نشریه مهندسی عمران
سال پنجاه و سوم شماره 4 (تیر 1400)

Pavement deterioration models are the most important components of any Pavement Management System (PMS). These models could predict pavement condition at any time in its service life. Pavement deterioration is a very complicated and uncertain process. Probabilistic deterioration models in comparison with deterministic ones could take into account these uncertainties. One of the most important probabilistic pavement deterioration models, is the trend curve model that is based on pavement roughness. In this research, roughness data of GPS-1 and GPS-2 pavement sections, which are in-service asphalt pavements respectively with granular base and stabilized base layers, have been extracted from Long-Term Pavement Performance (LTPP) database. These data then were used for analyzing pavement deterioration uncertainties. For this purpose, Chi-square (χ2) and Kolmogorov-Smirnov (K-S) statistical tests were used to determine probability distribution of pavement future condition over its current condition ratio in different years. Results showed that lognormal distribution is more fitted with actual data in long-term pavement life. Having this distribution, pavement deterioration model was developed based on roughness index using trend curve model. Utilizing proposed model, the pavement management system could predict pavement future condition taking into account uncertainties of deterioration process and with optimal budget assignment, could maintain the network condition at a specified risk level. This could prevent of any future risk regarding the pavement deterioration uncertainties.

Corrosion in reinforced concrete structures reduces the strength capacity and ductility of members and concrete elements. The use of fibers to improve mechanical properties of concrete has long been considered by engineers. In this study, an experimental study was conducted to investigate the effect of macro-polymeric fibers and hooked metal fibers on corrosion-free, non-corrosive reinforced concrete beams. Two types of macro-polymeric fibers and hooked metal fibers with 0% and 0.5% volume percentages were tested at three levels of corrosion of 0%, 7% and 9%. An accelerated corrosion test was used from a 3% salt pool. Finally, the reinforced concrete beams were subjected to bending loading tests. Structural behavior of reinforced concrete beams in corrosion beams and non-corrosion beams and with fibers and non-fibers were evaluated and compared. Based on experimental results, corrosion reduces the ductility of the specimens and the use of metallic and polymeric fibers in non-corrosion and corrosion specimens of the first and second surfaces causes a two-fold increase in ductility. Macro polymer fibers are more effective in increasing the shape of the samples compared to the hook metal fibers in corrosion samples. Increasing the percentage of corrosion in non-fibrous specimens decreased the maximum resistance of the specimens, but in specimens with fibers, no significant change was observed in the bearing capacity of the samples with increasing corrosion percentage.

Penetration tests are one of important geotechnical insitu tests by which, different soil parameters can be estimated. The advantages of these tests are easiness, high speed, and repeatability. In this research, a penetrometer called as “Manual Dynamic Penetrometer (MDP)” is utilized to perform tests on dry Firoozkuh Sand with three different relative densities. The MDP is similar to other penetrometers used in geotechnical engineering, but the dimension is different which causes to generate more power to penetrate into the soil with deeper layers. The aim of this research is to investigate the effect of cone geometry as well as applied energy on test results. To do so, three different cone diameters and cone apex are considered. In addition, the mass of the hammer is also changed in three different values. The comparison of results indicate that the come apex does not influence the penetration value; however, the cone diameter plays the role. It is also seen that the applied energy has direct relationship with the penetration. Since the mechanism of the cone penetration is similar to that of pile driving, it was also shown that it is possible to estimate the residual internal friction angle of the soil by using empirical formula proposed by Meyerhof.

Due to heavy rainfall, underground water level and pore water pressure increase each year, which can cause failure of the earthen slopes. Retaining wall is one of the main structures that is used to increase the earthen slopes stability. In the present study, the stability of earthen slopes relative to the critical hydrological cases was simulated by Slope/w software and the pore pressure behind the retaining walls over 10 meter height which causes to instability was simulated using Seep/w software. The studied parameters are: precipitation intensity, soil type, position and the diameter of drainage. Also the kind of drainage has been considered as a variable parameter and horizontal and chimney drainages were used. Results showed that for fine grained soils with intensive rains condition, using of one horizontal drainage could not provide the stability of retaining wall. While in the same conditions, for coarse grained soils, the retaining wall will be stable by using of one horizontal drainage and drainage will be able to discharge all of the excess water behind the retaining wall. Also the chimney drainage system provided the best results and the stability of the retaining wall did not face any danger under the worst circumstances. For overturning moment and water pore pressure behind the wall, linear and non-linear regression relations were produced in dimensionless form. The accuracy of the regression relations were proper and the acceptable results could be expected.

