletal structures, in comparison to optimum structures attained by the GSA and ICA.

Temperature changes is one of the major factors that causes cracks in concrete pavements. Temperature changes causes expansion or contraction and thus creates a movement in the concrete slab. Friction between the concrete slab and the sub-base layer resists this movement, and induces thermal stress in the concrete. In this research study, the thermal stress created in concrete pavement by a drop in temperature and other intensifying factors (such as friction changes in layers interface), are investigated using numerical analysis method. In current research two finite element models are used to analyze the friction and temperature drops stresses. The first concrete slab modeled does not have a dowel bar and the second includes the dowel bar with or without misalignment. Finite element models using ABAQUS software are created for concrete pavement with and without dowel bars, and with various coefficient of friction between the concrete slab and the sub-base layer. The effects of coefficient of friction between the concrete slab and the sub-base layer and temperature changes on frictional and tensile stresses in the concrete slab are analyzed for various cases. The results obtained in this research study indicate that the high temperature drops (about 30 °C) during the 7 to 8 initial hours of construction of concrete pavement and a high coefficient of friction in the layers interface are the main causes of cracks in concrete pavements. The combined effects of these factors, high temperature drops and high coefficient of friction in the layers interface, worsen the conditions. The reason for increased chance of occurring cracks during the initial days of the concrete formation, is reduction of tensile strength of concrete during this period. In second part of the research, the thermal stress created in the concrete pavement with dowel bars deviating from the horizontal (a vertical tilt in the bars) is analyzed too. The research results show that the amount and the distribution of frictional and tensile stresses in the concrete slab when the dowel bars have no misalignment and are well lubricated, have conditions similar to the concrete pavements without dowel bars. Meanwhile numerical analysis results show that misalignment of the dowel bars and temperature drop, increases the tensile stress around the dowel bars and increases the threat of concrete disintegration. Ultimately, the results of numerical analysis are compared with the tensile strength of concrete during the initial hours of concrete construction. Results show that a 33˚C drop in temperature and a coefficient of friction about 3, creates a tensile stress of 124000 Pascal in the concrete slab, which can cause cracks in the concrete pavement during the initial 7-8 hours of concrete pavement construction. Furthermore, a vertical tilt in the dowel bars causes a considerable increase in tension stress around the dowel bars. In order to prevent cracks during the initial days and hours of forming concrete pavements, the coefficient of friction in the layers interface should be reduced using friction reduction factors, such as polyethylene sheets, concrete pavement should not be made in conditions with severe temperature drops, and dowel bars should be implemented with no or allowable misalignment.

Physical modeling is one of the most applicable researching methods in Geotechnical Engineering. Physical models simulate Geotechnical Engineering phenomenon in small scale to evaluate the effect of different parameters on them. In geotechnical physical modeling, reaching to a targeted specific weight (γ) and Density Ratio (DR) for sand beds are important. Air pluviation is one of the most adoptable methods for preparation of uniform and repeatable sand beds of required density in physical modeling. In this method sand in a container falls from an opening bellow it through the air. With different openings, there are different types of air pluviation. It may consist of a single or multiple nozzles, single or multiple sieves or a narrow aperture that pours a sand curtain. A pluviator can be stationary or portable. Stationery pluviation is a traditional method that commonly used for preparing small samples. In this method the hopper is station and nozzle outlet is small and sand pours in a limit surface of sample, therefore uniformity of sand beds decreased. Also in the horizontal direction, stationary pluviation results in a great segregation in soils which contain fines. In a Travelling pluviator the hopper usually moves above the area of interest, in a certain pattern and the sand pours uniformly from nozzle or aperture in the sample or model box. This paper presents the details of a test series with a portable curtain rainer pluviator that has been developed for modeling the sand beds in model box in geotechnical laboratory in Ferdowsi University of Mashhad. The new portable sand pluviator has been designed and developed for preparation of sand beds in a box with large dimensions (1.8 m length, 0.4 m width, 0.8 heights). The main function of the pluviator was reproducing sand beds behind the wall in the model box. The apparatus consists of a hopper with a capacity about 20 kg which is placed on a rigid modular frame. The hopper frame is connected to a modular wheeled frame that could move back and forth longitudinally by a belt on a pair of rails. The modular frames could justify the height of sand fall during pluviation and keeps the sand fall height constant. The belt is connected to a series of gearwheels that moved by a stepping motor. The direction of motion is reversed automatically when certain steps of moving finished. The velocity of the hopper could be controlled in the range of 0.4 to 4 cm/s. The sand in the hopper exits from an aperture which is connected below the hopper and could be replaced. Different aperture widths used to change the deposition intensity. In these tests the Firoozkooh sand NO.161 used for calibration. The influence of different parameters such as Height of fall, sand flow Curtain velocity, sand curtain width and Sand deposition intensity (DI) evaluated on Relative Density (RD) of sand beds with obtaining several samples during calibration. As the results clearly shows, by increasing the velocity of container, decreasing the curtain thickness and increasing the height of fall, relative density will increase. The test results show the very good repeatability and uniformity in sand for physical models in a large domain of Relative densities (3% to 93%).

