نشریه مهندسی عمران مدرس
سال بیست و سوم شماره 6 (بهمن و اسفند 1402)

Collapsible soil has a semi-stable, non-compacted, and relatively porous structure. These types of soils become damaged and experience noticeable deformation or sudden settlement due to increased moisture or excessive loading. This type of soils is categorized as problematic soils that, if they are placed under structures or inside the earth structures, can cause many problems in terms of stability and operation and cause financial and life losses. This paper attempted to evaluate and zone the collapsible soils in Semnan city. The studied points were examined using field experiments and also by consolidation test. Investigation of being problematic and the collapsibility of the collapsible points have been performed using the “Jennings and Knight” and “ASTM D5333” criteria. Collecting geotechnical data from 141 locations in Semnan city, 24 points with collapsibility potential were identified. The novel result of present study is an effective step to reduce the risks related to construction on the sites having collapsibility potential in the Semnan.

Training of professional drivers has been considered widely in the countries, greatly developed in traffic safety. Also in our country, tangible increasing in statistics of road and urban car accidents is observable which led the authorities to set professional courses for drivers. The main purpose of this project is ranking the courses and headings of training professional drivers. Required data were collected as questionnaire sheets, answered by 39 experts and 80 professional drivers about the loading and passenger transportation. At last five training courses (Professional driving skills, Vehicle specification, Occupational health, Road transportation rules and regulation, Criteria of handling and inhibition of different loads) and headings of each course, That is a total 24 headlines, were ranked by FAHP-FTOPSIS hybrid model. Results show that professional driving skills, public transportation criteria, professional health and safety, containment and carrying loads criterion and vehicle specifications were ranked from 1 to 5 respectively. In the course professional driving skills, roads help and rescue, principles of safe driving, defensive driving skills, driving in special conditions, per-travel measures and driving primary principles were ranked from 1 to 6 respectively. In the course of vehicle specification titles of new systems and technologies, repair and maintenance skills, material recognizing and details of settings and interior equipment were ranked from 1 to 4. In the course of professional health titles of sleepy and tired feelings effects, drug using effects, professional ethics drivers illness and healthy diet and traveling life skills were ranked from 1 to 5 respectively. In the course of transportation criteria titles of prohibited and violations, regulations criteria, acquaintance of different insurances and importance of them and documents were ranked from 1 to 4 respectively. In the course of containment and carrying loads which is particular for freight drivers, carrying dangerous loads, principles of different loads containment, tools of load containment, size and weight of different loads and connection and disjunction of trailers were ranked from 1 to 5 respectively.Training of professional drivers has been considered widely in the countries, greatly developed in traffic safety. Also in our country, tangible increasing in statistics of road and urban car accidents is observable which led the authorities to set professional courses for drivers. The main purpose of this project is ranking the courses and headings of training professional drivers. Required data were collected as questionnaire sheets, answered by 39 experts and 80 professional drivers about the loading and passenger transportation. At last five training courses (Professional driving skills, Vehicle specification, Occupational health, Road transportation rules and regulation, Criteria of handling and inhibition of different loads) and headings of each course, That is a total 24 headlines, were ranked by FAHP-FTOPSIS hybrid model. Results show that professional driving skills, public transportation criteria, professional health and safety, containment and carrying loads criterion and vehicle specifications were ranked from 1 to 5 respectively. In the course professional driving skills, roads help and rescue, principles of safe driving, defensive driving skills, driving in special conditions, per-travel measures and driving primary principles were ranked from 1 to 6 respectively. In the course of vehicle specification titles of new systems and technologies, repair and maintenance skills, material recognizing and details of settings and interior equipment were ranked from 1 to 4. In the course of professional health titles of sleepy and tired feelings effects, drug using effects, professional ethics drivers illness and healthy diet and traveling life skills were ranked from 1 to 5 respectively. In the course of transportation criteria titles of prohibited and violations, regulations criteria, acquaintance of different insurances and importance of them and documents were ranked from 1 to 4 respectively. In the course of containment and carrying loads which is particular for freight drivers, carrying dangerous loads, principles of different loads containment, tools of load containment, size and weight of different loads and connection and disjunction of trailers were ranked from 1 to 5 respectively.

