https://sjce.journals.sharif.edu/ Sharif Journal of Civil Engineering en daily 1 Fri, 20 Mar 2026 00:00:00 +0330 Fri, 20 Mar 2026 00:00:00 +0330 https://sjce.journals.sharif.edu/article_24231.html - https://sjce.journals.sharif.edu/article_24123.html There are numerous uncertainties in determining the rotation capacity and overstrength factor of shear links, which have raised concerns among structural designers regarding the design provisions in the AISC 341 code for accurately characterizing the behavior of shear links in eccentrically braced frames. Researchers attribute these past ambiguities to the failure mode of the links, as the maximum force developed in the link is proportional to the rotation capacity and, consequently, its failure mechanism. To address some of these previous uncertainties, this study examined the failure mode of short and very short shear links made from ASTM A992 steel. For this purpose, a parametric study was conducted using the finite element software ABAQUS, considering the effects of local buckling, cumulative damage under cyclic loading, and the influence of crack initiation and propagation on the reduction of strength and stiffness. According to the results, the code provisions lead to conservative outcomes (by more than 40%) for the rotation capacity of shear links, especially very short shear links. Thus, one of the main reasons for the occurrence of a large overstrength factor in shear links is their rotation capacity exceeding 0.08, which leads to strain hardening in the steel material and the development of forces greater than the plastic shear strength of the section. Furthermore, examining the failure mode of the links showed that, with an increase in web slenderness, the location of damage initiation and tearing shifts away from the stiffener-to-web connection and moves towards the center of the web panel. Additionally, in short shear links, particularly in models with smaller link length ratios, failure typically begins with vertical cracks near the stiffener and then propagates at the end of the stiffener into the link web. However, in very short shear links with smaller length ratios, web tearing occurs at the intersection of the flange and web.  https://sjce.journals.sharif.edu/article_24122.html In designing structures subjected to seismic forces, selecting an appropriate system based on seismic performance and building height is essential. Special Truss Moment Frames (STMF) are an innovative structural system designed to provide adequate lateral stiffness and control deformations. This system, combining steel trusses and columns instead of traditional beams, is highly efficient in absorbing lateral seismic forces, making it suitable for tall buildings and large spans. This study investigates the influence of the number of stories and the number of Vierendeel special segment panels in the STMF system on its seismic performance parameters. The analyzed models include nine cases with two, five, and eight stories, each designed with one, two, and three special segment panels. These models were developed in the ETABS software for preliminary design, while nonlinear analyses, including pushover and time history, were conducted in OpenSees. The pushover analysis was performed following FEMA P695 guidelines, and the nonlinear dynamic time history analysis was conducted based on ASCE 7 standards with 11 pairs of far-field ground motion records. The results highlight the high ductility of the STMF system, which increases with the number of stories and special segment panels, along with average over-strength factors of 2.5, which are close to the ASCE 7 recommended value of 3. The average transient story drift remained below 2%, while the average residual drift was approximately 0.15%, both within the permissible limits outlined in the code. Moreover, the models exhibit desirable seismic performance without any indications of non-compliance under severe seismic demands. In terms of design, increasing the number of panels in the special segment reduces the amount of structural steel required. This occurs because longer special segments result in lower expected shear forces, leading to smaller cross-sections for members outside the special segment. Conversely, models with shorter special segments demonstrate higher lateral stiffness and greater base shear capacities. Overall, this research confirms that the STMF system with Vierendeel special segments offers excellent seismic performance and can serve as a suitable and cost-effective option for designing structures with large spans. https://sjce.journals.sharif.edu/article_24114.html Damage detection methods are integral components of structural health monitoring systems. Identifying damage in structures using vibration-based methods has always been one of the most important and popular topics among researchers in structural health monitoring. Vibration-based damage identification includes extracting a feature that can be used to measure the minuscule changes caused by damage to the structure. In recent years, advances have been made in using chaotic excitation and representing damage-sensitive features based on the properties of the chaotic attractor. These types of damage-sensitive features try to measure the minuscule changes caused by structural damage by comparing the chaotic attractors obtained from the structural response. The high sensitivity of chaotic systems to small changes makes attractor-based features suitable for identifying structural damage. One of the most widely used attractor-based features is the Generalized Interdependence, which has a reasonable sensitivity to damage and relatively low computational complexity. Also, the comparative nature of this feature can help identify damage in the presence of environmental variables such as noise. However, this feature has limitations that make its use exclusive to particular instances. e.g., in structures where the exact location of the damage is known beforehand. In the damage identification method presented in this research, improvements like adding a damage sensitivity factor and applying controls over the operation have been made to this feature to remove these limitations while preserving its exceptional properties in detecting damage in structures. In the structure examined in this research, where the generalized interdependence feature does not show the slightest decrease in dependence due to damage, the improved feature detects damage by showing about 20% better performance in finding a reduction in the dependence between two points of the structure. Two points of the structure are selected to be located at different distances from the damage. In other words, the improved feature can measure the different impacts due to damage on these two points.  