Amirkabir University of TechnologyAUT Journal of Civil Engineering2588-289910420261001Enhancing performance of tuned mass dampers in mitigating seismic response of nonlinear structures610110.22060/ajce.2026.25078.5963ENAmir HosseinJafariehDepartment of Civil Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, Iran0000-0001-6625-7720SainaEbrahimniaDepartment of Civil Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, IranJournal Article20251110Tuned mass dampers (TMDs) are widely used to mitigate seismic vibrations. However, studies have shown that TMD effectiveness diminishes in nonlinear systems and varies under different ground motions. This study investigates TMD performance in elastic and inelastic single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) structures. Numerical models were constructed in OpenSees and subjected to 20 ground motion records. A parametric analysis examined the influence of TMD stiffness on displacement and inter-story drift using nonlinear time history analysis. The TMD stiffness ratio was systematically varied to identify an optimal value that maximizes response mitigation in nonlinear systems. Results indicate that traditional TMDs, tuned to the structure's fundamental frequency, often underperform in nonlinear systems. In some cases, they may amplify responses at higher ductility levels. For SDOF systems, reducing TMD stiffness below traditional values noticeably improves performance. Optimal TMD stiffness was determined by minimizing displacement ratios. For MDOF structures, reducing TMD stiffness below the traditional value decreases the response ratio in the upper stories of elastic structures and in all stories of inelastic structures. Notably, optimal TMDs selected by minimum total story displacement ratios differed from those selected by minimum inter-story drift ratios. This improved stiffness-based tuning strategy was subsequently applied to a Tuned Structural Mass Damper (TSMD) for nonlinear systems. The TSMD utilizes a portion of existing roof mass, thereby eliminating the need for additional weight. For SDOF systems, the TSMD demonstrated considerably better performance. In MDOF systems, TSMDs reduced inter-story drifts in inelastic structures and mitigated drift amplification in upper floors.https://ajce.aut.ac.ir/article_6101_2cfa47a65809ea0496bbf9aa363dc5da.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-289910420261001Predicting the durability of stabilized soil blocks using non-destructive testing.613510.22060/ajce.2026.24822.5954ENZohrehGhafori FardDepartment of Civil Engineering, Faculty of Engineering, Yazd University, IranMaryamMokhtariDepartment of Civil Engineering, Faculty of Engineering, Yazd University, IranMohammad MehdiKhabirDepartment of Civil Engineering, Faculty of Engineering, Yazd University, Iran0000-0003-3434-7603MehrdadJalilianDepartment of Polymer, Faculty of Polymer, Iran Polymer and Petrochemical Research Institute, Tehran, IranJournal Article20250928The use of non-destructive tests for predicting the durability of stabilized earthen blocks, in addition to environmental benefits, enhances the reliability, safety, and cost-effectiveness of structures. The durability of earthen blocks, defined as their ability to withstand environmental factors such as moisture, temperature variations, and erosion, plays a critical role in the lifespan of structures, reducing maintenance costs, and preserving the environment. This study aims to predict the durability properties of earthen blocks stabilized with synthetic copolymers and to develop predictive models based on a combination of destructive and non-destructive tests. The destructive tests included freeze–thaw cycles, wet–dry cycles, and erosion tests, while the non-destructive tests comprised water absorption, ultrasonic testing, contact angle measurement, and image processing. The results were modeled using Response Surface Methodology (RSM) in Design Expert software. The findings demonstrated that non-destructive tests effectively reflect the changes in blocks under various conditions, and their appropriate combination enables accurate prediction of earthen block performance. Multivariate models described the degradation trends, environmental cycle sensitivity, and the effects of polymer content and construction quality better than univariate models. Additionally, some non-destructive tests played a key role in durability prediction and can be selected as primary indicators for rapid assessment.<br><br>The results indicate that combining non-destructive testing and modeling is an effective alternative to destructive testing, contributing to significant reductions in cost, time, and resources in sustainable earthen block projects.https://ajce.aut.ac.ir/article_6135_4cc5400e63624c44fadeda99f57588a6.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-289910420261001Relating Power Draw and Fractal Dimension to Operation Parameters in a Lab-Scale Ball Mill614310.22060/ajce.2026.24685.5943ENImanMoradiDepartment of Mining Engineering, Amirkabir University of Technology (Tehran Polytechnique), Tehran, IranAli AkbarAbdollahzadehDepartment of Mining Engineering, Amirkabir University of Technology (Tehran Polytechnique), Tehran, IranMehdiIrannajadDepartment of Mining Engineering, Amirkabir University of Technology (Tehran Polytechnique), Tehran, IranJournal Article20250905The goal of this study is to determine how the setting of operational parameters in a laboratory-scale ball mill affects the fractal dimension and power draw. The trials were designed using Design Expert software. Three optimization tests were used to evaluate the resultant mathematical model, and the results indicated that it had adequate validity. Percent solids, grinding time, and mill speed are operational parameters of the mill examined in this research. The results show that increasing the percent solids reduces both the fractal dimension and the amount of particles smaller than 25 microns. Increasing the solid content from 25 to 45 percent and from 45 to 65 percent results in increases and decreases in power draw, respectively. As the grinding time increased, the power draw reduced. On the other hand, the reduction ratio and weight of particles smaller than 25 microns and, consequently, the fractal dimension increased as grinding time increased. The findings suggest that a higher mill speed will lead to a greater power draw. The fractal dimension, reduction ratio, and weight of particles smaller than 25 microns will all rise if the mill speed is increased from 55% to 75% of the critical speed. Increasing mill speed from 75% to 95% only increases power draw without significantly affecting other parameters.https://ajce.aut.ac.ir/article_6143_de9621d4c6fa69ce8aaa90f00e9110c5.