One of the most important issues in today's world is the pollution of water with toxic and dangerous metals. Cadmium is one of the toxic metals that enter the surface and groundwater through various industrial wastewaters. In this paper, polyethylene oxide-based silica monolith was synthesized with a uniform porous structure and was used to remove cadmium ions from the aqueous medium. The chemical and physical properties of silica monolith were characterized by SEM, BET, and FTIR techniques. The results of BET and SEM analysis showed that the monolith has a mesopore structure with a specific surface area of 543 m2g-1. The synthesized silica monolith was used as an adsorbent for cadmium removal in a batch adsorption process and the effects of operating parameters including pH, adsorbent concentration, cadmium initial concentration, and contact time were investigated. The Central Composite Design method was used to optimize the effects of operating parameters. The results of the experimental design showed the importance of pH and adsorbent concentration parameters. The analysis of equilibrium data indicated that the maximum adsorption capacity of the monolith for cadmium is 153 mg g-1. The kinetic data were analyzed with various models and results indicated the importance of chemical adsorption. The results of regeneration and reuse of monolith as an adsorbent showed that the synthesized monolith has a high ability to adsorb heavy metal ions from an aqueous solution and can be an option for water treatment at industrial scale.

In this paper, formulation of a recently proposed time-weighted residual method has been developed for the vibration analysis of Timoshenko beams under moving loads. Employing pre-integration relations as well as equilibrium equations, is the main idea of this method. In the first step of the proposed method, the time interval is subdivided into a number of sub-intervals and then the acceleration field in each sub-interval is defined as the combination of an unknown function and an exponential series with constant coefficients. Finally, the solution of the problem is estimated by the time-weighted residual method along with exact satisfaction of the initial and the boundary conditions at the two ends of the beam. Storing the information of solution at each time step on the exponential coefficients, is the most important advantage of this method, so that the solution is progressed in time without the need to discretize beams and only by using an appropriate recursive relation to update the exponential coefficients. In order to investigate the accuracy and efficiency of the proposed method, the results of solving three sample problems of constant and accelerated moving load on the beams with different boundary conditions, are compared with the results of finite element method. This comparison illustrates the speed and accuracy of the proposed method in estimating the internal shear forces and bending moments rather than those obtained by the finite element method.

Increasing rate of energy consumption in building sector has led the constructors towards the low-energy consuming methods. The enhancement of thermal performance of structural elements in conjunction with mechanical properties yields to the decrease in environmental impacts. In this paper, thermal performance of ASTM mortars has been investigated. Considering the limitations of typical methods in the measurement of thermal parameters, in this investigation, the parameters of lag time, decrement factor and thermal conductivity of mortars have been measured using the method of hygrothermal chamber. Results show that type O mortar with the minimum thermal conductivity of 0.264 (watt per kelvin-meter) and the maximum lag time of 66 minutes, had the significant thermo-buffering capacity among the ASTM mortars. However, due to the low cementitious materials in the mixture of the mortar, type O lacks of the acceptable strength features. Consequently, the optimum type of mortar must be produced in which the thermal performance has the same value of the mechanical properties. KEYWORDS Mortars, Masonry structures, energy consumption, thermal performance, ASTM standard

Today, structural health monitoring techniques that can detect damage in early stages have become very important. For these reason, such techniques must be able to detect slight damages. However, a large number of algorithms that have proposed so far for damage detection are unable to identify early-stage damages. One of the approaches that can be employed is multifractal method. In this paper, a damage detection technique is proposed based on multifractal detrend fluctuation analysis and blind source separation. In the first stage, the accuracy of three methods of blind source separation is compared and the most efficient method in decomposing structural vibration signals is selected. These methods include blind modal identification, combined method, and sparse coding. Three structural models are employed to investigate efficiency of the procedures which consists of a range of numerical MDOF model with limited degree of freedom to real structures. In the second stage, a damage index is proposed based on the width of multifractal spectrum. Results show that the aforementioned method is able to identify various damage patterns and can detect slight damages.