https://sjce.journals.sharif.edu/article_24118.html One of the most vulnerable parts of a building during an earthquake, which can severely impact its functionality, is the non-structural walls or separating masonry walls. The 2016 Kermanshah earthquake highlighted that in some newly constructed buildings, while the primary structural elements, such as columns and beams remained intact, non-structural components, specifically walls, suffered significant damage, creating hazardous living conditions. These damages not only pose serious safety risks to occupants but also lead to substantial repair and reconstruction costs. Following the earthquake, modifications were made to building bylaws to enhance the reinforcement of non-structural elements, such as separating walls, aiming to improve overall structural stability. However, these regulations primarily apply to newly constructed buildings, and a large number of older structures, built before the implementation of these bylaws, still lack sufficient resistance in their non-structural elements, particularly walls. Thus, the need for strengthening these walls is evident, and the application of polyurea coating is one viable solution. In this research, the effectiveness of polyurea coating in enhancing wall resistance was evaluated through four four-point bending tests conducted on four different masonry walls with various forms of cold-applied polyurea coating. The experimental results demonstrated that walls coated with polyurea exhibited significantly higher load-bearing capacity compared to uncoated walls. Furthermore, displacement at the midpoint of the coated walls was considerably lower than in uncoated samples, confirming the effectiveness of polyurea in strengthening masonry structures. Specifically, walls treated with full polyurea coating and cross-framed polyurea coating showed a 45% and 39% increase in bearing capacity, respectively, compared to uncoated walls. Additionally, displacement in these coated walls decreased by 50%. Considering the optimal balance between structural resilience and cost-effectiveness, the application of polyurea coating in the form of a cross-frame or full coating is highly recommended to improve the resistance of masonry walls against out-of-plane loads, such as earthquakes and explosions. This method not only enhances the overall safety of buildings but also significantly mitigates damage risks during seismic events.  https://sjce.journals.sharif.edu/article_24121.html Ultra-Thin Bonded Wearing Course (UTBWC) is utilized as a preventive maintenance option to extend pavement life by postponing the need for rehabilitation or reconstruction operations. UTBWC usually consists of a thin open-graded asphalt mixture over a polymer-modified emulsion membrane, which is applied by special pavers. Regarding the open-graded structure and rough texture of UTBWC, their winter maintenance differs from conventional pavements, leading to some challenges in the maintenance process. In this regard, this study aims to investigate the winter maintenance of UTBWC overlays through a comprehensive literature review, case study evaluation of a UTBWC section in Minnesota (performance and economic assessments), and field survey on the experiences with the UTBWC winter maintenance from Department of Transportation (DOT) specialists of some US states that are located in cold regions. The results showed that the winter maintenance of UTBWC sections, due to their porous structure and open-graded aggregate texture, which promotes greater accumulation of snow and ice, requires more deicing materials and more frequent snow plowing, which results in higher winter maintenance costs. Also, to avoid the accumulation of blown snow on the UTBWC surface, it is recommended to avoid the use of UTBWC in rural windy environments where the roadway runs in a direction perpendicular to the common wind direction. Economic assessment of the UTBWC section shows that the winter maintenance of UTBWC was more costly than the conventional mixtures and overlays. On the other hand, the results of the case study showed that the performance of UTBWC, in terms of Ride Quality Index (RQI), was better than the conventional Hot Mix Asphalt (HMA) overlay, which can reduce the overall maintenance cost and make UTBWC an economical preventive maintenance option. Therefore, decision-making regarding the management and maintenance of these overlays can be facilitated by considering a multifaceted approach, including technical, economic, and environmental performance. Also, a better understanding of the behavior of UTBWC and its maintenance methods can help to make more effective and better decisions for the implementation of this type of wearing course in the cold regions. https://sjce.journals.sharif.edu/article_24147.html In designing structures subjected to seismic forces, selecting an appropriate system based on seismic performance and building height is essential. Special Truss Moment Frames (STMF) are an innovative structural system designed to provide adequate lateral stiffness and control deformations. This system, combining steel trusses and columns instead of traditional beams, is highly efficient in absorbing lateral seismic forces, making it suitable for tall buildings and large spans. This study investigates the influence of the number of stories and the number of Vierendeel special segment panels in the STMF system on its seismic performance parameters. The analyzed models include nine cases with two, five, and eight stories, each designed with one, two, and three special segment panels. These models were developed in the ETABS software for preliminary design, while nonlinear analyses, including pushover and time history, were conducted in OpenSees. The pushover analysis was performed following FEMA P695 guidelines, and the nonlinear dynamic time history analysis was conducted based on ASCE 7 standards with 11 pairs of far-field ground motion records. The results highlight the high ductility of the STMF system, which increases with the number of stories and special segment panels, along with average over-strength factors of 2.5, which are close to the ASCE 7 recommended value of 3. The average transient story drift remained below 2%, while the average residual drift was approximately 0.15%, both within the permissible limits outlined in the code. Moreover, the models exhibit desirable seismic performance without any indications of non-compliance under severe seismic demands. In terms of design, increasing the number of panels in the special segment reduces the amount of structural steel required. This occurs because longer special segments result in lower expected shear forces, leading to smaller cross-sections for members outside the special segment. Conversely, models with shorter special segments demonstrate higher lateral stiffness and greater base shear capacities. Overall, this research confirms that the STMF system with Vierendeel special segments offers excellent seismic performance and can serve as a suitable and cost-effective option for designing structures with large spans. https://sjce.journals.sharif.edu/article_24146.html Large dams are structures considered national assets, and any incident involving them can be catastrophic in terms of loss of life, property, and social impact. Most large concrete dams have been gradually constructed over the past century. Many of these dams were built without sufficient understanding of the foundation and abutment conditions, without a proper grasp of load processes and probable environmental conditions in their design, or with incorrect assumptions about the behavior of materials and structural systems. Given that the weakness of unreinforced concrete used in the main body of dams under tensile and shear conditions leads to sudden and brittle