Modares Civil Engineering journal
Year:2018 | Volume:18 | Issue:5 |Papers Count:21

One of the effective ways to mitigate earthquake damage in structures is passive control of structures. Yielding metallic dampers are economic passive control devices, which are easy to fabricate and install on the structure. In this paper, the aim is to develop a design procedure for steel structures equipped with a combination of yielding metallic dampers so that, dampers will experience specific nonlinear behavior when subjected to various seismic hazard levels. For this purpose, the first step is to have the seismic hazard spectra with different return periods for the intended site of construction. In this research, this step has been taken by using the Tehran probabilistic analysis hazard project data and then plotting uniform hazard spectra with 75-year, 475-year, 975-year and 2475-year return periods. In the next step, behaviors of structures equipped with yielding metallic dampers have been investigated in the form of one-storey one-span, one-storey two-span and multi storey multi span frames. Required equations for behavior of these structures under monotonic loading is developed to begin the design process, the performance criteria for the structure and the damper is proposed. By using the derived equations, design of one storey, one span frame, as single degree of freedom structures based on performance criteria has been carried out. These single degree of freedom structures have different periods and strength reduction factors. After designing the single degree of freedom structures, nonlinear static analysis results have been compared with result of nonlinear time history analysis. For this purpose, 7 earthquake records have been chosen and scaled based on Iranian code of practice for seismic resistant design of buildings and used for dynamic analysis. Results have shown that all performance criteria of 75-year and 475-year hazard levels have been satisfied but for 975-year and 2475-year hazard levels, six cases have satisfied the desired critera with 12 percent error. Performance criteria for dampers used in multi degree freedom structures have also been proposed and a method for designing these systems based on the concept of uniform drift in all stories have been presented. Three, 3-storey, 6-storey and 9-storey buildings equipped with dampers have been designed based on proposed method. Time history analysis have been carried out for each return period to check if the desired performance have been achieved. For these analyises, 7 earthquake records were chosen and scaled based on Iranian code of practice for seismic resistant design of buildings. Comparison of performance point displacement levels and the displacements obtained from 28 nonlinear analyses, has shown up to 13 percent error. Meanwhile, the displacement levels of each set of dampers for 75-year, 475-year, 975-year and 2475-year return periods, confirmed efficiency of proposed design method and all dampers met the mentioned performance criteria. The results also showed that when hazard level increased, the difference between the results of nonlinear time history analyses and static nanlinear analyses have also increased.

Introduction. Reactive dyes have been increasing in textile industries for dyeing natural and synthetic fibers. Discharge of dye-bearing waste-water makes an adverse effect on aquatic environment because the dyes give water undesirable color. The major environmental and health problems associated with water pollution caused by the discharge of untreated textile effluent are due to disorders in the aquatic environment because of use of toxic chemicals. The aim of this study was to investigate the adsorption potential of as-produced activated carbon from grape wood residue (Vitis Vinifera) in order to remove Reactive Blue 19 (RB19) and Reactive Blue 21 (RB21) dyes from aqueous solution. Activated carbon is the most common adsorbent for the removal of many dyes. Activated carbons are made from various agricultural wastes by physical and chemical activation. The preparation of activated carbon from agricultural waste could increase economic return and also provides an excellent method for the solid waste disposal thereby reduce pollution. Method: The adsorbates in this study included three reactive dyes, Reactive Red 23 (RR23), Reactive Blue 19 and Reactive Blue 21. All dyes were commercial grade and employed without further purification. The activated carbon was synthesized from grape wood biomass by activation of phosphoric acid (H3PO4) with impragnation ratios of 1: 1 1: 2, 1: 3, 1: 4. The FTIR, BET, and SEM techniques were used to characterize the as-prepared carbon materials. In addition, dye adsorption experiments were carried out, which measurements are taken for all of the samples under in the same condition, at pH of 2, adsorbent dose of 0. 01 g/l, initial dye concentration of 250 mg/l, sworking volume of 100 ml, and contact time of 120 min. Results and discussion: The results showed that the carbon sample activated under imprenation ratio of 1: 4 and temperature of 600oC, that obtained a special surface area of 1850 m2/g, and total pore volume of 2. 40 cm3/g, and pore size distribution of mesoporous at 86%, had maximum adsorption capacity of 1932 and 908 mg/g for RB19 and RB21 dyes, respectively. The adsorption behaviors of three reactive dyes (Reactive Blue 19 23, Reactive Blue 21) onto this biomass activated carbon were investigated in batch systems. The experimental data were analysed by the Langmuir, Freundlich and Sips models of adsorption. Equilibrium data of dyse fitted well with the Sips model. The rates of adsorption were found to conform to the pseudo-second-order kinetics with good correlation. The equilibrium adsorption capacity of the Activated carbon was determined with the Langmuir equation found to be 1914 mg/g for Reactive Blue 19 and 1195 mg/g for Reactive Blue 21. Conclusion: This study showed that activated carbon produced from annual pruning vineyards waste has a high potential in the treatment of textile wastewater. Also results indicate that Activated carbon from grape wood could be employed as low-cost alternative to commercial activated carbon in wastewater treatment for the removal of acid dyes.

Studies have shown that compressible materials between a rigid retaining wall and backfill reduced static and dynamic forces on the wall. Nowadays, panels with low density are used. Expanded polystyrene, which is one of the geo-synthetic products known as geofoam, is a compressible material. Geofoam is one of the geo-synthetic materials that are made of foam. Geofoam is very practical in geotechnical engineering due to its low bulk weight versus soil bulk weight and high compressibility, rapid and simple implementation, thermal insulation, and resistance against water absorption. It can be used in retaining walls, road construction projects as light fillers, and to reduce stress due to vertical loads in the base and sub base layers. Geofoam is one of the geosynthetic product which is made of lightweight expanded polystyrene (EPS) or extruded polystyrene (XPS). EPS geofoam is a block or planar rigid cellular foamed polymeric material that can be used in geotechnical applications. Studies have been shown that geofoam placed directly against a rigid retaining wall can reduce static loads on the wall. This study employed a finite difference method program, FLAC (Itasca, Version 7. 00), with considering yielding and non-yielding states for retaining walls to evaluate the effectiveness of geofoam panels in improving the static behavior of retaining walls. To determine the effects of geofoam in soil displacement and earth force acting on the rigid wall, parameters such as the height of retaining wall, density and thickness of geofoam, cross-sectional shape of geofoam panel behind the wall, and also using of two geofoam panels with four panel spacing (50, 100, 150, 200 cm) have been studied via static analysis. In this numerical study three gravity – type retaining walls at heights of 3, 6 and 9 meters and geofoam panels with densities of 15, 20 and 25 (kg/m3) at three relative thicknesses of t/H=0. 05, 0. 2 and 0. 4, were modeled. According to the results using of EPS15 with density equal to 15(kg/m3) which has the lowest density among other geofoam panels has a significant role in reducing of lateral stresses. Although the performance of geofoam in non-yielding retaining walls is better than yielding retaining walls. The results of the present research are as follows: 1-According to results, increasing the geofoam thickness increases soil lateral displacement and reduces forces on gravity retaining walls. The same effect can be achieved by reduction of geofoam density with equal thickness. In other words, Forces on gravity retaining walls are reduced and soil lateral displacement is increased by a reduction of geofoam density with equal thickness. 2-Using two geofoam panels with distance of 50 cm, unlike 3-meter high wall, is proper in the 6 and 9 meters yielding retaining walls. 3-Trapezoidal geofoam increases soil lateral displacement and reduces forces on retaining walls compared to a rectangular geofoam panel with the same cross-sectional area. 4-Effect of geofoam on the reduction of forces on non-yielding retaining walls is more than that on yielding walls. 5-According to results, stiffness of geofoam panel (K=E/t) has significant role in reducing of lateral forces acting on retaining walls. In this study, it was observed that K ≤ 5 MN/m3 provide the most effective range for the design of these system to reduce static force.