The aim of this study is to decrease the silica fume (SF) content of UHPC by using natural zeolite (NZ) with different levels of replacement (25%, 50% ,75% and 100% by volume), in order to mitigate autogenous shrinkage with almost equivalent mechanical performance. The results demonstrated that addition of NZ as replacement of SF had a positive effect on maintaining internal RH in the higher range as well as in reducing the autogenous shrinkage of UHPC. The mixtures with 25%, 50%, 75% and 100% replacing SF by NZ had lower autogenous shrinkage compared to reference mixtures containing 100% SF. The results of Thermogravimetric and microstructure analysis indicated that NZ had appropriate pozzolanic activity. The results of the compressive strength test showed that by replacing 50% SF with NZ, the 90 days compressive strength of 164.37 MPa could be achieved, which was only slightly lower than the reference mixture with a 90 days compressive strength of 169.07 MPa. replacing SF with NZ yielding a cost-effective solution. By replacing 50% NZ replacement of SF, UHPC mix with 90 days compressive strength over 150 MPa, with low autogenous shrinkage and relatively low cost can be produced.

Experimental and numerical studies on Steel Plate Shear Wall (SPSW) and its successful performance under last earthquakes have introduced this system as a lateral bearing system. There are lots of unknown information about SPSW despite of numerous studies that have were done. The effect of crack on the SPSW behavior is one of unknowns about SPSW that due to its complicity in nonlinear analysis, it has not been evaluated comprehensively. Because of thin steel plate and inherent of welding, emerging of crack on SPSW is deniable. So, in this paper the effect of central and edge crack and their growth on the behavior of SPSW have been studied. Results showed that the central crack are more destructive than edge cracks. The crack with long length lead the SPSW to fracture in elastic zone. Due to difficulty of crack modeling and crack analysis, the necessary relations have been proposed to obtain pushover diagram that without FE modeling the proposed relation estimate the pushover diagram of system in good agreement with FE results.

One of the undesirable modes of failure in reinforced concrete (RC) beams is the shear failure prior to bending one. One of the methods to prevent the occurrence of shear failure at a low level of shear forces is to provide the minimum shear reinforcement in RC beams. This paper investigates the effect of crimped end-hooked steel and modified polymeric fibers on the shear behavior of RC beams with normal strength. The experimental results of this study are then compared whit the shear behavior of the cross-section having the minimum shear reinforcement under similar conditions and the possibility to replace the minimum shear reinforcement by the fibers according to ASTM C1609 along with the fiber acceptance requirements based on ACI 318-2011, is evaluated. For this purpose, 16 half-scale reinforced concrete beam specimens with the shear span-to-effective depth ratio of 2.6 were made in three groups. The first four specimens were without the shear reinforcement and fibers, the other four specimens were without the fibers and reinforced with the minimum shear reinforcement and, eight other specimens were without shear reinforcement containing a hybrid of steel fiber (0.75%, 1%) and polypropylene fiber (0.25%). Moreover, the effect of longitudinal reinforcement ratio (2.5%, 4%) on the shear behavior of the beam specimens was investigated. After using the four-point loading test, it was observed that the combination of the crimped end-hooked steel and modified polymeric fibers would improve the shear behavior of RC beams and could be a good substitute for the minimum shear reinforcement.

