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Considering that a significant portion of the share of energy consumption among consumer sectors is in the home and commercial sectors and this share is still increasing, there is a need for research in energy consumption management and evaluation of effective indicators in the building industry. Building the country is vital to optimizing energy consumption. One of the most appropriate ways to optimize fuel consumption in the building and housing sector is the implementation of zero energy buildings which is considered as the main solution in the world. In this research, after analyzing the population and statistical sample, data were collected to evaluate effective criteria and options related to energy consumption management. First, fuzzy Delphi method was used to evaluate the sub-criteria and select the main options of each. At first level the criterion is discussed and at the second level the data analysis and research model is analyzed through paired comparisons using fuzzy hierarchical analysis technique. Finally, the most important indicators and criteria are obtained using fuzzy hierarchical analysis. According to the research findings, among the energy consumption optimization management indices investigated by the FAHP method, the economic, construction and utilities indices with 0.333, 0. 201 and 0.176 have the highest management priority, respectively. Energy-efficient optimization has a zero-energy building approach.

One of the challenges in the health monitoring of bridge structures is the "data" extraction from the structure. This is done by sensors in the structure. The layout and use of the fewest possible number of sensors, so as to provide the most needed data on structural status, has always been of interest. There are shortcomings in the methods used to determine the location of sensors in bridges, such as the use of one optimization indicator, determination of the number of sensors experimentally, high environmental noise, and a long calculation time. In order to overcome these shortcomings, a new MSE-MGA (Modal Strain Energy-Modified Genetic Algorithm) method is proposed in this study. In this method, two modal strain energy indices and modal contribution coefficient are used to reduce the noise effect of vehicles passing through. All the appropriate locations of the sensors are selected by these indices, and then the optimal number of sensors and their location are determined by using the genetic algorithm. The results show that increasing the number of sensors from a given optimal value has no effect on increasing the required data. Also, the simultaneous use of two optimization indices has resulted in the elimination of a large number of inappropriate points for sensor placement, resulting in a significantly reduced computational time. To investigate the performance and practical application of this method, a model of a steel bridge is modeled and the optimal number of sensors and their layout are determined.

Due to the increasing need to use rebar in construction, many efforts have been made to optimize its use. One way to reduce rebar usage is to use welded splice instead of overlap splice. However, the Iranian Concrete Code only refers to the welded splice generalities and there are no rules on how to splice. Therefore, the purpose of this study is to investigate the tensile strength of welded splice bars with different configurations. For this purpose, rebars with diameters of 10, 14, 18, 22 and 25 were connected to each other by a variety of discontinuous and continuous overlap patterns by welding with the E6013 electrode. Then the tensile strength of the connected rebars was obtained by tensile test. Then, with Abaqus software and the birth and death method, a variety of splice patterns were modeled and the results were compared with laboratory results. The results show that the optimum welded splice is the model with discontinuous weld with a weld length of 5d.

Buckling-restrained braced frames can considerably reduce the seismic responses, because of their high energy dissipation capacity. However, they have big residual drifts subjected to great earthquakes. In this paper, buckling - restrained braced frames with eccentric configurations connected to frames with post-tension connections is studied. The results show that this system is able to decrease the residual drift. For evaluation the proposed method, 3 and 6 story frames, for different combinations of self - centering parameters are designed. Self-centering parameters are gradient of disengage connection and ratio of self - centering. Base shear used for the models are calculated using performance-based seismic design. Performance-based seismic design is obtained based on energy-work balance using pre-selected target drift and yield mechanism. Then in Abaqus software, pushover and cyclic analysis method for different combinations of self-centering parameters on the frames is done. Pushover analysis verifies the design method. Cyclic analysis show that the residual drift is decreased by adding frames with post-tension connections to a buckling – restrained braced frame with eccentric configuration. The results show that in order to reach self - centering, the ratio of base shear of the frames with post-tension connections to the total base shear is required to be more than 50%.

In recent years, the use of composite rebars in reinforced concrete structures has received much attention due to its high corrosion resistance, significant tensile strength, and appropriate non-magnetization characteristics. Due to the lower modulus of elasticity of composite rebars than steel rebars, concrete beams reinforced with composite rebars have relatively lower shear strength compared to beams reinforced with steel rebars. On the other hand, shear failure in concrete beams reinforced with composite rebars is generally brittle and requires accurate prediction of the behavior of these members. Therefore, in this study, the shear strength of concrete beams reinforced with composite rebars is predicted using a combination of GMDH type neural networks and genetic algorithms based on a wide range of experimental results. The key effective parameters that consider in this study are the width of the web, effective depth of the beam, shear span to depth ratio, concrete compressive strength, modulus of elasticity of FRP longitudinal bars, and longitudinal reinforcement ratio. The accuracy of the proposed method has been verified by comparing the model predictions with the collected experimental results and existing shear design equations. The results show that the proposed model has more accurate results in calculating the shear strength of concrete beams than other existing relationships. A sensitivity analysis is also performed to assess the effect of the input parameters on the shear strength of FRP-reinforced concrete beams.

Collapse performance evaluation of structures has been a concern for researchers due to its complexity and uncertainty in modeling and simulation. Concentrate plastic hinges are best candidates for modeling collapse behavior of structures. Collapse fragility curves are affected by various sources of uncertainty. Existing uncertainties in modified Ibarra and Krawinkler moment-rotation model for concrete moment frame buildings were investigated in this paper. LHS simulation method was used to generate random variables considering the correlation among modeling uncertainties in one component and two structural components. Collapse responses including mean collapse capacity and standard deviation were obtained for each simulation by generating random samples for uncertainties using incremental dynamic analysis (IDA). As much effort is needed for implementation of IDA, MLP artificial neural networks, GMDH artificial neural network and response surface method were used to estimate and anticipate the collapse behavior of the structure. Results show that using above methods will lead to high accuracy anticipations with an error of less than 10% for GMDH neural network and an error of less than 7% for MLP and response surface methods.

While the fibers in concrete cause soft rupture, the compressive and tensile samples are not ruptured after failure. This is one of the benefits of metallic fibers, especially the sinusoidal and hooked fibers: using these gives residents the opportunity to escape during an earthquake. In addition to positively impacting mechanical properties, metal fibers improve the matrix of concrete, provide ductility and response to impact load, and control crack width and propagation. Fly ash and micro-silica improve the durability and performance of concrete and are effective in protecting the environment: they can, thus, be used to replace cement. In this study, the samples’ compressive and tensile strength was prepared: they were of non-fibrous concrete and concrete containing steel fibers with 6 different percentages (0.4, 0.6, 0.8, 1, 1.2, 1.5). They were also composed of metallic fiber and polypropylene in three different compositions (0.3PP + 0.8SF, 0.4PP + 0.4SF, and 0.15PP + 1.5SF). These were investigated: seismic parameters were extracted after achieving the optimal percentage (the percentage with the highest compressive and tensile strength given economic considerations) under the loading protocol SAC/BD 97.02. This allowed investigation of the curves of hysteresis, energy absorption, lateral displacement, and effects of the use of these fibers. The major properties of pozzolanic materials were considered in the last step of this research: fly ash and microsilica were added to concrete containing metal fibers with the optimum percentage of metallic fibers. These were compared with concrete containing metallic fibers and non-fiber concrete. Thereafter, the appropriate percentage of cement replacement was determined so as to better understand the effect of the use of fly ash and microsilica in preventing the buckling of buckling restrained braces.