cracks of large dimensions, a combination of various incidents can create a concerning scenario, either gradually or abruptly, posing a serious threat to the safety of the dam and reservoir system. Even modern knowledge and technology cannot entirely rule out the possibility of errors or unintended uncertainties in the behavior of these strategic structures. As a result, risk management practices, including the study of past events and minor and major incidents, have become crucial in the evaluation and assessment of large dam systems. Through systematic or case studies on the behavior and service life processes of these systems, there is hope for a deeper understanding of the dam-reservoir-foundation system's behavior, thereby enabling the prevention of similar incidents in the future. The objective of this study is to investigate the most significant historical damages sustained by large concrete dams and analyze the factors contributing to each incident and its various dimensions. In most cases of dam failure, it is impossible to attribute the damage to a single factor. Typically, major damage or failure in a concrete dam results from a combination of factors that interact with one another or form a chain of events leading to the primary failure. Overall, based on past incidents and research, it becomes clear that although factors such as overall foundation weakness, unforeseen mechanisms resulting from geological or geotechnical deficiencies within the foundation and abutment, issues arising from complex thermal loads, seepage, and unforeseen earthquake characteristics are recognized as the most common causes of severe incidents, in most cases, it is human error—stemming from a lack of sufficient knowledge about the system, ignorance of available knowledge, or non-technical managerial decisions—that enables these physical factors to take effect. Such errors during the design, construction, and operation phases provide the opportunity for the above-mentioned physical factors to exert their influence. Finally, it should be noted that most major incidents occur during the early years of the dam’s life, particularly during the initial reservoir filling, underscoring the absolute necessity of a gradual, step-by-step approach and the strict enforcement of monitoring regulations during this critical period.  https://sjce.journals.sharif.edu/article_24115.html Due to its complex and multifaceted nature, the construction industry has always faced many safety challenges. Safety management is critical in countries like Iran, which face limitations regarding training, equipment, and regulations. This article aims to provide a comprehensive review of safety management in the construction industry and provide new approaches to improve it. For this purpose, first, the existing literature in the field of safety management in construction projects is reviewed, and then the challenges in this field are identified and analyzed. In this research, using historical accident database data and in the framework of building information modeling, a semi-automatic approach to identify and evaluate safety risks in the design phase has been developed. To achieve this goal, a plugin was developed for Autodesk Revit, which, by analyzing building components in 3D models, identifies different risks and classifies them based on the severity of the results they create in varying levels of risk (high, medium, and low). Also, the plugin automatically suggests appropriate preventive measures by leveraging OSHA standards and helps users manage risks and prevent them from occurring. In this way, a comprehensive risk assessment process is implemented from the stage of identification and evaluation to the provision of control measures and documentation on these incidents. The results of this research show that by using new technologies, such as building information modeling and implementing preventive strategies in the design phase, it is possible to improve the safety level in construction projects significantly. https://sjce.journals.sharif.edu/article_24124.html Seismic isolators serve a vital function in mitigating structural damage resulting from lateral loads and in diminishing the forces exerted upon the structure. In structures that are isolated, the displacement may experience a substantial increase, which, in the case of bridges, could potentially result in the collapse of the deck from its supports. In addition, isolator systems may have low energy absorption capacity. Controlling displacement and ensuring adequate energy dissipation in isolated structures under wind and earthquake loads proves the importance of incorporating devices like energy dampers alongside seismic isolators. Yielding dampers are a category of dampers recommended in previous research, which are produced in various types. These dampers utilize the inelastic deformation of ductile metals to dissipate the energy. One effective type of damper for energy dissipation in isolated structures is the bar-shaped damper with cantilever bars. In these dampers, the bars are positioned vertically, so that energy is dissipated regardless of the direction. The energy-absorbing elements in these dampers are the cantilever bars, with one end connected to the substructure and the other to the isolated structure. As relative displacement occurs between the substructure and isolated structure, the bars undergo bending and enter the plastic deformation range, so that dissipating earthquake energy occurs. The behavior of these dampers is influenced by parameters such as bar diameter, bar length, number of bars, and bar yield stress. Hence, determining the effect of each parameter on damper performance is crucial for selecting a suitable damper. In this study, after modeling a bar damper with a cantilever bar in the ABAQUS finite element software, the effect of changes in each of these parameters on the damper's energy dissipation was analyzed. The results demonstrate that energy dissipation in this damper is most sensitive to changes in bar diameter, followed by the number of bars, bar length, and bar yield stress.  https://sjce.journals.sharif.edu/article_24166.html Predicting the bearing capacity of rock masses can be challenging when the values of rock mass properties have high uncertainty. This challenge becomes even greater when the rock mass exhibits time-dependent behavior. Therefore, in this paper, the bearing capacity of strip foundations located on rock masses with time-dependent behavior is investigated. For this purpose, FLAC software is used and the visco-elasto-plastic CVISC model is assigned to the rock mass. Also, the Hoek-Brown criterion constant, uniaxial compressive strength of rock mass, GSI (geological strength index of rock mass), Kelvin shear modulus, Maxwell viscosity, and Kelvin viscosity are selected as random parameters. Initially, using the results obtained from this software and using the response surface methodology, the relationship between these input parameters and the bearing capacity of the rhological rock mass is determined. Then, a normal distribution and mean and standard deviation values are assigned to each of these parameters. In the next step, using the Monte Carlo method, a large number of random numbers are generated and, considering the relationship