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To directly measure the strength and permeability of concrete, a core should be separated from the concrete and then tested in the laboratory with destructive methods. For example, to measure the permeability of concrete by existing standards, concrete must be broken and divided into half. Also, acute conditions such as temperature cycles that concrete faces in summer can have negative effects on concrete characteristics. Therefore, in this research, by using innovative tests, in addition to investigating the effect of temperature cycles (40, 80, 120, and 160 cycles) on the permeability and surface resistance of concrete at different ages, measuring the depth of water penetration and resistance Concrete is compressed without breaking it. According to the results, by using the calibration charts and the equations obtained from the methods of the cylindrical chamber and friction transfer, it is possible to obtain the depth of water penetration and the compressive strength of concrete without the need to break the concrete and with a correlation coefficient of over 96%. It was also observed that the cycles of temperature changes have negative effects on the durability and surface resistance of concrete in such a way that the number of 40, 80, 120, and 160 cycles of temperature changes increases the permeability of concrete by 4.1, 8.7, and 7 12.5 and 16.5 have been equaled. Also, the acute conditions of temperature changes have negative effects on the surface resistance of concrete in such a way that the surface layer resistance of concrete has decreased by more than 44% under 160 cycles of temperature changes. Considering that the surface layer of concrete has a direct relationship with the penetration of harmful substances into the concrete, it was observed that with the increase in the strength of the surface layer of concrete, the volume of water penetration into concrete has decreased. By increasing the resistance of the surface layer by 15%, the volume of water infiltration into the concrete has decreased by about 140%.

In this research, the effect of soil stabilization with cement at the same time as its reinforcement with fibers has been studied on the shear strength of sandy soil exposed to freeze-thaw cycles. In order to achieve this goal, laboratory studies were carried out with the help of unconfined compressive strength tests (UCS tests) on different compounds obtained from mixing cement, fibers, and sandy soil. More than 336 cylindrical laboratory models with dimensions including 3.6cm in diameter and 8cm in length have been made. Various modes have been observed during the failure of the samples, including shear, tensile, plastic yielding, and composite failure modes. The fibers used in the present research are waste products of tire factories known as DTY. Percentages of 2, 4, and 6 for cement and 0, 0.5, and 1 for fibers with lengths of 0.5, 1, and 1.5 cm were used relative to the weight of dry sandy soil in making the samples. Uniaxial cylindrical samples were tested for unconfined compressive strength after 7 and 28 days of curing time and under 0, 1, 2, and 3 freeze-thaw cycles. The results show that the act of stabilizing the soil with cement, along with reinforcing it to a certain amount of fibers, improves the uniaxial compressive strength before and after freezing and thawing cycles. This amount depends on the percentage of cement and the curing period. Also, adding cement in a certain curing time increases the unconfined compressive strength before and after applying the cycle, increases stiffness, reduces the ductility and toughness of the sample, and brittle failure when breaking occurs in the soil. Also, the addition of fibers, to some extent, improves the weaknesses caused by soil stabilization, such as reducing the failure axial strain, decreasing the residual strength, and the toughness of the materials in the conditions before and after freezing and thawing.

In the present study, the seismic behavior of hunchbacked block-type gravity quay walls rested on non-liquefiable dense seabed soil layer is investigated, and the optimal geometries for these wall types are proposed by performing non-linear time history dynamic analyses using Lagrangian explicit finite difference method. For this purpose, first, a reference numerical model of the hunchbacked quay wall is developed, and its seismic response is validated against the well-documented physical model tests. Then, the optimal hunch angles corresponding to the minimum horizontal displacement and zero rotation of the hunchbacked quay wall are estimated through the sensitivity analyses on the hunch angle of the wall, the friction angle of the backfill, and the ratio of hunch height to wall height. Subsequently, the statistical relationships are presented to predict the optimal hunch angle of the walls using multiple non-linear regressions based on the supervised machine learning technique. The results of non-linear dynamic analyses show that the deformation pattern, the movement mechanism, and, consequently, the seismic response of the hunchbacked quay wall change considerably with the variation of the hunch angle of the wall. In this regard, the rotation angle of the wall towards the seaside due to seismic loading decreases, and the deformation pattern and the movement mechanism of the hunchbacked quay wall alter from overturning towards the seaside to overturning towards the landside with an increase of the hunch angle. For all considered values of the ratio of hunch height to wall height and the backfill friction angle, increasing the hunch angle in the range of 25 to 35 degrees leads to a significant decrease in wall deformation. While increasing the hunch angle in the range of 35 to 50 degrees has less influence on reducing the wall deformation. For hunch angle values greater than 50 degrees, increasing the hunch angle has the opposite effect on improving the seismic performance of the hunchbacked quay wall and its seismic-induced deformations increase. Additionally, in the ratio of hunch height to wall height equal to 0.7, the optimal hunch angles corresponding to the zero wall rotation and the maximum reduction in the horizontal displacement of the wall decrease from 42.7 to 9. 23 degrees and from 53 to 34.5 degrees, respectively, with an increase of the friction angle of the backfill soil from 15 to 45 degrees.

Fragility curves are utilized to evaluate the probability of exceeding the damage index for structures exposed to seismic hazards. The Monte Carlo simulation method, which involves generating random numbers, is computationally expensive for calculating fragility curves. To address this issue, several methods have been proposed to produce fragility curves at a reduced computational cost. This study presents a method that enhances the seismic representation of high-dimensional models to generate accurate fragility curves for steel structures while significantly decreasing computational costs. This method selects uncertain variable values based on the results of initial incremental dynamic analyses. The fragility curves are divided into three zones, and an equation is proposed to estimate mean damage values associated with the boundaries of these zones. Additionally, polynomial response functions were generated to estimate the fragility curves. The proposed method is applied to generate the fragility curves for three steel structures, one with 4, 9, and 12 stories. Fragility curves are generated for four damage levels: non-structural damage (DS1), structural retrofitting required (DS2), intensive structural damage (DS3), and collapse (DS4). The resulting fragility curves are compared with those generated by the Monte Carlo simulation method and other existing methods. The comparison demonstrates that the proposed method achieves fragility curves with a significant decrease in computational costs compared to the Monte Carlo method while also exhibiting higher accuracy than other methods. The maximum error of the proposed method is approximately 20%, whereas Cornell's and the conventional HDMR methods exhibit errors of up to 80% and 60%, respectively. The errors of other methods increase significantly for fragility curves associated with high damage levels and 9- and-12 story steel structures, where nonlinear structural behavior is pronounced. In contrast, the increase in error is not significant in the proposed method. The findings of this study can be utilized to assess the seismic impact of various stochastic factors, such as random eccentricity or loading-related parameters, on the vulnerability of steel structures.

Helical nails are a new type of reinforcement element that has been widely used during the last decade. This has caused that despite their widespread use, the seismic behavior of geotechnical structures reinforced by them is still unknown. Therefore, the present attempted study to evaluate the effects of some structural parameters on the dynamic performance of helical soil-nailed walls (HSNWs) using shaking table tests. For this purpose, eight reduced-scale wall models were constructed with different inclinations, lengths, and arrangements of helical nails and then subjected to input excitations with different durations. The response of each model to base excitation was determined in the form of fundamental frequency, acceleration amplification, facing displacement, and failure mechanism. The results showed that although a uniform increase in the nail length along the wall height significantly improved the seismic performance of the HSNWs, this improvement could also be achieved to some extent by increasing the length of the nails locally in the lower and upper halves of the walls reinforced by horizontal and inclined nails, respectively. The use of inclined nails instead of horizontal ones was an efficient solution to reduce the lateral displacement, acceleration amplification, and changes in the frequency content. The effectiveness of this solution was reduced with the use of shorter nails in the upper half of the wall and eventually minimized by reducing the length of the nails across the wall height. The nails located in the lower half of the wall were identified as having the greatest effect on the seismic performance of HSNWs when horizontal nails were used. The opposite occurred when inclined nails were used. A parabolic failure surface with a specific inflection point was observed to be the potential failure surface of the HSNW. The dimensions of the potential failure surface increased with an increase in the length and inclination of the nails. Also, a combination of overturning and base sliding was identified as the predominant deformation mode in HSNWs, although the base sliding mode faded with an increase in nail inclination.

The shear wall is one of the most important systems to resist lateral loads in the building. In addition to controlling the lateral displacement of the structure and dealing with the lateral force, this system significantly increases the stiffness of the structure. The purpose of this article is to investigate the nonlinear behavior of semi-supported steel composite shear walls at the edges under monotonic and cyclic loading near- and far-fault. In this article, after verification, firstly, the semi-supported steel shear wall is modeled and analyzed using ETABS software to select the boundary members and the critical opening. Then, the base model of the semi-supported steel shear wall is converted to a semi-supported composite shear wall, and finally, it is modeled and checked using ABAQUS software. Among the investigated variables are reducing the thickness of the concrete coating on both sides of the steel plate of the wall, using concrete coating on one side of the steel plate of the wall, and increasing the thickness of the steel plate of the wall. The results showed that the addition of concrete to the SSSW model (converting the model to SSCSW) increases the initial in-plane hardness by 350%. Also, when concrete was added to the SSSW model, the ductility increased by 150% in two states near and far from the fault. Comparing the ultimate strength (peak of the cyclic diagram) also showed that regardless of the type of cyclic loading pattern, the calculated value for SSCSW is 28% higher than SSSW.

