_1745930787 20250429161627000 CMV Verlag khoffman@cmv-verlag.com Golestan University (Technical and Spiritual) & Asst. Prof. Morteza Jamshidi (Financial) Journal of Civil Engineering Researchers jcer 2538-516X 2538-516X 03 01 2025 7 1 Mohammadhossein Mansourghanaei In this laboratory study, a mixed concrete design containing 500 kg/m3 Portland cement was prepared, and elastic modulus testing, X-ray diffraction (XRD) analysis, and scanning electron microscope (SEM) image analysis were performed on concrete samples at 21 and 600 °C after a curing age of 90 days to investigate and evaluate the microstructure of concrete at room temperature and under high temperature. The results of the tests indicate that high temperature causes a decrease in the results, so that the elastic modulus of concrete experienced a decrease of 71.63% from 73.33 GPa at 21°C to 24.12 GPa at 600 °C, and in the XRD analysis, a decrease in the height of the peaks of hydrated elements is observed. The low peak height of calcium hydroxide in the XRD spectrum indicates a proper polymerization process in conventional concrete. In SEM analysis, at a temperature of 21 °C, due to the completion of a large part of the polymerization process, the tree structure, pores and unhydrated particles are seen in their minimum amount, but after applying a temperature of 600 °C to the concrete sample, with damage to the microstructure of the concrete and the hydrated calcium aluminum sulfate (C-A-S-H) and hydrated calcium silicate (C-S-H) gels, an increase in the tree structure, pores and cracks is evident in the concrete sample. 03 01 2025 62 70 https://creativecommons.org/licenses/by/4.0 10.61186/JCER.7.1.62 https://www.journals-researchers.com/ojs/index.php/jcer/article/view/164 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/164/171 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/164/171 Journal of Civil Engineering Researchers jcer 2538-516X 2538-516X 03 01 2025 7 1 Mahsa Zarehparvar-Shoja https://orcid.org/0000-0003-2158-8029 Rasoul Shadnia https://orcid.org/0000-0002-3012-8473 Amin Amin Kazemi Beydokhti https://orcid.org/0000-0002-4724-0373 This study utilizes nanofilament-based nanotechnology, such as carbon nanotubes (CNTs), to improve the mechanical characteristics of concrete as a building material. One of the important and effective factors in adding carbon nanotubes to cement composites is their proper dispersion in the mixture. Therefore, in this research, different methods of dispersing carbon nanotubes in cement mortar have been investigated. They were first functionalized through covalent bonding to prevent carbon nanotubes from accumulating in the water. To achieve the appropriate distribution of carbon nanotubes in water and maintain the stability of their dispersion, different surfactants including Polycarboxylate (PCE), Sodium dodecyl sulfate (SDS), Cetyltrimethylammonium bromide (CTAB), Polyethylene glycol (PEG) were employed. At that point, utilizing visual perception and UV test, PCE/PEG surfactant was presented as a reasonable surfactant for the scattering of carbon nanotubes. Once the most suitable dispersal technique was identified, the impact of incorporating multi-walled carbon nanotubes into concrete was investigated with varying weight proportions. The study revealed that even at low concentrations (0.015%, 0.030%, and 0.045%) relative to the cement weight, the inclusion of carbon nanotubes decreased the porosity of the concrete nanocomposite, resulting in a denser and more compact composite. As a result, it increases the concrete samples' compressive, tensile, and bending strength. 03 01 2025 34 47 https://creativecommons.org/licenses/by/4.0 10.61186/JCER.7.1.34 https://www.journals-researchers.com/ojs/index.php/jcer/article/view/156 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/156/168 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/156/168 Journal of Civil Engineering Researchers jcer 2538-516X 2538-516X 03 01 2025 7 1 Mohammadreza Oliaei https://orcid.org/0000-0001-7965-5808 Mohammad Amin Hamidi Moghadam https://orcid.org/0009-0008-3656-0874 Concrete-filled steel tube (CFST) columns are widely used in high-rise buildings around the world due to their numerous structural advantages, including high load-bearing capacity, favorable inherent ductility, substantial energy absorption capabilities, and the elimination of the need for formwork. However, in Iran, these structures have not yet been widely implemented in practice, highlighting the need for further research in this area. Additionally, challenges such as buckling and local delamination between the concrete and steel under loading remain key issues for these columns. Research indicates that circular CFST columns provide the strongest confinement