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-289910420261001Monitoring the Behavior of the Shiadeh Earth Dam Using PLAXIS Software and Prediction Settlement with Radial Basis Function Algorithm614910.22060/ajce.2026.23972.5908ENSeyed RaziAnishehDepartment of Civil Engineering, Razi University, Kermanshah, Iran0000-0002-9761-0029MohammadSharifipourDepartment of Civil Engineering, Razi University, Kermanshah, Iran0000-0002-7183-3291ArashAzariDepartment of Water Science and Engineering, Razi University, Kermanshah, Iran0000-0002-9643-3331Journal Article20250303The specialized instruments installed in earth dams play a crucial and vital role in monitoring, controlling, and managing the structural stability of these dams against applied forces and destructive natural factors. In this study, the Shiadeh earth dam, Currently, all precision instruments installed on the dam are out of order, rendering it impossible to record any potential deformations or settlements. Therefore, this research focuses on predicting the dam’s settlement during its operational phase, using historical data from the period when the instruments were fully functional and reliable. The prediction process was carried out using the advanced Radial Basis Function (RBF) algorithm. Within the scope of this study, both static and dynamic analyses were performed using the advanced PLAXIS 3D software to model the dam’s behavior and evaluate its settlement along the crest. The settlement prediction results obtained through the RBF algorithm, when compared with ground survey data from micro-geodetic points located on the downstream slope of the dam, show acceptable agreement, confirming the validity and accuracy of the modeling approach employed. The analysis of crest settlement using PLAXIS 3D modeling indicates that throughout various reservoir impoundment conditions across different seasons, the dam maintained a high safety factor and demonstrated stable performance. The maximum recorded deformation at the dam crest was found to be 0.789 meters. In the three-dimensional PLAXIS model, the effect of the strike-slip fault was also taken into account, which led to intensified deformation.https://ajce.aut.ac.ir/article_6149_b04c387c8384ca083a71b8da516f65f6.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-289910420261001Relative Humidity Forecasting as an Influent Factor in Hydro-climatology616410.22060/ajce.2026.23975.5909ENYaserSabzevariDepartment of Water Science and Engineering, College of Agriculture, Isfahan University of Technology, 8415683111, IranInstitute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 84104, Bratislava, Slovakia0000-0002-3805-2792SaeidEslamianDepartment of Water Science and Engineering, College of Agriculture, Isfahan University of Technology, 8415683111, IranSaeidOkhraviInstitute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 84104, Bratislava, SlovakiaJournal Article20250305Climate change is one of the major environmental challenges of the present era. Among the key climatic parameters, atmospheric humidity plays a crucial role in defining weather conditions, agriculture, human health, and various economic activities. Therefore, This study explores the forecasting of relative humidity (RH) as a significant factor in hydro-climatology using the ARIMA(0,1,1) model. The research utilizes historical RH data from 1993 to 2022, coupled with the Mann-Kendall test for trend analysis and time series techniques, to evaluate both past and future RH trends. The results indicate that while RH experienced a decreasing trend over the past three decades, this trend was not statistically significant because of Z statistical equal= -0.01 that is fewer than 1.96 threshold. Further analysis using the ARIMA model forecasts a slight increase in RH in the coming years. These findings suggest that, despite the absence of significant past trends, RH may show modest upward changes, which could influence future hydro-climatic conditions. The study highlights the importance of incorporating RH forecasting into hydro-climatological models for more accurate predictions of climate behavior and water resource management. Additionally, the research underscores the utility of time series analysis in understanding long-term climate variables and their implications for environmental planning.https://ajce.aut.ac.ir/article_6164_2d5951d1e3b31dfb7fd2dcc172df17fd.pdfAmirkabir University of TechnologyAUT Journal of Civil Engineering2588-289910420261001Finite Element Analysis of Bearing Capacity of Concrete-Filled Double-Steel Tube Brace-Column K-Joints Under Monotonic Loading619710.22060/ajce.2026.25858.5994ENSadaf QasimShekhlerDepartment of Civil Engineering, Urmia University of Technology, Urmia, Iran0000-0002-0498-2553TaghiMofidDepartment of Civil Engineering, Urmia University of Technology, Urmia, Iran0000-0002-0498-2553Journal Article20260516The application of concrete-filled double-steel tube (CFDST) joints in structural engineering has received great attention due to their high load-bearing capacity, excellent ductility, and favorable seismic performance. In this study, the load-bearing capacity of CFDST brace-column K-joints under monotonic loading was examined using the finite element method via Abaqus. The numerical results were successfully validated against experimental and analytical models from the literature, showing good agreement in load-displacement response and failure modes. A parametric study was conducted to investigate the effects of brace diameter, column-brace angle, and sandwiched concrete between the inner and outer steel tubes on the failure behavior and overall capacity of the K-joint. Results indicate that the load-bearing capacity decreases with increasing brace diameter and with increasing brace-column angle. Models with sandwiched concrete exhibited significantly higher peak loads compared to hollow joints, due to the composite action enhancing stiffness and delaying local buckling. The maximum load resisted by the CFDST K-joint reached 2755 kN, representing a 156% increase over the joint without concrete. Although concrete infill substantially improves stiffness and capacity, the compressive strength level of the concrete plays a negligible role; thus, even low-strength concrete can be effectively used. Comparison of ultimate displacements also revealed that concrete-filled models possess much greater ductility than hollow ones. The novelty of this study lies in the simultaneous parametric investigation of brace diameter, brace-to-column angle, and concrete infill on the load-bearing capacity of CFDST K-joints using a validated finite element model.https://ajce.aut.ac.ir/article_6197_64ff7983a47d331b13a81156e2f4d29d.pdf