Hybrid concrete-steel buildings in height are usually referred to as buildings that have two lower and upper parts of concrete and steel materials, respectively. Due to the change in mass, stiffness, and damping in the vertical direction, these buildings have complex seismic behavior. Therefore, in this study, the seismic behavior of hybrid concrete-steel buildings at mid-rise height against far-field ground motions was considered. Initially, different models in groups of 7 and 13 stories were designed by considering different ratios of the number of concrete to steel floors. The connection of the upper steel section to the lower concrete section was considered a pin joint in nonlinear modeling in Opensees software due to its implementation. Then, incremental dynamic analysis was performed on all models using 22 different far-field records. Also, the maximum structural response diagram at the threshold of complete damage level was obtained according to the outputs of incremental dynamic analysis in different stories under all records, along with their average. Fragility curves were extracted at four damage states based on the HAZUS technical report. The results showed that there was a critical area at the junction of the steel frame with the concrete in which the structural response value underwent a sudden change and made this area inclined to much damage, which in the groups of 7 and 13 stories reached 65.2% and 98%, respectively. Finally, the median collapse capacity was obtained from fragility curves for hybrid buildings at different heights. As the number of concrete floors increased, the median collapse capacity of the model increased, which indicated the better seismic performance of the hybrid concrete-steel building. Among the investigated models, the lowest level of fragility was when the ratio of the number of concrete floors to the total floors of the Hybrid concrete-steel building was almost equal to 0.6.

The use of fibers is often aimed at increasing the ductility and load-bearing capacity of the desired concrete, and controlling the spread of cracks by adding fibers to the concrete causes this. The fibers improve the behavior of the concrete after the first crack due to the bridging property on the micro-cracks. In this paper, 15 concrete mixing designs in the form of 90 cubic specimens with dimensions (15 * 15 * 15) cm for the compressive strength test and 42 specimens with dimensions (15 * 15 * 60) cm for the flexural strength test have been made. Three mixing designs were made as a reference with 3 water-to -cement ratios (0.24, 0.29, 0.34) without fibers and with fibers with 3 different lengths of polypropylene fibers with lengths of (6, 12, 18) mm, respectively. A mixing scheme with 40 mm long hook metal fibers and another mixing scheme with a combination of 40 mm hooked metal fibers and 12 mm polypropylene fibers were investigated. Microsilica gel and super-lubricant were used to increase the smoothness and efficiency of concrete. The highest average compressive strength of 28 days was related to samples with composite fibers with a resistance of 72.52 MPa, which was 12.9% higher than the reference sample. The concrete sample with metal fibers with an average bending strength of 12.85 MPa has the highest strength among all the concrete mixing designs of this research and shows a 60% increase in bending strength compared to the sample without fibers. In the concrete samples tested with polypropylene fibers, after the compressive strength test, with the increase in the length of the polypropylene fibers, the workability and compressive strength of the concrete decreased, but the plasticity of the concrete samples increased. After the flexural strength test, the flexural strength and ductility of the concrete samples increased with the increase in the length of the polypropylene fibers, but it led to a decrease in the workability of the concrete.

Despite the knowledge of steel shear walls for many years, not much attention was paid to it. Steel shear walls without stiffeners and with stiffeners have been used in America in recent years. This system is 50% cheaper compared to the bending frame. After the events of September 11, a number of scientists were thinking of creating resistant and impervious structures against explosive and seismic loads economically by combining this system and the concrete shear wall system. Steel shear walls are easier to implement. Also, the accuracy of the work is at the level of normal executions, and by observing it, the reliability coefficient is many times higher than that other types of systems. The execution speed of steel shear walls is high, and because of this, the execution costs are reduced. Also, the efficiency of the shear wall system is more and more suitable than all the advantages of centralized bracing systems such as X and V shape and off-center steel bracing systems. The resistance against the overturning anchor caused by the lateral loads and the horizontal load of the floor is the most important task of the steel shear wall. The constituent members of the steel shear wall system include a steel plate wall, two boundary columns, and a floor horizontal beam. Also, the horizontal beams of the floor are used as transverse stiffeners in the sheet beam. The goal of centralizing the steel shear wall system is that the beams and columns remain in the elastic range. In this article, five-, ten-, and twenty-story buildings with steel shear walls were designed using the strip equivalent brace method in ETABS, and then seven acceleration maps far from the fault were selected, scaled, and modeled in ABAQUS software. The five-class model was compared with the non-centralized model. According to the results of the push-over analysis of the five-story steel shear wall model, the beams and columns remained in the elastic range in the self-centering model, and according to the hysteresis obtained from the push-over analysis of the steel shear wall, they have more energy consumption. The results showed that the drift, maximum drift, maximum displacement, and the ratio of the maximum acceleration value of the roof to the acceleration of the selected records in the self-centering steel shear wall have increased compared to the non-self-centering ones.

Aluminum foams are among the materials that have many applications in the construction of various building elements, including sandwich panels. This category of materials has unique features due to low density, the presence of small holes, sound insulation, thermal insulation, and corrosion resistance. In this paper, the Voronoi tessellation method is proposed to simulate the porous configuration of aluminum foams, which has the high capability to generate a porous structure with different densities. It is demonstrated that the Voronoi tessellation method can generate porous structures with different densities, hole sizes, and wall thicknesses stably. Moreover, the Voronoi tessellation method has a high speed and can be used to construct different sizes of aluminum foams. A comparison of the configurations obtained from the Voronoi tessellation method and experimental tests demonstrates the capability and competence of this method in generating the porous structure of the aluminum foam. In order to investigate the mechanical behavior numerically, the uniaxial tension test is applied to the aluminum nanofoams using the molecular dynamics (MD) method. The MD analysis is performed in the LAMMPS open-access software using the embedded-atom model (EAM) interatomic potential. The periodic boundary condition is imposed in all the boundaries of the atomistic model to satisfy the essential condition of the representative volume element (RVE) based on the homogenization theory. After minimization and relaxation of RVE, the uniaxial tension test is applied in an increment manner to reduce the strain rate effect. The evolution of the stress-strain curve, along with the stress contours, are presented for the aluminum nanofoam during the uniaxial tension test. Young’s modulus of nanofoam obtained by numerical analysis is compared to that of experimental data to confirm the accuracy of the computational modeling. Moreover, the results emphasize the high dependence of the mechanical behavior of aluminum nanofoams on the density and porosity.

Considering the seismic conditions of Iran and the many damages that occur as a result, it is necessary to change the current performance of structural design to achieve better performance in the seismic system. On the other hand, environmental concerns have prompted civil engineers to identify appropriate methods of reusing construction waste. The purpose of this research is to investigate the behavior of concrete made with recycled materials as a wide foundation, which has the role of seismic isolation for low- or medium-height buildings. In this research, the effect of crumb rubber and recycled concrete aggregate on concrete was examined in a laboratory. The design basis of its resistance is 30 MPa. The first mixture, as a control mixture, does not contain rubber granules, Forta fibers and recycled concrete aggregate. In the other three mixtures, the difference in the amount of recycled concrete aggregate is 40%, 50%, and 60% instead of coarse aggregate. Also, the percentage of rubber granules is constant, about 15% of the total volume, and the amount of Forta fibers is about 0.5% of the total volume. Compressive strength, Flexural strength, and Shear strength tests were performed on the 4 mentioned mixtures at the age of 28 days in a laboratory. The results of the compressive strength test showed that the addition of recycled concrete aggregate, rubber granules, and Forta fibers significantly reduced the compressive strength value. The results of the flexural strength test indicated that the additives cause a noticeable reduction in flexural strength, and this reduction intensifies with the change in recycled concrete aggregate percentage. The results of the shear strength test represented a considerable increase with the increase in the percentage of recycled concrete aggregate. Based on the test results, it is concluded that this type of composition material can be used as a foundation isolator, which showed a favorable shear behavior.

In recent years, the mixture of sand and rubber particles has been used in various fields of civil engineering, such as the stability of roofs, retaining walls, and drainage materials in landfills due to its durability, cost-effectiveness, and solving environmental problems. The purpose of this study is to investigate the effect of tire crumb on the shear strength and dilation in a static state and the liquefaction resistance in a dynamic state. In this regard, in this research, a static and dynamic undrained triaxial test was performed on a mixture of Babolsar sand and tire crumb (size between 1 and 8 mm) under constant confining pressure. The effect of parameters such as the amount of different tires’ crumbs (0, 5, 10, 20, and 30% by weight) and different relative densities on the static and dynamic behavior of the mixture of sand and rubber crumb and the created pore water pressure was investigated. In the static (consolidated-undrained) triaxial test, the relative densities of the sand–tire mixtures were 45, 60, and 80 percent. The tests were carried out on the specimens at 100 kPa cell pressure. Also, the specimen was loaded at a strain rate of 0.30% per minute for all the tests until the axial strain reached 20%. In cyclic triaxial tests, the relative density of the sand–tire mixtures was 45 percent, and the confining pressure of 100 kPa was used in the experiments. The sinusoidal waveform was applied to the specimen with a frequency of 0.5 Hz. For accuracy evaluation, the behavior of the sand-tire mixture, as well as corrections such as membrane penetration corrections, membrane force, and cross-sectional area, were applied. The results showed that adding tire crumb to sand reduces the shear strength and dilation of sand. Also, the ratio of the mean diameter of tire particles to the mean diameter of sand particles affects the behavior of shear resistance and dilation of the sand-tire mixture. As the ratio of the mean diameter of tire particles to the mean diameter of sand particles increases, the shear strength and dilation of the sand-tire mixture increases. Also, increasing the amount of tire crumb in sand reduces the excess pore water pressure and, as a result, reduces liquefaction potential in cyclic loading. This behavior can be attributed to the compressible nature due to the low elastic modulus of the tire crumb.

