https://sjce.journals.sharif.edu/ Sharif Journal of Civil Engineering en daily 1 Sun, 21 Jun 2026 00:00:00 +0330 Sun, 21 Jun 2026 00:00:00 +0330 https://sjce.journals.sharif.edu/article_24288.html -- 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_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 commercial port of Kish Island with regard to the desalination plants was investigated using field measurements and numerical modeling. In 3 stages of field measurement, 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 the 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, the average temperature and electrical conductivity (EC) increased by 16% and 14%, respectively. This is due to the effect of the west breakwater on current reduction, which 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 reefs 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_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_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 Ghiyasvand 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), 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 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_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_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 void percentage, binder percentage, aging, and binder type of asphalt mixtures. The output layer generates fracture 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, air void 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 air void percentage, binder percentage, test temperature, and loading rate in developing reliable predictive models for asphalt mixture behavior. 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_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_24239.html This study investigates the bond behavior of braided ropes made from recycled polyethylene terephthalate (PET) as a potential alternative to conventional steel reinforcement in fiber-reinforced cementitious composites (FRCC). Pull-out tests were conducted according to RILEM RC6 standards on FRCC specimens containing different volume fractions of steel fibers, using steel rebars and PET ropes with equal diameters (14 mm). The experimental results revealed that the maximum pull-out force was approximately 30 kN for steel bars and 7.6 kN for PET ropes, indicating a 75% reduction in bond strength for PET compared to steel. However, the displacement corresponding to the peak load was about 23.5 mm for PET ropes and only 0.6 mm for steel bars, representing a 40-fold increase in ductility for PET. In all experiments, PET ropes failed internally without being pulled out from the matrix, while steel bars exhibited bond-slip failure. The inclusion of steel fibers in the matrix significantly enhanced the bond performance, especially in terms of energy absorption and post-peak ductility. For instance, in specimens containing 1% steel fibers, the maximum pull-out load of the PET ropes reached 7.6 KN at a displacement of 9.3 mm, showing a clear improvement over fiberless samples. The experimental observations were further analyzed by comparing the bond–slip responses of PET and steel reinforcements, which demonstrated that PET exhibits a gradual softening after peak load instead of a brittle bond loss. This characteristic suggests a more stable and energy-dissipating interfacial mechanism. In addition, the use of recycled PET not only provides a sustainable and eco-friendly reinforcement option but also contributes to reducing construction waste and CO₂ emissions. Such properties make PET ropes particularly suitable for structures requiring high ductility and seismic resilience. The findings of this study can serve as a reference for future modeling of PET–concrete interface behavior and for developing design guidelines for sustainable fiber-reinforced composites. 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 performance improvement. 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_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_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_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_24256.html A group of water-source pollutants whose concentration and distribution were either negligible or undiscovered in the past, yet can leave undesirable effects on the environment and living organism are called emerging chemical pollutants, such as pharmaceutical compounds. Developing effective and efficient methods for removing this group of pollutants can be a great step for persevering the environment. This study presents a practical and economical method of synthesizing nano silica-gel dendrimers with the aim of absorbing Rifampicin. Our method begins by the conversion of the silica-gel core to a dendrimer, followed by the addition of branches (chemical functional groups) to the said core, resultingly creating an inexpensive and environment-friendly absorbent. In addition to trapping pollutant particles within its branches, this absorbent is also capable of forming hydrogenic and Van der Waals bonds with antibiotic molecules. The FESEM, TGA, XRD, and FTIR methods of analysis were used to determine the morphology and structure of the absorbent. Furthermore, the absorption rate of Rifampicin was studied across various in vitro conditions, such as various temperatures and detention time. The results suggest that the synthesized nanoparticles -with an average diameter of 47 nm- share a homogenous net-like structure and include the desired functional groups. The absorption process is further facilitated due to the formation of hydrogenic and Van der Waals bonds between the hydroxyl groups present in the absorbate and the