Modares Civil Engineering journal
Year:2017 | Volume:17 | Issue:2 |Papers Count:20

Structural Health Monitoring (SHM) provides a way to evaluate safety and durability of a structure during its service life in order to ensure the serviceability and sustainability. Therefore, the sensor technology is a critical part to operate SHM system for recording relevant data through its lifespan. Sensor is a device capable of identifying the probability or the value of parametric changes and showing them as a relevant output (typically electrical or optical signal). Making materials electrically conductive may be useful in many different ways such as creating piezoresistive sensors with the ability to acquire stress-strain or load-displacement data or creating sensors with the ability to acquire data on the extent of damage to the concrete. The piezoresistive sensor is capable of detecting the applied forces to the structure based on the changes in the electrical resistance. But the damage detection sensor operates based on the contacting conduction of CNTs. This means that by increasing the amount of CNTs in concrete, a three-dimensional contacting network of CNTs is built. When the amount of CNTs exceeds the percolation threshold, the contacting conduction will affect the electrical conduction of nano-composites. One of the most significant and economical types of the sensor is the damage detection sensor which is provided by mixing conductive fibers (such as carbon nanotubes (CNT)) with concrete. For preparing damage detection sensor, CNTs and surfactants were mixed in the water for 10 minutes using a magnetism stirrer at 5000 rpm. Then, the mix was prepared at one ultrasonic energy dispersion. The cement and CNTs were added to high-speed mixer to be uniformly mixed. After adding aggregate to the mixer, the concrete was placed in pre-oiled molds and by applying appropriate vibration, any trapped air was released. The specimens were cured for 28 days and they were tested under the static loading by Instron-Tech. test equipment. In order to remove the effect of polarization - which is due to the movement of free ions in the concrete sensor during the measurement - an alternating current generator was used to nullify this phenomenon. After preparing the sensors, two main factors affecting the performance of concrete sensors are the amount of CNTs and their dispersion quality in the mixture. The goal of this study is to determine the optimum amount of CNTs with regard to the combined effects of the surfactant and the CNTs dispersion quality on the performance of the sensor. In this regard, various criteria such as sensitivity of the sensor (Se), the Absolute prediction errors as electrical criteria and flexural strength as mechanical criteria are involved. The results demonstrate that the sensor provided by 0.15 wt% CNTs, superplasticizer and SDS as a surfactant has the best performance. Also, the static criteria indicates that the quality of the dispersion (using proper surfactant material) and the amount of CNTs are effective on the sensitivity and the Absolute of the prediction errors, respectively.

Use of different synthetic dyes in textile industries has increased in recent decade, resulting in release of the dye-containing industrial effluents into natural aquatic ecosystem. Since most of dyes are usually very recalcitrant to microbial degradation, removal of dye from effluent is a main concern in many studies. Different processes are used for treatment of dye effluent. In last few years, studies are focused on advanced oxidation process (AOPs) methods such as UV-ZnO, UV-H2O2, UV-O3 and UV-TiO2. Photocatalytic process such as UV-ZnO is an efficient method that treats non-degradable wastewater by active radicals. The photocatalysis needs a photo-reactor that contacts reactant, products and light. In recent years, different types of photo-reactors have been used for wastewater treatment. In some reactors, nano-photocatalysts are utilized in slurry form, and the other particles are coated on bed. In Photocatalytic reactors with fixed bed, nano-photocatalysts are immobilized on bed and do not need separation unit. However, the main disadvantage of these photo-reactors is the low mass transfer rate between wastewater and nano-photocatalysts. Consequently, Different optimal photo-reactors have been developed for increasing mass transfer rate. In this study, a novel photocatalytic cascade disc reactor coated with ZnO nano-photocatalysts is applied and in order to increase mass transfer rate, artificial roughness are created on the surface of disks. Applying artificial roughness changes mass transfer rate by providing vertical mixing, creating secondary currents and increasing the Reynolds number. This photo-reactor has a number of advantages including: eliminating the need for catalyst separation units as the catalyst is immobilized; creating flow mixing by non-mechanical method; increasing oxygen transport from gas phase to photocatalyst surface by providing the flow cascade pattern. The photo-reactor is used in order to remove Reactive Yellow 81 (RY81) dye from textile industry effluent, by means of UV-ZnO process. RY81 is a reactive dye composed of 10 Benzene rings and two –N=N azo bonds. The effect of initial Concentration of dye, pH, Catalyst surface loading and flow rate on removal efficiency is investigated, and the optimal value of those parameters are reported as 50 mg/L, 8, 40 gr/m2 and 80 cc/s, respectively. A rate equation for the removal of RY81 is obtained by mathematical kinetic modeling. The Langmuir-Hinshelwood kinetic model is one of the most common kinetic models that are used for studying the kinetics of heterogeneous photo-catalysis. Results of reaction kinetic modeling indicate the conformity of removal kinetics with Langmuir-Hinshelwood model, and the constants kL-H and Kads are obtained as 7.17 mg L-1 hr-1, 0.122 mg-1 L, respectively.Considering various operational parameters into an equation, using regression analysis is appropriate. In this study, nonlinear regression model is developed for prediction pseudo- first order rate constant as a function of initial concentration of dye, pH, catalyst surface loading and flow rate. This equation properly predicts (R2=0.95) the removal rate constant of RY81 removal in the photocatalytic cascade disk reactor under different operational conditions and a good consistency is observed between the calculated results and experimental findings.

In this paper, a modified linear-quadratic-Gaussian (MLQG) optimal control algorithm is proposed for controlling the seismic response of the frame structures. Environmental loads (e.g., earthquakes) cannot be measured at the moment of calculation and exertion of the control forces to the structures. So these loads are not included in the conventional control algorithms, such as the linear quadratic regulator and the linear-quadratic-Gaussian control. Therefore the command of LQG optimal controller is merely a proportional feedback of the estimated state of the structure at the moment of exertion. This state approximation is performed by optimal state estimator or Kalman filter. In the proposed control algorithm, new variables are considered in the state space equation of the motion and also in both of Kalman Filter estimator and the optimal regulator. The new variables include control force and earthquake force, acceleration of the ground motion, which is non-measurable during the exertion of control force. This technique makes the controller be a combination of the control force in the last step and proportional feedback of the states in two last steps. According to the proposed control algorithm, two ways are selected. In the first, command control is the sum of the control force and ratios of the estimated state and measurement output of sensors, which are obtained and used in previous time step. The estimated state of system, used in the first command control, is calculated by the conventional and known Kalman Filter. In the second strategy of control, the Kalman Filter estimator is firstly modified based on new state space equations, and then the estimated state of structure is used for calculation of command control. Numerical simulation of a seven-storey structure with active control system under two far-fault earthquakes, including Northridge and Kobe, and two near-fault earthquakes, including El Centro and Hachinohe, are performed to show effectiveness of two proposed controls on mitigation of structural responses and compare to those of a uncontrolled structure and a structure controlled with conventional control. Also by sensitivity analysis, performance measures of controllers are investigated against changes of some controlling and perturbation parameters of systems or uncertainties. The performance measures include percentage reduction of the roof displacement of the controlled structure relative to that of the uncontrolled one, the root mean squares of normalized displacements, accelerations and control forces produced in controlled structure and total control energies exerted by all stories’ active devices under various controllers. The studied uncertainties are covariance of measurement noises and ambient loads. Increasing covariance of ambient loads as well as decreasing that of the measurement noise results in roof displacement reduction together with need to increase control energy. The analysis results demonstrate that performance of the proposed controllers, specially the second one, are better and also stable and robust under intensity and variations of uncertainties. So that the greatest reduction in maximum displacement (even up to 80 percent) compared to uncontrolled displacement of structure and meanwhile, very low energy consumption (about 10 percent of the maximum energy used by other controllers) are attained by the second proposed control strategy.