Mechanically stabilized earth (MSE) walls are commonly used as bridge abutments to support bridge deck loads. In this type of abutment, the use of a tiered configuration can play a prominent role in reducing induced horizontal stress, reducing lateral deformation, and, consequently, improving the performance of bridge abutments. Despite the importance of this issue, the influence of various factors on the performance of tiered MSE abutments under deck loads is not yet fully understood. Therefore, by simulating a bridge deck on a tiered MSE abutment in the form of a strip footing, the effects of the reinforcement type, the connection type of the deck to the abutment, and the deck location were investigated. For this purpose, three two-tiered mechanically stabilized earth walls (T-TMSEWs) were constructed using three different reinforcements and then loaded with strip footings at three different distances from the wall crest. By preventing and allowing the footings to tilt, the influence of the degree of footing freedom was also examined as the third variable. Particle image velocimetry showed that the use of a two-tiered configuration in MSE abutments and a decrease in the soil–reinforcement interaction and stiffness changed the slip surface geometry and prevented the development of deep slip surfaces in the lower tier. It was found that although the decrease in reinforcement stiffness and its interaction with soil decreased the bearing capacity of the strip footings on two-tiered MSE abutments, they also reduced the lateral pressure induced in T-TMSEWs by strip footing. Also, allowing the footing to tilt was found to be an effective solution for minimizing the deformation of the backfill surface and the induced lateral pressure. Moreover, a comparison of the results with analytical methods showed that the construction of MSE abutments in a two-tiered configuration reduced the lateral pressure in the upper tier. This became more noticeable with a decrease in the soil–reinforcement interaction and reinforcement tensile stiffness and an increase in the distance from the footing to the wall crest.

The tendency towards reinforcement of cement-treated sands with the inclusion of fibers has increased in recent years. This is due to the fact that fibers reduce the brittle behavior and improve the mechanical properties of the sandy soil samples. Since 2019, because of the coronavirus pandemic, the use of disposable surgical face masks has become increasingly popular among the public, and their burial, reproduction, and reuse have become one of the major environmental problems. Therefore, in this research, an attempt has been made to reuse the surgical face fibers in the application of cement-reinforced sands. In this regard, samples with 2, 4, 6, and 8% cement contents, reinforced with different amounts of fibers (0, 0.25, 0.5, and 0.75%) in different relative densities (35%, 50%, and 70% sand) were prepared and after 7 days of the curing period, their tensile behavior using brazilian tensile splitting tests. The results showed that the addition of cement percentage and increasing relative density have a significant effect on improving the tensile strength index of cement sands. The percentage of surgical face mask fibers 0.25% is the optimal amount of added fibers (the maximum tensile strength in this percentage of fibers). The definition of the key parameter (the ratio of porosity to cement content) and several empirical relations for estimating the tensile strength of reinforced and reinforced samples with very good accuracy are presented.

The understanding of architecture as an ecology of interactive systems moves past limitations and restricted tendencies toward spatial environments that are adaptive, perceptual, and behavioral. In this framework, the environment seeks to build interaction scenarios to activate relationships between components. In this case, architecture moves away from well-known models that always lead to disciplined responses and toward understanding adaptive ecologies that include active particles for communication and exploration. The current research investigated and discussed the design of a system that can replace the current methods of planning the construction of infrastructure units in the future. The result is the simulation of a cellular self-assembly system that can produce and rebuild its structure when needed. Therefore, there is a revolution in construction and a complete revision of architectural standards and construction planning, disremembering demolitions and laborious construction costs. This study aims to explore the function of quorum sensing, a mechanism of intra-species communication that serves as the central regulatory system in the formation and concurrent response to environmental changes. The algorithmic design features of the system's constituent units were also examined. During the assembly process, extracellular matrices act as the milieu in which individual cells interact with one another and the desired environment as constructed building blocks. This allows for parallel assembly and error correction at a general level, both automatically, and has significant implications for the field. The proposed model uses a two-level control system (micro-macro) to ensure that the interactions among the components, on the one hand, and between the components and their environment, on the other hand, are in line with the objectives of the plan and the balance of the whole system. This two-level approach primarily follows a bottom-up process at the scale of the interaction of its constituent particles and subsequently utilizes a top-down process during the overall regulation of the system through the extracellular matrix. Ultimately, the simulation results obtained using Grasshopper3d software were shown in three scales: small (chair), medium (shelter), and large. This approach has been demonstrated to be effective in previous research and offers a promising framework for further investigation in this field. This research can take essential steps in developing simulator machines to build a construction self-assembly system based on sequential configurations and numbers.

In this research, the experimental investigation of the inertial interaction of soil-pile raft structure has been conducted for slender structures supported by the combined pile-raft foundation with emphasis on the new concept of design method (performance-based design). Most of the former studies based on this concept have focused on the surface foundation, where the surface foundation's rocking motion acts as a source of energy dissipation to protect the superstructure. Meanwhile, less attention has been paid to the surface foundation combined with piles (Combined pile-raft foundation) as an economic support system for high-rise and heavy structures. Mainly, the focus of optimizing these foundations through parametric analysis has been on variables such as pile arrangement and pile length for vertical static loading. When the heavy structures are subjected to the lateral load caused by the earthquake, the foundation experiences significant inertial moments. Thus, the nonlinear behavior of the foundation is not far from expected. The present research intends to examine the rocking behavior of combined pile-raft foundations as the foundation of slender structures. Evaluating the response of the superstructure and its possible benefit from the nonlinear behavior of the foundation is the principal goal of this research. In this regard, using experimental models, some characteristics of combined pile-raft foundations, such as the arrangement of piles and the relative length of the piles, have been investigated on the response of the superstructure. Three physical models were constructed in the laboratory. Each model contained a single degree of freedom superstructure supported by a floating pile raft foundation in sandy soil. Two characteristics were considered for evaluating pile raft characteristics: pile configuration and pile length ratio. The superstructure was identical in all three physical models. An experimental procedure based on forced vibration tests was presented to assess the dynamic response of the models at different levels of foundation nonlinearity. According to the experimental measurements, the nonlinear behavior of the foundation has a significant role in the response of the superstructure. Dynamic demand reduction as well as drift reduction are the two most important factors that benefit the superstructure from foundation nonlinearity. Accordingly, the dynamic behavior of the models is divided into two individual phases. Also, comparing the results of the models showed that the arrangement of piles and the relative length of the piles in the combined pile-raft foundation have a significant impact on superstructure response.

Traditional patterns could be an effective solution for water consumption and pollution-related problems in the construction industry. However, the water footprint of traditional buildings in Iran has not been investigated. Iran has rich experience in constructing traditional buildings. This paper presents a comprehensive analysis of the grey and blue water footprints of the construction of traditional buildings in Iran with emphasis on different climate zones. The results are compared with modern buildings (concrete and steel). High-quality data related to 11 materials factories and 34 traditional buildings (stone, wood, clay, and brick) are presented. Blue and grey water footprints of building materialization are calculated using the water footprint network and life cycle assessment methods. The focus is on the structures of buildings. The grey and blue water footprints of modern structures are 327 times and 1.5 times larger than the grey and blue water footprints of traditional structures, respectively. Steel and cement production are influential parameters in the greywater footprint of modern structures. Employee meals have the greatest impact on the water footprint of traditional structures. The blue water footprint dominates the water footprint of traditional structures, which is 2.26 times larger than the greywater footprint. Stone structures have a blue water footprint of 0.85 m3/m2, which is dominated by the blue water footprint of employees' food (38.82%) at construction sites. They have a smaller blue water footprint than adobe and brick structures (1.41 - 1.42 m3/m2) and are close to the water footprint of wooden structures. The water footprint of brick structures is mainly influenced by the energy used (57.04%) for brick production. On the other hand, the greywater footprint dominates the blue water footprint of modern structures, which is 99.61 times larger than the blue water footprint. Steel structures have a blue water footprint of 1.86 m3/m2 and a greywater footprint of 208 m3/m2, the main pollutant of which is cadmium. Concrete structures have a blue water footprint of 1.60 m3/m2 and a greywater footprint of 137 m3/m2, with mercury as the main pollutant. From the water footprint viewpoint, it is better to use concrete structures than steel structures if both have suitable properties for the conditions they are used in. According to the results, the non-use of traditional buildings leads to an increase in water consumption and pollution.