Ballast is a layer between sleeper and sub-ballast that is composed of broken stones. Since ballast bears heavy loads, its high quality is important. If the ballast is gradually crushed and fines are generated, stone permeability and drainage property will be damaged and finally, instability will be resulted. If the above problems occur at ballast, its substitution is necessary that has high costs. For Ballast quality control several tests has been suggested in 301 railway magazine that after the test on Ballast, the results are compared with allowable values and Ballast quality was controlled. Ballast grains subjected to train loads, contain numerous cracks. From the fracture mechanic point of view, when stress intensity factor at the crack tip reaches the mixed-mode fracture toughness, crack growth begins and Ballast grains crush. Ballast crushing and abrasion are the main reasons for ballast contamination which is the main source of various defects, particularly geometric defects in the railway. Since disc-type specimens are among favorite test samples for determining mode I and mixed mode fracture toughness in brittle materials like rocks, Therefore it is suggested to add the determination of the mixed-mode fracture toughness I and II with the semi-circular bend specimens subjected to three-point-bend loading to the ballast quality control in 301 railway magazine. In this research, discussed the importance of fracture toughness in extraction, crushing and operation of Ballast, then the finite element method and experimental is used to analyze a semi-circular disc specimens under bending load and the fracture toughness of two Ballast mine, Anjilavand and Gaduk was determined. Anjilavand and Gaduk mine is two Ballast mines in Iran that using them for Ballast layers in railway substructure. The crack parameters KI, KII and T are calculated for different mixed-mode from pure mode I to pure mode II. YI, YII, and T* are the non-dimensional forms of KI, KII, and T, respectively. These parameters are functions of the crack length ratio, the crack angle and also the location of loading supports in the semi-circular bend specimen. The curves of YI, YII, and T* extracted for various combinations of modes I and II. Since the results for mixed mode fracture resistance of brittle materials are usually presented in a normalized form as KII/KIc versus KI/KIc, where KIc is a material constant called the pure mode I fracture toughness, using the mixed-mode fracture criteria, capped failure modes I and II for both ballast rocks were extracted and compared. Fracture toughness of Anjilacvand specimen is greater than Gaduk specimen that shows the Anjilavand Ballast for operation in railway is better than Gaduk Ballast.

In an open channel, A hydraulic jump is the rapid varied flow which results water surface level increment and energy dissipation. In most cases, by this phenomenon energy dissipation process is carried out in downstream of hydraulic structures such as weirs, sluice gates and so on. The hydraulic jump is controlled by utilizing a structure called stilling basin. Building such structure can be very costly. Several approaches, such as bed roughness, chute blocks, baffle blocks and end sill, have been proposed to reduce the construction cost. For the first time, it is recommended to use the suspended anchored spherical energy dissipator blocks. From a practical point of view, this structure is very similar to baffle blocks but due to having less drag coefficient compared to the baffle blocks, they will suffer less force. Therefore, the slab thickness of basin decreases to a certain extent. Furthermore, due to fluctuations, using such dissipators leads to an increase in energy dissipation. These blocks have a relative density lower than water and are anchored by a thin resistant plastic to the floor of stilling basin. To the best of the authors’ knowledge, there are no studies on using these structures in the basin and analysis of their influences on the hydraulic jump characteristics. There are several interesting questions about the effect of such structures on the conjugate depth, jump length, and optimization of the stilling basin design, as well. The main goal of the authors’ study is to answer these queries. In this work, 30 experiments were conducted in the range of froud numbers of 5-8 and in the form of four arrangement types. It should be noted that, five experiments belong to testing the designed bed without any blocks. The Experiments were carried out in a flume with glass walls, 8 m length, 35 cm width and 40 cm heights. In order to form the hydraulic jump, the height of the walls were extended up to 80 cm in the beginning part of the flume and a chute with 30 degree angle and the height of 40 cm was set up. Next, in order to modeling such structures the obstacles diameter was set to 4 cm i. e. 1. 2 times more than highest initial depth in classical hydraulic jump of present study. The size of the anchor length was chosen in such a way that the blocks do not enter into the roller environment and remain in front of impinging jet stream into the stilling basin, since no energy dissipation will occur if they enter into the roller ambient. The results showed that the arrangements decrease the jump length and conjugate depth respectively, in average to 31% and 21%. Additionally, the energy dissipation using the suspended blocks in average is around 68% that is approximately 11% more than smooth bed. In all arrangements for experiments, conjugate depth reduction and energy dissipation increment is not impressive compared to one another, but even so the most and lowest effective arrangement respectively, was type four and type three.