Engineering knowledge Development has provided new methods and techniques in the manufacturing industry, the possibility to construct structures that are considerably lighter, higher and more flexible. The sensitivity of such structures against wind power is more than that of traditional and low level structures. The wind is driving force for many of the phenomena affecting the urban environment, such as indoor and outdoor air, heat transfer, pollution dispersion and air quality. Despite their importance to human life in the cities, however, urban streams are still not fully understood. Basically, wind power has a significant and decisive role in the design of tall structures and the design and analysis of wind effect and its forces are required to be studied more carefully. One of the most important and effective parameters in the equilibrium behavior of structure and the comfort of individuals in it is the vibrations of the structure that is introduced by turbulence percent. Because of the density of surrounding vegetation and structures in areas close to the ground, turbulence percentage is more at low altitudes. Regulations according to geographical location and weather conditions of area has certain definitions on the behavior of tall buildings. In this study, the regulations of the US (America Society of Civil Engineers ASCE2010) is used. In all field studies, wind engineering is an important issue to determine the atmospheric boundary layer flow around the structures. Atmospheric boundary layer is the boundary layer of air on the surface of the earth at a height above the surface, assuming the friction of natural flow of wind ineffective. Air flow is divided into the mainstream and the boundary layer flow (atmospheric). The most important parameter that separates the two streams is liquid-friction (viscosity, fluid friction). Friction in the mainstream s almost negligible. However, in the boundary layer it is very important. Thus, each area, with any area coverage has a different boundary layer height. Many studies have been conducted on new methods and facilities for simulating atmospheric boundary layer. Comparison of velocity profiles generated in the atmospheric boundary layer is an important issue addressed in previous studies. After reaching a suitable environment that ideal regulation conditions in terms of matching the profiles of wind speed obtained with regulation profiles of wind speed, required studies and results such as the percentage of turbulence in this study can be obtained. In this study, by using previous studies results on simulating atmospheric air boundary layer in the wind tunnel, software modeling profiles of wind speed around the two buildings during the build in various stages of side walls completion were created with different shape in plan, and the turbulence percentage generated around both buildings were checked. It is identified that the amount of turbulence in terms of height in buildings during construction increases to a height equivalent to the height of the gradient (height of boundary layer atmospheric) by increasing elevation, vegetation and coverage of the side walls. From this height, due to the exit from the gradient height and reduced barriers to wind such as buildings surrounding the vegetation, this parameter is reduced and at higher altitudes is almost zero. However, at a height equivalent to the height of the wind tunnel, it is shortly increased because of the wind collision with upper surface of wind tunnel. Finally, structures that has more aerodynamic properties in their plan show better behavior against wind power.

In the design process of a moment resisting frame (MRF), the principle of weak–beam and strong–column should been considered because of the occurrence of plastic hinge in the beams. This mechanism is caused because the frame is capable of dissipating significant energy and remaining stable in the inelastic region. Stability is defined as the ability of the frame to maintain its elastic level of resistance throughout the entire inelastic range of response. Using this principle, plastic hinges can be developed in the beams adjacent to the connections and usually very close to the column face. This mechanism allows the cracks to be caused by the plastic hinging. The cracks can also propagate into the connection core region, and initiate a brittle failure mechanism. Furthermore, the mechanism has not been established in many existing MRFs - designed based on the previous codes. Hence, the methods have been proposed and developed in order to relocate the plastic hinges away from the column face. Fiber Reinforced Polymer (FRP) has been used as a strengthening solution of beam–column connections and successfully reported for retrofitting existing structures. In fact, the web–bonded FRP retrofitting system can control the mechanism of plastic hinge and provide the strong–column weak–beam concept. Due to many advantages, such as high strength, low weight, endurance and convenience, Carbon Fiber–Reinforced Polimers (CFRPs) have been used in strengthening concrete structures. However, the strength and stiffness of CFRP are severely reduced at elevated temperatures, which will affect the strengthening effect seriously. In this study, six schemes are proposed for strengthening concrete beam–column connections using CFRP and the seismic performance of strengthened connections is investigated. In order to achieve this purpose, seven downscaled RC exterior joint of a typical ordinary MRF are chosen, and modeling this strengthened connection is implemented in a general finite element program, ABAQUS software. In the finite element model of strengthened concrete beam–column connection, the concrete is modeled using the damaged plastic model. The sheets of CFRP are also considered as the elastic and orthotropic model. These schemes of strengthened concrete beam–column connections are tested under moderately monotonic/cyclic loads. In order to verify the finite element model of the connection, the analysis results of this model is compared with the experimental investigation on the external beam–column connection repaired using CFRP. The results demonstrate the verification of the finite element model. Selection of the best scheme of strengthened concrete beam–column connection using CFRP is based on the improvement of the seismic performance of connection such as the load–carrying capacity, the energy absorption, the initial stiffness and changing failure mechanism of connection. The nonlinear results show that the proper layout of CFRP sheets can increase the load–carrying capacity, the energy absorption and the initial stiffness of connections. Furthermore, the proposed schemes of strengthened concrete beam–column connection cause the failure to relocate from the column face and locate in beam. Therefore, the best proposed scheme of strengthened concrete beam–column connection using CFRP can be recommended and utilized in the practical projects of concrete structures.