Calculating the failure probability of structural problems with linear boundary condition functions is usually done at a low level and by first-order methods due to simple concepts and the need for few calculations. These methods are only suitable for providing an estimate of the probability of structural failure, and especially when the function expressing the performance of the structure is linear, they are accurate in providing the final answer. But when the limit function is nonlinear, due to inherent problems in this method, they are unable to accurately estimate the safety level of the structure. For such problems, it is necessary to use accurate methods of estimating the probability of failure, such as simulation methods. The use of concepts in the first and second order methods of reliability along with the use of an optimization algorithm will reduce the volume of calculations, but this factor causes assumptions and simplifications, derivation of functions and estimating the sensitivity of failure probability is also a part of the structure design process. It can be proven that for many design problems with nonlinear boundary condition function, the answer provided by these methods will not satisfy the probabilistic constraints of the problem, or the answer provided is not the most economical design option. Also, many existing methods in this group are unable to provide answers for problems with low failure probability, especially when the variables of the problem have non-normal density functions. Therefore, the present study has investigated the performance of these methods in dealing with various structural problems, and the strengths and weaknesses of each method are discussed. Three different issues have been studied in this research with seven analytical and simulation method, to achieve this goal. The first problem is to verify the results. In this case, the failure probability of a reinforced concrete beam was calculated by the Monte Carlo Simulation (MCS) and compared with the results obtained from the precise gradient method used in previous studies. The results of this problem showed a 0.5% error in the results, indicating the accuracy of the responses. The existence of very small differences between the results obtained from Monte Carlo and the results of previous researchers in estimating the integral of failure probability related to the discussed problems, indicates the high accuracy of the Monte Carlo method, and it is possible to use the results obtained from Monte Carlo as a suitable criterion in the analysis of these problems. used to compare the results. Also, analysis of two problems including three-span steel beam, two-degree-of-freedom seismic system using seven methods including MCS, SS, IS, LS, WSM, FORM and SORM were also put on the agenda. The results indicate that SS has high accuracy in solving nonlinear and complex problems. WSM has shown a significant decrease in the number of function calls. The LS method has a great performance in calculating the reliability of problems with a low failure probability. Therefore, in general, it can be stated that the first-order method (FORM) is the simplest safety estimation method (with low accuracy for non-linear functions) and simulation methods are the most accurate methods (with conceptual complexity or high calculations).

Today, the use of self-healing concretes has attracted the attention of various researchers. In this paper, the effect of Bacillus subtilis bacteria with different concentrations were used for evaluation on concrete containing zeolite.The mentioned bacteria were produced in the laboratory and added to the concrete mixing plan. In order to evaluate the effect of Bacillus subtilis bacteria on specimen with zeolite, resistance and durability tests including compressive strength, ultrasonic, water penetration test and water absorption tests were performed on the specimen at different ages. Also, using scanning electron microscope (SEM) and optical microscope, the self-healing of concrete was evaluated. The results of the compressive strength test showed that the specimen containing zeolite with a concentration of 2.8×108 cells/ml increased the compressive strength by 16.76% and the specimen without zeolite increased the compressive strength by 13.51%. Also, the presence of Bacillus subtilis bacteria in the mixing design led to a 15% decrease in water absorption of specimens without zeolite and 30% of specimens with zeolite. Based on the results of the experiments, the most suitable concentration, for the simultaneous improvement of the resistance parameters and durability among the different concentrations of Bacillus subtilis bacteria, is suggested to be 2.8 x 108.