for concrete, whereas square CFST columns exhibit higher local buckling under loading. Furthermore, embedded steel profiles significantly enhance the overall performance of these columns. In this study, a finite element model of CFST columns with embedded cruciform profiles is validated using Abaqus software and subsequently analyzed parametrically. The objective of this study is to evaluate the seismic and axial performance of the "primary column cross-sections" and the "embedded steel profiles" with equivalent areas. The findings of this research demonstrate that filling the internal space of steel columns with concrete substantially improves axial and lateral performance, although it slightly reduces lateral ductility. Additionally, stress analysis reveals that the type of embedded steel profile directly influences the enhancement of load-bearing capacity and lateral performance. Results also show that square CFST columns outperform their circular counterparts in terms of axial strength and stiffness, though they exhibit lower axial ductility. Moreover, the results indicate that embedded profiles with concentrated mass at the center (central profiles) significantly enhance axial performance, whereas those with mass concentrated along the perimeter (peripheral profiles) exhibit the lowest axial performance but the highest lateral performance criteria. 03 01 2025 22 33 https://creativecommons.org/licenses/by/4.0 10.61186/JCER.7.1.22 https://www.journals-researchers.com/ojs/index.php/jcer/article/view/155 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/155/167 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/155/167 Journal of Civil Engineering Researchers jcer 2538-516X 2538-516X 03 01 2025 7 1 Hadi Faghihmaleki https://orcid.org/0000-0002-3078-4948 Mehrshad Jafariyan Jolodar https://orcid.org/0009-0001-9429-1501 In recent years, most of the laboratory research on the comparison of the mechanical behaviour of reinforced concrete containing industrial metal fibres and recycled chips has been carried out abroad, and it is necessary to carry out special studies on reinforced concrete with domestic materials, so that we can produce a recycled reinforced concrete from metal waste and recycled chips that is resistant to acid attack and can be used in the construction industry. First we prepare the materials and fibres required for the test, then we design an optimal mixing plan in which industrial metal fibres and recycled chips are used in different percentages. The recycled chips are added to the concrete mix in such a way that the amount of chips we add reduces the amount of fine-grained sand, and the chips replace a small percentage of the sand. Concrete samples are then taken according to the mix design and tested after curing at a specified age. We compare concrete samples containing industrial metal fibres and recycled chips after exposure to an acidic environment with a concrete sample without fibres exposed to an acidic environment to understand how much the presence of fibres and chips in the concrete mix has increased the resistance of the concrete to acid. 03 01 2025 48 54 https://creativecommons.org/licenses/by/4.0 10.61186/JCER.7.1.48 https://www.journals-researchers.com/ojs/index.php/jcer/article/view/153 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/153/169 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/153/169 Journal of Civil Engineering Researchers jcer 2538-516X 2538-516X 03 01 2025 7 1 Majid Motiolhagh https://orcid.org/0009-0002-6351-8846 Kamran Yeganegi https://orcid.org/0000-0003-0421-6258 Maryam Ebrahimi https://orcid.org/0000-0001-5837-8864 The primary aim of this article is the identification and selection of the optimal strategy for the exit of a significant capital volume invested in the construction of commercial centers in the face of investment risk in the construction of commercial complexes, along with influential factors in challenging economic conditions such as exchange rate fluctuations, transregional power sanctions, stagflation, excessive supply and growth in commercial complex construction in the country, etc., specifically focused on the Royal Mall Kish project. Indeed, the effectiveness and reliability of formulating and selecting exit strategies based on successful implementation and the creation of a sustainable economic cycle for a commercial complex are deemed essential and prerequisite. The research method employed is qualitative. In the qualitative section of this study, through interviews, we identified the relevant factors affecting exit strategies, considering the current conditions and business environment to achieve ultimate goals. These factors are ultimately categorized into three dimensions: structural, behavioral, and