Abstract
Structural buildings are susceptible to both fire and earthquake events throughout their lifespan, which may occur concurrently or sequentially. Fires typically reduce a structure's stiffness and strength, and earthquakes can trigger fires, forcing structures already compromised by seismic activity to endure post-earthquake fires. This study investigates the post-fire performance of an innovative metallic trapezoidal damper, attached to the diagonal member of a concentric braced frame, through parametric and numerical analysis using the finite element method (FEM). Findings reveal that temperatures up to 200o C have minimal impact on the damper's performance. Dampers with thicker flange plates exhibit a greater reduction in structural parameters compared to those with thinner flange plates. Additionally, the reduction in structural parameters is more pronounced at lower ultimate temperatures (Tu) than at higher ones. When the capacity ratio of the web plate to the flange plate ranges from 1 to 3, structural parameters show a steeper decline, but this reduction rate decreases when the capacity ratio exceeds 3. Furthermore, the reduction rate at Tu=800oC is lower than at Tu=200oC.
Address
Chanachai Thongchom: Research Unit in Structural and Foundation Engineering, Department of Civil Engineering, Thammasat School of Engineering, Thammasat University, Pathumthani 12120, Thailand
Ali Ghamari: Department of Civil Engineering, Il.C., Islamic Azad University, Ilam, Iran
Denise-Penelope N. Kontoni: Department of Civil Engineering, School of Engineering, University of the Peloponnese, GR-26334 Patras, Greece; School of Science and Technology, Hellenic Open University, GR-26335 Patras, Greece
Abstract
In this study, analytical formulations are developed to estimate the fundamental periods of reinforced concrete buildings based on the roof (peak) displacement and the maximum interstory drift ratio. Unlike existing empirical equations reported in the literature, the proposed formulations are derived using equivalent shear and flexural beam models, ensuring a more rational representation of the lateral stiffness and deformation characteristics of building structures. Furthermore, an original formulation has been developed to enable the application of the proposed approach to shear-type building systems. Additionally, a complementary approach has been developed to enhance the applicability of the proposed method to reinforced concrete frames with infill walls. Comparative analyses using SAP2000 show that the proposed equations provide more accurate and comprehensive fundamental period estimates than existing seismic code relationships.
Key Words
fundamental period; maximum interstory drift ratio; seismic codes; top displacement
Address
Stelina Driza, Ahmet Eyol and Kanat Burak Bozdogan: Faculty of Engineering, Canakkale Onsekiz Mart University, Canakkale, Turkey
Abstract
Masonry structures have been a large part of the built environment for centuries, yet they remain highly vulnerable to seismic actions. Recent earthquakes have emphasized the need for reliable assessment methods and effective strengthening strategies. This paper presents a numerical investigation of unreinforced masonry (URM) walls retrofitted with reinforced concrete (RC) layers and subjected to in-plane cyclic loading. Three wall configurations were analyzed: a reference URM wall without retrofitting, a wall retrofitted with a 60 mm RC layer on one side, and a wall retrofitted with two 30 mm RC layers on
both sides. The seismic performance was evaluated using key indicators, including global capacity curve, ductility factor, stiffness degradation, and energy dissipation. The results show that RC retrofitting significantly enhances the seismic response of URM walls, improving load capacity, crack distribution, ductility, and energy dissipation. Among the studied configurations, the double-sided retrofitted wall achieved the best overall performance, highlighting the effectiveness of symmetric RC layers in reducing seismic vulnerability.
Address
Ait Hammou Hamza and Moulay Ali Chaaba: Department of Civil Engineering, National Higher School of Engineering (ENSAM), Moulay Ismail University, Meknes, Morocco
Abstract
In a recent strategy aimed at substituting non-renewable resources with natural, renewable alternatives that have
minimal economic and ecological impact, asphalt concrete mixtures incorporating plant fibers have increasingly attracted global interest. The present paper compares the mechanical properties of a reference asphalt concrete with those of esparto grass fiber (EGF)-modified asphalt concretes containing 0.1%, 0.3%, and 0.5% fibers by weight of aggregates. The results show that the mixture with 0.1% EGF achieved the best performance, with notable improvements in Marshall stability and stiffness modulus compared to the control mix. In contrast, EGF had no significant effect on compaction or water resistance (Duriez test). Overall, the findings indicate that low fiber dosages can enhance the mechanical performance of asphalt mixtures while contributing to more sustainable pavement materials.