Natural gas transmission pipelines transport the natural gas at elevated temperature and high internal pressure. The pipelines will expand when they are put into operation under the influence of increased internal pressure and temperature. The movement due to such expansion is significant for large diameter pipelines which operate at high pressure and elevated temperature. The pipeline needs to be restrained near compressor stations in order to prevent the transmission of such movement to equipment and facilities within the station. Concrete anchor blocks are commonly used to restrain the movement of buried pipelines on both sides of compressor stations. Anchor blocks for transmission pipelines are usually massive because of the high axial stress in the pipe which results in large thrust force. Current design procedures are usually based on providing an adequate margin of safety against block sliding, block overturning and soil bearing pressure. This paper presents the results of an analytical study on the response of soil, pipeline and anchor block at different operating pressure and temperatures. Nonlinear finite element analyses which include modeling of soil-pipe and soil-block interactions are carried out to evaluate the design procedures. The results indicate that the concept used in current design procedures is fundamentally flawed because it is based on controlling forces rather displacements. Based on the results of these analyses a more rational design procedure which is based on controlling the displacements is introduced. The proposed design procedure results in a substantial reduction of the size of anchor blocks.

In this paper, the performance of the strip of scrap tires (Geo Scrap Tire(GST)) with horizontal transverse members evaluates as reinforcement elements in mechanically stabilized earth walls (MSEWs) by large scale pullout test (i.e. 1.4 m × 0.8 m × 0.8 m). In this regards, the experimental pullout results of GST reinforcement compared with theoretical equations and conventional reinforcement of Geosynthetic Strip (GS), Steel Strip (ST) and Steel Strip with Rib (STR). The experimental pullout results showed that the innovative suggested reinforcement element performed better than the other strips so that the GST strip was capable of increasing pullout resistance by more than 3, 2.5 and 1.5 times compared to the steel strip, the geosynthetic strip and the ribbed steel strip. The results show maximum pullout resistance of GST affected by the S/B ratio and with adding three horizontal transverse members can be increasing pullout resistance by more than 5.9, 4.9 and 3.2 times compared to ST, GS and STR. Thus, using GST reinforcement with three horizontal transverse member needs a smaller length (less than 30%) comparing to conventional strip reinforcement (ST, GS, STR). Therefore, using Geo Scrap Tire reinforcement can open a new horizon in solving the problem of scrap tires and assure geotechnical engineers in achieving superior and more economical systems of reinforced soil walls.

This study aimed to Evaluation of Factor Affecting Suppliers’ Capacity Building at Isfahan Water and ‎Wastewater Company in 2019 ‎by descriptive method of survey type and with applied purpose. The statistical ‎population ‎consisted of three groups including employer, ‎consultant, contractor factors, all of whom were ‎reported 50 ‎persons were selected by using census sampling method. The used questionnaire was a researcher-‎made questionnaire developed ‎by the researcher, based on 50 items and 4 components (legal-‎formal, contract, management and financial) ‎based on a 5-point Likert scale. The face, content and construct validity of the questionnaires are confirmed. ‎‎Questionnaire reliability coefficient by use of Cronbach's alpha was (0.711) in ‎the legal-formal dimension, ‎‎(0.889) in the contract dimension, (0.946) in the management ‎dimension (0.871) in the financial dimension and ‎the total reliability of the questionnaire was ‎estimated as (0.961). The findings of the study indicated that ‎the status of the outsourcing process for the ‎suppliers’ capacity building is above average. In addition, in the ranking of ‎effective factors in the increase of the suppliers’ ‎capacity in the outsourcing process, the financial component ‎with the mean rating of (2.78) ‎was the first rank; the legal-formal component with the mean rating of (2.49) was ‎the second ‎rank; contract component with the mean rating of (2.43) was the third rank and management ‎‎component with the mean rating of (2.30) was the fourth rank