Estimating the pressure required to maintain the tunnel face is one of the most important factors regarding safe and optimal excavation using mechanized tunnel boring machines in urban areas. Applying a pressure more or less than the balance to the face would cause collapse and blow out in the tunnel face respectively. This pressure depends on several factors such as soil type and its engineering specifications, underground water conditions, excavation method, amount of surcharge and tunnel section area. In this paper, the influence of soil elasticity modulus, friction angle and underground water condition on the optimum amount of face pressure in granular soils were studied. For this purpose, a 3D finite element model was used employing the ABAQUS software (Ver. 6. 14). The model takes into account relevant components of the construction process as separate components in the model (including: soil and ground water, tunnel lining and tail void grouting). Twenty-four steps have been performed according to the real construction sequences to achieve realistic model’ s results. As regards, there are too many parameters involved in mechanized excavation, the geometry of tunnel, lining segments, injection grout and the surrounding soil properties are adapted from the under construction of Tabriz urban railway line 2 project. The tunnel lining and TBM shield were simulated by S8 shell elements. The soil under the ground water level and the grout material were modelled as saturated porous media using pore pressure elements (C3D8P). The soil behaviour was assumed to be governed by an elastic perfectly-plastic constitutive relation based on the Mohr– Coulomb criterion with a non-associative flow rule. Tunnel lining and TBM shield were simulated as an elastic behaviour. The ingress of ground water into the tunnel was not considered in this study. The paper gives a detailed description of the model components and the stepwise procedure to simulate the construction process. More than 70 3D models were analyzed and optimum pressure in the tunnel face was determined through measuring the amount of induced average displacement in the tunnel face. For various elasticity modulus, internal friction angle and underground water conditions different values of face pressure were applied in tunnel face and corresponding average tunnel face displacement were measured for each state. Results show that elasticity modulus of soil has a remarkable effect on the amount of the optimized face pressure and for minimize the tunnel face displacement, elasticity modulus should be considered in calculation of the applied face pressure. As the soil elasticity modulus increase the value of optimum face pressure decreases. Also the face pressure was calculated using analytical and experimental methods and the results were compared with the obtained optimum pressure. The results are in good agreement with those obtained from the COB method. In the cases with low elasticity modulus (less than 20 MPa in this study) the COB method obtained face pressures are less than optimal pressure resulted in this study. This difference increase with lowering of ground water level.

The lap-splice length of reinforcing bars is one of the practical aspects of the bond between concrete and reinforcing bars. Providing the adequate bond between the reinforcing steel and concrete in splice length is essential in structural concrete design. The bond strength of spliced bars in concrete depends on several factors such as surface deformation of reinforcing bars, embedment length, concrete cover, bar diameter, confinement, concrete strength and environment conditions. One of the major degradation processes of bond strength in reinforced concrete is the corrosion of reinforcement. In addition, to reducing the bond strength, corrosion of reinforcement leads to reduced flexural capacity and serviceability of reinforced concrete structures and ultimately affecting the structural safety. There has been little discussion about the simultaneous effect of stirrup spacing and corrosion of reinforcements on bond strength and flexural strength of lap-spliced reinforced concrete beams. Therefore, in this research, the simultaneous effect of stirrups distance and corrosion level on the flexural strength and behavior of lap-spliced reinforced concrete beams with different stirrups spacing was experimentally investigated. A total of 12 reinforced concrete beams were constructed and tested. The test beams were 150 mm deep, 100 mm wide, and 1500 mm long. The beams were divided into three main groups according to the type of reinforcement corrosion, S: stirrup corrosion, T: tensile rebar corrosion, and W: stirrup and tensile rebar corrosion. Three different stirrup spacing (53mm, 80mm, and 160mm in splice length) were considered in each group. After constructing and curing the specimens for 28 days, we fully immersed them in ponds containing chloride sodium 5%, and accelerated corrosion procedure was simulated for them by applying an electrochemical method. The accelerated corrosion process was induced by impressing a constant direct current 150 μ A/cm2, on average, on the tensile steel bars. The degree of corrosion in all of the beams was 10%. After the accelerated corrosion process was completed, the beams were subjected to four-point loading by a 100-ton universal testing machine with a speed of 2 mm/min. The results are discussed in terms of normalized bond strength and residual ultimate strength of corroded beams with different stirrups spacing in each group. The rust products of bar corrosion had greater volume than the steel which increases stress in the concrete and results in cracks in splice length in all beams. Due to these cracks, the bonding of bar and the concrete decreased. The use of stirrups with low spacing in splice length can increase the bond strength by controlling the crack widths and maintaining the bonding of concrete surrounding reinforcement. Of course it should be noted that in specimens in group S, the decrease of stirrup spacing led to decline the ultimate strength capacity. Corrosion cracks interaction was the cause of reducing the confinement of longitudinal reinforcements in Group S. At the same degree of corrosion, the average reduction of flexural strength in Groups S, T and W were 15. 3%, 7. 5% and 14. 3%, respectively. The experimental results obtained in this study are close to the results of Esfahani and Orangan equations, and the amount of existing error can be corrected using the correction factor.

Stimulating the following vehicles by the leading ones repeatedly is created by the different reasons such as a sudden drop in the speed of the leading vehicle and lane changing maneuvers that result in stop and go traffic. It leads to several negative effects, such as reduction in safety, and increase in travel delay. When follower driver of platoon receives the last released wave of downstream to upstream in the traffic oscillation, he or she makes different reactions with respect to the released wave. They result in forming different behavioral patterns and behavior diversion from equilibrium driver. The behavior change analysis of the driver-vehicle unit is an indispensable factor for increasing and decreasing frequent repetitions in traffic oscillation. In this paper, employs vehicle trajectory data from Next Generation Simulation (NGSIM) program. The vehicle trajectory data of two freeway sites of the NGSIM program, Interstate 80 (I-80) and US highway 101 (US-101), were used in transportation and traffic research (NGSIM, 2006). Platoons of vehicles identified through a traffic disturbance classify in deceleration phase based on driver behavior. When the follower vehicle receives a deceleration wave, the follower’ s reaction may be to create a high or low speed drop. Driver behavior in deceleration phase leads to congestion classify into four behavioral patterns: under reaction and over reaction based on maneuvering errors of follower driver. Follower vehicles react different responses to deceleration wave in deceleration phase. The reactions result in low and more speed drop between Newell driver, low and more delay time of moving vehicles. A high speed drop, more safe spacing, results in the development of under reaction pattern. Also, a low speed drop, lower safe spacing, results in over reaction. In this paper, behavior diversion parameter and time of deceleration phase are assessed, based on observed behavioral patterns and using data envelopment analysis. Follower vehicles with different numbers in traffic stop and go traffic is considered as decision making units, leading to different decision-making units in the vehicle platoon. Using data envelopment analysis method, efficient units for trajectory data are analyzed, which is based on any behavior that indicates the delay in the vehicle platoon. More performance of behavior diversion parameter and time as result of any decision making unit are identified based on any diffused deceleration wave and follower spacing of receiving deceleration wave that results in the lowest delay time of vehicle platoon of deceleration phase. The results of the analysis show that the most effective decision making unit of overreaction behavioral pattern is created in the vehicle platoon at the same spacing and velocity values but the amount of different acceleration wave and behavioral changes. Based on under reaction pattern, the greatest delay in the platoon is proportional to the different speeds and spacing but the same deceleration wave which represents the most inefficient driving situation of a vehicle following the vehicle platoon. Present results can help traffic engineers in simulating vehicles movements of freeways to evaluate vehicle moves of F level of service for calculating delay and speed drop of vehicle platoon.