between the above input random variables and the resulting output (bearing capacity of the rock mass with the time-dependent behaviour), probability distributions for the output of the problem are determined. The results of this research indicate that the Kelvin shear modulus of the rock mass is the most effective parameter in predicting of the value of the bearing capacity, and the resulting distributions follow the normal distribution. Besides, if the uncertainty of the rock mass parameters increases, the standard deviation of the results also increases. Also, the amount of positive skewness also increases. As a result, the probability that the bearing capacity of the rock mass is less than the average value is greater. Thus, in various construction projects, the bearing capacity of rock masses needs to be examined based on probabilistic methods. https://sjce.journals.sharif.edu/article_24220.html - https://sjce.journals.sharif.edu/article_24052.html Examining the connection behavior of the ceiling panel to the wall panel is the most important part of understanding the structural behavior of three-dimensional buildings of sandwich panels with sprayed concrete. In this article, a new idea has been presented by the author in order to connect the corner of the ceiling to the wall due to the high degree of uncertainty of the panels. To use the indefinite degree capacity of these panels in transferring efforts caused by gravity loads and earthquakes. The provided connection, like the panels, are manufactured in a modular and artificial way in the factory and installed in the workshop. The connection is made using the bracing system with the specifications of the welded grid rebar of the panels and is indicated by the abbreviation BWC. The behavior of this type of connection and its comparison with the laboratory results of PCI prescriptive connection details and the laboratory results of connection details based on the design considerations of the ACI code are considered. All the samples have been tested in real scale and under reciprocating load. The results show that the rotational ductility coefficient of BWC connection details is equal to 3.4, for ACI details it is equal to 2.8 and for PCI details it is equal to 2.4, which indicates that the BWC connection sample is more malleable than the other two samples. The bearing capacity of the BWC sample is 0.9 ACI connection details and the failure mechanism in both BWC and ACI samples is due to the stiffness of the panel rebars in the alignment of the connection spring and is of soft failure type. While in the PCI connection details, the failure mechanism was caused by the sliding of the connecting rod in the wall panel of the brittle failure type. The process of reducing the hardness of the BWC connection in different loading steps is very gentle compared to the other two connection details. The results show that the use of the prefab default for this type of buildings and the use of PCI details and instructions for this type of buildings by the manufacturers of this product is incorrect and requires a change of approach. The connection details proposed by the author of BWC have shown good strength and ductility characteristics. https://sjce.journals.sharif.edu/article_24091.html Existence of shallow foundations adjacent to retaining walls (RWs) is one of the challenges faced in construction projects such as bridge abutments, urban constructions, development of intra-urban highways. In this situation, it is expected that retaining walls are affected by the adjacent foundations and an additional lateral pressure is applied to them. This additional pressure, like the lateral pressure due to the backfill, is affected by the wall deformability. Therefore, its amount should be determined according to the possibility or impossibility of lateral movement occurrence in RWs. Based on this concept, the retaining walls are classified into two categories: yielding retaining wall (YRW) and non-yielding retaining walls (N-YRWs). A comparison between these two types of retaining walls shows that although the lateral earth pressure acting on YRWs is far less than N-YRWs, more significant lateral displacements should be expected in YRWs. This may disrupt the serviceability of the wall as well as its adjacent foundation. Therefore, in addition to using YRWs as a solution to mitigate the lateral pressure mobilized behind RWs, reinforcing the backfill is another solution whose effectiveness in mitigating the backfill pressure on YRWs has been reported in several studies. The effectiveness of this solution in N-YRWs is still unknown, while the use of reinforcement elements such as geocell and geogrid below foundations is known as an efficient method in improving their behavior. Hence, an experimental study was conducted on the non-yielding retaining walls (N-YRWs) including different arrangements of geosynthetic layers below the strip footing adjacent to them. For this purpose, thirteen reduced-scale N-YRWs were constructed with different arrangements of geocell and geocell-geogrid layers, and then vertically loaded using monotonic loading. Converting more footing pressure into lateral pressure and improving the pressure-settlement behavior of footing were found to be the disadvantage and advantage of installing geocell layer under footing located on N-YRWs, respectively. Moreover, the response of wall models to vertical loading showed that 3Bf can be considered as an optimal width for the geocell layer in non-yielding retaining walls to minimize settlement, maximize bearing capacity, improve subgrade modulus, and prevent excess horizontal pressure on the wall. https://sjce.journals.sharif.edu/article_24145.html In recent decades, the efficiency of various active control tools in improving the seismic performance of structures has been investigated. Active control systems are one of the structure control strategies that modify the dynamic characteristics of the structure to deal with the destructive effects of possible earthquakes and minimize the responses. The critical damping state for the structure is a condition in which the velocity and displacement of the structure are minimized. The active control system can establish this condition for the structure as a regulator. When the structure controlled by the active method is in the critical damping state, the feedback gain matrix depends only on the velocity. Therefore, the use of velocity sensors is sufficient. Since the critical damping condition is sensitive to changing the system characteristics, the purpose of this research is to investigate the uncertainties assuming the establishment of the critical damping state. A ten-story shear building with active tendons in all stories subjected to earthquake vibration is considered to model and investigate parameter uncertainties, sensor/actuator faults, and failure of actuators. The effect of mass, stiffness, and damping uncertainties is evaluated, the partial failure of various sensors/actuators is assessed and the importance of each actuators failure is illustrated. The results showed that the designed controller can provide a 100% damping ratio for all vibration modes. In other words, the poles of the system are placed on the left side and the real part. The results illustrate that the