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CONTENTS
Volume 29, Number 2, August 2025
 

Abstract
This paper introduces an advanced method for analyzing the mechanical behavior of functionally graded porous (FGP) beams resting on a Winkler-Pasternak elastic foundation. The approach integrates high-order deformation theory with Timoshenko beam theory to enhance accuracy. The governing equations are derived using Hamilton's principle, and the state-space method is applied for their resolution. The study examines three different boundary conditions and two porosity distribution patterns—symmetric and asymmetric. It systematically investigates the impact of porosity, boundary conditions, foundation parameters, span-to-height ratio, and porosity distribution on the natural frequencies of FGP beams.

Key Words
boundary conditions; elastic foundation; FGP beams; state-space approach; vibration analysis

Address
Tlidji Youcef: 1) Department of Civil Engineering, University of Tiaret, Algeria, 2) Materials and Structures Laboratory, Civil Engineering Department, University of Tiaret, Algeria
Benferhat Rabia and Hassaine Daouadji Tahar: 1) Department of Civil Engineering, University of Tiaret, Algeria, 2) Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria

Abstract
This study investigates structure-soil-structure interaction (SSSI) effects on foundation forces and settlements of adjacent reinforced concrete buildings under seismic loading. SAP2000 was incorporated for developing a 3D finite element model for analysing two identical three-story RC frame buildings with a 50 mm seismic gap between them. The study compares three scenarios: Non-Interaction Analysis (NIA) with fixed base, Soil-Structure Interaction (SSI) for a single building, and SSSI for two adjacent buildings on the same soil domain. Response spectrum analysis following IS 1893:2016 was implemented. The results show that SSSI significantly redistributes foundation forces, with reductions up to 7% in some footings and increment up to 13% in others compared to SSI conditions. Footings in alignment with adjacent buildings experience the most pronounced force amplifications. Settlement patterns under SSSI conditions show distinct asymmetry, with increment up to 15.8% under gravity loading and 7.6% under seismic loading compared to SSI conditions. These findings suggest that conventional fixed-base analysis may underestimate foundation forces and settlement values, potentially reducing effective seismic gaps and increasing pounding vulnerability. The research offers valuable insights for seismic design practices in densely populated urban environments where buildings are constructed in close proximity.

Key Words
axial forces; finite element method (FEM); response spectrum analysis; seismic analysis; settlement; soil-structure interaction (SSI); structure-soil-structure interaction (SSSI)

Address
Department of Civil Engineering, Maulana Azad National Institute of Technology, Bhopal, India

Abstract
This paper investigates the impact of time lag, defined as the time difference between the arrival of seismic waves and trains at the observation point, on the dynamic response of the vehicle-bridge system (VBS). Firstly, a 9x32 m simply-supported bridge (SSB) model of the high-speed railway (HSR) was modelled using OpenSees, where the wheel-rail interaction was simulated using a self-developed wheel-rail element. Subsequently, fifty seismic waves were selected from the PEER Strong Motion Database using the dual-band ground motion selection method tailored to the site characteristics. A series of numerical simulations were conducted, examining the mutual influence between seismic waves and track irregularity, as well as the influence of the number, intensity, and time lag of seismic waves on the VBS's peak response. The findings reveal that: (1) For a 32 m SSB system, the VBS's dynamic response becomes stable and reliable with more than 35 seismic waves, albeit at the expense of reduced computational efficiency. (2) Higher seismic intensity results in larger peak responses and greater variability in the VBS's seismic response. (3) In most cases, a smaller time lag between seismic waves and trains amplifies the system's dynamic response more. The peak dynamic response is largest when seismic waves and the train arrive at the bridge mid-span simultaneously, posing the most significant risk and requiring increased attention. (4) The system's dynamic response is smaller under positive time lag conditions (where the train arrives first) than under negative time lag conditions. (5) Slower train speeds reduce the dynamic response but do not eliminate the risks associated with the coupling effects of earthquakes and train-induced vibrations. Overall, the number and time lag of seismic waves should be carefully considered in the seismic dynamic analysis of VBS.