In this study, the impact strength multi-layer slabs reinforced by steel and nylon fibers, as well as the combination of these two fibers under the influence high velocity projectile, was investigated. To achieve this goal, 30 slabs one layer and three layers with dimensions 40  40  7. 5 cm were reinforced by 1% of the fiber, 30 slabs made 10 different models, each with 3 models sample was made. A non-fiber model, as a control sample, and other slab specimens all have a constant volume 1 percent fiber, the difference being in the type and composition the fibers in different layers the slabs. The slabs were made with Kalashnikov, PK Kalashnikov and Dragunov guns at a distance 50 meters tested. In the test the projectile's encounter, three parameters penetration depth, area the damaged front and rear area and the volume damaged area in the samples were calculated and compared. Based on the results obtained, steel fibers can increase the resistance concrete slabs against the impact the projectile and reduce the surface area and volume the damaged area and significantly reduce the penetration depth. Steel fibers at best reduced the penetration depth 64 % in the Kalashinkov gun and reduced the area and volume the damaged area in the Dragunov weapon by 88 % and 98 % respectively. Also, steel fibers can prevent crack expansion by increasing the bond strength, provided that the fibers the nylon have a much lower impact than steel fibers. the nylon fiber could reduce the penetration depth and demolition area the sample in Kalashnikov weapon by 37 % and 59 %, respectively, and reduce the volume damaged area in the Dragunov weapon by 84 %, respectively. In addition, in this research, 12 samples cubic pressure were placed on the side 10 cm, 12 cylindrical tensile samples 10 × 20 cm and 12 small bending beams with dimensions 32  8  6 cm and tested. It was observed that steel and nylon fibers cannot have a significant effect on the compressive strength, As a result the addition one percent the steel fiber, nylon and a combination these, this increase is 7. 7, 2. 6 and 6. 4 %, which can be neglected. but steel fibers can significantly increase the tensile and flexural strength the concrete. addition one percent the steel fiber could create a 2. 5 – times increase in tensile strengths and increase the resistance 2-times in bending specimens. This is the nylon fibers do not have a significant impact on the tensile and flexural strength. Adding one percent the nylon fibers in the tensile and flexural samples could increase the resistance these specimens by 16 % and 24 % respectively. It was observed in the bending test of beams that steel and nylon fibers can be bent by bending in the cracks to increase the shape the weld so that the change in the maximum area the beam with the addition one percent steel fiber from about 4 mm in the control sample increase to about 25 mm.

Chromium is one of the toxic heavy metals that increase its concentration naturally or through anthropogenic sources such as human activities. The presence of chromium in excess of the maximum permitted levels may lead to the threat to humans and biota. Therefore, the present study aimed to remove hexavalent chromium from aqueous solution by manganese ferrite nanoparticle. MnFe2O4 nanoparticles are an effective absorbent for the removal of organic and inorganic materials. In this study, MnFe2O4 was prepared based on co-precipitation method. The adsorbent properties were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD). The absorbent were prepared to remove hexavalent chromium from aquatic solution. In order to obtain the highest removal percentage and understand the mechanism, the effects of different factors such as pH, time, initial concentration and temperature were investigated. In this research, the effects of pH (2, 5, 7, 9 and 11), contact time of 2 to 360 minutes and concentrations of 1 to 200 mg/l and temperature (283 to 328 K) for the removal of hexavalent chromium were considered. The agitation parameter was kept constant for all experiments at 170 rpm. The results of the adsorption were interpreted by Langmuir and Freundlich isotherm models. The Cr concentration in each sample was detected by atomic absorption (AA240). Moreover, first-order, and second-order models were also considered for the evaluation of adsorption mechanism. Further, the intraparticle diffusion model for chromium adsorption on adsorbent was studied. The thermodynamic variables including the standard enthalpy, standard entropy, and Gibbs free energy for the adsorption process were calculated. The results of nanoparticle synthesis showed that the nanoscale dimensions were less than 200 nm, and the shape of the spherical particles followed the cubic spinel structure. Moreover, the pH of zero point of the nanoparticle was 6. 8. The results of the removal of chromium from aqueous solution showed that hexavalent chromium were more effectively removed at pH=2 in solution. Kinetic studies showed that the removal of chromium followed the second-order kinetic model. Intrinsic particle diffusion model showed that single-particle intrusiveness was not present and absorption consists of two steps: first, pushing the absorbent layer onto the adsorbent surface and then penetrating the molecule inside the pores. Isotherm observations also expressed that the removal of chromium is followed the Langmuir model, and the maximum absorption capacity of the hexavallent-chrome is 34. 84 mg/g. The resulting value of n=2. 92 (Freundlich isotherm) indicates the chemical absorption of chromium on the adsorbent of hexavalent chromium. The effect of temperature on the removal of chromium showed that the increase in temperature from 283 to 328 ° C led to increase in the absorption of chromium by nano-adsorbent. The highest adsorption rate occurred at 328 ° K. The amount of Δ G was negative and Δ H reacted positively. This is indicated that chromium-reacted manganese ferrite is chemically thermostable and spontaneous. From the above results it can be concluded that the absorption of chromium on manganese ferrite is chemical. The present study showed that manganese ferrite nanoparticles have a high potential for removal of hexavalent chromium from aqueous and wastewater solutions.

The ogee spillways are constructed to regulate the flow in reservoir of dams. When the excess waters overflow the ogee spillway, the velocity at toe of spillway is pretty high and the flow has a huge amount of energy. The bucket spillway is used in order to reduce the amount of such energy. Next, the trajectory flow combines with air and the flow loses its energy significantly. If the materials at downstream of spillway are erodible, the probability of the scour exist; as a result, the stability of spillway endangers. Therefore, the prediction of scour hole depth in this area is quite significant. In this study, the depth of scour at downstream of the bucket spillway simulated using the Extreme Learning Machine (ELM) model. One of the most popular methods based on the artificial intelligence is the feed-forward neural network (FFNN). The training speed of this algorithm is very low. It's due to the use of the gradient based algorithms such as the back propagation (BP) which has low speed and the adjustment of the parameters related to the network is iterative. The extreme learning machine (ELM) is a Single Layer Feed-Forward Neural Network (SLFFNN) which selects the number of nodes randomly and determines the output weights analytically. This algorithm is much faster than conventional neural networks and has a good generalization performance. The use of this method has had a good performance in different fields and its comparison with FFNN-BP has showed that this method in addition to reduce high computational costs has a higher accuracy. In current study, to evaluate the performance of ELM models, the Monte Carlo simulation (MCs) is applied. Monte Carlo simulation is a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. Their essential idea is using randomness to solve problems that might be deterministic in principle. They are often used in physical and mathematical problems and are most useful when it is difficult or impossible to use other approaches. Monte Carlo simulation is mainly used in different problems such as optimization and numerical integration from a probability distribution. Also in this study, the k-fold Cross Validation (k-fold) is used for evaluating the models ability. In k-fold cross validation method, the original sample is randomly partitioned into k equal sized subsamples. In the k subsamples, a single subsample is retained as the validation data for testing the specific model, and the remaining k-1 subsamples are used as training data. The cross-validation process is then repeated k times (the folds), with each of the k subsamples used exactly once as the validation data. The k results from the folds can then be averaged to produce a single estimation. The advantage of this method over repeated random sub-sampling is that all observations are used for both training and validation, and each observation is used for validation exactly once. The k value was considered 5 in this study. In this study, to validate the results of numerical models, the Azmathullah et al. (2005) experimental measurements were used. They measured the scour depth at the downstream of bucket spillway. Next, the effective parameters on scour depth were identified and six ELM models defined. In other words, one model simulated the scour depth with combination of five input parameters including the discharge dimensionless parameter, the ratio of the total head to the tailwater depth (H/dw), the ratio of the bucket radius to the tailwater depth (R/dw), the ratio of the mean sediment size to the tailwater depth (d50/dw) and lip angle of bucket, and five models predicted the output variable using four input parameters. In addition, the sensitivity analysis was carried out in order to identify the effective factor. This sensitivity analysis showed that the discharge dimensionless parameter was the most effective factor. Also, the superior model was introduced by analyzing the results of all models. This model had reasonable accuracy and was the function of all input parameters. For example, the determination coefficient and scatter index were obtained 0. 993 and 0. 071, respectively. Also, The RMSE and MAPE for this model were obtained 0. 240 and 8. 891, respectively. Additionally, the maximum, minimum and average discrepancy ratios for the superior model were respectively calculated 1. 567, 0. 360 and 0. 991.