Petrochemical industry is one of the major industries playing significant role in the economy of Iran. In general, petrochemical effluents contain various contaminants including suspended solids, organic matters, oil and grease, metal salts, sulfide, ammonia, hydrocarbons, cyanides, volatile organic compounds and other toxic substances. In most of petrochemical complexes, wastewaters are treated by activated sludge process along with the oil/water separation systems as a pretreatment. Since the performance evaluation of wastewater treatment plant is required to assess the effluent quality, to meet higher treatment requirement and to know the feasibility of handling higher hydraulic and/or organic loadings, this study was conducted to evaluate the performance of a full-scale petrochemical wastewater treatment plant.Wastewater treatment system consists of a screening unit, an API, an equalization basin, coagulation and flocculation, DAF system, an aeration tank, primary and secondary clarifier and filtration. The treatment plant was designed to treat the wastewater generated from different units of petrochemical complex with reuse purposes of treated effluent. To evaluate the performance of the treatment plant, 12-h composite flow weighted samples were carried out in 4 days within 6 months and were analyzed for COD, BOD5, TDS, TSS, phenol, cyanide, oil, ammonia and TKN in accordance to standard methods. Microbial structure of activated sludge was also evaluated.According to the results, the actual average influent flow was significantly lower than the average design flow based on the long-term data and our measurements. This increases the hydraulic retention time (HRT) in all units in the WWTP. Based on the results, the values of COD, BOD5 and TSS in the influent and effluent were 1319 ± 230, 967 ± 491 and 227 ± 174 mg/l and 73.6 ± 19.6, 33.6 ± 25.9 and 6.4 ± 5.9 mg/l, respectively. The ratio of BOD5/COD was calculated about 0.58 indicates a good potential for biodegradability of the wastewater. The results also revealed that 68.5% removal of COD and 81.9% removal of BOD5 have been occurred in preliminary and primary units while; these units are usually designed for the elimination of oil and suspended solids as well as the equalization of quantitative and qualitative parameters of the influent. At an organic loading of 0.48 ± 0.15 kg/m3.d, the removal efficiencies for COD and BOD5 in biological unit were calculated about 37 and 46% respectively. The mean value of MLSS within the biological reactor was 1463 mg/l. In addition, the mean plus standard deviation values of MLSS measured in returned activated sludge (RAS) were 2323 ± 1080 mg/l. According to the daily average concentrations of COD in the effluent of the WWTP, in some cases within the study period, the COD values were exceeded from national discharge standards. Microbial analysis showed that among the isolated bacterial strains, the genus belonging to Alcaligenes, Pseudomonas, Bacillus and Moraxella as heterotrophic nitrifying bacteria was identified as predominant strains in biological unit.Based on the results, in 64% of our measurements (135 days from 209 days of study period), the daily average effluent COD values were above national guidelines for surface water discharge (60 mg/l). In 3% of the time during the study period, the daily average values of COD in the effluent were more than 200 mg/l. The results also indicated that the average effluent concentration of oil was significantly higher than the expected design value.

Response evaluation of buried steel pipelines at intersection with active faults is among the top seismic design priorities. This is because the axial and bending strains induced to the pipeline by step-like permanent ground deformation may become fairly large and lead to rupture, either due to tension or due to buckling. Surface faulting has accounted for many pipe breaks during past earthquakes, such as the 1971 San Fernando (USA), the 1995 Kobe (Japan), the 1999 Izmit (Turkey), the 1999 Chi-Chi (Taiwan) events and more recently, the 2004 Mid Niigata earthquake in Japan. Literature review reveals that the analysis of pipeline subjected to fault motion is previously studied on the case of strike-slip fault. Whereas, a 3D large scale finite element analysis is a powerful method and allows a rigorous solution of the problem with minimizing the number of necessary approximations. The aim of present work is to examine and compare the mechanical response of continuous (welded) buried steel pipelines crossing active reverse faults by three dimensional FEM. General-purpose finite element program ABAQUS is employed to accurately simulate the mechanical behaviour of the steel pipe, the surrounding soil medium and their interaction. Meanwhile, non-linear geometry of the soil and the pipe through a large-strain description of the pipeline-soil system and the inelastic material behaviour for both the pipe and the soil are considered. For 3D FEM continuum model, an elongated prismatic model is considered, where the pipeline is embedded in the soil. Four-node reduced-integration shell elements (type S4R) are employed for modeling the pipeline cylinder, whereas eight-node reduced-integration brick elements (C3D8R) are used to simulate the surrounding soil. The analysis is conducted in two steps: gravity loading is applied first and subsequently fault movement is imposed. Seismic fault plane is assumed to be located at the middle cross-section of the pipeline. The steel pipeline was of the API5L-X65 type, with a bi-linear elasto-plastic stress–strain curve given by Ramberg-Osgood model. The mechanical behavior of soil is described through an elastic–perfectly plastic Drucker-Prager constitutive model. A contact algorithm is considered to simulate rigorously soil–pipeline interaction which accounts for large strains and displacements. Analysis proceeds using a displacement-controlled scheme, which gradually increases the fault displacement. Quasi-static analyses were carried out by applying fault offset components to soil block in the continuum FE models through a smooth loading function of time. Buried steel pipelines have been analyzed for reverse fault motion to study the influence of design parameters via: crossing angle, backfill properties, burial depth, pipe surface property, pipe material and cross-section properties on maximum compressive strain, and buckling of the pipeline. The following main conclusions were obtained based on the response of studied pipeline subjected to reverse fault motion using the FEM model.- For the steel pipeline subjected to reverse fault motion, compressive strain was always found to be more critical than the tensile strain.- The capacity of the buried pipeline to accommodate the reverse fault offset could be increased by adopting: a loose granular backfill, a shallower burial depth, near-parallel orientation with respect to the fault line, a smooth and hard surface coating, and increasing pipe-wall thickness.- Finally, the obtained information can provide either guidance for developing improved earthquake-resistant design or countermeasures to mitigate damage to pipelines crossing active reverse faults.