The presence of heavy metal contaminants in clays causes changes in soil properties, which increases the risk of contaminant transport into the clay layer. Various techniques have been developed recently to remediate contaminated soil. These methods include electrokinetics, biological treatment, and immobilization. Among them, cement-based stabilization/solidification technique is very common. Generally, cement-based systems are frequently used because of their affordability and great durability. This method uses the two mechanisms of chemical stabilization and physical solidification to retain heavy metals and decrease the mobility of contaminants. Even though several researches have been performed to address the different aspects of cement-based solidification/stabilization, there has been a lack of research on the stabilization/solidification of heavy metals in the presence of two different heavy metal ions. Therefore, the objective of this study is to determine to what extent the pH variations affect lead and cadmium retention and release in single and double-component cement-based stabilization/solidification systems. To accomplish the aforementioned objective, first, the retention capacity of lead and cadmium, in cement-based S/S of contaminated bentonite in single and double-component heavy metal systems is investigated. The effect of pH on the stabilization/solidification process was determined by conducting a series of XRD tests in order to investigate and differentiate the stabilization and solidification mechanisms. In the next step, the amount of released cadmium and lead ions during the TCLP test was determined in single and double-component systems in order to investigate the effect of pH and the simultaneous presence of lead and cadmium in the release of these heavy metals. According to the achieved results, the maximum retention capacities of lead and cadmium occur in the pH ranges of 8.5 to 11 and 10 to 12, respectively. Furthermore, retention in the double-component system is always lower than that of the single-component system, assuming a similar initial concentration. In addition, XRD results illustrate that the intensity of the peaks of cadmium and lead chemical compounds has increased for the samples their pHs take place in the safe zones. This indicates an increase in the contribution of the stabilization mechanism. According to the results of this paper, at a similar contaminant concentration, the intensity of the C-S-H peak increases with an increase in cement percentages. This indicates progress in the contribution of the solidification mechanism in the retention of heavy metals. Still, the release of these heavy metals is always lower than the maximum allowable value reported by the US EPA in the above-mentioned pH ranges. Moreover, the results of this research show that the amount of released cadmium and lead in the double-component system is more than that of the single-component system, assuming similar initial concentrations. Based on the definition of the safe zone, in the defined pH range, the contaminant is retained during the TCLP test mainly by chemical stabilization (precipitation). In fact, in the above range, an increase in the amount of cement has not shown a significant effect on the amount of heavy metal desorption. This finding is supported by the results of retention tests.

Damage to the structure during operation has always been possible, and therefore the issue of monitoring the health of important structures in order to control and manage safe operation has received attention in recent years. The process of extracting the parameters involved in identification the inherent characteristics of the target structural systems in order to monitor and detect damages is possible with different methods which have been introduced and investigated under the title of environmental modal analysis, which have been developed both in the time domain and in the frequency domain. Among the time domain methods, we can mention the stochastic subspace identification (SSI) method. The stochastic subspace identification method is one of the Output Only Modal Analysis (OOMA) methods that has been taken into consideration assuming the existence of uncertainty in modeling as well as noise in data observation and measurement, and system parameters are identification by applying statistical relationships to the output data. Due to the high accuracy of the covariance-drived stochastic subspace (SSI-cov) method which performs data monitoring by constructing the covariance function related to the recorded output data, therefore this sub-method has been used. Due to the limitation in the number of sensors that can be installed in real structures, the use of the Reference-based covariance-drived stochastic subspace identification (SSI-cov-ref) method will make it possible to identification the structure under investigation with a limited number of sensors and if there is damage, Its location can be recognized. The efficiency of the reference-based covariance-drived stochastic subspace identification method with a more limited number of sensors can also be presented. In order to damage detecting in the structure, the method of measuring changes in the modal strain energy of the members in healthy and damaged states has been used, and an index called modal strain energy has been defined and presented But in the case of damage in the structure, the undamaged members will also have strain energy due to the strain effect of the damaged members. Therefore, by using the probabilities approach, it will be possible to provide an index of the probability of structural member damage under a specific failure scenario using different information sources based on the mode shapes. In the following, using the genetic algorithm in the form of an optimization problem, the installation location for the available sensors for the target structure is optimized and presented. During the current research, after finite element modeling in MATLAB software and dynamic analysis of several samples of structure with the assumption of installing a limited number of sensors ,and the results obtained from the output of the reference-based covariance-drived stochastic subspace identification method using the changes in the modal strain energy of the members And the Bayesian strategy has been used in the damage detection in the affected members, and the efficiency of the proposed method has been discussed in the framework of the mentioned process. Based on the results obtained from the output of the proposed process, the affected members will be identified and distinguishable.
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Nowadays, the environmental pollutions caused by the increase in population and the development of industries threaten the health of the inhabitants of the planet. The most important pollutants of water and soil resources are heavy metals that lead and zinc are the most abundant elements among them. The presence of large amounts of heavy metals in the soil causes groundwater pollution and eventually the occurrence of many dangerous diseases including cancer, digestive disorders, kidney diseases, mental retardation and blood and brain diseases. The movement of water in the surface and underground streams is one of the main causes of the release of heavy metals in the soil which causes transfer of pollutions from the contaminated soil to the surroundings and entrance of these harmful metals into the human diet. The main purpose of this study was to evaluate the selective absorption of lead and zinc by Kaolinite clay in single and binary-component systems. For this purpose, the Kaolinite clay was firstly mixed with the lead and zinc in distilled water at ratio of 1:20 to prepare model contaminated suspensions. Three specimens were prepared for each sample according to the EPA (1983) and EPA (2010) methods. The effect of different pH (i.e. 2 to 12) and pollutants concentrations (i.e. at concentration of 20 Cmol kg-1) on the adsorption capacity of Kaolinite was measured using spectrophotometer. It was found that by decreasing in pH to 2 in both single and binary component pollutant systems (at concentration of 20 Cmol kg-1), the adsorption percent decreased significantly. However, the adsorption of lead in pore fluid was higher than zinc in alkaline and acidic conditions for both binary and single-component systems. The adsorption percent of Pb2+ was not changed in both systems, however, adsorption of Zn2+ was significantly reduced in the binary system-component compared to the single system-component. In addition, the adsorption percent of Zn2+ in alkaline (pH=12) and acidic (pH=2) conditions decreased by about 50 and 20% in the binary system-component compared to the single system-component, respectively. Furthermore, the findings indicated that Langmuir isotherm had the highest consistency in the single and binary-component systems for lead and zinc contaminations at the studied concentration. The results of absorption kinetics in both systems illustrated that the lead absorption rate was decreased 0.15% in binary-component system compared to the single-component system at concentration of 20 Cmol kg-1. In contrary, the zinc absorption rate in the combination system was reduced 87.5% at this concentration. On the other hand, the adsorption kinetics of lead metal at the test concentration for kaolinite clay in both systems had the same constant as the pseudo-first and second order equations because in both systems the amount of lead adsorption did not change. Instead, the rate of adsorption on zinc had a significant change in the binary system compared to the single state. the resulting values were more consistent with the pseudo- second order equation. In general, the ion adsorption of Pb2+under all environmental conditions in the pore fluid was more than Zn2+ in both systems due to the lower value of the first hydrolysis constant (pk1) of lead compared to zinc (i.e. Pb(7.8) > Zn(9.0)). By comparing the values of k1 and k2 in the concentration of pollution in the experiment, it was found that k1 of lead and zinc metals for a concentration of 20 Cmol kg-1 was higher than k2  and this represented the higher reaction rate to the Kaolinite clay for lead compared to zinc.