Corrosion of rebar is a complex process and one of the most important factors of failure of reinforced concrete structures which reduces the strength and serviceability of the structures. The crack width is an important parameter for designing and evaluating the performance of concrete structures. This paper presents an analytical model to calculate the crack width caused by corrosion. Crack propagation due to corrosion product expansion was investigated at different stages across the concrete cover starting from the reinforcing bar-concrete interface through to the surface. A merit of this model is that it is directly related to the factors that affect the corrosion induced cracking process. Then, the predicted crack width was chosen as a random variable in the calculation of structural failure probability using a stochastic gamma process, after which life cycle costs and the optimum repair period were determined using a renewal process. Furthermore, the effects of structural parameters, including rebar diameter and corrosion rate, on the probability of failure and maintenance costs were investigated, indicating that crack width and life cycle costs are most significantly affected by corrosion rate. That is, a 16-times increase in corrosion rate results in 32 percent reduction in repair time. Moreover, it is to be noted that increasing the allowable fracture limit by 10 percent resulted in the doubling of optimum repair time. In other words, the optimum repair period is significantly affected by the allowed fracture limit which indicates the threshold for structural repair.

Mathematical simulation of groundwater resource systems is one of the essential tools in managing these valuable resources and calibration of the groundwater simulation models is the time-consuming, and complicated step of these systems. Automated calibration, developed in recent years by researchers with different algorithms, is one of the effective methods to overcome these computational problems. On the other hand, lack of field data in terms of time and space and the hydrological and hydrogeological complexities leads to many uncertainties in the calibration results. The SUFI-II algorithm is an uncertainty-based automatic calibration method that is capable of calibration and uncertainty analysis of numerical simulation models. In this paper, for the first time, this algorithm is used to calibrate and analyze the uncertainty of hydrodynamic parameters (hydraulic conductivity and specific yield) of the MODFLOW model. The results of model implementation for the Ardabil plain groundwater model (Northwestern Iran), indicate an average of 62 percent of the observation data within the 95 percent confidence interval. Finally, the best intervals of parameters are determined for the hydraulic conductivity and specific yield by the proposed approach. Also, the calibration of the groundwater model has been carried out using PEST. According to the results, the root-mean-squared error (RMSE) value in this case (RMSE = 3.37) is higher than the SUFI-II method (RMSE = 1.86), which indicates better performance of the SUFI-II algorithm than the PEST model.

Traditionally, the seismic design of buildings has been based on strength criteria. In spite of the design using elastic codes, the damage was very high because the elastic method of seismic design has failed to provide insight into how the building behaves during earthquakes. The current study demonstrates that conditions can be created to minimize building failure in a strong earthquake by the use of nonlinear analysis to properly distribute the strength in the components, stories, and the entire building. It is also shown that the type of analysis will play a significant role in achieving the proper optimal strength distribution. To achieve this, a main 3D reinforced concrete special moment frame was designed using static linear analysis. The optimal strength distribution pattern of the frame was estimated using repetitive nonlinear dynamic analysis (nonlinear response history analysis, in chapter 16 of FEMA P-1050-1) for accurate design of the frame and the building sections were determined. The estimated strength distribution and proposed distribution of the code for the designed building were compared using nonlinear dynamic analysis under an ensemble of 22 near-fault and far-fault ground motions. The best type of analysis for the seismic design of reinforced concrete special moment frame in far-fault and near-fault zones was identified.

The formation of a plastic hinge at the bottom of steel shear wall columns can lead to a total collapse of the structure. To overcome this defect, Semi-supported Steel Shear Wall systems (SSSWs) are introduced. In these systems, boundary columns are separated from the mainframe columns with a specific distance and only tolerate the lateral seismic forces. So, even these columns experience the plasticity, the mainframe does not experience any damages. Evaluating the behavior of SSSW is restricted to some limited laboratory studies. Since experimental evaluation of the effects of factors such as wall web thickness, web stiffness (one or both side), and the shape of boundary element is too much expensive, in this paper the effect of aforementioned parameters on elastic stiffness, energy absorption capacity, ultimate strength and ductility is evaluated by finite element simulation. First, the numerical model verified and the other models have been produced based on the verification model. Based on numerical simulation the results show that changing the shape of boundary columns does not affect the linear and non-linear response of SSSWs. But using vertical and horizontal web stiffness in one or both sides of the shear wall plus using mid-span secondary column increases the elastic stiffness, energy absorption capacity, ultimate strength while decreases the ductility due to increasing the out of plane stiffness of shear web plate. Moreover, increasing web panel thickness from 2 to 4 mm, increases the elastic stiffness, energy absorption capacity, ultimate strength, and ductility.