A large number of flow types - that are encountered in nature and technology– consist of phases. Advances in computational fluid mechanics have provided the basis for further insight into the dynamics of multiphase flows. Currently, there are two approaches for the numerical calculation of multiphase flows: the Euler-Euler approach and the Euler-Lagrange approach.In the Euler-Euler approach, different phases are treated mathematically as interpenetrating continua. In FLUENT, three different Euler-Euler multiphase models are available: the volume of fluid (VOF) model, the mixture model, and the Eulerian model. For sedimentation, Eulerian model must be used. The Eulerian multiphase model in FLUENT allows modeling multiple separate, even interacting phases. The phases can be liquid, gas, or solid in nearly any combination. The Lagrangian discrete phase model (DPM) in FLUENT follows the Euler-Lagrange approach. The fluid phase is treated as continuum by solving the time-averaged Navier-Stokes equations, while the dispersed phase is solved by tracking a large number of particles through the calculated flow field.Sediment transport by fluid flow is one of the most important two-phase flows in the nature. Due to existence of secondary current in channel bends, the mechanism of flow and sediment transport in these channels is much complex and locating lateral intake at outer bank of the bends decreases this complexity.In this paper, mechanisms of sediments transport into the intake have been evaluated in a 180 degree bend channel with lateral intake. These mechanisms are simulated by the Eulerian and Discrete phases models in fluent software. The intake is located at the outer bank of an 180o bend at position 115o with 45° diversion angle. The effect of diversion discharge rate and diversion angle on mechanism of sediment entry to the intake are also considered.Turbulence model is k-ε model. Models were run in different times and the results are compared with laboratory results. The result in Qr=40% shows that the mechanism of sediment entry consists of continuous entrance from downstream edge of intake and periodic entrance from upstream of the intake. However, in Qr=25%, the mechanism of sediment entry only consists of continuous entrance from downstream edge of intake. The two models (Eulerian and Discrete phases) have shown good results. The rout mean square errors for outer boundary of the path of the particle at the channel’s bed are measured for two discharges (25% and 40%).Number of particles in discrete phases is limited; therefore, this model cannot display the depth of sediment. The Eulerian model displays the bed topography very well. Measuring mean square errors shows that the model operation for topography simulation is very well. This model accurately shows the location of intermittent dune and location of sediment accumulation. The discrete phase model can show the particle trapped place more proper than the Eulerian model.Due to increase in intake discharge, dimensions of sediment accumulation is decreased. Mechanism of sediment entry to lateral intake is affected by diversion angle of intake. Minimum sediment is entered to lateral intake at diversion angle equal to 50 degree.

Thin-walled panels are widely used in different engineering applications. Bridge and building plate girders, box columns and girders, frame bracing systems, liquid and gas containment structures, shelters, offshore structures, ship structures, slabs, hot-rolled W-shape steel profiles, steel plate shear wall systems and many other naval and aeronautical structures are examples of engineering elements that use plate of various thicknesses, according to their applications. The knowledge of the actual behavior of plates in such structures can be, of course, helpful in understanding the overall behavior of the structures. In general, plates in thin-walled structures may be under various types of loading, such as shear loading. Yielding of material and geometrical buckling of plates are two independent phenomena which may well interact with each other in shear panels. Depending on the material properties, slenderness, aspect ratios, and boundary conditions of perfectly flat plates, the yielding may occur before, after or at the same time as buckling. Buckling in slender plates is a local and sudden phenomenon followed by large out-of-plane displacements and loss of stiffness. Slender plates are capable of carrying considerable post-buckling additional loads due to stresses in the inclined tension fields. On the other hand, a plate with low slenderness ratio yields before buckling and thus, no post-buckling capacity is expected. In between, plates with moderate slenderness ratios, experience both material yielding and geometrical nonlinearity almost at the same time. In the present paper, behavioral characteristics of shear panels with simple or clamed boundary conditions are studied. Three different materials (carbon steel, stainless steel and aluminum) and various plate slenderness ratios are considered for adopting the finite element method. Results of nonlinear static analyses of different shear panels show that slender plates, depending on the slenderness ratio, carry a relatively small shear load in the elastic stage until the occurrence of shear buckling. However, additional capacity in the post-buckling stage of these plates, prior to yielding, is significantly large. The plates reach their ultimate shear capacity slightly after yielding and their post-yield capacity is not significant. Note that the ultimate shear strength of slender plates is considerably lower than their nominal shear yield strength. In plates with intermediate slenderness ratio, yielding of material and buckling occur concurrently (simultaneously). They carry a relatively large shear load in the elastic stage before yielding/buckling. They have also some post-buckling/post-yield reserves before failure. The ultimate shear strength of moderate plates is somehow lower than their nominal shear yield strength (yield strength in shear). In stocky plates, yielding precedes buckling, thus the shear capacity in the elastic stage before yielding is significant. The plates have some post-yield capacity and the ultimate load is coincident with the occurrence of plastic buckling (if happens). The ultimate shear strength of stocky plates is almost equal to their nominal shear yield strength. Moreover, results of quasi-static cyclic analyses of different shear panels show that the energy absorption capability, as expected, is very sensitive to the slenderness ratio of panels. By decrease in the slenderness ratio (increase of thickness), amount of the absorbed energy is substantially increased. For a specific slenderness ratio, steel shear panels exhibit higher energy absorption than panels with aluminum materials. However, aluminum material of this study has higher yield strength than that of carbon steel and stainless steel materials. This, of course, highlights the important role of the modulus of elasticity in the energy dissipation capability of shear panels. Yield strength of the material and panel boundary conditions have no important role in the amount of dissipated energy, compared to the material modulus of elasticity.

Pollution of the soil by hydrocarbon is a significant Geo-Environmental problem that may affect the environmental quality of soil, groundwater and air. Soil can be contaminated by organic materials attributable to leakage from underground or aboveground storage tanks and accidental spills. The response of soil to the contaminants not only depends on the local environment but also is influenced by factors such as particle size, bonding characteristics among particles, and ion exchange capacity. The transport of contaminant components from soil into groundwater can cause serious problems. Use of contaminated soil and its stabilization can be considered in earthworks such as embankments, backfills, and roads where there is no pathway for leaching of contaminants to underground water or if the contaminants pose no risk to the public and the environment. In some areas, the native soil is contaminated with hydrocarbon substances. For performing projects in such areas, use of local soil is dictated for construction as a result of haulage distance and economic considerations. Thus, the treatment and stabilization of local soil must be considered. On the other hand, in the areas where the soil has been contaminated and the treatment is not economical, effects of the contaminating substance on the soil behavior should be evaluated for the design of the projects. Therefore, understanding the mechanical behavior of contaminated soils and their treatment is important. Improving the mechanical behavior of clay soils by stabilization is a means of fulfilling geotechnical design criteria.An investigation on the behavior of a contaminated clay soil with Anthracene and its treatment is carried out through an experimental program. Anthracene is a representative of a group of hydrocarbon, which are called PAHs (Poly Aromatic Hydrocarbons). PAHs are created due to incomplete combustion of fossil fuels or wastes.In order to investigate the effect of cement on the stabilization of clay contaminated soil with Anthracene, several specimens are prepared by static compaction method at maximum dry density and optimum moisture. The specimens are of natural clay soil, contaminated soil with Anthracene, soil-cement and Anthracene-contaminated stabilized with different percentage of cement (5, 10, 15 and 20%) in different curing times (3, 7, 14 and 28 days). Atterberg limits and Unconfined compressive strength (UCS) tests are conducted on the specimens. The results of the experimental work show that adding Anthracene to clay soil, changes the compaction parameters. As an example, the dry specific weight of soil is reduced and the optimum water content is increased. Although, adding cement to the Anthracene-contaminated soil improves the compaction of soil, it increases the dry specific weight and reduces the optimum water content. In addition, adding the Anthracene may change the unconfined compressive strength of soil and will reduce the strength of soil. The strength of the contaminated soil is increased by adding cement. The amount of increase in the strength is depended on the percentage of cement and curing (type or time). The results show that Atterberg limits are increased by adding Anthracene to the clay soil, but are reduced by adding Anthracene or cement to soil-cement. The results indicate that adding the Anthracene to the soil, changes its structure to flocculated shape, but decrease of friction between soil particles due to adding Anthracene, may lead the soil particles to move easily together. By the way, the results of this research show that the cement could stabilize contaminated soil with Antracene.