The amplification pattern of earthquake waves and extensive damages due to that in alluvial valleys are influenced by two phenomena such as alluvial characteristics and topographic features of the site. Therefore, local effects assessment of the site is considered as one of the effective parameters in designing reinforced structures to withstand seismically excitations. For the first time after the destructive and historic earthquake on November 12, 2017, in Sarpol-e-zahab, using geotechnical reports of drilled boreholes by housing foundation, this article has studied two dimensional modelings of the subsurface structure of Fooladi zone. Sarpol-e-zahab's bedrock accelerogram was also used to perform nonlinear dynamic analysis using ABAQUS software. The response spectrum of different parts of soil surface was used in one and two-dimensional forms to investigate the impacts of topographic and stratigraphy factors. Determining the dominant dynamic period of the site and the maximum amplification values are the other findings of this study. The amplification graph over different times shows buildings with the periods from 0.7 to 1.1 seconds have been affected amplification and site factors more than any other period. In the end, considering the calculation of the average shear wave velocity up to 30m borehole, the investigated land showed the highest compatibility with level 3 of land type classification table of Standard Code No.2800 and response spectra obtained from this study were compared with design spectrum of Standard Code No.2800. Contrary to the fifth edition published report of the International Institute of Earthquake Engineering and Seismology (IIEES), the findings generally show the right and appropriate performance of the Standard as well as using tall structures with sufficient safety.

Pipe racks or pipe bridges are one of the most important refinery structures which are used to maintain pipes and other equipment at the required levels and are usually made of concrete, steel or a combination of these two. Measures should be taken to reduce the damage of piping system due to separation of pipe-racks, the separate behavior of each of these parts during the earthquake, and also the large force involved in the separation of the pipe supports. Dampers are one of the most powerful earthquake engineering tools as a passive control system. Although the use of dampers in pipe-rack structures is unusual, it can be very useful in some cases. In this study, the function of dampers in a four-part pipe-rack under the influence of faults near faults and earthquakes was investigated. Our Findings revealed that when dampers placed in a longitudinal braces, the use of dampers in the pipe-rack has a very good performance and reduces the damage to the structures and piping system after the earthquake. Adding dampers to these structures can dramatically reduce the inter-levels drainage and acceleration of floors, and thus protect the pipes. In this way, these structures can fully maintain their usability during the earthquake and can be exploited immediately after the earthquake, which is very important in refineries.

Shear walls can be designed to have sufficient bearing capacity and deformation and absorb energy due to nonlinear shear-bending and axial load - bending, interactions. However, in the event that reinforced concrete walls do not have sufficient seismic resistance, the effective solution is to use new composite wall options. The use of steel trusses, consisting of steel columns and embedded steel brace in the reinforced concrete shear wall is one of the types of composite shear walls. In this study, seismic behavior of composite shear wall with embedded steel truss is investigated. For this purpose, various models of these walls have been modeled using finite element method at 5, 10 and 15 storys. The influence of various factors such as bracket area, column area, and axial load ratio on the performance of this system against lateral loads is evaluated. The influence of various factors such as brace area, column area, and axial load ratio on the performance of this system against lateral loads is evaluated. The results show the steel braces to increase lateral bearing capacity and column steel has been more effective in absorbing energy. Axial load had a greater effect on increasing the initial hardness. But , to avoid the adverse effects on ductility behavior, the axial load ratio must be limited to the medium level

The present article involves evaluating the efficiency of an active viscous damper in controlling vibrations caused by near and far field earthquakes. Being installed on chevron bracing systems, the damper is able to provide necessary controlling forces to diminish vibration amplitude up to its' saturation limit. Many researchers have worked on the concept of seismic active control under far field waves. But the efficiency of this system is not guaranteed in near field ones due to time delay phenomenon. Pulse and shock entity of near field seismic waves leads to decreasing active control effects and the present research also proves the fact. A computer based algorithm is developed using Newmark instantaneous optimal control method in MATLAB software.The performance of this code is validated and evaluated based on three different reference problems. Then the analysis results of a 7-storey structure are calculated based on the code. The analyses are developed using both controlled and uncontrolled states. Also near field and far field earthquake records are used in this process and the results are compared in different tables and graphs. Based on the results, it seems that active control systems in spite of their effectiveness in near field earthquakes, needs necessary scheming and changes in the process.

Design, construction and maintenance of liquid storage tanks, which have been extensively used to store liquid in industrial factories, oil refineries and petrochemical sites, are crucial. Vulnerability of liquid storage tanks have been recognized regarding to the experiences of major earthquakes occurred specifically in Japan, United states and Turkey. Therefore, evaluation of seismic responses of steel storage tanks is important. In this research, due to the complexity of ground motion behavior and the effects of different parameters such as frequency content of excitations on damage assessment of liquid storage tanks, more precise seismic analyses under near-fault and far-fault ground motions considering bi-directional horizontal components is carried out. For this purpose, the fixed base steel liquid storage tanks with height to diameter ratio equal to 0.4 is considered. The finite element analysis of the tank-liquid is carried out using ABAQUS software considering fluid-structure interaction based on added-mass method and nonlinear time history analysis. Significant difference between the seismic responses of the tank to uni-directional and bi-directional earthquake is obtained. More interestingly, the effect of frequency content of excitations on the dynamic response of steel liquid storage tanks are discussed.

Health-care applications are those types of uses that, in the event of inaccurate location, may lead to irreparable loss of life in addition to the economic and financial constraints. The geographical location is the main component of access to medical services. Therefore, the importance of optimal and suitable location for this type of user should be considered. In this paper, a compilation of GIS capabilities and an ANP model in a fuzzy environment was conducted to determine the optimal locations for the establishment of a hospital in Markazi province, Arak city. For this purpose, firstly, effective and suitable criteria for locating the hospital in view of the location is the geographic and geographical conditions of Arak, hospitals, experts, books and articles were selected and then weighed in fuzzy environment. Finally, the results obtained by fuzzy GIS in fuzzy mode were used by five fuzzy operators (AND, OR, SUM, PRODUCT, GAMMA) combined in ArcGIS. According to the results obtained from five fuzzy operators, the accessibility criterion, which had the highest weight, was prioritized in order to find the optimal location for the establishment of hospital, and the locations were identified with the least distance from main road/paths for quick and easy access in the shortest time to the hospitals.

Awareness of the probability of failure and the safety index of a structure designed and implemented on the basis of regulations and codes can enhance the designer's attitude towards the failure or safety of the structure. This paper examines the probability of failure and safety index of 3D steel moment frames. A three-story steel moment frame and a six-story steel moment frame loaded and designed on the basis of the previous drafts of National Building Regulations of Iran have been selected. In order to perform the finite element analysis of the 3D moment frame and system reliability analysis, a program with CSHARP programming language is written incorporating the Monte Carlo method. In reliability analysis, the uncertainties in the yield strength and the Young's modulus of steel, gravity loads and lateral forces, cross-sectional and plastic section modulus of the frame members were considered. The calculation of the probability of failure and the safety index of the framing system in two cases, according to the old, 2008 edition and new, 2013 edition of Iranian National Building code, Part 10: Steel Structures, have been done and compared. It was noted that assessment of buildings constructed on the basis of the old regulations with new drafts of National Building Regulations of Iran resulted in decreased safety levels. Also, the effect of statistical correlation between gravity loads and lateral forces in determining the frame safety index has been investigated. The sensitivity analysis performed for the steel coefficient of variation showed that its variation after the value of 0.07 can have a significant effect on the reliability of the steel moment frame.