Autonomous vehicles are a proper option for children's school trips due to their high potential. Parents are the main decision-makers in choosing their children's school trip mode, and it is essential for policymakers to be aware of their behavior and willingness, especially when technology is not yet available to the public. Previous studies of self-driving cars (SAVs) have focused on the rejection or acceptance of this technology by adult users, while SAVs are an attractive option for students' educational trips. Few studies in this field emphasize the need to do it, but in the current study, unlike previous studies, the factors affecting the behavior of parents who are unable to make a decision in this regard have been investigated using mathematical modeling. The virtual link of the current study questionnaire (in six sections) was uploaded by the school principals in the educational groups of the selected schools with the parents after experimental questioning and correction. Data analysis shows that almost a high percentage of parents (29%) have not been able to give a definite opinion about whether or not their child uses autonomous vehicles. In this article (for the first time), the factors affecting the inability of parents to make decisions are studied. The binary logit model on the May 2021 questionnaire of parents of fourth to ninth-grade students in Kerman schools (1435 cases) has a correct estimation percentage of 77.1 and a good fit coefficient equal to 0.4. The estimated model shows that the behavioral characteristics and accidental history of parents influence their decisions. In the case of Kerman, parents who have a history of fatal accidents in close relatives and who have a high level of concern about the way they drive and the possibility of a high-traffic accident in public transportation have not been able to decide whether to reject or accept this technology.

Nonlinear Time History Analysis (NTHA) contains a complex and rigorous process for structural seismic evaluation. Nonlinear static (Pushover) analysis can simplify this process. This paper aims to develop an energy-based seismic assessment methodology using pushover analysis. This methodology can estimate the response of mid-rise buildings with much fewer computational operations than NTHA and consider higher mode effects. Other advantages of the proposed procedure include using the capacity curve of Multiple Degrees Of Freedom (MDOF) systems directly instead of the Equivalent Single Degree Of Freedom (ESDOF) and computing the energy demand of the structure based on the mean spectrum corresponding to the desired hazard level instead of the various earthquake record spectrums. The proposed methodology converts the pushover capacity curve to the energy capacity curve for each mode, and the energy demand curve is superimposed on it. The intersection of these two curves is considered the target response. NTHA and Modal Pushover Analysis (MPA) are employed to validate and compare the proposed methodology with other ones. Also, 4, 8, and 9-story steel moment frame buildings are selected, modeled, and analyzed using OpenSEES software. The results show that the proposed methodology can estimate the responses of the building with reasonable accuracy compared to the mean results of the NTHA. Also, the proposed method significantly reduces the error of the responses compared to the MPA. Nevertheless, it can be concluded that the proposed energy-based methodology can be a simple, efficient, and rapid alternative for NTHA.

Leachate is a hazardous liquid that leads to numerous environmental problems. Soil pollution is one of the most important of these problems caused by poor leachate management facilities and limited land availability. Studies show that soil characteristics change during contamination, and these changes are a function of the type of soil and leachate. Therefore, it is necessary to evaluate the static and dynamic behavior of soils after contamination with leachate. Despite the importance of this issue, studies in this field are limited only to static behavior, and the effect of leachate on the dynamic behavior of soils remains almost unknown. Hence, an experimental effort has been made in this study to evaluate the effect of waste leachate sampled from the Alborz landfill on the dynamic parameters of three different clays under different overburden pressures (6.29, 18.88, and 31.47 kPa). For this purpose, the amount and type of heavy metals in the leachate were first determined using an inductively coupled plasma (ICP) spectrometer. Then, cylindrical soil samples were prepared in three different leachate contents (0%, 6%, and 12.5%) and subjected to a simple dynamic shear test. Moreover, the samples were photographed using an SEM microscope to investigate the effect of leachate on the soil texture. Based on the hysteresis loops obtained from simple shear tests and, subsequently, amounts of shear modulus (G) and damping ratio (D) calculated from them, it was found that pollution and its increase cause an increase in the shear modulus and a decrease in the damping ratio so that the growth of the shear modulus and the decrease in the damping ratio are affected by the type of soil and are more pronounced in soils with a lower paste range. It was also observed that the greatest effect of leachate on improving the shear modulus of the soil can be seen at lower levels of pollution. The increase in the influence of shear modulus and damping ratio of clay from overburden pressure was identified as one of the effects of soil contamination with leachate, which was more evident in clays with high paste range.

Three-dimensional analyses are conducted to study the effects of ground motion and the presence of velocity pulse on the pile responses in liquefiable soils. Liquefaction of soils is an important issue in geotechnical engineering. Soil liquefaction occurs when saturated or partially saturated soil substantially loses strength and stiffness in response to applied stress, such as shaking during an earthquake or other sudden changes in stress conditions. The forward directivity effect, which includes a large velocity pulse at the beginning of the velocity time history of the ground motion and contains most of the seismic energy from the rupture, is the most damaging phenomenon observed in near-field ground motions. To investigate the effect of near-field ground motions on the seismic response of a soil-pile system, a three-dimensional model consisting of the two-layered soil and the pile is constructed. Modeling is conducted by using the FLAC 3D software. The P2PSand model is applied for the modeling of sandy soil. P2PSand model refers to a Practical TWO-surface Plastic SAND constitutive model for general 3D geotechnical earthquake engineering applications aimed at capturing essential soil dynamic characteristics. The model is a modified extension of the fabric-dilatancy-related sand plasticity DM04 model developed by Dafalias and Manzari. The Dafalias-Manzari two-surface model (DM04) is a critical-state compatible and state parameter-related plasticity model developed in the framework of Bounding Surface theory, which has been widely implemented and studied. Dynamic analyses are conducted for the soil-pile system under the excitations of four selected ground-motion suites that were recorded on the rock. The results show that near-field velocity pulses have a considerable effect on the behavior of the system and cause sudden large displacement demands on the piles and soil. The pulse in the record of near-field ground motion has caused the pore water pressure coefficient (Ru) to increase and liquefaction in the upper soil layer.

Three-dimensional analyses are conducted to study the effects of ground motion and the presence of velocity pulse on the pile responses in liquefiable soils. Liquefaction of soils is an important issue in geotechnical engineering. Soil liquefaction occurs when saturated or partially saturated soil substantially loses strength and stiffness in response to applied stress, such as shaking during an earthquake or other sudden changes in stress conditions. The forward directivity effect, which includes a large velocity pulse at the beginning of the velocity time history of the ground motion and contains most of the seismic energy from the rupture, is the most damaging phenomenon observed in near-field ground motions. To investigate the effect of near-field ground motions on the seismic response of a soil-pile system, a three-dimensional model consisting of the two-layered soil and the pile is constructed. Modeling is conducted by using the FLAC 3D software. The P2PSand model is applied for the modeling of sandy soil. P2PSand model refers to a Practical TWO-surface Plastic SAND constitutive model for general 3D geotechnical earthquake engineering applications aimed at capturing essential soil dynamic characteristics. The model is a modified extension of the fabric-dilatancy-related sand plasticity DM04 model developed by Dafalias and Manzari. The Dafalias-Manzari two-surface model (DM04) is a critical-state compatible and state parameter-related plasticity model developed in the framework of Bounding Surface theory, which has been widely implemented and studied. Dynamic analyses are conducted for the soil-pile system under the excitations of four selected ground-motion suites that were recorded on the rock. The results show that near-field velocity pulses have a considerable effect on the behavior of the system and cause sudden large displacement demands on the piles and soil. The pulse in the record of near-field ground motion has caused the pore water pressure coefficient (Ru) to increase and liquefaction in the upper soil layer.

One of the most common methods of identifying modal parameters in the field of operational modal testing is the method of identifying sub-random space and frequency domain analysis. Unfortunately, the scope of these methods' application is limited to static signals with a long pick-up time, and if the above conditions are violated, the results will be erroneous; This is in the context that the above two conditions are not met regarding the earthquake signal, and so far the reliability of these methods and their error rate in the face of this group of signals have not been studied. In this regard, in this study, the performance of these methods in earthquake conditions (both conditions are violated) is studied. For this purpose, an numerical model of two two-dimensional frames with different heights (five and ten floors) is created and stimulated by using 20 earthquake records in the near and far fields. Using the obtained results and comparing them with the results of the numerical model, the error values for the modal parameters are obtained; Also, with the statistical study of the errors in the estimation of the frequency of the structure, the probability distribution function of the error and an estimate of the distance of the error are suggested .The results of the study showed that (a) the method of identifying random subspace has a better performance than the method of frequency domain analysis; (B) The random subspace detection method is not able to detect the first modes and is proposed to identify higher modes; (C) the efficiency of the frequency domain decomposition method decreases with increasing structural height; (D) By optimizing and locating the sensors, the performance of the frequency domain analysis method is dramatically improved. However, in the random subspace detection method, the detectability increases with the number of sensors.

One of the main damages of the nonstructural masonry walls during an earthquake is its instability and collapse on the combination of deformation at the in-plain direction caused by lateral inter-story drift of structures and out-of-plane inertial forces applied to the wall because of earthquake acceleration. In most of the researches, only one of these actions was investigated, or their interactions were not directly investigated. In this research, a combination of in-plane and out-of-plane loadings was carried out, and the effect of reinforcing on the nonstructural walls by using fiber mesh reinforced mortar and bed joint rebar has been investigated. For this purpose, three wall specimens with scale of 1 to 1 were made of Leca blocks. Walls were subjected to a combination of in-plane cyclic loading and out-of-plane loading. The results showed that nonstructural walls, without reinforcement, failed under out-of-plain force in low in-plain drift, and the test process was stopped. On the other hand, strengthening the nonstructural wall with fiber mesh reinforced concrete caused an increase of 15% and 54% in the drift ratio related to the reduction of the wall resistance and the maximum in-plane force compared to the nonstructural wall, which was strengthened with bed joint reinforcement.

