https://ijce.sbu.ac.ir/ Interdisciplinary Journal of Civil Engineering en daily 1 Tue, 10 Mar 2026 00:00:00 +0330 Tue, 10 Mar 2026 00:00:00 +0330 https://ijce.sbu.ac.ir/article_107290.html Reinforced concrete (RC) columns are critical load-bearing components of structural systems, and their cyclic behavior is strongly influenced by the axial load ratio. Variations in the axial load ratio affect the stiffness, strength, ductility, energy dissipation capacity, and damage accumulation of RC columns. Therefore, evaluating the effect of axial load ratio is essential for accurate seismic performance assessment. In this study, the influence of different axial load ratios on the damage evolution of RC columns under cyclic loading was investigated using a nonlinear finite element model validated against experimental data. The Park–Ang damage index was used to evaluate damage evolution. The results showed that increasing the axial load ratio enhanced the initial stiffness and load-bearing capacity but reduced the deformation and energy dissipation capacities, resulting in faster damage accumulation. The maximum cumulative hysteretic energy and the highest Park–Ang damage index were observed at an axial load ratio of 0.20, highlighting the significant influence of axial load ratio on damage evolution. Comparison with experimental observations showed that although the Park–Ang damage index captures the overall trend of damage evolution, its values cannot accurately represent the actual damage states without calibration. https://ijce.sbu.ac.ir/article_107374.html Urban expansion and replacing natural land with impervious surfaces drive (UHI) formation. Along northern Iran, this phenomenon is influenced by urban development, hydrological fluctuations, and the Caspian Sea’s declining water level, which weakens its climatic moderating effect. This study examined ten-year changes in (LST) and Caspian Sea water extent (2015–2025) across Gilan, Mazandaran, and Golestan provinces. The framework relied on cloud computing and processing Landsat 8/9 imagery in GEE . Water bodies were delineated using the (MNDWI), while LST was retrieved from Landsat thermal bands. Satellite-derived temperatures were validated against NASA POWER data. Linear regression showed strong agreement (R^2 of 0.8376, 0.8699, and 0.8830 for Rasht, Sari,and Gorgan). Findings revealed a complex link between water extent shifts and thermal behavior. The most pronounced water retreat occurred in 2022, exposing barren coastal land and intensifying thermal hotspots. An exceptional thermal peak of 30.8 °C in 2021 potentially heightened evaporation and subsequent water retreat. Interprovincial comparisons demonstrated that Golestan experienced higher surface temperatures than Mazandaran and Gilan due to its drier climate and more pronounced shoreline retreat. Overall, Caspian Sea hydrological changes significantly drive thermal instability along northern Iran's coast.Consequently, sustainable planning for coastal cities must integrate sea-level decline scenarios and climate-adaptation strategies.