In PPP toll road projects, public sector supports project companies that face the risk of revenue, by different mechanisms. It is necessary for the public sector to evaluate these mechanisms before granting them to the private sector. This study evaluates the support mechanisms defined in the Iranian PPP toll road projects legislations by real options and compares them with a proposed mechanism. Additionally, the uncertainty of the project revenue during the concession is modeled by the options theory. The impacts of the revenue risk on public and private sectors is evaluated by Monte Carlo simulation in a Flexible-term mechanism, a Flexible-term mechanism alongside a Revenue Guarantee mechanism defined in the legislations, and a Flexible-term mechanism alongside a proposed Guarantee based on Barrier Option. Subsequently, the sensitivity of these impacts to the revenue projection errors is analysed. This process is implemented in a real PPP freeway project. The results show that the combining Flexible-term and Revenue Guarantee mechanisms improve the financial viability of the project, indicating the continuance of adequate yearly cash flows through the whole concession period. Adjusting the Revenue Guarantee defined in legislations by Barrier options reduces the public sector’s payment commitments. The analysis of the uncertainties of the project revenues reveals that the revenue projection errors have a great impact on the consequences of the revenue risk on both parties. Since the public sector often faces budgeting challenges to support projects, the proposed mechanism can help public sector decision-makers to better allocate financial resources by supporting the projects that struggle with financial viability. The sensitivity analysis of revenue projection errors on risk impacts in each mechanism provides public sector decision-makers with a broader and more realistic spectrum of the revenue risk impacts on pubic and private parties.

In this study, the use of precast laminates, made of high-performance fiber-reinforced cementitious composite (HPFRCC), was investigated for strengthening of continuous reinforced concrete (RC) beams. HPFRCCs are characterized by their high tensile strength and remarkable durability properties. To find the effect of strengthening, eight continuous (two-bay) RC beams were tested under monotonic load in the middle of spans; two of which were the control specimens and six of which were strengthened specimens. The HPFRCC laminates were prefabricated with 25 mm thickness and bonded to the tensile surface of beams using epoxy and mechanical anchorage. The longitudinal bars were added to laminates in four specimens to survey their effect on strengthened beams. Comparison of results declared that the load carrying capacity was increased up to 59 % in strengthened beams. Ductility index of the strengthened beams was acceptable, and also up to 35 % growth in energy-absorption capacity was observed. Applying laminates to the tensile surface delayed crack propagation and decreased the midspan deflection. Also, stiffness of specimens in the cracked concrete stage was increased up to 78 % that led to decrease the service deflection. It is concluded that the use of HPFRCC laminates, especially in case of applying longitudinal bars, is an efficient method to enhance the flexural capacity of continuous RC beams.

This paper presents an approach for evaluating structural resistance degenerate due to reinforcement corrosion and for predicting future structural performance during the service life of the deteriorating reinforced concrete beams due to corrosive environments. a finite element method is adopted for envisioning the nonlinear flexural behavior of intact and corroded RC beams based on Ultimate strength design method and Load and resistance factor design method approaching this aim, the impact of corrosion of embedded reinforcing element on the flexural capacity of corroded reinforced concrete structures is estimated. A stochastic degeneration model based on gamma process is utilized to assess the probability of failure of structural flexural capacity over the lifetime. Optimal repair planning and maintenance strategies throughout the service life are circumscribed by evaluating the cost for maintenance and the risk of structural failure. Based on the conclusions from the numerical model including two RC beams subjected to reinforcement corrosion the following results are drawn: The permissible deterioration limits that describe the thresholds of the deterioration for the safety and repair requirement, held major effects on the probability of failure. The results from the worked example show that the proposed method can afford reliable predictions for structural strength deterioration and efficiently implement a risk-cost-benefit optimized repair procedure through the service life of the structure affected by bar corrosion. The lifetime distribution increases 5years for LRFD method and 3.5 years for USTD method while allowable limits enlargement 10%. The lifetime distribution extends 5years for LRFD method and 3.5 years for USTD method while allowable limits increase 10%.

Nowadays, the glass fiber-reinforced polymer (GFRP) sheets have been known to be one of the most effective composite materials that are used to increase the strength and durability of concrete structures. Owing to the light weight, corrosion resistance, high tensile strength and the ease of application without any interruption of the services, the use of these sheets has become very wide spread. In recent years, some organizations in Iran have opted for the use of GFRP sheets for the strengthening and protection of their concrete structures that are located in the areas exposed to the Persian Gulf water. Therefore, in the present paper, the results of the permeability tests conducted on GFRP strengthened concrete samples, using the newly developed “Cylindrical chamber” method are discussed. Since the deterioration of concrete structures exposed to extreme environmental conditions due to the water penetration, appears to be a critical issue, the above mentioned samples have been exposed to different cycles of wet-dry, high and low temperatures and freeze- thaw tests, before measuring their permeability’s. The results showed that the temperature change cycles have a small effect on the permeability of GFRP in comparison to the freeze-thaw and wet-dry cycles. The penetrated volume of water after 30, 90, 150 wet-dry cycles, was 61%, 100%, 18% lower than the respective values obtained after the same cycles of temperature changes. Considering the freeze-thaw conditions it was found that similar cycles of freeze-thaw tend to increase the permeability of the samples by about 12%, 36%, 29%, compared with the respective values of the temperature change conditions.

In this paper, the influence of Winkler type elastic foundation on the free vibration behavior of non-local Euler-Bernoulli beam with varying cross-section is semi-analytically investigated. For this purpose, the governing equation of motion is derived based on nonlocal elasticity Eringen’s model and Hamilton’s principle. The power series approximation is applied to solve the fourth order differential equation, since in the presence of variable cross-section, stiffness quantities are not constant. Based on this semi-analytical methodology, displacement component and cross-section properties should be expanded in terms of power series of a known degree. The natural frequencies of non-local beam with variable cross-section are then derived by imposing the boundary conditions and solving the eigenvalue problem. The results of this research are compared with the obtained results by other researchers and there is a good agreement. At the end, the effects of different parameters such as: end conditions, nonlocal Eringen’s parameter, tapering ratio and Winkler spring constant on non-dimensional natural frequency of nano-beam are studied in detail. The outcomes of this study indicate that the increase of nonlocal parameter and non-uniformity ratio causes to decrease the dimensionless natural frequency. However, with increasing the Winkler elastic constant, the non-local frequencies increase. Furthermore, it is shown that the effect of Winkler elastic foundation is predominate than the tapering ratio and Eringen’s parameter on the natural frequency of nano-beams.

Steel shear wall with corrugated plate is a lateral load resistant system. In recent years, researchers have made investigations in this Field. In this study, the behavior of this system under pushover loading has been evaluated. For this purpose, 20 samples of steel shear wall system with corrugated plate with bay to height ratio of 0.85,1.4,2,2.5 And in 1,2,4,6,10 Stories has been designed. Then these samples with finite element software (Abaqus) were analyzed. Results of this study show that the initial stiffness of this type of shear walls is high And it's resistance in drift about 0.1 percent reaches to the highest amount. But when the plate is subjected to interaction buckling it's stiffness and resistance has been decreased significantly. Also, Results of this study shows that before the plate reaches to buckling limit; a greater percentage of shear force is resisted by plate but after plate's buckling frame has more contribution in resisting shear force. In this study mechanism of creation of tension Field in this type of systems has been evaluated and relation for determination of tension Field's angle was proposed. In the end, in this study, a method for estimating pushover diagram of shear wall system with corrugated plate for one and several story structures has been presented. This solution was founded on the interaction between frame and corrugated Plate and by results of experimental and numerical samples was verified.