After the Northridge earthquake, a set of prequalified connections were introduced by international design codes. Thease connections include reduced beam secrion (RBS) moment connection, bolted unstiffended and stiffended extended end-plate moment connection, bolted flange plate (BFP) moment connection, welded unreinforced flange-welded web (WUF-W) moment connection, kaiser bolted bracket (KBB) moment connection, conxtech conxl moment connection, sideplate moment connection, simpson strong tie strong frame moment connection, double tee moment connection, slottedweb (SW) moment connection. After ensuring the seismic performance of this set during earthquakes, concerns surfaced that forming plastic hinges in beam elements would result in either making repairs impossible or incredibly expensive in the event of a moderate or severe earthquake. Hence, a type of replaceable connections was introduced wherein plastic hinges would be placed in pre-determined elements. Their intuitive replaceability feature would make repairs and reutilization of the structure a much easier task. In this study, the experimental investigations of 4 full-scale samples of a replaceable rigid connection under cyclic loading were carried out. The results of the experiments demonstrated that in the proposed connection, the plastic hinge is formed in the fuse element while the beam and the column maintain their elasticity, allowing the connection to be replaced. Also, taking into account the early buckling of the fuse plates installed on the beam flanges, the moment capacity of the connection is decreased by 22 percent compared to the moment capacity of the fuse. According to the results obtained from the backbone diagrams, stiffness of the connection after replacing the fuse plates in P12 and P15 samples has decreased by 8.61% and 6.14%, respectively; this could be due to slight changes on the holes on the beam web and flanges as well as changes in the pre-tensioning forces of the bolts. Investigations have revealed that, the 20% increase in the moment capacity of the fuse (using 15 mm-steel plates instead of 12 mm in the fuse plates of the beam flanges) has increased the cumulative energy dissipation of the connection by 12%.

In some roadway projects, especially in a mountainous region, the mechanically stabilized earth walls must be constructed in front of stable features such as a rockface for a variety of reasons, including the construction of new roadways, widening of urban transportation corridors, and reduction of rockfall risk. There has been limited research into the dynamic performance of the MSE wall adjacent to the rock slope; thus, the seismic behavior of this retaining system is still poorly understood. The most common methods for seismic stability analyses of reinforced-soil retaining walls are based on pseudo-static limit-equilibrium approaches, where seismic coefficients are applied to the potential failure soil mass. In the pseudo-static method, the assignment of an appropriate lateral seismic coefficient (Kh) that would be able to simulate the seismic inertial force induced in the sliding wedge has a considerable effect on the accuracy of the analyses. Since earthquake acceleration is the main cause of the inertial force induced in the failure mass, the seismic acceleration coefficient (Kh) is determined mostly based on the peak ground acceleration at the wall base level. The seismic events are transient in nature, and the earthquake-induced forces vary in intensity during vibrations. However, in the pseudo-static method, the seismic force is applied to the failure soil mass indefinitely. Therefore, the use of peak ground acceleration could lead to over-conservative results. To overcome this limitation, the seismic coefficient is usually expressed as a fraction of the peak ground acceleration for design purposes. The value of this fraction has not been clearly defined for reinforced-earth retaining walls. Most of the proposed methods for calculating the seismic acceleration coefficient are based on theoretical assumptions, and the validation of this important parameter has not been evaluated based on an experimental approach. In this study, initially, the seismic behavior of the polymeric-strip reinforced-earth retaining walls built on the rock foundation is investigated using shaking table tests. Then, the assumptions of the pseudo-static approach are simulated by push-back pressure tests. To apply back pressure to a model wall, a special apparatus was designed and made in the Tarbiat Modares University laboratory. Finally, the horizontal seismic coefficient is estimated by comparing and adjusting the result of the shaking table and push-back pressure tests. The results presented are based on the acceptable seismic performance of the retaining wall and are compared with the previously proposed relations and AASHTO design code.

During operation, a variety of factors, including earthquakes, wind, fatigue, the environment, and many others, can always cause damage to structures and the characteristics of the structure change as a result of the damage. The availability of low-cost methods for detecting damage in truss bridges makes it possible to examine a greater number of operating bridges and ultimately reduces future losses and risks. As a result, researchers' pursuit of suitable methods for detecting damage in structures has grown significantly over time. Bridges have always been the focus of researchers' efforts to comprehend their behavior and develop methods for identifying damage because of their significance as the infrastructure of every nation. In this study, an eight-span truss bridge was subjected to a moving load in a laboratory process, and the vertical displacement response of only one desired point of the truss lower chord is measured, in the damaged and intact condition. On the other hand, the influence line diagrams of all truss members have been extracted during the modeling in finite element software. The efficacy of this method in detecting damage in truss bridge screw connections has been evaluated using fourteen distinct damage scenarios. The results show that if damage occurs in the bridge connections, the difference diagram of displacement responses of two healthy and damaged states and the influence line diagram of the member whose connections are damaged will match in terms of shape and can be an indicator to identify the damage. This method works for all of the truss bridge's members, and it has worked even when more than one member was damaged. Considering that this method has been numerically validated in the previous study, using a more accurate displacement sensor with less noise and using conditions closer to those of the numerical analysis improves the accuracy of the results.

Mortars are heterogeneous construction materials whose raw materials, manufacturing processes and application conditions have continuously evolved throughout time . Mortars are artificial construction materials that consist of; one or more mineral adhesives whose main function is to connect loose grains using different chemical changes in their mass, aggregates that are used to create volume stability on the mortar mass and water that is used to mix the mortar components into a sticky dough. Materials must be carefully measured and mixed to give the desired balance to bring out its essential properties. Therefore, in this research, 11 mixing plans for mortar, which is a kind of reactive powder concrete, with sand to cement ratios of 4.5, 4.75, 5, 5.25, 5.5, 5.75, 6, 25 6.5, 6.5, 6.75, and 7 were made and the effect of increasing the ratio of sand to cement was evaluated, and by analyzing the results of compressive strength, it was observed that the highest compressive strength was at the age of 1, 7, 14, and 28 days of the sample with a sand-cement ratio of 4.75 and at the ages of 42, 56 and 90 days, it corresponds to the sample with a sand-to-cement ratio of 4.5 and by analyzing the flexural strength results, it was also observed that the highest flexural strength is related to the sample with a sand-to-cement ratio of 4.5. Then the effect of adding 1% of polymer resin to 11 sand-cement ratio was investigated. From the analysis of the results, it was found that adding 1% of polymer resin at the age of 1 day causes a decrease in compressive strength compared to samples without polymer resin. But with increasing age of samples in high sand-cement ratios, an increase in compressive strength is observed. The highest compressive strength at ages 7, 14, 28, 42, 56 and 90 is for the sand-cement ratio of 4.75 and the highest flexural strength was observed at the sand-cement ratio of 4.5.

Collapsible soils are one of the moisture sensitive soils that experience sudden and significant settlements due to wetting. These soils are widely distributed and constitute about 10% of the total land area of the world, which are typically located in arid and semi-arid areas. In foundation engineering, the most important issue in dealing with these soils is to measure their collapse potential with different water infiltration patterns. The effect of parameters such as initial soil conditions, loading conditions and gradation quality on the behavior of these soils has been investigated. The amount of clay in the soil is considered as an important factor in the behavior of the collapsible soils. Water enters the soil from different sources, but the existing devices and tests to measure the collapse potential are not capable of modeling water infiltration patterns. In this study, an apparatus was used that simulates different water infiltration patterns based on the direction of water movement (from top or bottom) and type of water distribution (point or wide). The results show that in oedometer tests and tests with the ability to simulate the water infiltration patterns, with the increase in the amount of clay in the sample, the collapse potential increases, but the amount of increase is not the same in different tests. The amount of increase in collapse potential due to the increase of clay in the sample is greater in single and double oedometer tests than in tests with the ability to simulate the water infiltration patterns, and for a more accurate prediction of the collapse potential, tests with the ability to simulate the water infiltration patterns should be used. Among the different water infiltration patterns in the soil, for the sample with clay compared to the sample without clay, the highest increase in collapse potential is related to the top-point water infiltration pattern ) and the lowest increase is related to the bottom-wide water infiltration pattern( ). But for the sample with 23% clay compared to the sample without clay, the highest increase in collapse potential is related to the top-wide water infiltration pattern( ) and the lowest increase is related to the bottom-wide water infiltration pattern.

Mass nonlinear dynamic analysis is unavoidable in many fields of earthquake and structural engineering, such as incremental dynamic analysis, probabilistic performance-based design, and optimization approaches. Using simplified models with fewer degrees of freedom instead of detailed original models to a great extent reduces the computational cost and prevents extremely time-consuming analysis. Among different simplified models for steel moment frames, stick models (such as shear beam models) only use the global story stiffness to estimate the original model responses, which do not consider the structural configuration. The stick models are only suitable for obtaining the general responses of the structure, such as global and interstory drift. However, simplified frame models are the more accurate simplified models that consider the details of the original frame, such as beam and column elements, nonlinear plastic hinge springs, and joint rotations. Substitute Frame is one of these models, which is a one-bay frame that predicts the structural responses for concrete and steel moment frames with very high accuracy. The purpose of this research is to develop a substitute frame model for steel moment frames with unequal bay lengths. For this purpose, the beam stiffness and nonlinear behavior of rotational springs were modified based on linear and nonlinear structural analysis approaches and the proposed model is called Modified Substitute Frame. In the following, to evaluate the accuracy of the proposed model, three types of 12-story buildings with unequal bay lengths were designed using ASCE7-16 and AISC 341-16 criteria and subjected to three different ground motion data sets, i.e., far field, near field with pulse and without pulse ground motions. The nonlinear time history analysis results showed that the Modified Substitute Frame predicts the original frame responses with very high accuracy. Moreover, the Modified Substitute Frame prediction was more precise than the Improved FishBone model which was recently presented for moment frames with unequal bay lengths.