Address
Abdelhalim Bensaada: Department of Civil Engineering, Faculty of Technology, University of Medea, 26000, Algeria; Civil Engineering and Environmental Protection Laboratory (LGPE), Civil Engineering Department, Faculty of Technology,
University of Medea, Algeria
Abderrahmen Younsi: Department of Civil Engineering, Faculty of Technology, University of Medea, 26000, Algeria
Melik Bekhiti: Department of Civil Engineering, Faculty of Technology, University of Djelfa, 17000, Algeria; Civil Engineering and Environmental Laboratory, Sidi Bel Abbes University, Algeria
Naas Alout: Department of Civil Engineering, Faculty of Technology, University of Djelfa, 17000, Algeria
Belgacem Choungache: Department of Civil Engineering, Faculty of Technology, University of Djelfa, 17000, Algeria
Smail Haddadi: Environment Laboratory, Water, Geomechanics and Structures, Faculty of Civil Engineering, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, 16000, Algeria
Abstract
In this study, we propose a method to alleviate the volumetric locking in the strain-smoothed 3-node triangular finite element. The strain-smoothed 3-node triangular finite element recently developed provides excellent performance. As Poisson's ratio close to 0.5, its predictive capability however deteriorates due to volumetric locking. To alleviate the volumetric locking, a node-wise smoothing process is employed only for volumetric strain while maintaining the formulation of the original strainsmoothed 3-node triangular finite element for deviatoric strain. The proposed strain-smoothed 3-node triangular element passes basic tests and exhibit alleviation of volumetric locking. Through various numerical problems, the performance of the proposed
strain-smoothed 3-node triangular element is demonstrated.
Key Words
finite element analysis; solid elements; strain-smoothed element method; volumetric locking
Address
Hoontae Jung, Yoon Sung Jeong and Phill-Seung Lee: Department of Mechanical Engineering, Korean Advanced Institute for Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea
Abstract
Rubberized concrete (RuC), incorporating crumb rubber from recycled scrap tires, offers a sustainable solution to the environmental challenge of tire waste disposal. Despite its potential, its optimizing mechanical properties, particularly strength, remains a critical challenge. This study explores the workability and strength characteristics of RuC produced by replacing fine and coarse aggregates with recycled crumb rubber (RCR). Replacement levels ranged from 10% to 100%, and water-to-cement (w/c) ratios of 0.48 and 0.30 were examined. The results revealed that increasing RCR content significantly decreased workability and compressive strength, primarily due to poor bonding between rubber particles and the cement matrix. However, a lower w/b ratio and the controlled use of superplasticizers partially mitigated these effects, improving both workability and tensile strength. The influence of the superplasticizer was clearly isolated through its application at consistent dosage levels across all relevant mix designs, ensuring that its effects were accurately assessed without interference from other variables. Compressive strength exhibited a reduction of more than 85% compared with the control mixes at 100% replacement, whereas the replacement of 10% fine RCR preserved over 80% of the reference strength. Splitting tensile and flexural strengths demonstrated reductions exceeding 70% at higher replacement levels, nevertheless, mixes incorporating 10-20% fine RCR at a w/c ratio of 0.30 achieved strengths close to those of the control specimens. Fine RCR performed better than coarse RCR in terms of workability and strength, particularly when replacement levels were kept below 30%. Furthermore, the impact resistance of RuC to cracking and final failure improved by 15%-17% at a 10% replacement level compared to the control. These findings highlight the potential of RuC as a sustainable material for selected non-structural and limited structural applications, emphasizing the importance of mix design optimization to balance sustainability with performance.
Key Words
coarse aggregate; concrete; crumb rubber; fine aggregate; water/binder
Address
Mohamed Ashraf Hegazi: Structural Engineering Department, Mansoura University, Mansoura 35516, Egypt
Mohamed M. Yousry Elshikh: Structural Engineering Department, Mansoura University, Mansoura 35516, Egypt
Mosbeh R. Kaloop: Department of Civil and Environmental Engineering, Incheon National University, Incheon, Korea; Incheon Disaster Prevention Research Center, Incheon National University, Incheon, Korea; Public Works Engineering Department, Mansoura University, Mansoura, Egypt
Jong Wan Hu: Department of Civil and Environmental Engineering, Incheon National University, Incheon, Korea; Incheon Disaster Prevention Research Center, Incheon National University, Incheon, Korea
Ibrahim Abd El-Mohsen: Civil Engineering Department, Damietta University, New Damietta 34517, Egypt