Buildings are always affected by a variety of natural and abnormal forces during their operation. Impact of vehicle collision is an abnormal load which is not usually considered in the design of structures. With the spread of terrorist attacks in many parts of the world, investigation the behavior of structures against unusual loadings, such as blast or vehicle collision has been considered. In this study, steel moment frames with knee braces (2, 5 and 8 story) were designed by SAP 2000 software in two-dimensional according to codes guidelines, and then time history analysis of them was performed by SeismoStruct software subjected to impact of light vehicle collision. The responses such as displacement, drift, acceleration of the stories and the base shear of the frames were compared under the effect of light vehicle collision impact with different velocity (from 10 to 120 km/hr). The results show that the velocity 90, 120 and 100 km/hr causes dynamic instability state in frames with 2, 5 and 8 story respectively. The results also show that the performance level of the mentioned frames based on the maximum stories drift and for the different velocities of impact. For example, in the range of impact velocity of 50 to 80 km/hr, the performance level of 2-story frame was "Life Safety" and regarding to 8-story frame, the performance level was "Immediate Occupancy" for velocities 10 and 20 km/hr.

Uncertainties are inevitable in the estimation of structural engineering issues and increase the cost of retrofitting. In the presence of uncertainties, the results of seismic evaluation are incorrect and create conservatism in acceptance criteria at structural performance levels. Considering and quantification of uncertainties in design and rehabilitation of structures reduces the existing conservatism and can lead to the economic design and rehabilitation of structures. In the seismic rehabilitation of structures, uncertainties have been studied on existing structures and have been applied by coefficients in guidelines. Adding a secondary system to rehabilitate of existing structure can enter uncertainties into the computation and can be effective for results of reliability. Therefore, in this study, reliability of rehabilitated steel moment frame with steel shear wall has been discussed in order to quantify the uncertainty of the steel shear wall. The selected structure is a nine-storey steel moment frame of SAC project, which was rehabilitated by steel shear wall. The studied structures were analyzed pre- and post-rehabilitation, with probabilistic variables considered for steel shear wall by OpenSees software. Based on results of incremental dynamic analysis and obtained fragility curves, the values of the reliability index have been obtained for the rehabilitated structure in the presence of uncertainties. Results showed that considering of uncertainties and reducing them can reduce the existing conservatism and the cost of rehabilitation.

There are a number of reasons for considering web openings in steel structures with I-sections. Design of these structural members is always a practical challenge in steel construction. There are several design methods available in the literature for design of these components. Most of these methods rely on the moment-shear-axial interaction curves. However, the preliminary studies have shown that the real performance of these reduced sections is in the form of diagonal struts. The objective of this study is to present a new model based on the tensile and compressive action of diagonal struts at reduced web region to calculate shear strength of the perforated section.For this purpose, the geometry and dimensions of the diagonal struts are described and the shear strength of reduced section is calculated accordingly. To assess the accuracy of proposed geometry and dimensions for diagonal struts, a topology optimization is conducted for two finite element models and results are compared to the proposed values based on which a good agreement is found between optimized and proposed geometries. Next, design curves are presented for calculation of shear strength followed by comparison of proposed model and its predictions with the ones obtained from numerical analysis. Comparing the predictions of the proposed model with the results of 120 finite element samples, the absolute mean error and standard deviation of absolute error were calculated to be 6% and 3.7%, respectively. This comparison shows that, although the presented model is simple and easy to use, it has acceptable accuracy and can be utilized for calculation of shear strength in perforated steel I-beams.

Past studies have shown that aftershocks can increase structural damage, especially for structures damaged in the mainshock and experienced nonlinear behavior. This damage is generally the result of increased lateral displacement of the structure and thus, it is necessary to estimate the lateral displacement of the structure under seismic evaluation accurately. Although the target displacement in the nonlinear static analysis method is calculated by means of relationships presented in performance-based design codes, the effect of the aftershock is not taken into account. In this study, the impact of aftershock on inelastic displacement ratio is considered as the most effective factor in determining the target displacement. The results showed that this ratio increases significantly due to aftershocks. The dispersion of the results led to the investigation of the hazard levels of the input earthquakes and subsequently using the scaling method of the accelerograms. For this purpose, a target aftershock spectrum was generated by a statistical study on the maximum acceleration ratio of the mainshock and its corresponding aftershocks, thereby the aftershocks scale to an independent target acceleration spectrum. Comparison of the responses from scaling revealed that dispersion in results are an inherent issue and cannot be resolved. Finally, by modifying in the current relationship of the code, a new formula has been proposed for the inelastic displacement ratio such that the mean error values were reduced as much as possible.

Many studies have been conducted showing that the mass damper improves the performance of structures against wind loads and seismic loads. This paper presents a model for passive tuned mass damper with softening stiffness; the Newton−Raphson method and state space were used to solve nonlinear equations of motion. To evaluate the performance of the proposed mass damper, an 11-storied steel structure subjected to the Northridge and Zarand earthquakes was evaluated. This structure was initially modelled and analysed without a damper and with the softening PTMD. Then the effect of varying angles of the mass damper was investigated; eventually the damper was converted into a non-linear semi-active tuned mass damper. To reduce the displacements of the damper, fuzzy control was used for the controller. The results show that the proposed mass damper with a 60-degree angle could reduce the displacement in the earthquakes of Northridge and Zarand by 48.8 and 36.2% on an average. The results of using different angles suggest that a 45-degree angle makes for the most favourable performance for the structure and mass damper. It points out that in the use of an isolator for the 11th floor, this floor has the potential for higher displacement than any other floor, but, in this article, using the controller and the proposed semi-active damper, it has been shown that this floor can also experience lower displacement.

Discrete singular convolution is a new numerical method that its ability to vibrational analysis has been demonstrated in the last decade. A lot of research on how to apply the complex boundary conditions of the different issues using this method is carried out and a variety of solutions have been proposed in this regard. Applying the boundary conditions in the governing equations of coupled shear walls, is a challenging issue. This paper proposes a new algorithm for applying the boundary conditions in the vibration analysis of coupled shear walls using the DSC method. In order to validate the proposed method, several samples were analyzed using this algorithm and the results were compared with the values obtained from three conventional numerical methods of Finite element (FEM), Differential quadrature (DQM) and Finite difference (FDM) methods. The great conformity was found between the results which emphasized the validity and integrity of the proposed method. In addition, the ability of the DSC algorithm was explored in terms of the computational speed, computational effort and the amount of computer memory required aspect and compared with the other conventional numerical approaches. It is concluded that the DSC is more efficient than the compared numerical methods from the results of this study.