Global population growth and industrialisation over the past two centuries have been increased the tendency toward increased use of fossil fuels. The rising trend in greenhouse gas emissions brought on by the usage of fossil fuels has contributed to global warming and, as a result, increased environmental hazards. Geothermal energy is a substantial source of clean, sustainable, and renewable energy that is utilized extensively for building heating and cooling and has a big impact on reducing greenhouse gas emissions. Energy piles as a convenient and efficient energy geo-structure receiving a lot of attention worldwide for use in building heating and cooling. Investigating the variables influencing the thermal interaction between the group of energy piles and its impact on reducing the extracted energy from the energy pile group is the goal of this study. The soil porosity, mass flow rate of the circulating fluid, pile diameter, pile length, and pile position have all been investigated using the COMSOL Multiphysics Software. The analysis of the simulation data reveals that as energy piles' diameters increase, so does the amount of extracted energy. The amount of energy extracted is significantly influenced by the soil's porosity, which causes thermal interaction to decrease and energy extraction to increase as porosity increases. It was found that the amount of energy extracted is not significantly affected by the mass flow rate of the fluid circulating in the pipe. If the amount of extracted energy calculated with respect to the pile length, as the length of the pile increases, the average energy extracted per meter of the pile decreases and tends to a constant value. When the pile diameter is kept constant, pile interaction tends to be reduced by increasing the ratio of the pile diameter to the pile spacing (s/D), and as a result, the amount of energy extracted increased. In the group of energy piles, it has also been found that the corner piles are the most and the center piles are the least effective piles.

Current methods of splicing columns with different depth sizes have a long total load path as well as large and expensive details. These details are sometimes overly complicated and hard to fabricate. To shorten the load path and make fabrication easier and more economical, a middle plate is proposed in this study to be placed between the two columns to connect them. The plate is butt-welded to both the lower and the upper portions of the column. Although this type of splice has been used occasionally in steel structures, its behavior is mainly unknown and research and code specifications regarding this type of splice are very limited. The current research studied the overall behavior of columns connected by this type of splice and obtained the minimum plate thickness required for typical columns to meet codes provisions. To provide the possibility of filling potential hollow sections with concrete, it is recommended to use a hallow plate in box-shaped columns. This study conducted finite element analysis on box- and H-shaped columns with different upper column depths. The influence of the plate thickness and shape on the strength and stiffness of splice in each combination was studied and minimum plate thickness was obtained. The splice exhibited satisfactory strength and stiffness in regular combinations. In combination with an upper column depth reduction of less than 5cm in box-shaped profiles and less than 7.5cm in the H-shaped profiles, the splice plate with a thickness of 5cm or more meets the criteria for both strength and stiffness. Decreasing the upper column depth increases the demand on the splice plate and a thicker plate is needed. Moreover, the shape of the splice plate, i.e., hollow plate or regular plate, had a large impact on the column behavior as the required thickness was greater in hollow plates. Results of stiffness analysis showed that decreasing the upper column depth and overall height of the column decreases the axial stiffness of the column.

Engineered cementitious composite is a cement-based composite material that exhibits significantly higher flexural, tensile, and compressive strength compared to ordinary concrete. The initial tensile strain capacity of ECC within the first two days of concreting is approximately 5%. However, as time progresses, the tensile strain capacity decreases to stabilize at a constant value of 3%, a level considerably higher than that of ordinary concrete. Moreover, ECC exhibits exceptional durability in sulfate, chloride, tropical environments, as well as resistance against freeze-thaw cycles. Its significance characteristics, including strain-hardening behavior, multiple cracking, and ductile behavior, distinguish it from the other types of concrete. To produce engineered cementitious composite, special materials such as fly ash and polyvinyl alcohol (PVA) fibers are required, but they are not available in the country. In this research, 13 different engineered cementitious composite mix designs were developed using locally available materials such as slag, limestone powder, industrial pozzolan, silica fume and polypropylene fibers. Then, the mechanical properties of different engineered cementitious composite mix designs, including compressive strength, modulus of rupture, energy absorption, and toughness indices have been investigated. The experimental results showed that optimizing the use of silica fume, and slag at rates of 10% and 28% by weight of cement, respectively, along with the inclusion of industrial pozzolan at a rate of 22% by weight of cement, improves the mechanical properties of engineered cementitious composite. Finally, the best engineering cement composite mix design was reinforced with glass grids (one and three layers) and subjected to a four-point bending and direct tensile tests. According to the results obtained from the four-point bending test of glass grid reinforced engineered cementitious composite panels, it can be concluded that increasing the number of glass grid layers enhances flexural strength, the area under the load-deflection curve, and energy absorption. For instance, the flexural strength of engineered cementitious composite panel reinforced with three layers of glass grid increased by 47.5% and 275%, respectively, compared to the flexural strength of an engineered cementitious composite panel reinforced with one layer of glass grid and an unreinforced engineered cementitious composite panel.

The retrofitting plan is effective when, in addition to being cost-effective, it minimizes casualties, reduces infrastructure damage, and limits the extent and scope of damages as much as possible. The design and construction of most explosion-resistant barriers in all types of structures are not optimal due to the high cost on the one hand and the low probability of explosion during the life of the structure on the other hand. In this research, the proposal of using the combined method of restraining net along with the blast wave absorber panel as a new model in protecting the building against external explosions has been studied. The rocket is restrained at a certain distance from the main structure by a resistant net and the panel absorbs the wave caused by the explosion. By conducting studies and experiments on various absorbent materials, the selected panel was introduced and its behavior against threats at different distances was evaluated numerically and in the field. The results of the simulations were in good agreement with the field tests, which can be generalized for different amounts of charge.

The durability of the rebar used in a concrete structure is very important for the safe and long-term use of that structure, and therefore, the root and the main cause of reducing the life and durability of that structure, which is corrosion, is of great importance. In this study, medium carbon steel bars with a diameter of 14 to 40 mm and a number of epoxy coated and fiber bars have been tested and the effect of simulated corrosion on the samples has been investigated by measuring the mechanical properties. The results obtained from this research can be effective in the field of rebar size selection according to its production method in different conditions. This result has been obtained according to the experiments. Mechanical properties are the main properties of steel rebar affected by corrosion that have been tested in this paper. In the measurement of mechanical properties by universal device, slight changes were seen depending on the type of device. In order to measure the rebar cross section more accurately, machining has been used to prepare the rebars after corrosion. The results of this research also showed that in 14 mm size rebar, with the progress of corrosion up to 0.68 mm, the amount of force tolerated decreased by 16.7% (from 102 KN to 85 KN). Also, in the next step, with 0.62 mm of corrosion progress, the amount of this force has reached 76.3 KN from 85 KN (i.e., 10.2% reduction). In the third stage, with the progress of 0.96 mm, the amount of force borne by the rebar has reached 69.7 KN from 76.3 KN, which is equivalent to a 2.5% decrease. Finally, considering the economic and various application conditions, suggestions have been made to improve the performance and increase the durability and long-term use of the structures with more confidence.

One of the methods of stabilizing soil slopes or excavated pits is soil nailing. The use of this method is common in different parts of the world and has a history of about four decades. However, the use of this method in cold regions is more limited than other regions with normal temperature conditions due to insufficient studies and lack of necessary information about the response of the soil nail wall under freezing conditions. Therefore, in this study, in order to help better understand the behavior of soil nail wall due to frost activity, using Abacus finite element software, a complete thermal-mechanical analysis coupling on a case soil nail wall in the Brunswick area Located in Maine, USA. In order to validate the numerical model, the results obtained from this simulation are matched with the results of field operations performed by Duchenne (2003) on the same soil nail wall. In the continuation, by applying successive freezing and thawing cycles on the mentioned soil wall, the amount of stress created in the nails strengthening the soil wall in different cycles were compared and the stability or instability of the soil wall was investigated. The results of the study of the amount of stress created in the nails due to the applying of three freezing cycles with normal temperature of the Brunswick region to the soil body show that with increasing the number of cycles, the stress created in the nails decreases in higher cycles than in lower cycles. Then, the effect of applying three freezing cycles based on a hypothetical critical temperature on the soil nail wall was investigated by comparing the highest stress created in the nails under the mentioned conditions with the rupture threshold Steel, it was concluded that the soil nail wall does not break. In the following, by examining the effect of tension cut-off on the behavior of the soil nail wall, it was found that the soil nail wall experiences an increase in displacement as well as an increase in the stress in the nails.