Suction caissons have been extensively used in oil and gas industry. Recently bucket foundations are considered an innovative foundation solution to offshore wind turbines. Skirted foundations are increasingly used in the design of offshore wind turbine structures and facilities to withstand combined vertical, horizontal and moment loading conditions. In this study, three-dimensional finite element models of bucket foundations in medium dense sand were analyzed under combined loading. Numerical models were validated by comparing the results of finite element analysis. Sensitivity analyses were performed at different length-to-diameter aspect ratios under combined load with different load eccentricities. The responses of combined load, from pure horizontal load to overturning moments with varying tower heights, to pure moments were compared. Results showed how combined bearing capacity of foundations would depend on aspect ratio and loading conditions. Ultimate limit states were represented as normalized capacities, and the expressions were derived from the results of analysis. Offshore applications of shallow foundations are not limited to the oil and gas industry. In fact, they are recently being used as a new solution to wind turbines. Offshore wind turbines are relatively sensitive to deformations, particularly tilting. In order to withstand against tilting due to wind and wave loads and large lateral and overturning forces, the foundations of offshore wind turbines are setup with peripheral steel skirts which transmit the seabed, trapping a soil plug. Foundations of offshore structures require carrying a very small vertical load, but large horizontal loads and overturning moments. Suction buckets are circular shallow foundations with large diameter, closed at top and open at bottom. Bucket foundations penetrate into the seabed by its self-weight to provide a seal between the skirt tip and the soil and then penetrate by applying an under-pressure inside the skirt compartment until full contact with the soil is obtained. The bearing capacity of the bucket foundations under combined loads increases due to embedment by comparison with a surface foundation (L/D = 0). The bearing capacity behavior of the bucket foundations can be expressed through failure envelopes that expand with increasing aspect ratio. In the literature, it is not clearly and quantitatively clarified how the bearing capacity depends on bucket embedment length but can be stated with increasing aspect ratio, failure mechanisms are forced deeper within the soil mass. In November 2002 the first Suction bucket foundation for using of the wind energy converter was installed at the large scale test facility in Frederikshavn. The project was at the time being the largest wind turbine in Denmark. It’ s total height of turbine was equal 125 m with a bucket diameter of 12 m and skirt length of 6 m (i. e. L/D =0. 5). In this report, the effect of aspect ratio on combined bearing capacity of bucket foundations installed in saturated medium dense sand was evaluated. Load-deformation behavior of suction buckets under loads was investigated and compared. The analysis was carried out by loading bucket foundations with a load that allowed the bucket to move freely. When considering the design of the foundations of offshore wind turbines, it is important to understand their elastoplastic deformation behavior as well as ultimate capacities.

One of the major obstacles to development of self-consolidating concrete (SCC) on the industrial scale and various applications is the high sensitivity or very low robustness of this concrete to conventional concrete. From this, in the present study, a total of eight SCC mixes have been produced and their rehology parameters were tested. A control mix (C) was the initial target and, seven series of mixes were developed with variations of each of the principal properties (i. e. filling and passing ability and segregation resistance) or using of AEA and VMA admixture. In order to evaluate the robustness of each mixture, in addition to the mixture with amount of water content, four mixtures were made that the water content of each mix was changed ± 3% and ± 6% relative to the base water content and then the rheological properties of each mixture were determined. The rheology parameters (yield stress, plastic viscosity) values were determined by a coaxial rhometer. This automated rheometer is a rate-controlled rheometer that was employed to carry out rheological measurements 10 minutes after the initial contact between water and cement. It consists of a four-bladed vane that is immersed into the concrete and rotated at various speeds while the torque acting on the vane is measured. the objective of using rheology measurements is to provide scientific parameters that are capable of describing multiple aspects of workability. This fact are true especially for self consolidating concrete that has several properties in fresh state. So, it is required to perform several tests to evaluation of these properties that in addition to increase the quality control time, it also raises the costs and reduces the accuracy. Therefore, it seems logical to determine rheological parameters that are an accurate test with high sensitivity Instead of measuring multiple properties of fresh state through different workability tests for achieving to a proper robustness index for SCC. Therefore a good approximation of the fundamental rheological quantities for cement based material can be obtained in terms of yield stress (τ 0) and plastic viscosity (μ ). In this study a rheograph is defined as a graph that X axis is yield stress (τ 0) and Y axis is plastic viscosity (μ ). This graph that to that has been named “ rheograph” is a convenient and essential tool to compare different concrete batches and examine the behavior relative to changed constituents, quantities of constituents, and/or relative to different times from water addition (and so forth). Thus rheograph is a systematical way to reveal the effects of slight decrease and increase in mixing water. The results of the study show that a slight increase in the amount of water increase the yeild stress of SCC, but decreasing water content in some concrete increase and in some concrete reduce the yeild stress. In contrast, in plastic viscosity of SCC, a slight decrease in the amount of water content increases the viscosity and a slight increase in the amount of water reduces the plastic viscosity of SCC. An appropriate index for estimating the robustness of SCC is the area enclosed between the rheological properties of concrete in changing the water content by ± 3% or ± 6%. According to this index, the addition of air entraining admixture to SCC improves robustness and reduces the amount of paste volume resulting in a severe reduction of robustness.