There are numerous old arch bridges in Iran that have been used as railway bridges for more than eighty years. In Iran's railway network, there are about 3,700 bridges which all of these have been designed based on service load in that time (low-speed trains) and are still serving for trains at maximum speed of 100 km/h. Using of high-speed trains has been spread all over the world in the last two decades. In recent years, the use of high-speed trains is necessary in the Iran. It is not possible at all to replace old masonry arch bridges due to field and economic constraints, so it is necessary to evaluate the dynamic behaviour of these bridges under the high-speed trains. To evaluate complex behavior of these bridges, results of field tests are required. Since it is not possible to perform field tests for all arch bridges, these structures should be simulated correctly by computers for structural assessment. The present study investigates two plain concrete arch bridge which are located in kilometer 23 and 24 of the old Tehran-Qom railway. The numerical model of the bridge is established in accordance with detailed geometrical properties of the bridges. The numerical model has been validated based on the existing experimental results. In the model updating procedure, the vertical deflection at the crown under static loading and the movement of the six-axle train by 60 and 80 km/h, as well as the first three modes of the bridges were selected as a calibration criterion. In the second step, different geometrical of Pardis high-speed train are used and totally 13 geometrical models have been detected and investigated. By using the finite element method and the macro-modelling approach, the km-23 and km-24 bridges were simulated and totally 26-time history dynamic analyses have been conducted. Dynamic behaviour of the bridge under moving load model of Pardis trains at speeds of 150km/h have been assessed. Finally, deflection and acceleration responses for all 26 dynamic analyses at the crown of the bridges have been extracted and compared. These analyses are conducted to the aim of finding opportunities and constraints in using railway masonry arch bridges in the Iran as it is necessary to use existing rail lines on the rail network, due to the high cost of the construction of new ones and the need to know the existing structures such as bridges and their properties under the impact of high-speed trains. A realistic prediction of the structure's response helps a rational operation of the bridges in the service, that’s why the correct understanding of the dynamic behaviour of railway bridges is essential. The results of present study indicate that these bridges have good behaviour under high-speed trains.

Considering the differences that exist between the laboratory and site conditions, the in-situ estimation of bond strength of repair mortars is important. Therefore, in this paper, the results obtained from the use of two methods, “Friction-transfer” and “Pull-off”, for measuring the shear and tensile bond strength of repair mortars applied to substrate concrete, are presented. Since the drying shrinkage of the repair mortar has considerable effect on their adhesion, the shrinkage of the mortars is considered. In order to increase the accuracy of the measured bond strength of the repair mortars, substrate concrete with saw cut surface was employed to minimize the interferences occurring between the pure adhesion and the mechanical keying effects of the rough surfaces. The age of the substrate concrete at the time of the application of repair mortar was 90 days and after curing under different conditions, the repair/concrete bond strength was measured at different ages. For measuring the shrinkages of the repair mortars, nine standard shrinkage samples were prepared and their shrinkages were measured. Regarding the effect of the curing process on the drying shrinkage of the repair mortars, two different curing systems of “covering with wet hessian and polythene sheet” and “stored in the laboratory”, for 7 and 90 days were considered. The results tend to show that, the amount of the aggregates and the associated cement paste have substantial effects the shrinkage of the repair mortars. It was also seen that the shrinkage causes reduction on the shear and tensile bond strength at the repair/concrete interface. Furthermore, the reduction of the shear bond strength seemed to be slightly more than the corresponding reduction of the tensile bond strength. A very high correlation was also observed between the related shear and tensile bond strength of the repair mortars.

As the population grew, cities expanded rapidly, requiring Super structures for residents to live in, as well as heavy structures such as bridges for faster population access to various locations. Also in big cities, tunnels are needed for various purposes, such as moving facilities, car lanes and subway tunnels, which is one of the concerns of engineers. On the other hand, most of these tunnels are built in cities in the vicinity of heavy structures that deliberately have deep and semi-deep foundations. Tunnel excavation has caused long-term and short-term displacements at the ground surface, which is more pronounced in piles adjacent to the tunnel excavation site. In such a way that the displacements formed in the ground are transferred to the piles and cause axial force in the piles. All these studies on the effects of drilling on adjacent structures and piles are very important in terms of drilling safety factor. Accordingly, in the present study, a three-dimensional analysis has been performed using ABAQUS finite element software. The effects of tunnel drilling with different diameters and locations on the deep foundation in the bridge near the drilling site have been investigated. The results showed that tunnel location, if improperly selected, has destructive effects on pile tip settlements, axial force changes of piles and tunnel surface settlements. Similarly, as the diameter of the tunnel increases, the number of piles in the pile increases sharply when the tunnel is located just below the tunnel site. Also, as the diameter of the tunnel increases, the number of piles in the pile group increases by about 29% when the tunnel is located just below the pile group. When the construction site of the tunnel is located between the group of piles and at a greater depth than the tip of the piles, the amount of settlements changes to a critical state and with increasing the diameter of the tunnel, the rate of subsidence of the pile tip increases by 48.9% and the amount of subsidence Increases by 54%.

According to the Eurocode, the partial safety factor (γM) is a coefficient related to the material properties considering the uncertainties in geometry and modeling, which design value for the material properties are determined by dividing the actual value of the material properties by this coefficient. In this paper, determination of γM considering uncertainties for the Persian historical masonry shear wall was studied. To this aim, behavior of different specimens of masonry shear walls (with constant thickness) under in-plane shear loading and constant pre-compression with four different aspect ratios (height to length) and six different boundary constraints (under the effect of lateral walls and ceiling), by considering the uncertainty effect for two parameters of modulus of elasticity and thickness of wall were studied by the nonlinear pushover analyses. The results showed that by increasing the aspect ratio, the lateral shear strength of the walls decreases and γM is increased, whilst by increasing the boundary constraints, shear strength of the walls increases and γM decreases. The more impact of the horizontal component (ceiling) was observed, as compared to the vertical component in one direction, increases the boundary constraints and the lateral load-bearing capacity. It was also observed that the decrease in the initial shear stiffness of the walls was characterized by an increase in the wall aspect ratio, although this parameter changed slightly with changes in boundary constraints. In conclusion, the value of γM for the Persian historical masonry shear wall materials is proposed between 1.1 to 1.8.

By reviewing the literature on steel slit yield dampers (SSD), this study investigated and compared the effect of new strip shapes and geometric patterns on the behavior of this type of dampers. This study investigated a reference slit-less sample (solid) along with nine samples with a single row of blades or slits and three different shapes and geometric patterns, namely simple or constant cross-section, linearly tapered cross-section, and parabolic tapered cross-section with an elliptical slit at three different heights. These samples were subjected to cyclic loading in the laboratory. After determining force-displacement hysteresis curves, the important behavioral parameters of the investigated SSDs were calculated and compared. Effective stiffness, effective damping, force capacity, and displacement under cyclic loading were among the considered parameters in the current study. Results showed that dampers with simple blades and elliptical slits exhibited the poorest and best performances, respectively. Findings also indicated that the elliptical damper offered the highest effective stiffness, greatest energy absorption, and specifically the longest durability to cyclic loads. At displacements larger than 5 mm, the increase in effective stiffness of samples with an elliptical slit was roughly 1.6 times greater than that of samples with linearly tapered cross-sections. The equivalent viscous damping within the aforementioned displacement range at the optimal dimensions for a sample with an elliptical slit was roughly 1.1 times greater than that in a sample with linearly tapered cross-section.