In the design of most of steel frames, the beam to column connections are assumed to be rigid or pinned. However, in many steel frames beam-column connections show semi-rigid behavior. Structures with semi-rigid connections contain systems with the connections in joints which are not completely rigid, but allow, usually, some relative movements in directions of general displacements.However, semi-rigid design has not received widespread attention due to its perceived complexity and the lack of effective tools for global analysis.Early experimental studies showed the importance of shear deformations in panel zone for stable energy dissipation under cyclic loading. Modeling of panel is very important because of its role in prevention of local failure of columns under ultimate limit state.A substantial effort has been made in recent years to characterize the behavior of semi-rigid connections. Recent studies and modern codes, especiallyEC3 and EC4, include methods and formulas to derive resistance and stiffness of panel zone. EC3 proposes a mechanical model for semi-rigid connection -in which each component is modeled by an equivalent linear spring. In this case, some components of the connection are showed by springs. These springs are assembled by a single bilinear (elastic–plastic) rotational spring alternating the connection, and is attached at beam-column intersection in the global analysis.Stiffness and strength of the springs inEC3 and EC4 depend on β factor which implies an approximation of the internal forces at the joint. Therefore, adopting accurate β factor requires an iterative process at the time of performing the global analysis of the structure. Modifying EC methods; E. Bayo et al proposed a new component-based method (or cruciform element method) for modeling the internal and external semi-rigid connections. In this model, a cruciform element (a four-node element) is proposed to avoid β factor, and the inherent initial assumption and iterative process that it requires, and includes the finite size and deformation modes of the joint.One of main problems with which structural engineer deals is consideringEnd Length Offset in conventional software. Extended end plate connection is one of beam-column semi rigid connections that is to evaluate by its behavior, using cruciform connection model and other panel zone models.In this paper, three 2-dimensional frames with extended end plate connections are modeled inMATLAB using cruciform element method and the results are compared with the analytical results of SAP2000 for eight cases (including four models regarding the presence of the panel zone and four models disregarding it). At one state, End Length Offset is considered just for beams and at the other, for both beams and columns (in two cases of Rigid Zone Factor: 0.5 and 1). The results show that modeling panel zones according to EC method and considering Rigid Zone Factor equal to 1 in columns and beams are the best assumptions for analyzing 2D frames with extended end plate connections. However, if the panel zones are not modeled, Rigid Zone Factor must be considered equal to 0.5 simultaneously in columns and beams - to give actual results.

Urban landfill site selection is a complex process requiring numerous environmental criteria. Thus, an integrated municipal solid waste (MSW) management plan - including all stages from waste generation to ultimate disposal - must be considered as an important environmental issue. Absence of correct supervision over the management and collection of MSW can create numerous environmental problems, especially for the people who live around such landfills. Thus, appropriate urban landfill site selection is a main issue related to the stability of cities and human environments. It can meet the ultimate goal of the requirements of urban solid waste management with regard to the ecologic, socio-economic parameters, and urban sustainable development principles. Preventing the negative environmental effects of landfills, site selection is the best choice helping the sustainable development and environmental conservation. Since inappropriate disposal of urban waste materials have negative effects on both environment and citizens’ health, it is imperative that officials take measures to create appropriate landfill sites. Landfilling is viable and common ultimate disposal methods for MSW in many developing countries. Many researchers believe that the proper site selection for landfill may reduce its negative environmental impacts. All the environmental effects of landfill should be taken into account during the siting process. In other words, different environmental criteria and socio-economical aspects should be considered to select an optimal option to achieve the least possible adverse effects. The present research deals with a GIS-based spatial decision-making with regard to the ecologic and socio-economic parameters for the determination of Arak city environmental capability to select a suitable, urban landfill site. First, the data were collected according to regional conditions and access to them. Since available data were as vectors, Euclidean distance function is used to convert them to raster layer. The purpose of this research, is selecting a landfill site based on a weighted linear combination (WLC) in geographic information system (GIS) environment. Since GIS can manage a large amount of spatial data, it can be served as an ideal tool in the siting studies. Moreover, combination of Multi Attribute Decision Making (MADM) and GIS is considered as a helpful method to landfill siting, regarding different complex factors. After the production of the raster maps of the information layers, the standardization of the layers was conducted based on the type of fuzzy membership functions (ascending or descending) between 0 and 1. Then the final weight of the layers was determined using the AHP method. The AHP process makes simultaneous combination of quantitative and qualitative metrics possible. In the next step, the fuzzy logic method was used to incorporate the information layers based on WLC. Eventually, 5 classes of suitability were obtained for urban landfill sites in Arak city with very low, low, moderate, high, and very high spatial suitability in the fuzzy class of 0.69 to 0.87. The greatest area for the selection of urban landfill sites in Arak city with high spatial suitability was found to be 1212.44 square kilometers but the least area with very low spatial suitability was found to be 270.73 square kilometers.