Nowadays, cement is broadly applied to stabilize the soil to improve the mechanical and engineering properties of different soils and to control their deformations and swelling behavior. Nevertheless, due to the high expenses, civil engineers have always been trying to find an economic pozzolanic alternative for cement. In this regard, lots of construction materials such as fly ash, lime, blast furnace ash, pond ash, rice husk ash, etc. are added to different soil materials to find an optimum replacement for the cement. Among the mentioned materials, rice husk ash (RHA), which is widely available in Guilan, Iran, is an environmentally dangerous material (if dumped in the nature). Hence, application of this material will be both economically and environmentally useful. Also, due to its high applicability, it can be easily applied in civil constructions. Hence, application of RHA in civil/construction projects will be considerably useful. On the other hand, different fibers (e. g. plastic, polyester, polypropylene, etc. ) are used for engineering purposes to both control the process of crack initiation and increase the material mechanical properties. The length of applied fibers, also, their percentage is two famous controlling parameters of applying fibers in soil stabilization programs. In this paper, a new soil stabilization method is introduced to stabilize Anzali sand using the combination of cement and RHA. Also, the possibility of cement replacement with RHA is investigated. Polypropylene fibers in 0. 2 and 0. 4 percentages are also added to the samples to control the growth of tensile cracks and to evaluate their effect on the compressive strength of stabilized samples. Hence, cement in 3, 5, 7. 5, 10 percentages, also, RHA in 3, 5, 7. 5, 10, 12 and 15 percentages are added to the sand samples to increase their compressive strength. Samples are cured for 28 days and unconfined compressive strength tests are conducted on the stabilized and reinforced samples. Based on the test results, compressive strength of all the samples were increase as cement and RHA percentages were increased. Also, RHA is introduced as a capable replacement additive for the cement. In order to make a generalization and provide a relationship for practitioners to use the results of the present study, different techniques can be adopted. Among them, artificial intelligence techniques are most in demanding ones. Neural networks, gen programming languages, genetic algorithms and evolutionary approaches can be applied to provide such relationships. In this paper, evolutionary approaches are considered and using evolutionary polynomial regression technique, simple predictive equation for forecasting UCS is proposed. In this regard, based on the results of conducted un-confined compressive strength tests, Evolutionary Polynomial Regression (EPR) technique is applied and a high accuracy predictive relationship for forecasting UCS of cement-RHA stabilized and polypropylene reinforced sand is presented (coefficient of determination of 94. 4%). In addition, sensitivity analysis based on Cosine Amplitude Method (CAM) is carried out to investigate the most and the least effective materials on the compressive strength of samples. CAM analysis showed that although cement and RHA have meaningful effect on the determination of UCS, polypropylene percentage is the most sensitive additive controlling the variation of UCS.

Petroleum is the major source of energy and the activities related to the petroleum industry leading to high volumes of wastewater and emissions different pollutants to water systems. According to studies, world oil demand will increase to about 107 million barrels a day over the next two decades, and about 32 percent of global energy will be provided from Petroleum by 2030. Thus wastewater resulting from oil and refinery industry is increasingly rising and discharges into the environment, which is a serious threat to the world's water resources. A large amount of water is used to extract and to refine the petroleum in oil refineries, thus produce the large amounts of wastewater. The wastewaters containing various kinds of pollutants with different concentrations are of environmental problems due to high organic load and hard-biodegradable compounds. With the increasing drinking water standards and environmental stricter regulations relation to discharge of sewage, electrochemical technologies have gained their importance all over the world during the last two decades and now electrochemical processes such as recovery of metals, electrocoagulation, electro-flotation and electro-oxidation can be effective technologies in the field of different wastewater treatment. In the electrocoagulation process by applying an electric current to the cathode and anode electrodes in a conductive solution by dissolving anode, coagulants produced in situ and cause the flocs is that they are floating with bubbles of hydrogen gas generated at the cathode. The metal ion generation takes place at the anode, while hydrogen gas is produced at the cathode. The metal ions form flocculates which trap contaminants while the hydrogen gas floats these particles. In this study, the electrocoagulation process was carried out with the use of a cathode and an anode made of stainless steel to reduce pollution from synthesis wastewater. For this purpose, the various parameters are optimized separately in this system by one factorial method, and then use experiment design methods. The effects of five parameters including the electrode surface, initial COD concentration, current density, pH and NaCl concentration were evaluated in the range of 23. 36 to 78. 36 cm2, 100 to 2500 mg/L, 2 to 30 mA/cm2, 3 to 11 and 0. 3 to 2 g/L, respectively, in the case of electrocoagulation process. The optimum conditions of electrode surface, initial COD concentration, current density, pH and NaCl concentration were achieved 23. 36 cm2, 900 mg/L, 20 mA/cm2, 8. 5 and 0. 5 g/L, respectively, for this process with energy consumption of 7. 3 kWh/kg CODRem and electrode consumption of 0. 4 Kg Fe/Kg CODRem during 60 minutes. The results of the experimental design of response surface methodology were confirmed the results of OFAT method with acceptable obtained error for the electrocoagulation processes. Based on results from experimental design of response surface methodology in this process, current density, time, pH and concentration of sodium chloride, respectively, were the most influential parameters. Electro-coagulation process seems to be an economic and environmental friendly process to remove the pollutants from wastewater. It has been demonstrated that electrocoagulation process with the use of stainless steel anode and cathode is a very effective and operative method to degrade Petroleum pollution and reduce COD.

In order to determine and predict the possible damage imposed on the structures, performance-based standards have presented certain levels and limits. The current study aimed to make a probabilistic evaluation of the special steel moment frames exceeding these levels through comparing the demand measure (DM) and the intensity measure (IM). It further tried to examine the performance of the sixth and tenth issues of the national regulations and Iranian 2800 standard in confining the damage imposed on this type of structures. The results of DM probabilities analysis based on IM parameter could be expressed in two ways: 1) the fragility curve of the probability exceeding the limit states, and 2) assessment of the probability of the annual mean exceedance of the limit states. Among numerous types of limit states, the global collapse of the structure is of utmost significance. The present study utilized both forms of these analyses. In the first phase of the research, cumulative distribution function (CDF) curves were used to assess the performance of the structures subjected to the records of various risk levels according to FEMA-350 guidelines. To this end, a ten-story and a twenty-story special steel moment resisting frame were modeled in OpenSees software. Then, fragility curves of the frames collapse were drawn at three performance levels of immediate occupancy (IO), collapse prevention (CP), and global instability (GI) through using the incremental dynamic analysis (IDA) and by means of the records introduced in The Next Generation Attenuation (NGA) for near-and far-fault records. Then, in the second phase of the study, the collapse probability of the structures under the study was estimated for Tehran city, which is located at a high seismicity zone. It is worth noting that these structures were designed and loaded according to the existing guidelines and were considered at the risk level 2 (risk level 2 according to the FEMA 356 and Iranian 360 guidelines) under the influence of the earthquake. Moreover, the median collapse capacity intensity (Ŝ CT) was calculated indicating the acceleration at which the structural collapse probability equals to 50%. Finally, the aforementioned curves were used and the probability exceedance of the frames under the study were obtained from three risk levels with the return periods of 75, 475 and 2475 years and the damage imposed on the frames were assessed and compared. The findings indicated that: 1) the special moment resisting frames influenced by the far-and near-fault records were safe at the performance levels of IO, CP, and GI and hence, the purpose of the seismic design and loading guidelines was fulfilled, 2) in general, the seismic response of the structures due to near-fault ground motions is more critical compared to those of the far-fault ones, but with an increase in the number of stories in high-rise building structures, the effect of far-fault ground motions on seismic response of the structure increases so that no significant difference would be observed in the structural ductility demands due to near-fault and far-fault ground motions, and 3) the highest certainty coefficient belonged to the ten-story frame under the influence of far-fault records and the lowest certainty coefficient belonged to the twenty-story structure under the influence of near-fault records. This clearly demonstrated the influence of increasing the height of the structure on its collapse probability and the impact of near-fault records.