functional groups on the surface of the nano-absorbent. A maximum elimination ratio of 85% was achieved at 38.57 C, given a 20-minute detention time at a pH of 5. Additionally, studying the experiment’s isotherm showed that the suggested Langmuir system has a better compatibility with in vitro conditions compared to the Freundlich, and Temkin models, yielding a maximum absorption capacity of 131 mg/g with R2=0.9941, and confirming the absorption process to be monolayered and homogenous. Kinetical examination of the experiment proved that a pseudo-second-order kinetic model can properly describe the process of Rifampicin absorption with R2=0.994, proving the absorption process to be chemical. Lastly, reduction and reabsorption of the nano-absorbent was attempted and achieved via a process comprised of ten consecutive cycles of washing with methanol, resulting in absorption rates of up to 60%; which speaks of this absorbent’s commendable reabsorption performance. Therefore, it could be concluded that the nano silica-gel dendrimer nano absorbent as a high-performance, environment-friendly, and recyclable solution, shows a great potential in the development of water and wastewater treatment. https://sjce.journals.sharif.edu/article_24272.html The control of web compression buckling in steel sections is essential to prevent local instability. The existing design criteria for determining web compression buckling capacity have been developed primarily based on research and test results on wide-flange sections, and there is limited information regarding the behavior of other section types. Moreover, the effect of bearing length is not considered in the proposed equation of AISC 360-22 for controlling web compression buckling. In this paper, the influence of bearing length on the compressive buckling capacity of steel section webs is investigated. Initially, a finite element model was developed using Abaqus software to examine the behavior of steel member webs under concentrated loading, and its accuracy was validated using numerical and experimental data. Subsequently, the behavior of 24 specimens, including IPE and IPB sections, was studied under the double compression loading condition defined in AISC 360-22. This study enabled the evaluation of the effectiveness of bearing length in enhancing the local stability of steel members. The governing failure limit state in steel members was identified as web compression buckling. The local failure capacity of steel member webs was determined using the AISC 360-22 specification and compared with the results of finite element analysis. For moment connections, in general, the equation provided by the design code proved conservative for IPE sections and non-conservative for IPB sections. The research results demonstrate that bearing length plays a significant role in web buckling capacity and its effect should be considered in determining web compression buckling capacity. Increasing the bearing length can enhance the web section capacity by between 18% and 106%. Finally, suggestions and modification factors for the criteria provided by AISC 360-22 for controlling the web compression buckling limit state are presented. These proposed coefficients improve accuracy and efficiency in the design of steel members. https://sjce.journals.sharif.edu/article_24279.html This study investigates the development of cracks and the enhancement of ductility in ‎concrete beams by introducing newly designed hybrid GFRP rebars incorporating polyurethane ‎foam cores as a means to overcome the well-known limitations of conventional GFRP ‎reinforcement. Although reinforced concrete is widely used due to its high compressive ‎strength, economic feasibility, and adaptability to various structural applications, the corrosion ‎of steel reinforcement remains a major concern that can significantly reduce structural ‎durability and increase maintenance costs. GFRP rebars have emerged as a promising ‎alternative due to their excellent corrosion resistance, low weight, and favorable mechanical ‎properties; however, their inherently low elastic modulus often leads to excessive deflection, ‎wider cracks, and brittle failure modes in concrete members. To address these drawbacks, this ‎research proposes a hybrid GFRP rebar system in which a lightweight and highly energy-‎absorbing polyurethane foam core is embedded to reduce brittleness, enhance deformation ‎capacity, and improve flexural performance. Four concrete beam specimens—one reinforced ‎with steel rebars, one with standard GFRP, and two with hybrid GFRP rebars containing 4-mm ‎and 8-mm foam cores—were tested through laboratory experiments and numerical simulations ‎using ABAQUS to evaluate flexural behavior, crack patterns, and ductility indices. The ‎experimental and numerical results exhibited strong agreement, confirming the reliability of the ‎adopted CDP model in simulating concrete behavior and failure mechanisms. Beams reinforced ‎with hybrid rebars demonstrated notably improved ductility compared with standard GFRP, ‎with the 8-mm core specimen showing a 131% increase in ductility over the standard GFRP ‎beam and a 37% increase over the 4-mm core specimen. Furthermore, the failure modes shifted ‎from brittle shear failure in the standard GFRP beam to shear-flexural and predominantly ‎flexural failures in the hybrid beams, indicating a more uniform stress distribution and enhanced ‎energy absorption due to the foam core. These findings highlight the potential of polyurethane-‎foam-integrated GFRP rebars as an innovative and effective solution for improving ‎serviceability, ductility, and overall structural performance in concrete beams.‎