The most dominant concern about the stability of bridges is the occurrence of local scour around piers and abutments. The local scour around bridge foundations has been widely studied by different researchers in recent years. Different methods have been proposed to control the scour depth and occurrence of scouring around bridge piers and abutments. Construction of bridge foundations in elevations deeper than predicted values is a usual method, in which, proper estimation of scour depth is very crucial. There are other available methods to countermeasure the scour, among which: installation of an amour layer around bridge piers and abutments. In this method heavy particles of stone or concrete blocks are placed around the bridge foundations, enhancing resistance of the bed to erosion and scour. Deviation of the flow from the bridge foundation is another way which usually transfers the scour to the midway channel at downstream of the structure. Installation of collars and spur dikes are the examples of this approach. Aninnovative method to mitigate scour around hydraulic structures is “soil compaction”. Compaction increases the relative density and soil resistance which mitigates scour and produce a time delay in scour hole development procedure. Effects of clay content percentage and compaction ratio on scour reduction around bridge piers are investigated in this paper. Experimental programs are conducted in a flume with 45 m length, 1.2 m width, 0.45 m depth and with a bed slope of 0.001. Uniform sand with median size of 0.73 mm and standard deviation of 1.27 is selected as non-cohesive material. The clay content liquid limit (LL) is 15.9, plastic limit (PL) is 49.2 and plasticity index (PI) is 10.9, which categorize the clay content as CH according to Unified Classification Standard. The experiments are performed in clear water conditions (vc/v=0.9) with a constant depth of 15 cm and a flow rate equal to 40 L/s (with a subcritical Froud Number of 0.31 and mean velocity of 0.31 m/s). In order to investigate the effect of clay content percentage and compaction energy on local scour, 5%, 10%, and 15% of clay were added to the soil. Thereafter, the specimens were compacted by different ratios. According to the experimental results, compaction leaves no effect on non-cohesive soil scouring rate and magnitude. However if the clay content percentage rises up to 10% -while the compaction ratio is 100%- the scour is completely eliminated. In order to assess the effect of compaction ratio on scour mitigation, the same mixture (with 10% clay content) was compacted to 70% of ultimate compaction energy. The results showed a 50% decrease in scour depth which is comparable to the previous case in the same compaction rate (70%). The percentage of the clay content was raised to 15% for another test. The results showed that the scour was completely captured. In a specimen with 15% clay content mixed with non-cohesive sediment materials -in saturated bed conditions- and with a relative density of 70%, the scour process around the bridge pier was completely controlled after 24 hours. The results prove that adding cohesive materials can postpone the local scour process significantly.

Roads and pavements are among the most important assets in any country and considerable amount of money is paid for their rehabilitation or maintenance, annually. Pavement surface is the most expensive and susceptible layer as it is in direct contact with traffic and also it experiences different environmental conditions during different seasons. Harsh weather condition and winter maintenance is another parameter that can increase the annual maintenance cost significantly. Winter snow and the resulting ice, can reduce pavement surface friction and therefore, deicing material such as deicing salt or calcium acetate are used to melt the ice and snow. Deicing material decrease the frost temperature and melt the remaining ice and snow and the resulting water flows due to the longitudinal and transverse grade over the pavement surface. The flowing water goes through longer distances in locations were the drainage system is not adequate.Although several researchers and scientists have studied the effects of deicing material on asphalt and concrete pavement deterioration, but what has not been fully studied is the simultaneous effects of deicing material and water flow on the rate of pavement deterioration under freeze-thaw cycles. Therefore, the focus of this study is to evaluate the combined effects of flowing water and deicing material on the deterioration of asphalt pavements under freeze-thaw cycles. Two types of asphalt samples were prepared and subjected to five different freeze-thaw exposure conditions. Deicing salt and calcium acetate were used as the deicing material in this study. The samples were also tested in an abrasion test apparatus and subjected to normal and frictional forces. This abrasion test apparatus was built based on the concepts used in Hamburg Wheel-Tracking Device. Marshall strength loss and weight loss of the samples were measured and used as a measure of asphalt deterioration.Results showed that the combined effects of water flow and deicers increases the deterioration of asphalt concrete samples under freeze–thaw conditions. Furthermore, deicing salt has more deteriorative effects on asphalt concrete in comparison to calcium acetate. In addition, results indicated that the water flow has significant effects on asphalt concrete pavement stripping and strength loss. Water flow slows down the formation of ice during freezing cycles by not allowing or slowing the formation of ice crystals and their agglomeration. In still plain water freeze-thaw chamber, a thin ice layer was formed in zero degrees of centigrade and its depth increased during the freezing cycles, while in the flowing plain water freezing condition, where the water flow was present, small ice particles started to form in areas in the chamber where the water flow was in its lowest level. Thereafter, the ice formation gradually expanded to the area with the highest level of water flow. Besides the mentioned effects of water flow, the presence of water flow decreases the freezing temperature of water in the asphalt concrete pores and, consequently, the hydrostatic pressure inside the asphalt concrete increases significantly. Therefore, the asphalt concrete deterioration process becomes faster and more severe when water flow is present in the freeze-thaw cycles.

Decrease in the strength and stiffness of soil due to liquefaction may cause large bending moments and lateral deformations in piles located in this type of soils. For reliable design of pile foundations in the liquefaction-susceptible soils, it is necessary to have an accurate evaluation of the lateral pressure. However, the pressure is exerted on the pile if the subsurface layers experience liquefaction and lateral spreading in the course of earthquake. In this study, a coupled Soil-Pile-Structure Interaction (SPSI) analysis method is used to investigate the behavior of piles in liquefiable soils. Interaction of soil-pile is simulated by using nonlinear p-y springs. The liquefaction effects are taken into account by introducing a degradation multiplier to the lateral resistance of soil. The degraded lateral resistance of liquefied soil is considered equal to 5% of its initial value for loose sand and 10% for medium sand. Fully coupled dynamic analysis of a soil column in free-filed condition is performed in OpenSEES (Open System for Earthquake Engineering Simulation). For simulating the interaction of solid-fluid phases based on the theory of saturated porous medium, u-p formulation is used. Liquefied soil behavior is modeled using “pressure dependent multi yield material model”. From the coupled analysis, time histories of excess pore pressure ratio at different levels are obtained. The values of excess pore pressure ratio (between 0.0 to 1.0) are used to interpolate the transient lateral resistance of soil from its initial value in the static condition (excess pore pressure ratio equal to 0.0) to its final degraded value in the fully liquefied condition (excess pore pressure ratio equal to 1.0). In order to verify the numerical model, results are compared with those of two centrifuge experiments. Both experiments include two soil layers and the pile is extended into the lower layer. In the first experiment, the loose sand layer is located above the medium dense layer and in the second experiment the medium dense sand layer is located above the dense layer. After verification of the numerical model, parametric analysis is performed to study the effect of various parameters on the dynamic response of piles and applied lateral pressure from the spreading liquefied soil to pile. Investigated parameters are thickness of the liquefaction layer, frequency of the input excitation, fixity of the pile cap, pile stiffness, maximum input acceleration and the relative density of liquefiable soil. The results show that the maximum bending moment in the case of fixed head occurs at the top of pile and in the case of free head at the depth of 1 ~ 3 meters. The maximum bending moment of pile is also greater in the case of fixed head pile; however, its lateral deformation is lower. Increasing the frequency of input motion and soil relative density or decreasing the liquefied soil thickness may lead to decrease of maximum bending moment and deformation of pile. Regarding the lateral pressure exerted on the pile, the results of analysis indicate that the lateral pressure is relatively constant at the depth of liquefied layer and is equal to 7 to 10 percent of the total vertical pressure at the base of liquefied layer.