contextual. The qualitative sample population includes active experts in this project. At theoretical saturation point, 8 experts were identified as participants in the research. Ultimately, 43 influential components on strategy selection and 5 exit strategies were identified in this project that can be determined as suitable strategies in the appropriate situation for decision-making regarding exit. 03 01 2025 12 21 https://creativecommons.org/licenses/by/4.0 10.61186/JCER.7.1.12 https://www.journals-researchers.com/ojs/index.php/jcer/article/view/151 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/151/166 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/151/166 Journal of Civil Engineering Researchers jcer 2538-516X 2538-516X 03 01 2025 7 1 Saurabh Kumar Anuragi https://orcid.org/0009-0008-7320-7527 The complex nature of slope engineering presents considerable challenges in accurately predicting slope stability using traditional methodologies. Due to the serious implications that can arise from slope failures, it is crucial to implement the most effective techniques for assessing slope stability. This study investigates a hybrid approach that integrates BPSO with SVC to enhance predictive accuracy in slope stability assessment. The methodology employs BPSO to optimize the selection of features that are critical to the prediction process. Additionally, grid search technique is utilized for fine-tuning the hyperparameters of the SVC. The research evaluates the performance of three SVC kernel functions: linear, polynomial and rbf. For the predictive analysis, six features identified as potentially influential were selected: height of the slope (H), pore water ratio (ru), unit weight of the soil (Ƴ), cohesion of the soil (c), slope angle (β), and angle of internal friction (ɸ).  To enhance the generalization capability of the classification models, a 5-fold cross-validation (CV) approach was implemented. The effectiveness of the models was evaluated using various metrics, including the area under the curve (AUC) and overall accuracy of the predictions. The findings of the study indicate that the hybrid approach, particularly the SVC employing the rbf kernel, significantly outperformed the other models in terms of prediction accuracy, achieving an AUC of 0.735 and an accuracy rate of 0.725. This underscores the potential of the proposed hybrid method as a valuable tool for accurately predicting slope stability and mitigating risks associated with slope failures in engineering applications. 03 01 2025 1 11 https://creativecommons.org/licenses/by/4.0 10.61186/JCER.7.1.1 https://www.journals-researchers.com/ojs/index.php/jcer/article/view/150 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/150/165 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/150/165 Journal of Civil Engineering Researchers jcer 2538-516X 2538-516X 03 01 2025 7 1 Mohamadreza Abdollahi-Kakroudi https://orcid.org/0009-0005-4256-2129 Morteza Hosseinali Beygi https://orcid.org/0000-0003-3839-6891 Leila Kalani Sarokolayi https://orcid.org/0009-0005-2695-0359 Due to the importance of bridges as vital arteries and the huge investment of countries in building bridges, the need for more accurate seismic analysis of bridges to better understand their structural behavior is inevitable. Like many structures, the effect of the rotational components of the earthquake on bridges has been less noticed by researchers and designers. This research has evaluated the effect of the rotational components of the earthquake to better understand the seismic behavior of bridge. For this purpose, in addition to three translational components, the rotational components of the earthquake, including two rocking components and one torsional component, have been considered in the three-dimensional seismic analysis of box-girder concrete bridges. By creating the rotational component of the earthquake by the Hong-Nan Li method, three box-girder bridges with pier heights of 12, 30, and 45 meters were subjected to the combined effect of six translational and rotational components, as well as three translational components were separately subjected to under a far-field earthquake with different soil and shear wave velocity. The results of the analysis show that the effect of the earthquake's rotational components on the response of stresses and displacement, depending on the type of earthquake and the characteristics of the bridge structure, can be particularly important. 03 01 2025 55 61 https://creativecommons.org/licenses/by/4.0 10.61186/JCER.7.1.55 https://www.journals-researchers.com/ojs/index.php/jcer/article/view/136 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/136/170 https://www.journals-researchers.com/ojs/index.php/jcer/article/download/136/170