Damage occurrence is always inevitable in structures. So far, many examples of damage types in engineering structures have been recorded with many losses of human and financial. For this reason, the detecting of structural damages during its exploitation to provide safety with the lowest cost has been the subject of many researchers in the last two decades. In this regard, the wavelet transform is a powerful mathematical tool for signal processing, has attracted the attention of many researchers in the field of health monitoring of structures. In this paper, due to the increase of steel plate shear wall in the building industry, it was considered the problem of detecting the location of the damage in steel plates. In this paper, due to the increase of steel plate shear wall in the building industry, it was considered the problem of detecting the location of the damage in steel plates. At first, the steel plate was modeled in ABAQUS finite element software with free support conditions, and then the healthy and damaged first eight mode shape was extracted. The primary and secondary modes shape was analyzed using discrete two-dimensional wavelet transform as a two-dimensional spatial signal. The results of the diagonal details of the wavelet analysis of secondary modes shape show the turbulence of the wavelet coefficients, compared with primary modes shape in damage locations; so that, wavelet analysis of the modes shape of the first mode, show damage location with the better equivalence of wavelet coefficients and the error of less than 6%.

Bridges are one of the major infrastructures of a country, which, in the event of severe seismic activity and the occurrence of collapse, can cause severe damage in different regions and create a severe crisis. Bridges with very long spans have always been a great challenge for engineers throughout history. Cable-stayed types of bridges are becoming more and more popular in the construction of long span bridges due to their advantages. A great number of cable stayed bridges in the world are located in the seismic zone and also near active faults so the effect of near field excitations on the seismic vulnerability of cable stayed bridges should be investigated probabilistically in accordance with far field excitations. Generation of vulnerability functions in the form of fragility curves is a common approach for assessing bridges seismic vulnerability. In this article, a set of analytical fragility curves for a case study cable stayed bridge (the Bill Emerson Bridge) are developed based on Incremental nonlinear dynamic analysis (IDA). The findings represent the effect of near fault excitations on the vulnerability of this long span bridge model. For example, the probability of a complete and extensive damage state for the considered cable stayed bridge in 1.5g for far field is 10 and 32 percent respectively, while in the near field, this value increases to about 19 and 44 percent, that indicates increase vulnerability of bridge in near field. The median values of seismic fragility for the considered bridge model decreased significantly in near field excitation in the Extensive and Complete damage states. The results can guide future regional risk assessments regarding the importance of including or neglecting near field excitations impacts on cable stayed bridge’s vulnerability.

Nowadays terrorist attacks on civilian facilities have increased.Paying attention to the design of construction sites against the impact loads due to the explosion is important. Identifying the nature of explosive loads and their impact on the structure is one of the important issues to be studied. The explosion is one of the complex phenomena including high strain rate which highly affects the structural elements behavior. Regarding the fact that existing steel structures are typically designed based on conventional gravity and seismic loads, it is required that the performance of these structures be investigated under the explosion load. In this study, the evaluation of simple steel frame behavior with different dampers against explosive load and earthquake is investigated. Nonlinear dynamics analysis is performed on models with 3, 5 and 10 floor structures and in accordance with UFC 3-340-02 at two different levels of explosive charge, in the SAP 2000 software. The results show that between XADAS, friction dampers, Viscose in diagonal system, in the seesaw system, U-shaped with flexural and shear performance and proposed pipe dampers, The displacement dampers have the greatest impact in reducing the structure response. From this Friction damper and pipe and U-shaped with flexural function is more effective.

Geometric nonlinear analyses are used in many structural problems, such as the determination of failure load, as well as the study of buckling mechanism. Nevertheless, due to the complex nature of this type of problems and the absence of a comprehensive analytical solution for them, numerical methods are utilized in practice to approximate the exact response of these systems. In the application of numerical methods, there are also some difficulties such as divergence or finding the correct path of equilibrium, especially in the case of bifurcation points. Hence, the main purpose of this research is to apply the modified energy method (introduced in the dynamics of structures) in quasi-static problems with geometric nonlinearity and bifurcation points so that the efficiency of this method can be compared to others, such as Newtonian numerical techniques and force-displacement-constraint approaches. To achieve the objectives of this research, after briefly reviewing the current force-based computational methods in practice, the energy method is described for such problems, and then the step-by-step process of its computer implementation will be presented. Afterward, by coding in MATLAB software and applying the method to numerical examples employed by other researchers such as truss and frame structures, the numerical results are verified by analytical solution as well as those obtained by other methods, such as Newton-Raphson and Arc Length techniques. Generally, the interpretation of the results obtained from performed simulations has shown that the presented numerical method in analyzing nonlinear geometric problems has better accuracy compared to the Arc Length method; moreover, it can well pass through bifurcation points in the force-displacement curve without divergence in comparison with the Newton-Raphson method.

Self-compacting concrete is a special concrete that flows with its weight in the form and does not need to shake. based on experimental findings, its compressive strength decreases with an increase in the specimen size; this phenomenon is called “size effect and its beginning is a nonlinear failure in concrete and other fragile materials. The purpose of this study was to investigate the size effect on compressive strength of cubic and cylindrical specimens in self-compacting concrete containing pozzolanic materials of microsilica and Taftan Pumice. To this end, the least squares (LSM) method and Bezant’s Size effect rule have been used to analyze the data. Seven designs consist of 3 different mixing designs of 2.5, 5 and 10% cement weight replaced by micro silica also 3 mixing designs containing 15, 20 and 25% weight of cement replaced by Pumice. An additional design was also made as a reference mix design. All Mix designs were cast in various size-cubic molds and also in standard cylindrical molds. According to the results, Mixes with 5% micro-silicon (M5) and 20% Pumice (P20) showed the highest compressive strength. The compressive strength ratio of cubic to cylindrical specimens was studied in all mixing designs. The results of the experiments show that self-compacting concrete cube specimens have a higher compressive strength than standard cylindrical specimens, and the compressive strength ratio of cubic specimens to standard cylindrical specimens with increasing cubic sizes from 5 to 15 centimeters decrease. On the other hand, the results show that the effect of size has decreased in designs with 5% microsilica and 15% pumice.

Concentrically braced frames (CBFs) have become prevalent as a lateral load resisting system due to their rigidity, low lateral displacement and ease of implementation over the last three decades. These advantages encourage the increasing utilization of this system in the construction industry. Despite the advantages of CBFs, the lack of ductility and buckling of the bracing element before yielding is the main disadvantage this lateral system. In the last three decades, studies have become focused on the ductility and energy dissipation of the CBFs that were modified in terms of using dampers and fuse segments. The current study aims to presents an innovative Composite Buckling Restrained Fuse (CBRF) to be used as a bracing segment. CBRF with relatively small dimensions is an improvement on Reduced Length Buckling Restrained Brace (RL-BRBs) as a hysteretic damper with different performance in tension and compression. Extra tensile elements in a novel configuration were used to compensate for the limitation of tensile strength that exists in bracing elements containing ordinary fuse segments. Here, some key design parameters of CBRF such as length and cross-sectional area of the core are discussed theoretically. Two specimens were designed and tested under cyclic loads. Moreover, the hysteretic response of the specimens was evaluated to calculate their strength adjustment parameters. The results indicate that the proposed CBRF has a ductile behavior with an average strain of 5% and high energy absorption capacity along with sufficient tensile strength.