Fire and explosion are often synergistic. A fire may occur after an explosion or a fire may occur first and then an explosion occurs. The consequences of a combined fire and explosion scenario about each component must be considered in the design or evaluation of the structure. The analysis of fire and explosion should be done together and the effects of one on the other should be carefully analyzed. In most researches and design guidelines, fire and explosion phenomena are investigated independently and their interaction is less considered. In this research, this issue is addressed and the fire after the explosion and the interaction and synergy of these two phenomena are studied together. The studied structure is a two-story steel structure with different occupancy (dwelling, office, etc.). which is subject to various explosions and as a result fire caused by the equipment inside the building. Explosive loading has been calculated using UFC 3-340-02 instruction charts and fire load using the concept of fire density and relationships of EUROCODE 1 and EUROCODE 3 regulations. In order to simulate explosive and thermal loading, Abaqus finite element software and combined thermal-deformation dynamic analysis have been used. The temperature caused by the fire has been used as a natural fire, and the cooling and post-cooling stages of the fire have also been investigated. After validating the proposed simulation with two valid laboratory works, the analysis of the structure's response against various types of explosive loads and subsequent fires was performed by a numerical model. The results of these investigations showed that the response and deformation of the structure in the chain combined analysis (applying the interaction of explosion and fire on the structure) compared to the independent combined analysis (independent analysis of the structure against explosion and fire and collecting the responses together) It increases by 15%, and considering the interaction of explosion and fire is not only important but also necessary, and not considering this interaction in most cases will cause the response of the structure to be less than the reality, and as a result, it will cause an unsafe design.