One of the most important parameters in the design of bridge abutments and piers is to calculate the depth of scouring. The previous relationships for measuring the scour depth were based on steady flow, and it is not expected that the amount of scour depth computed from these relationships is accommodated to the actual value during a flood wave. Inasmuch as in this condition, the flood hydrograph occurs in an unsteady state in which the discharge is variable between base and peak values. In this study, experiments were conducted to measure the clear-water scour depth of a rectangular abutment under steady and unsteady flow conditions by approaching flood waves with triangular hydrographs and equivalent stepped hydrographs in a compound channel. Then, by using the measured scour depths values in steady flows, a relationship is calculated to estimate the maximum scour depth in terms of dimensionless time parameter and flow intensity. By changing the peak discharge time parameter, the effect of slope at ascending and descending part of the triangular hydrograph on the scouring was investigated. A comparison of the scouring of two stepped hydrographs with the same time duration showed that the difference between the scouring values was 1.5%. Moreover, the results of the scour depth measurements of triangular and stepped hydrographs were compared.

Due to the advantages of semi-active control methods over passive and active methods, the development and performance of these methods to control the structural response under dynamic lateral loads has been widely considered. One of the most developed devices for semi-active control is Magneto-Rheological (MR) Dampers, for which various models have been proposed to simulate its dynamic behavior. In this paper, a 10-story linear shear building is studied under twenty-eight far and near-field earthquakes in MATLAB. In order to control the vibration of the structure, a Magneto-Rheological Damper with Clipped Optimal Control Algorithm is used. In this simulation, in addition to considering the effect of actuator saturation, the actuator’s dynamics is also considered using the Modified Bouc-Wen model. In addition, the effect of the damper’s position is investigated in the current study for three different configurations (lower, middle and upper stories). Furthermore, using the obtained results from this algorithm, a statistical study was carried out under different types of near and far-field records. The results indicate that placing a Magneto-Rheological damper on the first floor shows the best performance. Results show that the current control system has the best performance under near-field records without pulse, with an average reduction of 21 percent in the structural response.

The strength behavior of soil is affected by strength parameters including soil cohesion and its internal friction angle. These parameters are influenced by factors such as soil density, soil type, loading rate, moisture content, confining pressure and Etc. In this paper, the effect of loading rate on shear strength behavior of clay-sand mixtures is investigated using triaxial test. In this research, 8 types of "clay:sand" composite materials with weight ratios of 100:0, 80:20, 60:40, 40:60, 30:70, 20:80, 10:90 and 0:100 were used. To investigate the effect of loading rate, samples were subjected to non-uniform loading rates of 0.1, 1 and 5 mm/min with defined load pattern. In this study, three confining pressures of 100, 300 and 500 kPa were used. The results of this study show that, depending on the amount of confining pressure, the sudden change in loading rate has different effects on the strength of samples with different percentage of clay-sand combination. Deviator stress variations as well as the slope of the stress-strain curve depend on the amount of sand at the moment of sudden change in loading rate. In other words, changes in deviator stress and slope of the stress-strain curve are directly related to the amount of sand from one limit to the next. This limit of sand is 40% for low confining pressure (100 kPa) and 20% for higher confining pressure (300 and 500 kPa)

In some structures, such as oil platforms and wind turbines, depending on the type of utilization, the footing is subjected to combined vertical load, horizontal load and bending moment (V-H-M). In this study, the behavior of the ring footings resting on sand subjected to combined V-H-M loading is experimentally investigated by conducting 100 tests using six load paths. Three values for the diameter ratio of the ring footing models are assumed, including n = 0.2, 0.4, and 0.6, along with a circular foundation (n = 0). The failure points were determined, on the basis of load-settlement diagrams, and by using the set of these points, the failure envelope was plotted in the vertical load-horizontal load, vertical load-bending moment and horizontal- bending moment spaces. This failure envelope follows a parabolic curve in V-H and V-M / B space, The results indicate a parabolic curve for the failure envelope in V-H and V-M/B spaces which is dependent upon the diameter ratio. Moreover, the most efficiency of a ring footing during eccentric or inclined loading takes place when n is within a range from 0.2 to 0.4.

