https://www.arce.ir/ Advance Researches in Civil Engineering en daily 1 Sun, 01 Dec 2024 00:00:00 +0330 Sun, 01 Dec 2024 00:00:00 +0330 https://www.arce.ir/article_250668.html This research presents a three-dimensional numerical comparison of helical and conventional pile ‎foundations subjected to sequential seismic and wind loading using PLAXIS 3D. Eight scenarios ‎were analyzed by integrating soil stratification, pile type, and layout configuration to evaluate ‎lateral displacement, stress distribution, and bending behavior under dynamic conditions. The ‎results show that helical piles consistently outperform conventional piles, reducing maximum ‎lateral deformation by approximately 15–40%. The greatest improvement is observed in clay-‎over-sand profiles, where deeper sand confinement enhances stiffness and limits pile curvature. ‎In contrast, sand-over-clay stratifications exhibit the largest displacements due to stiffness ‎inversion and the dominance of weak deep clay layers. Wind loading applied after seismic ‎excitation further increased displacement in all cases, highlighting the cumulative effects of ‎multi-hazard loading and post-seismic soil softening. Overall, the findings provide quantitative ‎insight into soil–pile interaction in layered soils and support the use of helical piles within ‎performance-based foundation design for dynamic environments.‎ https://www.arce.ir/article_250669.html Rapid growth in private-vehicle use and limited upgrades to traffic infrastructure have led to chronic congestion at key intersections in Baghdad. The Al-Faris Al-Arabi Roundabout is a critical bottleneck, with long queues and unstable circulating flow during peak hours. This study applies an integrated approach that combines field traffic counts, a commuter-perception survey, and microscopic simulation using PTV VISSIM to assess existing conditions and test improvements. Baseline results show average delays of about 80 s/veh, queues exceeding 150 m, and Level of Service (LOS) D, while more than 70% of surveyed users report daily delays above 20 minutes and noticeable stress and health impacts. Two mitigation strategies are evaluated: a flyover connecting Al-Mansour and Al-Zaytoun Streets, and adaptive signal control at the roundabout entries. The flyover reduces delays by roughly 19% and queues by 38%, whereas adaptive signal control achieves delay reductions of about 14.5% and queue reductions near 30%, with lower cost and faster implementation. The findings highlight the value of combining field data, user perceptions, and simulation to support congestion-mitigation decisions in rapidly developing cities like Baghdad. https://www.arce.ir/article_250671.html Soil–structure interaction (SSI) alters stiffness, damping, and load paths in braced high-rise frames, but the comparative efficiency of bracing layouts under SSI remains insufficiently quantified. This study numerically evaluates a 15-story reinforced-concrete frame on clay soil using Hardening soil with small-strain stiffness soil model (HSsmall)using PLAXIS 2D, testing five steel bracing configurations—X, K, V, inverted-V, and single diagonal—subjected to three recorded earthquakes (Northridge, Imperial Valley, Kocaeli). Response metrics include interstory drift ratio (IDR), roof displacement relative to the moving base, raft rotation, and settlement. The bracing schemes and the small-strain soil formulation are detailed to ensure like-for-like comparison under SSI. Across free-vibration checks, SSI lengthened the fundamental period relative to a rigid base, confirming the role of foundation compliance. Under Northridge and Imperial Valley, bracing reduced peak IDR by ~44–48% and ~46% (from ~1.01% and 0.80% to 0.43–0.56%), with K and X consistently top performers and the diagonal layout least effective. For Kocaeli, drift gains were smaller (31–37%), reflecting longer-period content and narrowing performance gaps. Roof-drift reductions were modest overall, whereas bracing frequently increased foundation rotation (with record dependence), revealing a drift–foundation-demand trade-off under SSI. These results indicate that configuration choice under SSI is motion-dependent; K/X provide robust drift control, but designers should verify raft serviceability where stiffening could elevate rocking and settlement demands. https://www.arce.ir/article_250672.html This study investigates the differences between modeling piles as Embedded Beam Rows and Volume Elements in supporting a pier foundation under dynamic loading. Using PLAXIS2D, the system was analyzed under uni-directional and bi-directional excitations derived from the Northridge earthquake. The results show that both modeling approaches captured the vertical load transfer mechanism; however, the foundation settlement in the Volume Element model was found to be about five times larger due to its explicit representation of pile-soil contact, allowing for soil yielding and nonlinear deformation. The Embedded Beam Row model, using simplified linear springs, produced a stiffer response and smaller settlements. Additionally, the horizontal acceleration at the tower head was higher than at the foundation, mainly due to dynamic amplification and the tower’s flexible cantilever behavior. The study highlights the strengths and limitations of each modeling technique, offering insights for future seismic analyses of pile-supported structures. https://www.arce.ir/article_250673.html Earthquakes cause severe economic losses worldwide, yet earthquake insurance penetration remains low in many seismic-prone regions. This paper provides a comparative review of earthquake insurance regulations in eight selected countries: Japan, New Zealand, Turkey, the United States (California), France, Spain, Chile, and Taiwan. The study examines legal frameworks, institutional structures, mandatory/voluntary nature, pricing mechanisms, government roles, and post-earthquake performance. Results show that no single model is perfect. Japan and Turkey have successfully implemented mandatory systems with government backing, while New Zealand offers an integrated public-private model. The United States (California) struggles with low take-up rates despite high risk. France and Spain utilize solidarity-based state reinsurance mechanisms. Chile achieves high penetration voluntarily due to strict building codes. Taiwan follows a Japanese-style mandatory fund. Common challenges include inadequate coverage, delayed claims, and public reluctance. The paper concludes with policy recommendations for earthquake-vulnerable countries, including Iran.