Concrete is the most widely used building material. In Iran, the consumption of chemical additive materials has been significantly more than the average consumption in the world. This is true especially in the case of ready-mixed concrete industry which is the major producer and contributor of concrete in the country. Ready-mixed concrete industry is among the highest potential sections that must pay attention to the valuable characteristics of chemical additives. Therefore, it is essential to develop the knowledge and technology of chemical additive materials over the past decades in Iran. One of the important cases about concrete structures, especially structures permanently or non-permanently located in the vicinity of water and chemicals, is blocked effect against leakage, influence, pressure or water containing chemicals attack. In this context, a type of concrete should be used that is commonly known as“waterproof”. Also, to prevent cracking, high ductility, supernatural strength and energy absorption capability fiber can be used in concrete or which many application instances can be found. To date, it has become clear that different types of fiber can increase strain capacity, resistance to impact, energy absorption, abrasion resistance and tensile strength of concrete. In this research, the influence of the strength of regular concrete and fiber concrete sealing substances has been investigated. For this purpose, compressive and flexural strength parameters of regular concrete and fiber concrete with steel fibers, polypropylene and glass are studied by adding common waterproof material with different percentages. In this study, concrete parameters of pressure and bending resistance are evaluated using material available in the Khormoj and fiber and waterproof material. Crushed sand from Bushehr province was used. All the stone materials in the concrete mix were thoroughly washed in the S.S.D state. Dashtestan Cement Type 2 according to ASTM C 150 was used for the mixture. Thus, compressive strength tests were carried out at 7, 28 and 90 days on the cubic samples, and bending strength tests were implemented at 7, 28 and 90 days on cubic rectangular samples. The tests were carried out on 34 mixture designs and 408 samples. The concrete mixture contained waterproof materials including powder sbf-wr201 (acidic neutral) and powder bc40 (acidic neutral) and liquid bc39 (alkaline) and steel, polypropylene glass fiber. In this study, a mixture design was prepared based on ACI 211 recommendations for concrete without fibers by weight method. Then fibers (polypropylene, steel and glass of 2, 2, and 1% of weight cement, respectively) and the waterproof material (with percentages of 1, 1.5, and 2% of cement weight) were added separately to the concrete mixture design. Thereafter, the mixture design was calculated for each compound. Results show that waterproof materials bc40 and sbf increase the strength and flexural compressive strength, and waterproof material bc39 decreases concrete strength and flexural compressive strength. The most important result of this study is that to add 1% of waterproof materials bc40 to the fiber concrete with steel fiber increased compressive strength by 27%, compared to the control sample containing fiber in 90-day strength. Also, in the flexural strength of this combination no significant change is seen.

Soil erosion, as a complicated natural phenomenon, is a global challenge threatening soil and water resources. Therefore, accurate understanding of soil erosion, sediment transport processes and their interactions is necessary for prediction of soil erosion. To distinguish between the dominant processes involved in soil loss, soil erosion has been classified into rill and interrill erosion. Rainfall-induced detachment and transport of sediment have a fundamental contribution to interrill and sheet erosion. Instead of observation of natural rain showers, simulation of rainfall is widely used for better understanding of processes involved in soil erosion and their interactions. Rainfall intensity is variable during natural rain showers. Peak rainfall intensity in an event can exceed the mean event intensity by an order of magnitude. Variations of rainfall intensity during arainfall event is called ‘event profile’. However, the available information is inadequate to understand its effects on runoff and soil loss processes. Thus, this study is aimed to quantify the effect of event profile on runoff and soil loss in rainfall-induced erosion. The experiments are defined based on the use of simulated rainfall on disturbed soils in a small laboratory detachment tray. The study is conducted in the rainfall simulation laboratory, Department of Hydraulic, Faculty of Civil and Environmental Engineering, Tarbiat ModaresUniversity, Iran. Since kinetic energy controls runoff and soil loss processes, the effects on the soil surface of rainfall events with the same average intensity may be different. Hence to study only the effects of event profile, four events with different temporal profiles of rainfall intensity, each with the same kinetic energy, were chosen; (a) constant intensity, (b) increasing intensity, (c) decreasing intensity and (d) increasing - decreasing intensity. The soil samples used in the experiments are from sandy soil (soil A) and sandy loam soil (soil B). Disturbed soil samples are collected, air dried, crushed to pass a 4.75-mm sieve, and thoroughly mixed. For each experiment, soil is packed into a drainable detachment tray to a specific bulk density. The test area of this tray is 15-cm width by 30-cm length and 15-cm depth. Eliminating the effects of soil moisture on results, soil is saturated from the bottom using drainage outlet tube connected to a water reservoir 24-hr before each experiment. The tray is setup at a slope of 0.5% and exposed to simulated rainfall events. Each treatment is tested in three replicates. For each simulation, runoff and sediment are sampled at regular intervals. Results show that while the peak runoff is affected by event profile for the two soil types, there is no significant difference in total runoff among rainfall events examined for both soil types. However, the soil type significantly affects the soil loss. In addition, it seems that the models which estimate interrill soil erosion directly from the rainfall intensity are expected to perform poorly in predicting soil erosion from varying intensity rainfall events. It may imply that various and complicated mechanisms might be activated in runoff and erosion under natural rainfall conditions. The results may indicate that negligence of the event profile may lead to inaccurate understanding of mechanisms involved in runoff and soil erosion.