Walls convergence of stilling basins is one of the ways to improve hydraulic jump to increase tailwater depth and energy dissipation at downstream of spillways of high head dams. On the other hand, occurrence of hydraulic jump in converged sections is accompanied with formation of shock waves. Technically, production and development of the mentioned waves are undesirable due to amplification of mixture of water and air and resulting, disturbance outbreak on occurrence of stable hydraulic jump. Many studies have been conducted on the characteristics of hydraulic jump over gradually expanding cross sections, but comparatively few have been carried out on basins with convergent wall. In this research, occurrence of hydraulic jump in stilling basin with convergent wall was studied using experimental model for three different geometry and initial Froude number equal to 3.17 and 4.46. Experiments were conducted in a flume with a length of 6m, width of 1m and depth of 0.7m. Angels of convergence (7.7º and 19.5º) and type of stilling basins walls (straight and curved) were intended as geometric variables. In all experiments, widths of upstream and downstream channels were considered 80 and 40 cm, respectively (contraction ratio=0.5). The flow discharges were measured by an ultrasonic flow-meter having the accuracy of 0.02 lit/s. Values of instantaneous velocity were measured in 10 vertical sections in centerline of the convergent stilling basins using an electromagnetic 2-D velocity meter having the accuracy of 0.5 cm/s. Maximum height of produced shock waves in the contraction sections and conjugate depths of hydraulic jump were measured by a point gauge having the accuracy of 0.1 mm. The measured values of conjugate depths ratio and energy dissipation were compared with the obtained results of analytical equations presented by Sturm (1985) and Montes and Chanson (1998). The average relative errors of calculation of the mentioned parameters were respectively achieved 9.75% and 17.15%. It should be mentioned that the equations tended to underestimate the conjugate depths ratio and energy dissipation values. The velocity and turbulence intensity profiles were demonstrated and analyzed based on the mean values of instantaneous velocity and minor fluctuation of instantaneous velocity. The effects of convergence angle and curvature of basin wall were investigated on changes trend of the profiles. The results showed that changes of the convergence angle has a considerable impact on the conjugate depths ratio, energy dissipation and length of hydraulic jump. As for a constant Froude number, increasing of the convergence angle to approximately 12º was averagely accompanied with decrease of the conjugate depths ratio and hydraulic jump length to the 34.4% and 35.5%, respectively and increment of the energy dissipation to the 33.2%. It should be mentioned that increasing of the convergence angle caused intensification of the shock waves. Moreover, effects of curvature of basin wall were investigated for an equal convergence angle. As regards it had insignificant impact on improvement of hydraulic jump characteristics and difficulty of its implement, so it is not economical. The obtained results of the present research can be very useful for designer engineers.

One of the most vital, essential human being requirements is water, which it has become increasingly sensitive owing to population growth, the need to develop agriculture and industry, and restriction in water resources. Considering this, the need to store water and to use its potential for generating hydroelectric power, which it can be achievable by constructing dams, will be necessitated. Concrete dams play a significant role in Infrastructure in each country. One important part of dams exiting in the world are made of gravity dams and earthquake seems to be the major threat for them in earthquake-prone areas. Hence, the dam fracture, with much stored water, might have brought many conspicuous threats about in these zones. Also, any structural damage could lead to some negative economic effects. These facts have increased the scholars’ attention to the mechanical behavior of dams during the decades. The Seismic analysis of gravity concrete dams, usually, had been considered in an ideal form by means of 2D Monolith in mechanism design and an earthquake effect coefficient. Lately, the research focus, however, has been more on linear time history analytics and fracture analysis of concrete dams in 3D. The numerical modelisation of huge structures such as dams is a proper tool for Seismic analysis and performance evaluation. The valley shape is one of the important parameters in the selection of the dam structure. This parameter plays a crucial role in both Seismic stimulation and its results. In this paper, a 3D finite element model of Pine-flat gravity dam, without interruption seams with a non-linear behavior of the dam’s material, is considered. . Loading has two stages: static and dynamic. In this modelisation, static loading includes both the weight of dam body and the load of filled Hydrostatic tanks. After static loading, loading of Seismic dynamic is begun. Owing to the importance of valley shape, the changes/ deformations of valley width and the dam response to every three elements of ground is investigated. The impact of the ratio changes of width in dam height, as well as the importance of the transverse component of ground motion, along the vertical and horizontal, has been explored. Interaction effects of dam-reservoir-foundation is considered in the considered analysis and ultimately, the output of which is compared with two dimensional model results. The aim of this study is comparing two and three dimensional seismic response of concrete gravity dams and also necessity of providing more realistic models for considering the effects of cross stream modes. Also, not only are interaction effects of dam-reservoir-foundation, the nonlinear behavior of concrete, studied different Valley shapes, and the effect of them on non-liner response investigated, but also the Seismic stability of gravity concrete dams under longitudinal, vertical and the chosen transverse record earthquake are separate and simultaneously studied. The effects of dam-reservoir-foundation interaction, nonlinear behavior of mass concrete, also different shapes of valley are studied and their effect on nonlinear response and seismic stability of concrete gravity dams are evaluated under two and three-component earthquake records.