Sediment transport by a fluid flow is one of the most important two phase flows in the nature. Predicting river behavior at bends is important since rivers rarely run on straight paths in nature, and most rivers have meandering forms. In a river bend the presence of centrifugal force leads to the formation of secondary flow. As a result water particles near the surface are driven outward and the flow at the bed of a channel is directed toward the inner bank. Therefore locating the intake at outer bank of bend is one of the ways to reduce sediment intern to the lateral intake. Due to the existence of secondary current in channel bends, the mechanism of flow and sediment transport is much complex whereas locating lateral intake at outer bank of the bends decreases this complexity. Lateral intakes are hydraulic structures, used for water conveyance for domestic, agricultural and industrial purposes, characterized by a very complex three-dimensional morphodynamic behavior: since streamlines near the lateral intake are deflected, some vortices are formed; also, the pressure gradient, shear and centrifugal forces at the intake generate the flow separation and a secondary movement responsible for local scour and sediment deposition. Knowing the mechanisms of sediment transport in the channel bends with lateral intake and the manner in which sediments can enter the diversion can help engineers in the better design of these hydraulic structures. In this paper, sediment transport phenomena and mechanisms of sediment entry to the lateral intake were carried out in a 180 degree channel bend using injection of sediment on rigid bed. In this order, a sediment injection device with uniform and adjustable rate were designed and made. The intake were installed in position 115 degree of bend with 45 degree diversion angle according to previous research suggestion. The sediment injection device were fixed at upstream of the bend and dried sediment with the rate of equal to the capacity of the channel upstream of the bend were injected. In order to analyzing the results, three components of flow velocity were measured using 3D Acoustic Doppler Velocimeter (Vectrino). Moreover, the sediment movement path in different times and diverted sediment ratio to intake are measured. In this research, effect of Froude Number and diversion discharge ratio on sediment transport in the bend and mechanism of sediment entry to the intake were considered. The results showed that in different Froud number and diversion discharge rate, after equilibrium time, a sediment accumulation occurred in section 45 degree of bend and another sediment accumulation occurred in section 135 degree of bend near inner bend. The reduction of Froud number caused development of bed forms and their heights. Also the results showed the mechanism of sediment entry to the lateral intake is affected by diversion discharge ratio. In Qr=40% (and Fr=0. 38), the mechanism of sediment entry were consisting of continues entrance from downstream edge of intake and periodic entrance from upstream of the intake but in Qr=25% (and Fr=0. 38), the mechanism of sediment entry were only consisting of continues entrance from downstream edge of intake.

Air pollution as a silent murderer of metropolitan residents, needs acute efforts. During the past few decades, after London 1954 black days, the world encountered a novel and anthropologic problem. Scientific researches for scrutinizing the air pollution sources and its effects on humankind and environment started and improved after chronic influences of contaminations have been revealed. Prognostication of pollutants and finding the relationships between parameters, seems to be undeniable. Ozone as a tropospheric gas, has severe impacts on the all creatures while the human beings are more delicate in conjunction with this gas where it can deteriorate lung ability and cause acute asthma and other pulmonary diseases. In the present article, the two most prevailing approaches for prediction, have been applied to the forecast tropospheric ozone value via considering other eight parameters. Sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and particulate matters (PM2. 5, PM10) as photochemical precursors, and also relative humidity, air temperature and wind speed as meteorological parameters, after data preparation, used for ground level ozone prognostication in Tehran, Iran, with a condensed population where suffers from severe air contaminations and high rate of daily death caused air pollution. The used data series, have been collected from 22 regions of Tehran during the two years (2014 and 2015). Two evaluation criteria; root mean square error (RMSE) and correlation coefficient (R), have been selected to compare the methodologies. Support vector machine (SVM) and artificial neural networks (ANN) as capable soft computing approaches have been used in numerous areas of science, opted in this research. Support vector machine with classification of other eight parameters and by 286 vectors as a classifier and 97 border vectors, sorted the 70 percent of data sets as training and the residual amount of parameters used as testing data sets. Radial basis function (RBF) selected as the Kernel function. Artificial neural network works as like as human brain and neurons between layers transfer datasets and process them during the run time, where in the recent paper the layer number of the created network is one for hidden layer and one for the output layer and 10 neurons have been exploited for the hidden layer and one for the output layer. Network type of this system is feed-forward with back propagation and TRAINLM used as training function and LEARNGDM used for adaption learning function. Both approaches depicted reliable and acceptable results, where RMSE and R values for support vector machine, respectively are 0. 0774 and 0. 8456, also artificial neural network resulted 0. 0914 for RMSE and 0. 8396 for R, which are reasonable outcomes. As the outcomes for training datasets were better than the results for testing datasets, both approaches showed that both of they did not over-trained, which is a serious and prevalent difficulty for soft computers. Support vector machine, with lower root mean square error and higher correlation coefficient disclosed as the better method for ground level ozone prediction. These series of studies are supportive for calibration of measuring systems and due to their expensiveness, soft computing can be the most reliable and affordable substitute. Also the analysis of tolerances among the parameters illustrated that CO, Temperature and NO2 are the most effective where, PM2. 5 had the least amount impact on O3 forecasting process.