response of the controlled structure in the critically damped condition is more sensitive to mass uncertainty and less sensitive to damping. The investigation of the sensitivity of the controlled structure in the critically damped condition to sensor faults showed that increasing the nominal and marginal value of sensor faults leads to increasing in the displacement responses and control forces. https://sjce.journals.sharif.edu/article_24156.html This research explores the compaction behaviour of Iraqi gypsum-sand soils stabilized with cement and cement kiln dust (CKD) at varying additive percentages (1%, 3%, 5%, and 7%) under different compaction levels (90% and 95%). Laboratory experiments were conducted using a modified oedometer to obtain Soil Water Retention Curves (SWRC) and assess the impact of matric suction on soil compressibility and water retention. The study reveals that both cement (3%) and CKD (5%) significantly improve the water retention capacity of the soil, reduce hysteresis effects, and enhance its resistance to compaction and swelling. These additives positively influence the soil’s water-holding capacity, thereby improving its performance in both saturated and unsaturated conditions. The Van Genuchten model was effectively used to describe the SWRC, demonstrating that cement outperforms CKD in terms of hydraulic behaviour due to the formation of stronger cementitious bonds, which contribute to better soil structure and stability.Additionally, the improvement analysis highlights that stabilization at higher compaction levels (95%) and under conditions of increased matric suction results in greater effectiveness, with cement-treated soils showing the most significant improvement in performance. This is particularly critical for applications in environments where soil behaviour under varying moisture content is a key factor. Furthermore, Scanning Electron Microscope (SEM) analysis confirmed the microstructural enhancements caused by cement hydration and the pozzolanic reactions of CKD, which help form a more stable and cohesive structure at the particle level.The results showed that adding 3% cement and 5% CKD reduced hysteresis and improved the SWRC curve, especially at 95% density. Also, at 95% density and 60 kPa suction, cement reached an improvement factor of 83% and CKD reached 33%.The findings underline the importance of both the type of stabilizing agent and the compaction level in improving the hydraulic properties and long-term stability of Iraqi gypsum-rich sandy soils. This research emphasizes the potential of using cement and CKD for soil stabilization, particularly in regions where moisture variability and soil behaviour are significant challenges. These insights contribute to the development of more durable and sustainable soil stabilization techniques in geotechnical engineering. https://sjce.journals.sharif.edu/article_24205.html In this study, a novel semi-rigid connection with a Controlled Damage Position (CCDP) is introduced for cold-formed steel (CFS) frames, and its structural performance is thoroughly evaluated through both finite element (FE) modeling and experimental tests. The connection is specifically designed to incorporate a flexural fuse at the beam-to-column joint, thereby effectively relocating damage concentration away from the column and directing it toward a predefined region intended for controlled localized yielding. The proposed connection was fabricated using galvanized steel plates, which were carefully cut and bent to thicknesses of 1-, 2-, and 3-mm. Comparative results between FE simulations and experimental tests demonstrated excellent agreement, with the maximum deviation being less than 9%, confirming the reliability of the FE modeling approach. A detailed parametric investigation was conducted to assess the influence of key geometric parameters, including plate thickness, inclination angle of the connecting components, length of the control segment, and the size of flange stiffeners. The results indicated that increasing plate thickness significantly enhanced both the flexural strength and the initial stiffness of the connection. Furthermore, the parametric analysis revealed that extending the control segment length increased the flexural capacity by up to 18% and the initial stiffness by up to 12%, whereas removal of this segment prevented the proper localization of the plastic hinge. Increasing the inclination angle of the sloped component improved flexural capacity by approximately 13%, while enlarging the flange stiffener length enhanced the flexural resistance by up to 35%, although excessive stiffening could potentially increase the likelihood of local buckling in the beam. Among all the studied configurations, the specimen with 2-mm plates and a 70-mm control segment exhibited the highest moment capacity and initial stiffness. Moreover, the obtained moment–rotation curves confirmed that the CCDP connection provided reliable semi-rigid behavior and effectively controlled buckling within the designated fuse region; in most specimens, no local buckling was observed in either the beam or the column up to a rotation of 0.07 radians. https://sjce.journals.sharif.edu/article_24206.html Project success in the construction industry refers to the achievement of predetermined goals for the project and the organization within specified time and cost constraints, along with the quality expected by the client. In this context, Iraq, as a developing country, faces numerous challenges regarding project failures. A more detailed examination of the reasons behind these issues could be beneficial for stakeholders in Iran's construction industry, especially since Iraq is currently one of Iran's largest trading partners. Understanding the factors contributing to the success of construction projects in Iraq can serve as a valuable guide for those involved in exporting technical services to this country. In this study, the factors influencing the success of construction projects in Iraq were identified through two sources: reputable scientific articles and interviews with 40 expert professionals. After prioritizing these factors, six final elements were identified, including the financial capability of the contracting company, support from senior management, utilization of consulting firms, evaluation and selection of the best contracting company, use of turnkey contracts, and coordination among various project sectors. Among these factors, three namely the financial capability of the contracting company, support from senior management, and evaluation and selection of the best company were presented quantitatively, while the other factors were presented qualitatively. In this research, school construction projects in Wasat province were selected as a case study, and 32 projects were analyzed to assess the impact of these six factors. Given that the projects had similar dimensions, construction methods, and costs, time delay was used as a key parameter to determine project success or failure. Based on this criterion, 17 projects were identified as successful and 15 as unsuccessful. Ultimately, a significant relationship was found among all identified success factors in these projects, and recommendations were provided for achieving success in similar