Today, one of the important issues in the industry is the failure of parts due to the presence of holes or cracks. Among the numerical calculation tools, the classical and extended finite element method is known as the most useful numerical tools in solving engineering science problems. Identifying and investigating the types of cracks, flaws and cavities in structures is one of the most challenging issues in the field of engineering. In this article, the crack detection of two-dimensional (2D) structures using the extended finite element method (XFEM) along with genetic algorithm(GA) and grey wolf optimization method (GWO) to detect the existing crack and flaws by minimizing an error function which is also called as objective function that the evaluation of it, is based on difference between sensor measurements and suggested structure responses in each try of the algorithm.  Damage detecting in 2D domains, as a non-destructive evaluation problem, is investigated using the extended finite element method along with the optimization method of genetic algorithm and grey wolf. The extended finite element method has been used to model the structure containing cracks and holes in the abaqus program, and genetic optimization and grey wolf method have been used to determine the location of the damage in which the codes were in matlab program. The extended finite element method is a powerful tool for the analysis of structures containing cracks without remeshing and is therefore suitable for an iterative process in structural analysis. Also, in these problems, due to the wide range of parameters, it is not logical and rational to use mathematical methods. For this reason, meta heuristic methods have been developed, and grey wolf optimization methods and genetic algorithm are among these common non-gradient methods that are suitable for solving the inverse problem. This problem is set so that the optimizer algorithm finds the existing crack coordinates or holes coordinates by minimizing an objective function based on the values measured by the sensors installed on the structure. Among the limitations of the classical finite element method in the investigation of various problems in the field of fault and crack detection, we can point out the dependence of the crack or cavity on the finite element mesh, re-meshing and in other special cases the use of singular elements, which are completely removed by using The extended finite element. In this research, in order to identify the damage, the genetic optimization algorithm and the gray wolf have been used. These algorithms are designed in such a way to determine the characteristics of the damage by minimizing an error function. The defined error function is defined as the difference between the response obtained from the algorithm analysis and the response recorded in the main structure modeled in ABAQUS software, at the location of the sensors. Finally, three reference numerical examples have been solved to evaluate the capability and accuracy of the proposed method, and the result of the results shows a reduction in the cost of solving and an increase in the accuracy of the results.

Vortex drops are compact hydraulic structures used in surface water and sewer collection systems to convey runoff from higher to lower elevations by creating a rotational flow inside vertical shafts. These structures are composed of three main parts: the intake, drop shaft, and dissipation chamber. Tangential intake is a steep tapering channel that generally has a junction with a rectangular approach channel with the horizontal bottom at the beginning and a narrow slot at the connection with the drop shaft. Many factors need to consider in the design of vortex drop shafts with proper hydraulic performance. The review of previous studies and the guideline designs for this structure indicates that most design relations were obtained either based on simplified assumptions or by conducting limited tests on laboratory scale models, which can cause desirable operation in practice. These conditions have forced engineers to set up laboratory models or numerical simulations of the initial design to evaluate the proper performance of the structure in big projects. With this introduction, one of the problems in the surface water collection network of Tehran is conveying high volumes of runoff from the surface of streets at the highway intersections to a lower level in the underground tunnels or pipes. Therefore the authorities pay more attention to necessary considerations in the design and use of these types of structures for the safe transfer of runoff downstream. In this paper, using numerical modeling, the hydrodynamics of flow in a real vortex drop shaft with tangential intake has been studied. In the design stage, a vortex drop structure in Tehran's urban drainage has been selected and evaluated by the Flow-3D numerical model. Based on the latest available design methods, Several tangential intakes with different geometry were assessed separately. Finally, the performance of the final drop shaft was simulated and analyzed using the numerical model. The final design simulation results showed that the flow in the tangential intake would enter the vertical shaft without forming a hydraulic jump. The flow in the vertical shaft is spirally attached to the wall with a central air core. A key design parameter is the ratio of the air core area to the drop shaft cross-sectional area that was greater than 0.49. The efficiency of energy losses at the tangential intake is about (9-15%), in the vertical shaft is about (23-40%), and in the energy dissipating chamber is (70-71%) depending on the flow rate. The energy loss efficiency in the whole structure was about (80-84%). The depth size needed to create a water cushion in the energy dissipation chamber was considered for three depths of 0.4D, 0.5D, and 0.6D. After numerical modeling, the appropriate depth for the water cushion was determined to be 0.6D. The results of the simulations indicated that the use of existing design methods only sometimes leads to optimal hydraulic performance in the structure. Therefore, reviewing the existing design methods, simulating the flow in the designed drop shaft, or setting up a laboratory model before finalizing the design is necessary.