In this paper, a modal pushover method is introduced for the assessment of the asymmetric-plan buildings in which, a load pattern is derived based on the story shears and story torque of building due to the simultaneous excitation in x and y directions. The proposed method is a single-run procedure and its significant advantage is its capability in consideration of the structural yielding in one direction on the total responses of the structure due to the simultaneous excitation in two orthogonal directions. In this method, in order to consider the instantaneous changes during the pushover analysis, two capacity curves of the structure are established based on the adaptive capacity spectrum method and the target displacement corresponding to each capacity curve is determined. Then, the structural responses at two pushover steps corresponding to the obtained target displacements are obtained. Eventually, the total responses of the structure are computed by combining the responses corresponding to the x and y directions. In order to evaluate the proposed method, this method has been applied to an irregular 20-story building subjected to the seven pairs of ground motion records and the obtained results are compared with the responses of nonlinear dynamic analysis as the exact responses. The results show the high accuracy of the proposed method in estimating the inter-story drifts of the studied building.

The high depth created favorable space for placing the openings which are to provide some capabilities such as mechanical and electrical installations, but these openings reduced load bearing capacity of the beams. One solution to the mentioned shortcoming is to use FRP-Composite sheets; the effect of FRP-Composites in improving load bearing and ductility of concrete members such as columns and beams is approved in previous investigations. This study utilizes the CFRP sheets to compensate for weakness arisen from the created openings. To this end, 5 deep beams with 10x50x120 cm dimensions, each having two circular openings with 20 cm diameter placed in symmetrical order, are constructed and undergone a three-point monotonic bending. The Externally Bounded Reinforcement (EBR) and Externally Bounded Reinforcement on Grooves (EBROG) methods have been utilized to install the FRP sheets in two configurations being wrapped around and inclined. The results have shown the superiority of EBROG method as well as the efficiency of the inclined orientation of strengthening sheets in increasing the load bearing-capacity. Also, Shear failure was the type of failure in beams and it has been observed that generally, diagonal cracks, which lead to the strut formation, tend to be formed in the beams. The cracks started from the support plates and propagated towards the loading plate. In addition to the extended cracking, the strengthened specimens have experienced debonding and failure in their composite strips. The strengthening strips have experienced failure in the wrapped specimen as a result of providing suitable confinement and leaving no chance for strip debonding as well as in the specimen with inclined strengthening strips as a result of the high efficiency of tensile stresses on the strips. Compared to the related non- strengthened specimens, the load bearing capacity increase arising from inclined orientation is 40% to 43%. In addition, this amount compared to the wrapped around specimen is about 16%.

Concentric bracings (CB) are one of the most prevalent lateral load bearing systems in steel structures. These bracings have a remarkable lateral stiffness and strength, but their compressive buckling prevents them from being ductile and absorbing optimal energy. Consequently, in recent decades, researchers have conducted extensive studies to improve the concentric bracing behavior, which resulted in the development of different design and execution methods for concentric bracings. In this paper, by using numerical and experimental studies, a new method is proposed to improve the behavior of concentric bracings. In this method, a local fuse (LF) is used along the brace. This fuse is restrained by auxiliary elements (AE) to prevent its local buckling under compressive load. This makes the brace behaves in a similar manner in both tensile and compressive cyclic loads, resulting in ductile behavior and high-energy absorption. In this study, by using numerical results, an investigation is done for proper position of the fuse along the braces and its optimal shape and length. In addition, an analytical study has been performed comparing the structural behavior of concentric braces with LF-AE braces. The results have been demonstrated that LF-AE braces have better performance than concentric braces.

One of the most important manifestations of sustainable development in any country is the country's productivity of sustainable sources of income. In fact, sustainable income is the basis for sustainable urban development. In the current century municipal financing is one of the most important issues in urban management, and in our country there has always been a discussion and a place for the challenge. Accordingly, in this paper, the aim of presenting an optimal model for sustainable municipal income for construction projects is based on the use of decision-making methods and calculation of the parameters of effective parameters in the assessment of sustainable earnings in the municipality of Karaj city. In this regard, Delphi method was used to validate the validity of the questionnaire using SPSS software. Therefore, the criterion of Evaluation, judgment by a group of experts and based on completing the questionnaire and conducting interviews with accurate experts in providing financial resources and urban management. The ranking of effective measures in assessing income municipalities using the Hierarchical AHP technique was done in Super Decision software and language quantitative meter using the method the average FOWA weighted weight has been paid to prioritize earnings resources. Based on the findings of the research in the city of Karaj, among the sources of income studied by the FOWA method, it can be seen that the transitional tax option from the government to the municipality using the AHP method with a coefficient of 0/150 and in Riskiness with a coefficient of 0/166 and risk aversion with a coefficient of 0/144 with 9 indicators of the highest priority in the assessment of the supply of municipal resources for the sustainable growth of development projects.

Investigation and evaluation of damages to surrounding structures and also estimation of rupture levels by considering the amount of deformations and the amount of adjacent gates are important issues in the nailing system in urban areas. In this research, we tried to evaluate the axial force of the nails and the deformation in concave and convex dams; in sandy and clay soils. In this regard, numerical modeling is carried out using the Abaqus CAE software in the soil environment and parametric studies are carried out for different corner angles in the excavation under the service load. The results of this study indicate the effect of concave cortical deterioration and the damaging effect of the convex corners, which is in contrast to the concave hedge, in gondolas with sandy soil as well as clayey soil. The maximum axial force of the nails in the clay soil is less than that of the sandy soil, which decreases with the approach to the hollow corner. For maximum seating and horizontal displacement of the Goodwall wall, there is also a turning point between the angular angles of 130 ° to 150 °, with a good turnaround. By comparing and analyzing land surface levels and rupture levels, we will find that the maximum level of earth's summation in sandy soils will be the highest level of rupture, and in clay soils, ground-level landings in the location of critical burst surface changes It is noteworthy.

Economic tools are definitely an effective way to encourage or enforce contractors to enforce environmentally-friendly practices. Previous studies on this subject mainly focus on the management of waste of construction and demolish (C & D) from the static point of view, which does not take into account the nature of its dynamic by taking all necessary activities in the waste chain. Therefore, the purpose of this paper is to explain the dynamics and relationships between the components of C&D waste management and to analyze the costs and benefits and cost of transportation and fuel consumption using the system dynamics approach. The findings show that the implementation of C&D waste management has many benefits, but the higher cost of landfill at authorized sites will result in more net profits, which will be accompanied by disadvantages such as environmental damage. In addition, the public is suffering from landfill in unauthorized locations and imposing environmental costs due to illegal evacuation. Simulation results also show that increased landfill in unauthorized locations increases fuel and energy consumption and therefore increases fuel consumption costs. This study by investigating and evaluating the researches and measures taken on the waste and waste spillway aims to clarify the use of a systematic approach using the dynamics of systems in a direction in which it is possible to use contract cost-benefit analysis to encourage contractors to disposal of Construction waste in a way that is conducive to the development of the building industry and the preservation of the environment and the resulting savings.

By increasing the height and slenderness of tall buildings, the wind-induced dynamic response especially crosswind response becomes the governing parameter in the occupant comfort requirement of tall buildings. In the present study, crosswind response of tall buildings has been investigated using the frequency domain analysis of multi-degrees-of-freedom systems based on the random vibration method. The tall structure has been modeled as a vertical cantilever beam with the masses lumped at the nodes. All the modeling and analysis procedure, including element meshing, determining the transfer matrix, calculating the matrix of crosswind force spectrum, and the numerical integration to obtain the root-mean-square (RMS) displacement and acceleration responses are carried out using MATLAB software. The effect of different parameters, such as basic wind speed, aspect ratio, side ratio for rectangle section and top to bottom width ratio for tapered tall buildings has been investigated. The results show that the slenderness ratio has an important role on the across-wind response. For tapered buildings, the crosswind displacement response decreases considerably with increasing the top to bottom width ratio. For the studied tall buildings, the crosswind acceleration response is higher than the occupant comfort level and it requires to be reduced using an appropriate control strategy.