projects. https://sjce.journals.sharif.edu/article_24207.html Magnetorheological (MR) dampers demonstrate intelligent behavior when subjected to a magnetic field, with their structural response controlled by adjusting the magnetic field's intensity. Various control algorithms and laws have been proposed to implement these control systems. Among the fundamental control laws for semi-active systems, the Skyhook and Groundhook control laws are particularly notable. A hybrid approach combining both of them can be employed to enhance the performance of these control laws. However, determining the optimal contribution of each control law—Skyhook and Groundhook—within the hybrid control law presents a significant challenge. In this study, an eight-story structure equipped with MR dampers is analyzed under the excitation of three earthquakes, Bam, Loma-Prieta, and Northridge, to evaluate the effectiveness of the proposed hybrid control law. The objective is to optimize the hybrid control law using the pattern search algorithm. The hybrid control law for structures with MR dampers can be implemented in two ways: on-off and continuous. In the on-off method, the voltage applied to the MR dampers is restricted to two extreme values, whereas the continuous method allows for voltage adjustment across the entire range between these boundaries. Through an analysis of both on-off and continuous hybrid control laws, it is evident that their performance in reducing the structure's displacement, velocity, and acceleration responses is nearly identical. However, the continuous hybrid control law achieves comparable efficiency with significantly lower control forces. As a result, the continuous optimal hybrid control law emerges as a simple yet highly effective solution. Furthermore, by assuming the same weight of force and displacement in the cost function, it is shown that the participation percentage of the Skyhook control law in the hybrid control law is much higher than that of the Groundhook control law. The optimal participation rate of the Skyhook law is obtained to be approximately 0.95. https://sjce.journals.sharif.edu/article_24216.html Global sensitivity analysis is a key component of hydrological modeling, enabling quantification of how changes in input variables influence simulated outcomes and supporting model development, calibration, and decision-making. Conventional sampling-based approaches, such as variance-based global sensitivity analysis, have been widely applied, yet they require substantial computational effort and very large numbers of model runs. These challenges have encouraged the development of data-driven methods that rely on available data, reduce computational burden, and avoid the need for predefined sampling schemes, making them an appealing alternative in many practical modeling situations where computational resources are limited. This study compares three data-driven global sensitivity analysis algorithms: permutation importance, partial dependence, and Friedman’s H-statistic. Each algorithm is described in terms of its underlying principles, advantages, and limitations for modeling variable importance and interactions. To evaluate their performance, the Sobol-G function, a widely used benchmark model, and the HBV rainfall–runoff model, a representative conceptual hydrological model, were employed, allowing assessment across both controlled mathematical settings and real-world hydrological conditions. The results indicate that permutation importance, when used with machine learning models such as random forests, typically obtains accurate ranking of influential variables and effective characterization of interaction effects, particularly in complex, nonlinear, and high-dimensional problems. These characteristics are especially important in hydrological applications, where identifying dominant drivers of model behavior is essential for reliable forecasting, uncertainty reduction, and system understanding. In addition to numerical measures, the role of visualization in global sensitivity analysis is highlighted. Visual tools such as bar charts, heatmaps, network diagrams, and partial dependence plots are described and compared, illustrating how they enhance interpretation and communication of findings by providing intuitive summaries of variable effects and interactions. However, caution is advised against over-reliance on visual representations without careful contextual examination, as misleading patterns may appear when graphs are misinterpreted or taken at face value. Overall, the study underscores the significance of data-driven sensitivity analysis as a flexible, efficient, and interpretable approach for improving hydrological modeling and decision support under uncertainty, particularly when computational constraints or model complexity limit the use of traditional sampling-based methods. https://sjce.journals.sharif.edu/article_24219.html The stability index, defined as the ratio of moments caused by secondary P-Delta effects to those resulting from design story shear forces, serves as a critical parameter in assessing structural behavior. These P-Delta effects, arising from the interaction between axial loads and lateral displacements, can significantly influence the overall structural response. While current design codes primarily provide static relationships for calculating the stability index - typically developed for lateral loads such as wind - this study adopts an innovative approach by investigating the stability index from both dynamic and nonlinear static perspectives. To obtain reliable results, three reference structures with varying heights (3-, 9-, and 20-story buildings) were analyzed using two advanced analytical methods: Incremental Dynamic Analysis (IDA) and Nonlinear Static Analysis. The research findings reveal that for low-rise buildings, when inelastic deformations are considered, static stability index values closely approximate their dynamic counterparts. However, for medium- and high-rise structures, significant discrepancies emerge between results obtained from the two methods. A key finding demonstrates that the dynamically computed stability index exceeds code-specified threshold values (0.1 and 0.25) for all cases except those with low acceleration levels (below 0.2g). The study further establishes that dynamic stability index values differ substantially from those recommended in current design codes. These results suggest that traditional stability assessment methods may prove non-conservative for tall structures subjected to severe dynamic effects. Significant influence of building height on the relationship between static and dynamic stability indices. Critical importance of considering nonlinear effects in stability calculations for tall structures. Necessity for developing new relationships that properly incorporate dynamic effects in stability index computation. These findings provide a solid foundation for updating structural design codes and developing more precise analytical methods. Future studies should investigate a broader range of structures with various lateral load-resisting systems to establish more comprehensive relationships for stability index calculation. Implementation of height-dependent correction factors in stability evaluation. Development of dynamic amplification