In most buildings, concrete and steel are used side by side, and according to the type of loads, various stresses are created at their interface. When the repair layer is in direct contact with the steel or reinforcement, the stresses caused by the shrinkage of the mortars as well as temperature changes have a negative effect on the adhesion between the repair mortar and the steel. According to the CEB-FIP MODEL CODE standard, the shear adhesion between mortar and simple reinforcement is equal to τ=0.3√(fc). But it has not provided conditions to consider the type of implementation. Considering that shrinkage causes shear stresses at the interface of mortar and steel, therefore, in this article, by using the in-situ twist-off test, the shear adhesion strength between mortar and plain steel has been evaluated under different processing conditions. The results of the twist-off test show that the above equation is used if the sample is under processing until the moment of the test, otherwise there will be a big drop in the amount of adhesion, which even reaches 50%. The results of the shear adhesion strength obtained from the twist-off test for the samples that were processed in water until the time of the test, at a young age are almost equal to the equation provided by the CEB-FIP Model Code standard. At older ages, the shear bond strength results from the twist-off test between mortar and steel are on average more than 10% higher than the equation provided by the CEB-FIP Model Code standard. For the samples that were processed for a week and then left in the open space, it is observed that there is a big difference between the shear adhesion strength obtained from the twist-off test and the equation provided by the CEB-FIP Model Code standard. For practical cases where processing is usually done for about seven days, it is suggested that the shear adhesion strength between steel and mortar is measured for samples that have been subjected to wet processing for at least one week and prepared and stored under appropriate conditions. According to the equation, τ=0.15√(fc) should be considered. The amount of 90-day shrinkage for mortar treated in water and left in open space is 0.1083 and 0.2679%, respectively. The amount of shrinkage for mortar processed in water is 59% less than the shrinkage of mortar left in the open space.

The advancement of technology with an increasing population has led to the requirement for high-speed mobility trains. High-speed transportation by trains requires passing through soft soil conditions, which requires stability. High-speed trains are used nowadays in developed countries to reduce travel time. When the train moves at a critical speed, it can significantly increase the dynamic responses of the components on the railway lines. The present study examines the results of 3D numerical modeling, considering the impact of the high-speed train passing through the mechanical earth wall stabilized by plate anchors. Numerical modeling was carried out using Plaxis 3D finite element software. The impact of various factors such as the speed of the train (180, 200 & 250 Km/h), the number of plates (single, double, and triple), and the number of train tracks (1 & 2 tracks) have been investigated. The Hardening soil with small strain model has been used for modeling the behavior of the backfill soil. In this study, the geometrical characteristics of the Thalys high-speed train were used to model the train passing through the walls of 6 meters that were stabilized with plate anchors. From the results, it was concluded that Increasing train speed from 160 to 250 Km/h increases the settlement under the rails by 11% and increases the horizontal displacement of the wall by 13%. It was confirmed that increasing train speed will result in an increase in the settlement under the rails and increases the horizontal displacement of the wall in all investigated cases. Increasing the number of plates along with decreasing their dimensions has a positive effect on the wall’s performance with regard to the horizontal displacement of the wall. Also, it should be mentioned that by increasing the number of train tracks from 1 to 2, the settlement under the rails increased by 5%, and the horizontal displacement of the wall increased by 20%.

Concrete quality control tests usually focus on the compressive strength of concrete, while neglecting other important properties such as impact and explosion resistance, which are essential for creating resilient concrete structures. Additionally, in the process of refining sugarcane, Bagasse, a yellow fiber that is considered a waste product, is produced. Khuzestan province alone produces around one million tons of Bagasse annually, which leads to environmental concerns. To address these issues, this research investigates the mechanical properties and impact resistance of concrete containing lightweight LECA aggregates and Bagasse fibers under compressive and impact loads. Initially, a target mix scheme is determined, and samples are made and tested after curing without the addition of Bagasse and LECA. Then, samples are made with the mentioned mixing design and the combination of Bagasse and LECA by weight ratio of (Bagasse unit, LECA unit). Additionally, samples using LECA (without Bagasse) with 10%, 20%, and 30% replacement of aggregates are made and tested after curing. Compressive and impact tests are performed on all samples in accordance with regulations using appropriate testing machines and procedures. Results indicate that concrete containing lightweight LECA and Bagasse fibers has a higher impact resistance than ordinary concrete, and that the use of LECA in concrete can create structural lightweight concrete.

Cement-based stabilization/solidification is a commonly used method to prevent the transportation of heavy metal ions in soils. The main objective of this paper is to investigate the controlling mechanisms in cement-based stabilization/solidification of Pb ion-contaminated bentonite under two different curing conditions: closed and open systems. In an open system, the stabilized/solidified sample continues to have access to free water, while in a closed system, the stabilized/solidified sample is prevented from accessing any external water after initial mixing. To achieve this objective, a series of geo-environmental experiments, including pH, solubility measurements, TCLP, and XRD, were performed. In the first step, the bentonite sample was contaminated with 100 cmol/kg-soil of lead nitrate. After achieving equilibrium, the contaminated sample was stabilized/solidified with 15% cement. The results indicate that when 15% cement is applied to the contaminated bentonite, the pH ranges from 10.5 to 11.5, which is a safe domain for lead precipitation. In other words, the minimum required percentage of cement for stabilization/solidification is the quantity in which the pH of the system is in the necessary range for heavy metal precipitation. This quantity is generally a function of the type and concentration of the heavy metal contaminant. According to the experimental results of this research, the method of curing does not have a noticeable impact on the stabilization process of stabilized/solidified contaminated bentonite. However, the XRD results show that more pozzolanic components have formed in the closed system. Therefore, the achievement of EPA criteria for TCLP experiments in cured samples in the closed system is attributed to the more significant progress in pozzolanic interaction and more formation of C-S-H and C-A-S-H components at 28 days for cured samples under closed conditions.

When a structure's fundamental period lengthens, often shear and floor acceleration increases. The contribution of higher modes in the dynamic response of structural systems with multiple degrees of freedom is significant in both the design of new structures and the evaluation of existing structures.Few research have looked at the impact of higher modes on base isolation systems in structures. To investigate the effects of higher modes on a building with a friction pendulum base isolation, a study was conducted on four different types of buildings: one with an L-shaped plan with two, four, and six floors; another eccentricities of buildings 5%, 10%, 15%, and 20%; and two others with a building with an L-shaped plan, where the second floor is half the mass of the first floor and next S shape plan. Eight layouts of the pendulum base isolation are considered for each building and their first mode, the second mode, and the mass participation rate of the first mode, the second mode, and higher modes are derived. Finally, in a linear time history analysis, the change in the maximum displacement of the base level is compared to the percentage of mass participation on the modes. The findings show that in four models, the percentage of first mode mass participation is decreased if the center of stiffness of the base isolation is aligned to the center of cumulative mass of the building, and the percentage of mass participation is increased in the second or third modes. The responses of the structure are thus determined by the second mode or higher modes. In general, the stiffness center of the base isolation must line up with the center of the base cumulative mass to produce the optimal design. And this pendulum base isolation layout’s displacement of the base level is also reduced.

Climate change and global warming pose significant threats to life on earth, leading governments worldwide to enact laws restricting carbon dioxide emissions. Traditionally, the use of Portland cement is a typical approach to increasing the bearing capacity, minimizing settlement, and improving seismic behavior of problematic soils. However, the cement industry's high energy consumption, uncontrollable emission of greenhouse gases, large carbon footprint, further depletion of natural resources, and high cost have become enormous challenges for all countries. Therefore, researchers continually seek new materials to replace ordinary Portland cement, contributing towards sustainable development. In this regard, the use of environmentally friendly, cheap, and readily available additives in modern soil methods of the construction cycle, particularly soil stabilization, is crucial. Geopolymer materials have recently emerged as serious alternatives to cement. This study aims to investigate the innovative reuse of eggshells through the geopolymerization process for engineering improvement of clayey soil. Alkali-activated binders are inorganic polymers that form repeated polymeric chains by polymerizing alumina and silica, sharing all oxygen atoms and using the alkaline cation. The combination of sodium hydroxide and sodium silicate was used as an alkaline activator in this study. The unconfined compressive strength (UCS) was the primary criterion for assessing the quality and effectiveness of the proposed solutions. This test was performed on selected combinations to assess the strength of the stabilized clay with different binder dosages and after different curing times. Moreover, the direct shear test was used to study the Mohr-Coulomb criteria parameters of the stabilized soil, namely the cohesion and angle of internal friction. Scanning Electron Microscope (SEM) microstructure observations of the natural and treated soil were conducted to investigate the strength development. The results showed that using 5, 7.5, 10, and 12.5% eggshell by dry weight activated by sodium hydroxide increases the UCS to 1.24 MPa, 1.21 MPa, 1.18 MPa, and 849 kPa, respectively, after 45 days of curing. The microstructural analysis results highlighted the reaction between the eggshell and the alkaline activator, resulting in the formation of an aluminosilicate gel.