Seismic sequence as a result of occurrence of strong and moderate earthquake ground motion in a short time strongly affects the seismic response of structures. This kind of excitation causes, in many cases, more deteriorated effects compared to the corresponding single ground motion. The aim of this paper is to investigate the effect of seismic sequence of earthquake ground motion on the seismic responses of steel moment frame structures considering soil-structure interaction (SSI). To this end, four steel moment frames with 8 and 16 stories are considered each of which have three and six bays. Soil-structure-interaction is considered by employing dampers and springs having specified damping and stiffness through cone method. For modelling SSI effects, three types of soil based on standard 2800 are considered. The time history of responses show that the relative displacement of structure is increased when the structure is subjected to the seismic sequence. As a result, the damage induced to the structure. It is noteworthy to say that the effect of seismic sequence is more in soft soil. The obtained responses show that a special attention should be paid for designing of steel structures in high seismic zone when they are subjected to seismic sequence excitation. Furthermore, soil-structure-interaction is an important parameter that should be considered for such conditions.Therefore, it is recommended that the effects of seismic sequence and soil-structure-interaction should be accounted for better estimation and evaluate accurate responses of steel shear frame.

In this research, the co-operation of steel and concrete in composite columns is considered. Using numerical modeling to study the behavior of these sections, a new type of composite sections named concrete-filled double-skin steel column is introduced. The factors affecting numerical simulation, which bring this simulation closer to the laboratory conditions, determine the axial resistance of the samples by changing the dimensions and geometry as well as the properties of the materials. The purpose of this thesis is to investigate the effect of concrete compressive strength on the axial performance of concrete-filled double-skin steel column CFDST concrete. A total of 20 samples with different parameters such as effects of concrete, loading capacity and width to thickness ratio on the strength of columns with square and round cross section in inner and outer walls were investigated by ABAQUS software. The results of the study showed that the loading capacity of CFDST columns under axial pressure increased by about 4% with increasing compressive strength of concrete in the inner wall. Also, studies showed that with increasing cross-section in the inner wall, the loading capacity in square columns increased by about 7% and decreased by about 3% in circular columns.

One of the most interesting topics in the geotechnical and geophysical engineering is the use of surface waves to characterize the earth subsurface layers. In a vertically heterogeneous media, the phase velocity of the surface wave is a function of the frequency (the frequency-phase velocity relationship is called dispersion curve). The dispersion curve is calculated by the shear wave velocity, compressive velocity, density, and thickness of each of the layers, which their properties can be increasing or decreasing from the surface to the half-space. In this paper, horizontal soil layers were modelled using finite element method based software (ABAQUS). Due to the different layering specifications, the models are divided into two main types: the layers’ characteristics increase with depth and the layers' characteristics decrease and increase with depth. An active impact source was used to create surface waves and the absorption layers with increasing damping (ALID) were applied to the model boundaries to prevent the wave reflection. Based on the gathered surface wave data, the dispersion curve was plotted using Frequency-Wavenumber Transfer method. In addition, the effects of different geophone offsets on the dispersion curve were investigated. The results showed that using the dispersion curve and phase velocity at high frequencies, the thickness of the surface layer can be calculated. Also, the slope of the dispersion curve at low frequencies indicates the number of the layers at different properties, and the steeper and closer to the vertical, means that a few number of layers are exist in the media. Furthermore, the effects of different geophone offsets were investigated and it was observed that geophone offsets should be limited to less than one-fourth of the layer depth in order to prevent the dispersion curve jumping to the higher modes. Furthermore, if the dispersion curve jumps to the higher modes at high frequencies, seismic data can be taken at a less geophones’ offset or the dispersion curve frequency range limitation is only before jumping to higher modes.

The construction of segmental precast concrete bridges is an increase due to its superior performance and economic advantages. This type of bridge is appropriate for spans within 50 to 250 m, known as mega-projects and the design optimization would lead to considerable economic benefits. In this study, a box-girder cross section of bridge superstructure with balanced cantilever construction method is assessed. The depth of cross section, thickness of top and bottom flange, thickness of webs and the count of strands of pre-stressed steel are considered as design variables. The optimum design is characterized by geometry, serviceability, ductility, and ultimate limit states specified by the American Association of State Highway and Transportation Officials (AASHTO) standard and AASHTO Load and Resistance Factor Design (LRFD) specifications. Genetic algorithm (GA) is applied for cost and weight optimization. To validate functionality of this algorithm, a real bridge constructed in the city of Isfahan, Iran (Esteghlal Bridge, completed in 2017) is optimized as a case study. The total of a 13% reduction in cost and weight of the bridge superstructure is observed. The cost optimization algorithm is run by considering different spans and relation between superstructure cost and span length is assessed. The efficiency of applying the GA in optimization of this kind of bridges is proved.

Recently, base isolation techniques are applied as a resisting system to protect the structures from seismic and dynamic loadings. Due to their importance, in this paper, an optimum arrangement of lead rubber bearing (LRB) and friction pendulum system (FPS) is investigated in irregular buildings and its performance is compared with a regular case. For this purpose, 3 types of irregularities have been adopted. Accordingly, 3, 7 and 10 story buildings have been performed and 12 possible combination have been applied for the isolators in each model. Afterwards, the numerical models have been analyzed using nonlinear time-history analysis and direct integration method and applying 7 earthquake records along the longitudinal and transverse directions of the building. The obtained results of the numerical study show that the application of FPS and LRB isolators in outer and inner columns respectively, led to a better performance compared to the other arrangements by reduction of the inter-story drifts as well as base shear and enhancement of the energy dissipation which is due to the characteristics of FPS isolators in balancing the applied forces with the building’s mass and prevention of torsion occurrence in irregular structures. Unlike the irregular buildings, application of FPS and LRB isolators in inner and outer columns, result in a better performance by reducing the story drifts in regular structures.

Structures are subjected to different kinds of loads during their lifetime, such as those caused by daily temperature swings, traffic loads, abrasion and severe loads like earthquake. The occurrence of damage in building structures, oil platforms, and generally all structural systems is inevitable. Different kinds of failure in various engineering structures have been observed so far, which have incurred massive financial losses and serious casualties. Most of such damages could be identified with structural condition assessment, and therefore crack propagation in and total collapse of the structure can be prevented by taking rehabilitation measures. The fact that in seismic prone regions where the occurrence of minor and local damages could lead to the total collapse of the structure increases the importance of structural health monitoring substantially. Hence, determining the damages in structures in order to monitor structural health, increase the safety of the structure, and determining the current condition of the structure seems vital. In this research, spectral strain energy is considered as an index for determining the location of the damage. By making a comparison between the spectral strain energy of healthy structure and damaged structure, damaged elements can be identified. In addition, the capability of the aforementioned method in the linear and nonlinear regimes will be assessed. To demonstrate the efficiency of the adopted procedure, numerical examples are provided whose results indicate precision and suitable performance of the proposed method in identifying damages in structures.