Due to the mechanical behavior of brb braces and concrete frames differing, combining these shows complex behavior in a seismic. It can be used to dual system Brb-Rcf in a concrete moment frame to Improve structural responses. Considering that the behavior of the BRB brace in compression and tension is similar; It can solve the unbalanced force in the Double-K bracing system. The desirability of the Double-K arrangement and its combination with the RCF system as a dual system should be investigated in order to investigate the possibility of using Double-K braces in the RCF system and reducing residual deformations in the case of the dual system. For this purpose, a series of buildings have been analyzed and designed in three structural systems: Rcf, dual frame with brb brace, and bare frame with brb brace according to relevant valid regulations. The pushover and time history analysis have been done, and the capacity curves, base shear, and residual deformation have been investigated and studied. Adding brb braces to the concrete moment frame and dually using them increased the structure's capacity. In the studied structures, from 84% increase capacity in 4-story structure to 94% increase capacity in 12-story structure. This increase is due to the interaction of the concrete moment frame and the brb braces in a dual system. Also, the use of brb braces has made the structure repairable. Because in the concrete structure of the moment frame and the bare frame, the failures were concentrated in the beams and a little in the columns, respectively, but in the structure with Brb-Rcf, the losses were mainly transferred to the braces, which are easily replaceable. Also, the reduction of residual deformation of the structure reduces causes the cost of repair and reconstruction in the structure. Investigations on the formation of hinge showed Due to the Double-K brace that no hinge was formed in the middle of the columns. the losses were mainly transferred to the braces, which are easily replaceable. Also, the reduction of residual deformation of the structure reduces causes the cost of repair and reconstruction in the structure. It was also observed that the structure in combination with the brace in the Brb-Rcf system is designed more economically and with fewer consumables. It is shown in the structure of 8, 4 & 12 story; that the base shear has increased in the frames with brb braces and this increase has been greater in the dual system due to the bending frame and the brb braces. Also, in the hinge, it was observed that the failures of the double structure were less and the types of failures were better according to the replaceability. In general, due to less failure and more base shear that the dual system  structure has, it can be said that the stiffness and resistance due to the interaction of the bending frame and the non-buckling brace has increased, which is the result of the good performance of the dual structure. By comparing the base shear, the suitability of these values ​​with the bearing analysis is clear, so that there also the results showed the increase of the base shear due to the interaction of the frame and the non-buckling brace.

Regarding the high cost of retrofitting and replacing the isolation system after an earthquake, re-centering seismic isolation systems have become one of the most popular research fields in the past decades. A new generation of seismic isolation is based on equipment with improved performance in terms of damping and re-centering capability. Since lead-rubber base isolation (LRB) is one of the most common seismic isolation systems, this paper focused on suggesting a re-centering LRB system with high damping capacity. The LRB isolation is based on an experimental study under a constant vertical load equal to 650 kN. The proposed combined system of LRB and friction yields a high damping capacity. A spherical shell is placed on the base isolation system, and the friction reaction emanates from this shell's sliding on the provided foundation. The primary purpose of this spherical shell is to increase the damping capacity of the isolation system. An adjustable friction reaction is reachable depending on the connection details of the spherical steel shell with the system's upper steel cap plate. The higher stiffness of this connection is provided greater friction force and, as a result, higher damping capacity. In short, this connection was performed as adjustable friction and can increase energy dissipation and maximum shear force, respectively, in the range of 12% to 80% and 6% to 230%. Increasing re-centering capacity is another goal of this study. It is of great interest to implement shape memory alloy (SMA) in the form of wires because of their re-centering capabilities. The axisymmetric design is implemented to reduce this hybrid system's vulnerability to earthquakes of arbitrary direction. The combined action of wires and the spherical steel shell provides the re-centering capacity of the system.The final system, which is a combination of LRB, friction mechanism, and vertical load transfer through SMA wires (MDLRB-SMA), exhibits enhanced properties such as reduced residual deformation, controllable shear reaction at each stage of the deformation, and increased damping capacity. The energy dissipation capacity of the MDLRB-SMA is shown to be increased by 50%, with a decreased residual deformation of up to 45% compared to the LRB. A set of parametric studies are also performed to investigate the influence of frequency, displacement amplitude, loading rate, the wires' configuration and properties, and the aspect ratio of the system's performance.