A scientific method for correct recognition and understanding of hydrologic phenomena is the investigation of their simple models. Generally, a model is a simple representation of a complex system. In mathematical models, behavior of the system is described by a series of mathematical equations, along with logical relationships between variables and parameters. Despite the various proposed mathematical models for modeling the hydrologic phenomena, there is not a unique approach in this respect. This might be due to spatial and temporal variability of hydrologic phenomena and also lack of mathematical tools for extraction of a proper pattern for these phenomena. These variations are the result of dependability of the phenomena on different agents. This problem has caused the past researches on hydrologic modeling to view the situation as random and probabilistic. The performance of most natural phenomena, including hydrologic problems, in short time scales, to be viewed as completely random and without any trend. But, with a change in time scale, and using sophisticated models, a type of interval and order will be observed. Nowadays, researchers believe that hydrologic phenomena, which have dynamic and nonlinear nature, could be better analyzed by nonlinear and deterministic chaotic models. Hydrologic components in lakes have non-linear and dynamic nature. However, since the changes that these components create in the lakes don’t happen suddenly, it is possible to study and predict some of these elements in the hydrologic cycle. Nowadays, with the evolution of computer models, it is believed that analysis, modeling and control of complex natural phenomena, including hydrologic processes, could be better performed with chaotic models than probabilistic models. Studying the hydrologic components in analysis of water resources systems, such as lakes, is very important in their quantitative and qualitative operation and management. Due to the importance of precipitation in variations of water level in Urmia Lake, located in north-western Iran, the chaos theory could be a powerful approach to analyze and model the complex behavior of such phenomena. Investigation of chaotic or random behavior of rainfall time series in the lake, for the choice of the best suited rainfall simulation approach, is an important and controversial issue that has been dealt with in this research. First, using the correlation dimension method (CDM), the monthly rainfall time series of Urmia Lake was analyzed over a period of 40 years (1967-2007). After calculating the delay time using average mutual information (AMI) and also calculation of the embedding dimension using false nearest neighbor (FNN) algorithm, the phase space was reconstructed, then the correlation dimension was determined. Thereafter, by using Lyapunov exponent and Fourier power spectrum, the existence of chaos was investigated. Results revealed that he presence of chaos in the rainfall time series of Urmia Lake is evident of the non-integer CDM of 2.56, positive value of Lyapunov exponent (maximum of about 2.5) and broad band Fourier power spectrum.Consequently, the system behavior is regular; in other words, the system is not considered as random. In such system, chaos theory is capable of extracting short-term time series from long-term records. In addition, the existence of low-dimensional chaos implies the possibility of accurate short-term predictions of precipitation.

Corrosion of steel bar has a complex process which leads to the reduction of cross section of steel bars and degradation of concrete structures. Corroded steel bars are among the most important issues in durability of concrete in the marine structures. Important effects of corrosion are seen in the damages made by corroded concrete structures including all kinds of structural and non-structural damages. Structural damages are more important because of the reduction of the safety factor of the structure in response to the applied external loads. These failures include reduction of bars’ cross-section and changes in the mechanical behavior of steel. Corrosion includes two processes: (1) corrosion initiation and (2) corrosion propagation. The corrosion initiation is related to the time when corrosive ions reach to the surface bars and chemical features are activated. Propagation is related to the time during which the structure loses its capability, subject to the loss of the cross-sectional area of reinforced steel bars, reduction of bond, and crack initiation and propagation. The predicted models of life-service of a reinforced concrete structure should contain two processes of corrosion. In new structures, the initiation time of corrosion and insurance for the whole time of corrosion initiation time is more important. Whereas, controlling the corrosion propagation must be regarded for existing structures.In this paper, statistical characteristics of the chloride diffusion coefficient, corrosion initiation time and corrosion rate including the best probability distribution function and its parameters are investigated based on Monte Carlo simulation of pitting corrosion data. The distribution function parameters of the corrosion variables i.e. the chloride diffusion coefficient, corrosion initiation time and corrosion rate were calculated using the Maximum likelihood method based on mathematical pitting corroded model. The model contains corrosion initiation and corrosion propagation processes. The probability density functions such as: Gamma, Gumbel, Lognormal, Normal, and Weibull were used in the statistical analyses of corroded pitting parameters. The best probability distribution function was selected using chi-square method. The Lognormal distribution function obtained the best probability function for the threshold chloride concentration, the corrosion initiation time and the corrosion rate. The corrosion initiation time depends on four basic random variables such as: compressive strength of concrete, concrete cover, threshold chloride concentration and surface chloride concentration. Thus, statistical effects of these random variables on corrosion initiation time are parametrically investigated using 10000 Mont Carlo simulations. It is obvious that increasing the concrete resistance leads to an increase in the corrosion initiation time and standard deviation of the density function. The concrete physical and mechanical characteristics are effective variables on the corrosion initiation time but the threshold chloride concentration and the surface chloride concentration are insensitive variables on the mean of corrosion time; however, they lead to significant changes in standard deviation of the corrosion time. Finally, Various bar diameters such as: F8, F12, F16 and F20 were investigated in time-dependent area of the corroded steel in concrete beams. Amount of the cover is important variable in corroded cross section of bars. Also, increasing bar diameter and decreasing corrosion period led to a reduction in the rate of the bars’ cross section.

Continuous population growth and enhancement of human life have led to an increase in waste production. Thus, waste management has become a problem of many countries. Over recent years, organic wastes management policies have been increasingly tending toward recycling. Compost process is widely applied to transform wastes into fertilizers, in which leachate management is a problem due to its adverse effects on the environment and human health. Control, collection, disposal, and treatment of leachate requires a special attention to prevent soil, surface and ground water contamination. The leachate contains toxic organic compounds and phenolic compounds. The first are resistant to biodegradation, nitrogen, aromatic and the latter threats human and aquatic life. This is why the leachate requires chemical treatment including advanced oxidation processes (AOPs). Combining UV radiation by the hydrogen peroxide (H2O2) is one of the advanced oxidation processes. During photolysis, UV radiation directly breaks down a complicated compound to more simple ones, by more energy than the compound binding energy. High energy cnsumption enhances the costs of this method. So it can be improved economically by controling parameters including pH and UV contact time that affect oxidation process.The leachate effluent was prepared from composting plant, Golestan, Iran. The leachate was characterized immediately after transferring to the lab. Furthermore, samplings were carried out three times to measure COD, BOD, total suspended solids (TSS), and turbidity of the stored samples. Total nitrogen contents of unviable cells were analyzed by Kjeldahl determination (2300 Kjettec Analyzer Unit, Foss Tecator, Sweden). The RSM approach used in the present study was under a CCD approach including four independent variables; initial pH, H2O2 and UV contact time. The design consisted of 2k factorial points augmented by 2k axial points and a center point where k is the number of variables. The two operating variables were considered at three levels; low (-1), central (0) and high (+1). With the RSM approach, ANOVA was carried out for a second-order response surface model. The significance of each coefficient was determined by the F -values and the values of probability (prob>F). The larger the magnitude of the F -value and the smaller the p -value, the more significant the corresponding coefficients. Values of ‘ prob>F’, less than 0.0500, also indicate highly significant regression at a 95% confidence level. A total number of 20 experimental runs was set.Optimal condition obtained for H2O2/UV process were of initial pH 7.5, hydrogen peroxide of 2.3 mL/L, and UV-contact time of 95 min. In these conditions, the removal rates of COD and color and turbidity for H2O2/UV process were 12.32%, 20.83%, and 8.68 NTU, respectively. The RSM applied in this study can present the effects of the operating variables as well as their interactive effects on the responses. In the present study, most effective factors on the advanced oxidation process including pH, hydrogen peroxide dosage and UV-contact time were tested. The results indicated that the H2O2/UV process has been successful in reducing turbidity but not in COD removal efficiency.