coefficients for P-Delta effects. Inclusion of higher-mode effects in stability assessments for tall buildings. Consideration of material nonlinearity and geometric imperfections in analytical models. The study's outcomes emphasize the need for code revisions to address stability concerns in modern tall building designs, particularly in seismic-prone regions. The proposed methodology offers a more realistic assessment of structural stability under extreme loading conditions. https://sjce.journals.sharif.edu/article_24222.html This study presents a numerical investigation into the cyclic behavior of steel column base connections equipped with replaceable yielding steel angles under cyclic loading conditions. Utilizing a combined methodology of finite element analysis through ABAQUS and the Taguchi design of experiments (DOE) approach, the research systematically evaluates the influence of three critical parameters: steel angle thickness, applied axial load ratio, and anchor bolt gauge distance from the column edge. The numerical model was rigorously validated against existing experimental results, demonstrating strong agreement and confirming its capability to accurately simulate the nonlinear hysteretic response of the connections. Nine strategically designed parameter combinations based on an L9 orthogonal array enabled an efficient exploration of the parameter space while capturing both individual and interactive effects. Statistical analysis via analysis of variance (ANOVA) identified the thickness of the steel angle as the most significant factor, accounting for approximately 59.43% of the variation in the maximum flexural moment capacity, followed by the gauge distance (24.95%) and axial load ratio (11.92%). The optimal parameter set—comprising a 10 mm angle thickness, 0.2 axial load ratio relative to column capacity, and 40 mm gauge distance—yielded a peak flexural moment capacity of 30.71 kN·m, closely matching the finite element prediction of 30.56 kN·m. Hysteresis curve analyses reveal enhanced energy dissipation capacity, increased initial stiffness, and improved ductility in the optimized configuration, although the connection behavior consistently remains within the pinned range as per ANSI/AISC 360-16 specifications. The concentrated plasticity in the replaceable angle elements effectively localizes damage, promoting easy post-earthquake repair without compromising the main structural components. A regression model derived from the DOE results facilitates reliable predictions of flexural capacity based on the aforementioned parameters, underscoring the practical utility of the Taguchi method in seismic design optimization. These findings provide critical insights into the design of resilient, low-damage steel column base connections capable of sustaining seismic demands while enhancing reparability and lifecycle performance. https://sjce.journals.sharif.edu/article_24223.html Desalination of seawater is one of the most effective methods, and in some cases, the only possible method for producing drinking water. The combined effect of desalination plants and port structures on the coastal environment can sometimes have specific environmental consequences. The dispersion from the desalination plants, especially the changes in salinity and temperature, has significant effects on coral reefs. In this paper, the effect of the development of the commercial port of Kish Island with regard to the desalination plants was investigated using field measurements and numerical modeling. In 3 stages of field measurment, water quality parameters were measured from 24 different points near the northern coast of Kish Island. The speed and direction of the current were also measured to verify the accuracy of the numerical modeling. The current and dispersion of thermal and salinity pollution were modeled using MIKE21 two-dimensional model. The computational domain was about 30 square kilometers in size and was discretized into four zones using four different element sizes. Comparison of the numerical modeling results with field measurements indicated acceptable accuracy. The results of the modeling of the salinity diffusion pattern indicate a significant spread in the zone surrounding the outfall of desalination plants and the Kish Island commercial port. Around the outfall, average of temperature and electrical conductivity (EC) increased by 16% and 14%, respectively. It is due to the effect of west breakwater on current reduction that resulted in increasing brine concentration. The ultimate point where the ambient temperature has increased by 3 degrees is 170 meters from the outfall. Therefore, considering the impact of temperature changes on coral reef is critically important. Given the absence of measured data on water quality parameters, current, and velocity direction across various tides at this location, the findings of this study contribute to a better understanding of the environmental status of the area. https://sjce.journals.sharif.edu/article_24230.html This study evaluates the effectiveness of thermal treatment for the stabilization and solidification (S/S) of lead in contaminated bentonite, with particular focus on phase transformation, leachability, and structural modification across a wide temperature range (25–900 °C). Lead-contaminated bentonite samples with different Pb concentrations were subjected to controlled heating, and the resulting mineralogical and environmental responses were analyzed using X-ray diffraction (XRD), Toxicity Characteristic Leaching Procedure (TCLP), solubility assessments, and pH monitoring.The results demonstrated a clear sequence of thermally induced reactions that progressively improved the immobilization of lead. At approximately 400 °C, a measurable increase in pH (to around 8.5) and a corresponding reduction in Pb²⁺ solubility indicated the onset of mineral transformations, including the initial formation of stable lead-bearing compounds. With further heating, dihydroxylation reactions became dominant near 700 °C, disrupting the smectite layer structure and facilitating the development of amorphous and crystalline phases such as mullite, cristobalite, and lead silicate. These mineral phases played a crucial role in binding lead within low-solubility matrices, thereby reducing its mobility. At this critical temperature, TCLP results confirmed that the concentration of lead released into the leachate dropped below the U.S. EPA regulatory limit of 5 mg/L, establishing 700 °C as the optimum stabilization threshold.When the temperature was elevated to 900 °C, leachability of lead was completely suppressed, signifying nearly total immobilization. XRD analyses and weight loss measurements (approximately 30% for high-concentration samples) further confirmed the transformation of bulkier nitrate phases into denser, more stable oxides such as litharge and massicot. These structural changes not only minimized contaminant release but also enhanced the long-term durability of the treated soils for environmental applications.Overall, the findings highlight that thermal treatment provides an effective pathway for lead immobilization in bentonite without the need for additional chemical stabilizers. The process capitalizes on sequential mineral transformations, with 700 °C identified as