Roller compacted concrete is a dry, hard concrete with zero slump, typically used in mass concrete structures where casting is done in stages with time intervals between each stage. However, the formation of joints in these concretes increases the penetration of destructive ions, leading to eventual failure and instability of mass concrete structures. This study aims to evaluate the impact of replacing part of cement with zeolite in reducing the destructive effects of joint formation in roller compacted concrete structural members. Samples were made with hot, warm, and cold joints, with zeolite replacing cement at percentages of 0, 15%, 30%, and 40%. Results showed that at 15% replacement percentage, samples had the highest compressive strength, so roller compacted concrete samples were made with 15% zeolite to test for Rapid Chloride Permeability Test (RCPT), water penetration depth, water absorption, ultrasonic pulse velocity (UPV), and electrical resistivity. The tests showed that replacing 15% of the cement weight with zeolite improves compressive strength in warm joint areas and reduces destructive effects of warm and cold joints on durability properties. The electrical resistivity test revealed that replacing 15% of cement with zeolite significantly reduces the permeability of specimens. Zeolite also reduces the permeability of roller compacted concrete specimens based on the results of water penetration depth, RCPT, and electrical resistivity tests, but increases water absorption and decreases UPV.

In this study, a new metallic damper, the Corrugated Honeycomb Damper (CHD), is presented. The CHD is designed for ease of manufacturing and implementation in various structures, with a stable energy dissipation characteristic when subjected to lateral loading. The basic configuration of the CHD consists of two steel plates that are bent to form trapezoidal corrugations. The plates are then welded together along the bent lines to build the honeycomb geometry. To investigate the behavior of the CHD, a closed-form expression for the elastic stiffness was first obtained using the matrix analysis method. A verified numerical model was then developed in ABAQUS software to study the non-linear behavior of the CHD, considering both material and geometric non-linearity as well as the potential for ductile steel damage. A comprehensive parametric study was performed, analyzing 12 CHDs with different geometric characteristics, and evaluating both monotonic and cyclic responses. Force-displacement and cumulative dissipated energy curves were extracted, and relevant elaborations were presented. Additionally, the equivalent stiffness and equivalent damping of the CHDs during cyclic loading were calculated, taking into account the principles of dynamics of structures. The results demonstrated that the CHD has stable and symmetric dissipative loops of energy, and that increasing the depth and thickness of the CHD can enhance its energy absorbing and load bearing capacities. Minimizing the width of the damper can fatten the hysteresis loops, but may also affect the ductility of the damper. Recommendations were given for the total height of the damper and the angle of bents to maintain stable hysteresis loops with respect to the target drift of the CHD.

The flexural performance of steel fiber reinforced concrete (SFRC) is significantly influenced by fiber properties such as fiber quality, shape, aspect ratio, orientation, and distribution. Digital image processing is an optical and non-contact measurement method that can determine the extent of sample size and deformation under any loading conditions. In this paper, eight reinforced concrete beams with and without steel fibers were selected, including four separate groups containing different volumetric percentages of steel fibers, designed and loaded with four-point bending test in accordance with the rules of ACI 318-19 design regulations. The first group consisted of two ordinary concrete beams as reference samples and six other concrete beams reinforced with steel fiber with a percentage of 0.5, 1.0, and 1.5%. Different longitudinal reinforcements (one state of minimum reinforcement and one state of maximum reinforcement in accordance with the provisions of the design regulations) were examined and analyzed in these specimens. Strain gauges were installed on the longitudinal bars to measure the strain during the loading process. Experimental results showed that the loads, flexural strength, ductility, and energy absorption of fiber-reinforced concrete beams were improved compared to similar conventional concrete beams. The highest ductility ratio among the samples made with tensile reinforcement was observed in the beam with a minimum longitudinal bar and 1.0% of fibers. The ductility of this sample was 30% higher than the similar non-fibrous sample with minimum longitudinal tensile reinforcement. The results showed that the ratio of ductility of the sample with maximum tensile reinforcement was decreased up to 46% compared to the companion beam with minimum tensile reinforcement. Significant increases in flexural strength, equal to 16, 23, and 29%, respectively, were observed in beams with minimum tensile reinforcement and containing steel fibers 0.5, 1.0, and 1.5%.

Building Information Modeling (BIM) plays a crucial role in managers' decision-making processes, as it has been proven to increase productivity, reduce costs, and improve the quality of construction projects. However, BIM implementation faces barriers in Iran and other parts of the world due to its novelty. This paper aims to analyze and identify these barriers in the Iranian AEC industry. A literature review identified 27 international barriers, which were categorized into four categories: Organizational/Cultural, Contractual, Legal, and Technical. Case studies of 28 private companies, including owners, consultants, and contractors, were conducted to identify 17 barriers to BIM implementation in Iran. Data was collected through document reviews, participation in meetings, semi-structured interviews, and direct observation, and then analyzed using N-Vivo. The barriers identified in the Iranian market had similarities and differences from those summarized in the literature review. Similar barriers included a lack of top management support, resistance to change, unwillingness to share data, lack of efficient workflows, lack of standard contractual frameworks, lack of interoperability of software, technical limitations in BIM software, lack of parametric objects library, and time and expenditure of model development. Seven new barriers were identified, including failure to complete tasks by other professional task groups, high salary expectations of BIM professionals, non-compliance with BIM Execution Plans (BEP), low value of incentives/penalties, difficulty in measuring work progress in BIM services, lack of efficient Common Data Environments (CDE), and internet connectivity issues. The identification and categorization of barriers is an essential step toward removing them and improving the implementation of BIM in projects.

Plasma is a subgroup of advanced oxidation technology (AOP) that has received considerable attention. It is currently being used to degrade persistent pollutants and inactivate organisms in environmental bodies. The objective of the present study is to decolorize tatrtrazine aqueous dye solution using cold atmospheric plasma technology. The main parameters selected for the study were initial dye concentration (4-20 mg/L), pH of the solution (2.2-9), input AC voltage (70-110), treatment time (10-30 minutes), and the electrode distance, which was kept at 8 mm throughout the experiment. The primary parameters investigated through the optimization tool of response surface methodology (RSM) software were color concentration, solution pH (2.2-9.4), power supply voltage (70-110 V), and detention time (10-30 minutes). The experimental reactor had a capacity of 15 ml. The color removal study of the plasma process showed that the optimal condition occurred at an initial concentration of 14 mg/L, voltage of 86 V, pH = 4.1, and plasma irradiation time of 18.7 minutes, resulting in a color removal percentage of 99.78%. According to half-life and efficiency yield calculations, the process was suitable for application in water pollution decontamination, with the lowest half-life achieved at the optimum condition (1.18) and the highest efficiency yield (108.3 mg/Kwh). The results extracted from the quadratic model illustrate the direct effect of retention time and initial voltage and the inverse effect of pH and initial concentration of industrial dye on the removal efficiency. The contact time had the major influence on efficiency via its coefficient in the model equation, while among interactive parameters, pH and contact time had the most interactive influence on the process. The reaction rate could also be described by the first-order kinetic model with an R2 value of over 95%.

This article proposes a new approach for identifying damage in structures through model updating. The approach is based on principal component analysis (PCA) of strain-based power spectral density (PSD) data. The proposed method detects damage, identifies damage location, and quantifies damage severity using an innovative sensitivity equation of strain-based data on a least square optimization. The data is obtained from incomplete measured structural responses, and the approach utilizes frequency domain data where changes in stiffness matrix of elements model damage. One of the crucial components for successful model updating is evaluating an accurate sensitivity relation. Highly sensitive structural indices such as PSD data require a valid sensitivity relation to yield satisfactory results. The PCA technique provides an advantage by transforming PSD data to PCs with the most significant changes and ignoring PCs that correspond to low changes caused by measurement errors. The presented approach embeds the PCA of incomplete PSD data and measured strain data for a damaged structure into a mathematical formulation to obtain an appropriate sensitivity equation. To prevent weakening the sensitivity equation, the proposed formulation does not employ derivatives of the PCs. The proposed method is applied to two steel structures, a 2-D truss and a 2-D two-story two-bay frame, to demonstrate its performance as a strong damage identification algorithm, even in the presence of measurement errors. Comparative observations indicate that the results obtained by the provided sensitivity equation and strain-based PSD data are more appropriate than the results of other strain-based methods such as PCA-FRF or using only PSD data.

Drought and moisture reduction can weaken and crack soil structure, altering its shear strength and permeability. This paper investigates changes in permeability of clayey sandy soil undergoing drying and wetting cycles, which are often overlooked during the design and construction of earth structures such as embankments and dams. To conduct the investigation, a sandy soil called Firoozkooh sand No. 161 and a kaolinite clay soil were selected and mixed in varying ratios to produce soil samples. Two mixtures of sand and clay were prepared with 20% and 30% clay and 80% and 70% sand by weight, respectively. The sand used was poorly graded and the clay was low plastic. Test samples were created using the maximum dry unit weight and optimum moisture content obtained from standard compaction tests. Permeability tests were then conducted on the prepared samples in both drying and wetting directions using a common triaxial apparatus. In addition, some Scanning Electron Microscope (SEM) images were taken of the soil combinations. Results from the permeability tests revealed that the drying and wetting process initially has a significant effect on the water entrance to the sample due to soil cracking, and the soil permeability reduces over time as water passes through the soil and is absorbed by clay minerals, closing voids and cracks. Eventually, the permeability of all samples, including those that underwent drying and wetting, reached a relatively constant value, and seepage became stable. Moreover, the samples that underwent the drying and wetting processes showed higher permeability than the initial samples prepared with optimum moisture content. The test results also indicated that completely dried samples do not necessarily have the highest permeability. Furthermore, SEM images revealed that samples with 20% clay content had more voids compared to those with 30% clay.