Reactive powder concrete (RPC) represents a new generation of cement-based materials composed of cement, reactive ultrafine powders, siliceous fine aggregates, super plasticizers and fibers. Due to its microstructural properties, this concrete demonstrates specific properties including high compressive and flexural strength, superb durability. Since this is a novel type of concrete, a single design code containing multiple experimental results of high quality, together with reliable stress-strain models for the nonlinear analysis of the structural members made of this concrete type is lacking. Although some experimental equations to predict the strength of the RPC members can be found in the literature, note that there are shortcomings in the information provided specifically regarding the RPC containing synthetic and hybrid fibers. Hence, in this study, ten different mix designs of RPC, containing steel fibers at the volume fractions of 1, 2, and 3%, polyvinyl alcohol fibers at the volume fractions of 0. 25, 0. 5, and 0. 75%, together with hybridizations of the two fiber types at the total fiber volume fraction of 1% were prepared, and then tested to obtain accurate and applicable equations as well as the compressive stress-strain curve with the purpose of estimating the mechanical properties and better predicting the behavior of this type of concrete. Then, the effect of the type and volume fraction of fibers, together with curing regime on the properties of RPC including the compressive strength, strain at peak stress, modulus of elasticity, and the shape of stress-strain curve was investigated. The obtained results indicate that as the volume fraction of steel and polyvinyl alcohol fibers increases, the compressive strength and strain at peak stress of the RPC specimens decreases; a trend which is also observed as the volume fraction of synthetic fibers in the concrete mix containing hybrid fibers increases. . The trend which is observed for the strain at peak stress in the RPC is very close to that for its compressive strength. The secant and tangential modulus of elasticity values of the RPC also demonstrate trends similar to each other, and the tangential modulus of elasticity in all the specimens has values higher than the corresponding secant modulus of elasticity. The RPC containing high volume fractions of steel fibers shows high modulus of elasticity values, due to the crimped shape of fibers as well as the strong cohesion they provide in the concrete. Heat treatment has a positive effect on the compressive strength and strain at peak stress of the RPC specimens, due to the acceleration of the hydration process of cementitious materials at high temperatures as well as the formation of a dense matrix. By using the nonlinear regression analysis of the data, experimental equations were developed for the parameters affecting the stress-strain curve of RPC. Finally, based on the experimental parameters obtained for all the RPC specimens, a model was proposed to predict the compressive stress-strain curve. By comparing the proposed model with the experimental results of the stress-strain curve of RPC, it can be said that the proposed model is capable of predicting the experimental results with a very good accuracy.

The pavement structure of rural roads under heavy traffic has essential importance because of both economical and technical considerations. In this research, different models of a case study rural road under the agricultural trailers traffic has been studied. To identify different road models, the structure-traffic index (STI) is used. The STI is the result structure number (SN) over traffic loading parameter. In this research, the STI index consists of two common fatigue and rutting distresses. The asphalt concrete sample was cored from the field and then, the resilience modulus experimental tests were conducted to identify the elasticity modulus of asphalt concrete. In this research, 5 types of 18 wheels and 5 types of 12 wheels trailers have been investigated. In each group, one type of the trailer was considered as critical trailer that the FH440 and ScaniaG400 are considered as critical trailer in tandem and tridem axle, respectively. First, based on the finite element (FE) simulation in the ABAQUS software it is concluded that the 12 wheels trailers with tridem axle have a more destructive effect on the pavement structure in comparison to 18 wheels trailers with tandem axle. The tensile strain at the bottom of asphalt concrete layer and compressive strain at the top of subgrade were exported from the FE simulations. In addition, the Scania G400 is defined as critical vehicle. Then, different models have been conducted to investigate the fatigue and rutting distresses. The results show 23% and 41% reduction in tensile stress at the bottom of asphalt concrete as the 2. 5cm and 5cm increases in asphalt concrete layer, respectively. The obtained results from the FE simulation show that the tensile strain at the bottom of asphalt concrete is 4. 5 times more than that the personal car and the STI index for the fatigue and rutting distresses is 0. 14 and 0. 11, respectively. In addition, this research investigates the effects of the cold asphalt concrete on rutting and fatigue distresses of pavement structure. The results show that the cold asphalt mixture made of base and subbase materials has 15% reduction in rutting distress. The results show that using the cold asphalt mixture in rural roads can improve the rutting resistance and effects of cold asphalt mixture on rutting resistance are more than that base and subbase layers. Comparing the results obtained from the FE simulations show a considerable compatibility of structural and traffic parameters in the pavement structure. Investigation of a rural road case study show clearly that design the road structure without considering the traffic parameters results in significant distress and cost in the pavement structure. It means that the design for the rural road without considering the pavement structure and traffic parameters results in under predicted design. The proposed STI index in this research is a new index to design the rural pavement structure and needs to be investigated more in future studies. The investigation of rural road against of truck and agricultural vehicle is a crucial problems in the rural roads and needs more investigations.

The seismic design of the structures is subjected to the uncertainties originating from various sources. To ensure that a safe design is achieved, the uncertainties must be considered in the seismic design process. The reliability-based seismic design is the proper approach that directly takes into account the uncertainties. In this approach, the performance objectives are the reliability-based seismic criteria expressed either in terms of an annual probability of exceeding a given performance level or in terms of a probability of exceeding a given performance level conditioned on the seismic intensity corresponding to a specific hazard level. It is obvious that the ultimate aim of the reliability-based seismic design of a building is not only to satisfy the reliability-based seismic criteria, but also to minimize the initial or life-cycle cost. The reliability-based seismic design optimization (RBDO) is the method that achieves the most economic design satisfying the reliability-based seismic criteria (probabilistic constraints). However, the RBDO is less preferred. This is because to ensure that reliability-based seismic criteria are achieved, the statistics parameters of the seismic demand and capacity must be determined through the results of the nonlinear dynamic analyses. On the other hand, the use of the nonlinear dynamic analyses in the RBDO method can lead to the increase of the computational cost so that the personal computers require several years to run it. In this study, a method to produce the reliability-based economic seismic design is proposed. Reliability-based seismic criteria are expressed in terms of a mean annual probability of exceeding a given performance level. The main goals are to ensure satisfying the reliability-based seismic criteria through the use of the results of the incremental dynamic analyses and to produce the economic seismic design within reasonable computing time. The proposed method achieves the two goals through determining the optimum design of the force-based design method that satisfies the reliability-based seismic criteria. The optimum design of the force-based design method depends on the value of the response modification factor. The value of the response modification factor of a building, which leads to satisfying the reliability-based seismic criteria, is in the range of one to a maximum value. From an economic point of view, the desirable value of the response modification factor is the maximum one, which results in a minimum design base shear and accordingly in an economic design. In order to respond to the two main goals, the method aims to determine the maximum value of the response modification factor of a building so that leads to satisfying the reliability-based seismic criteria. The proposed method is used to produce the seismic design of a 4-story building for two reliability-based seismic criteria. The steel special moment resisting frame is considered as the lateral load resisting system in the studied building. The results reveal that the proposed method can efficiently produce the economic seismic designs satisfying the reliability-based seismic criteria within reasonable computing time. While the designed frame by Zacharenaki et al using existing RBDO method can not satisfy spesifications of reliability.