Key Words
bridge engineering; OpenSees; peak response; seismic response; time lag; vehicle-bridge system

Address
Liu Hanyun, Zhou Naya, Mao Na and Hu Peng: School of Civil and Environmental Engineering, Changsha University of Science & Technology, Changsha 410114, China
Mao Jianfeng: National Engineering Research Center of High-Speed Railway Construction Technology, Changsha 410075, China

Abstract
This paper reviews the current literature on the use of artificial intelligence in soil structure interaction (SSI) analysis and design. This paper provides a comprehensive review synthesizing current AI applications across multiple SSI domains, balancing breadth of coverage with analytical depth in each subdomain. These include some of the significant features of the review such as the foundation engineering, underground structures and seismic SSI. Some approaches such as artificial neural networks, support vector machines, genetic programming and Bayesian methods are briefly described with respect to the SSI application area. The applicability of these techniques, their shortcomings and modern trends are viewed critically. The paper presents an overview and discussion of various articles in the field of AI for SSI over the last decade. Based on the analysis, some of the major issues that may be encountered in applying AI for SSI problems are discussed as well as possible future research avenues are pointed out. The present review will thus provide the readers a single source of information compiling the state-of-the-art advances in using AI in soil-structure interaction.

Key Words
artificial intelligence; foundation engineering; geotechnical engineering; machine learning; seismic analysis; soil-structure interaction; underground structures

Address
Department of Civil Engineering, Maulana Azad National Institute of Technology, Bhopal, India

Abstract
Semi-continuous steel shear walls are one of the lateral-resistant systems that do not apply any force to the column until the final moment. Since these shear walls are connected to the structure only at the bottom and top, they are prone to buckling, and the presence of stiffeners improves their behavior. In this research, parametric studies were conducted to investigate the seismic behavior of these shear walls equipped with stiffeners. For this purpose, the numerical model was first verified using two experimental samples. Then, the influence of the stiffener placement geometry on the seismic parameters of the frame, including elastic stiffness, ultimate strength, ductility, and energy dissipation, was investigated. The stiffener geometry was considered in three different shapes, while the shear wall width was considered in ten modes. Also, the effect of stiffener geometry on the dynamic behavior of the frame was evaluated. The research findings indicate that when a stiffener is added, it reduces the out-of-plane buckling and causes the maximum stresses to concentrate at the bottom of the shear wall. Moreover, increasing the width of the shear wall directly impacts the effect of stiffeners. Additionally, using X-shaped stiffeners results in the highest energy dissipation, elastic stiffness, and strength.

Key Words
energy dissipation; numerical analysis; push-over analysis; reinforced concrete frame; steel shear wall

Address
Department of Civil Engineering, University of Mazandaran, Babolsar, Iran

Abstract
The reliability of bridge piers under seismic action is critical to the overall seismic performance of a bridge. RC piers, though cost-effective, are prone to damage due to self-weight, brittleness, and poor crack resistance, leading to steel corrosion and reduced load capacity. To address these limitations, this study introduces an HSREC (High-Strength Reinforced Engineered Cementitious Composite) pier system utilizing ECC materials and high-strength reinforcement to enhance seismic performance. Nonlinear seismic models were developed in OpenSees and validated experimentally to analyze the seismic responses of RC, REC, and HSREC piers under varying reinforcement strengths and replacement rates. The analysis reveals that HSREC piers exhibit improved bearing capacity and displacement compared to traditional RC piers, leading to enhanced seismic resilience. Additionally, the replacement rate of high-strength steel bars was found to be a critical factor in improving energy dissipation and reducing vulnerability. The study further demonstrates that under high-intensity earthquakes, the top displacement of REC and HSREC piers was notably lower than that of RC piers. For rare seismic, the probability of severe damage was significantly reduced for both REC and HSREC piers, underscoring the substantial improvements in seismic resilience. These findings underscore the potential of integrating ECC and high-strength steel reinforcement as a promising strategy to enhance the safety, durability, and seismic performance of bridge piers in seismic-prone regions.

Key Words
bridge piers; engineered cementitious composites (ECC); finite element modeling; high-strength reinforced engineered cementitious (HSREC); high-strength steel bars; nonlinear time history analysis; nonlinear time history analysis; seismic performance; seismic vulnerability

Address
Syed Basit Ali, Yan Liang, Li Yan, Pei Chen and Pinwu Guan: School of Civil Engineering, Zhengzhou University, Zhengzhou 450000, China
Jingxiao Shu: 1) School of Civil Engineering, Zhengzhou University, Zhengzhou 450000, China, 2) Henan Province Expressway Network Management Center, Zhengzhou 450000, China

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