the balance point between effective stabilization and preservation of soil properties. Moreover, the synergy between thermal reactions and the alkaline environment was found to be a decisive factor in optimizing retention capacity. This work contributes to the development of sustainable thermal remediation techniques for heavy-metal-contaminated soils. https://sjce.journals.sharif.edu/article_24237.html Unpleasant odors emitted from urban surface‐runoff canals pose a significant environmental and public health challenge in large cities such as Tehran. These odors, primarily caused by anaerobic decomposition of organic matter and the inflow of untreated wastewater, degrade water quality, generate public dissatisfaction, and reduce the environmental health and livability of urban areas. Despite their widespread impact, the spatial distribution and intensity of odor emissions in such canals are rarely monitored systematically. To fill this gap, this study introduces a practical framework for monitoring, quantifying, and predicting odor intensity in urban surface water canals. The proposed framework was implemented and evaluated in a pilot project along the Ghiasvand Canal in Tehran. Weekly field sampling was carried out at ten critical locations over a ten‐week period, during which key water‐quality parameters (including pH, electrical conductivity (EC), total dissolved solids (TDS, and dissolved oxygen (DO), and water temperature) and meteorological variables (such as air temperature, wind speed, and relative humidity) were collected. In addition, odor intensity was measured with a portable Odor meter. Pearson, Spearman, and Kendall correlation analyses, along with a random forest regression model, were employed to examine and predict the relationships between physicochemical and atmospheric variables and the odor intensity. Correlation analyses indicated that water temperature, electrical conductivity, and air temperature were positively correlated with odor intensity, whereas DO showed a negative correlation, indicating its critical role in odor suppression. The developed model performed well in predicting odor intensity, achieving an accuracy of 83% for both training and testing data. This study demonstrates the potential of integrated field monitoring and machine learning approaches to support practical odor management in urban water systems, leading to improved environmental quality and public well-being. While the framework was applied to a specific case in Tehran, the results and approach are broadly applicable to similar urban settings facing odor-related challenges. https://sjce.journals.sharif.edu/article_24238.html The measurement of failure characteristics in the semi-circular bending (SCB) test of asphalt mixtures has significantly expanded over the last decade, with laboratory study results being published in numerous studies. The purpose of this article is to develop neural network models to predict the fracture energy and fracture toughness of asphalt mixtures based on data mining principles. For this purpose, 3290 data points from SCB fracture test results of asphalt samples were collected from 102 credible articles. Out of these, 1627 data points are used to predict fracture energy and 1663 data points are used to predict fracture toughness.The input layer of the neural networks includes data collected on fracture mode, loading rate, test temperature, sample thickness, notch dimension, presence of modifier, maximum nominal aggregate size, air percentage, binder percentage, aging, and binder type of asphalt mixtures. The output layer generates the energy and fracture toughness for each assumed input. The results show that the constructed neural network models can predict fracture energy with 75% accuracy and fracture toughness with 70% accuracy.The sensitivity analysis reveals that the loading rate, test temperature, airvoid percentage, and binder percentage are the most influential characteristics on the prediction models' results. The integration of data mining principles and neural network algorithms enhances the prediction accuracy of asphalt mixture properties, which can aid in designing more durable pavement materials.The accuracy of the models was validated using metrics such as Root Mean Squared Error (RMSE) and Mean Squared Error (MSE), with RMSE values of 0.727 for fracture energy and 0.170 for fracture toughness. The regression analysis between actual and predicted values showed R² values of 0.75 for fracture energy and 0.70 for fracture toughness, indicating robust model performance.In conclusion, the neural network models based on collected SCB test data exhibit acceptable performance in predicting the fracture energy and toughness of asphalt mixtures. The study's findings highlight the importance of considering key input variables such as airvoid percentage, binder percentage, test temperature, and loading rate in developing reliable predictive models for asphalt mixture behavior. https://sjce.journals.sharif.edu/article_24239.html This study investigated the bond behavior of braided ropes made from recycled polyethylene terephthalate (PET) as a substitute for steel rebar in fiber-reinforced cementitious composites (FRCC).For this purpose, pull-out tests were conducted according to the RILEM RC6 standard on steel rebar and PET ropes with the same diameter, using FRCC laboratory specimens containing different percentages of steel fibers. The results showed that the pull-out force was approximately 30 kN for the steel rebar and about 7.6 KN for the PET rope, indicating a 75% reduction in bond strength for the PET material.However, the displacement corresponding to the maximum load was about 23.5 mm for PET and 0.6 mm for the steel rebar, demonstrating a 40-fold increase in ductility for PET compared to steel. The PET ropes experienced rupture in all specimens but did not pull out of the concrete, whereas the steel rebars detached from the concrete by slipping. These results suggest that despite the lower tensile resistance of PET ropes, their bond behavior, especially in areas requiring high ductility, can be considered for use in specialized design applications.This study investigated the bond behavior of braided ropes made from recycled polyethylene terephthalate (PET) as a substitute for steel rebar in fiber-reinforced cementitious composites (FRCC).For this purpose, pull-out tests were conducted according to the RILEM RC6 standard on steel rebar and PET ropes with the same diameter, using FRCC laboratory specimens containing different percentages of steel fibers. The results showed that the pull-out force was approximately 30 kN for the steel rebar and about 7.6 KN for the PET rope, indicating a 75% reduction in bond strength for the PET material.However, the displacement corresponding to the maximum load was about 23.5 mm for PET and 0.6 mm for the steel rebar, demonstrating a 40-fold increase in ductility for PET compared to steel. The PET ropes experienced rupture in all specimens but did not pull out of the concrete, whereas the steel rebars detached from the concrete by slipping. These results suggest that despite the lower tensile resistance of PET ropes, their bond behavior, especially in areas requiring high ductility, can be considered for use in specialized design applications.