coupled shear wall with two-side connection and self-centering is a dual System, Including shear wall with Coupling and Self centering Which are joined together by truss elements in the alignment of the floors. In this dual system, beams coupling and plates have the function of energy dissipation and the self-centering frame has the function of reversibility. In this study, we investigate numerical studies on seismic performance of coupled shear wall and self-centering Primary pre-tensioning force and without pre-tensioning force with post-yield hardness under 12, 16 and 20% slope in ABAQUS software discussed. Therefore, 9 samples of 6 story coupled shear wall and self-centering Primary pre-tensioning force and without pre-tensioning force are designed in way performance-based plastic design and these samples have been subjected to and analyzed with push-over, cyclic, and time history analyzes. The results show that the coupled shear wall with two-side connection and self-centering Primary pre-tensioning force state with 20% slope stiffness compared to post-yield hardness, less residual drift, less relative lateral displacement distribution, Self-centering Better, less energy dissipation. Also, the distribution of relative lateral displacement and residual drift in self-centering Primary pre-tensioning force samples is less than without pre-tensioning force And in performance-based plastic design on relative lateral displacement distribution and residual drift performance is the same as force based design method, also, The distribution of the relative lateral displacement of the stories and the residual drift are the same in the self-centering Primary pre-tensioning force and without pre-tensioning force.

In the present study, the effect of material properties and slenderness ratios on the nonlinear behavior characteristics and energy dissipation behavior of steel plates (including stainless steel, mild structural steel and low yield point steel) under shear loading is studied using FEM. First, the steel shear plates with respect to their slenderness ratio and nonlinear behavior are qualitatively and quantitatively classified into very slender, slender, moderate, stocky and very stocky. To quantitatively determine the slenderness classes for each steel materials, modified theoretical relationships are presented separately using statistical analyses of the obtained results for various steel plates. Also, new relationships for assessment of inelastic (moderate plates) and plastic (stocky plates) buckling loads are proposed, that can estimate buckling loads for moderate and stocky plates more accurately compared to the available theoretical relationships in AASHTO. In general, with increasing slenderness ratio, the capability of steel plates for energy dissipation, due to the occurrence of buckling and the resulted pinching in the hysteresis loops, is gradually decreased. In the case of very stocky plates, the capability of plates for energy dissipation is only dependent on the material yield stress, while in the class of slender, moderate and stocky plates, it is dependent to both of the slenderness ratio and material yield stress. In the case of very slender steel plates, the capability of different steel plates for energy dissipation, disregarding the material yield stress and the plate slenderness ratio, seems to be similar, less or more, for various steel materials.

The present investigation is studied the effect of the replacement of different percentages of natural zeolite (Ze) pozzolan powder on the mechanical properties of recycled concrete made from coarse masonry recycled aggregates. In made concretes, natural aggregates were replaced with recycled coarse masonry aggregates at 25%, 50% and 100% levels. For improve the mechanical properties, natural zeolite was replaced by cement at 10%, 20% and 30% levels. In total, 195 standard cubic and cylindrical concrete samples in the 16 mixing designs were made and compressive strength tests at 7, 28 and 91 days, splitting tensile strength, modulus of elasticity and ultrasonic pulse velocity at 28 days of age were evaluated. the results showed that, at replacement levels of 20% natural zeolite with cement was had the greatest improvement in the mechanical properties of natural concrete but in combination with recycled aggregates, the replacement of 10% natural zeolite by cement was improved the mechanical properties of recycled concrete. also the results showed that, 10% of natural zeolite, using up to 50% of coarse masonry recycled aggregates, Improvement some mechanical properties of recycled concrete was showed relative to conventional concrete without pozzolan, but replace 100% coarse natural aggregates with recycled masonry, mechanical properties of recycled concrete have significantly decreased compared to natural concrete without pozzolan.