Abstract
This study investigates the effects of sleeve characteristics on the mechanical performance of grouted sleeve connections through two experimental investigations. Four sleeve types with five different specifications were selected. The first investigation focused on the effect of reinforcement-to-sleeve clearance, involving 60 specimens subjected to unidirectional tensile test. The second examined the effects of sleeve material and internal construction through 36 specimens under the unidirectional tensile test, high-stress cyclic tension-compression test, and largedeformation cyclic tension-compression test. The results indicate that the increased reinforcement-to-sleeve clearance reduces connection strengths and increases deformation. Nevertheless, all specimens, including those with a sixgrade size mismatch, satisfied the performance requirements in current specifications, suggesting that the existing provisions are relatively conservative. In addition, internal ribs and shear grooves within the sleeve can enhance load transfer, but the effectiveness diminishes as clearance increases. During cyclic tension-compression loading, tensile fracture was the primary failure mode with specimens satisfying the specified strength and deformation criteria. Residual deformations and stiffness degradation were observed but remained within acceptable limits. Furthermore, sleeve material and construction influenced the overall stiffness of connections. Ductile cast iron sleeves demonstrated the highest stiffness, followed by machined steel sleeves, while rolled steel sleeves showing the lowest. These findings provide valuable experimental evidence for optimizing sleeve design and improving the reliability and efficiency of grouted connections in prefabricated construction.
Key Words
experimental investigation; grouted sleeve connection; mechanical performance; reinforcement-to-sleeve clearance; sleeve material and construction
Address
Zheng Lu: Department of Disaster Mitigation for Structures, Tongji University, Shanghai, 200092, China; State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai, 200092, China
Zhijie Wang, Xinghua Li, Gan Xu, Jianbao Li: Department of Disaster Mitigation for Structures, Tongji University, Shanghai, 200092, China
Abstract
This study explores the impact of soil-structure interaction on the design and analysis of a base-isolated RC frame building. The building's preliminary design employs the direct-displacement base design approach for low design inter-story drift that is compatible with the fully operational performance range. The lead rubber bearing serves as an isolator for the isolated building. The design forces and moments are determined by simulating the single-degree-of-freedom, base-isolated building, taking into consideration the impact of soil-structure interaction. The foundation is meant to keep eccentricity and safety factors within acceptable ranges. It is considered that the lateral deformation components include displacement generated by the isolator, the superstructure, and the foundation's rocking and swaying relative to the soil. The difference between the basic period with and without soilstructure interaction is also investigated. The approach is confirmed by time-history analysis of various soil profiles and base-isolated building layouts.
Key Words
base-isolated; deformation components; fundamental period; inter-storey drift; soil-structure interaction
Address
Manisana Rajkumar, Sunil Singh Mayengbam: Department of Civil Engineering, National Institute of Technology Manipur, Lamphelpat, Imphal, Manipur, 795004, India
Abstract
This study examines the role of aluminosilicate nanotubes (ANTs) in improving the performance of thermally cured geopolymer concrete (GPC) prepared using Class F fly ash and metakaolin. The main objective is to enhance early-age strength, durability, and microstructural stability of GPC under high-temperature conditions relevant to geothermal environments. ANTs were incorporated at 0-3.0 wt% of binder, and specimens were cured at 80oC. A systematic experimental program was conducted, including tests on flowability, compressive and tensile strength (3 h to 28 days), drying shrinkage, water absorption, and pore structure. Microstructural and chemical analyses were performed using XRD, FTIR, SEM, and TGA/DTG. Statistical evaluation was carried out using ANOVA and Tukey's HSD test to confirm the significance of results. Results show that ANTs reduce workability due to increased water absorption. However, significant improvements in mechanical and durability properties were observed. The optimum dosage of 2.0 wt% ANTs increased 1-day compressive strength by 32.77% and enhanced early tensile strength by up to 191%. This mix also showed the lowest water absorption and drying shrinkage, along with a denser pore structure. Microstructural results confirmed improved gel formation and matrix compactness. Hence, the study demonstrates that controlled incorporation of ANTs, especially at 2.0 wt%, can effectively enhance the performance of thermally cured GPC. This approach offers a durable and sustainable solution for construction in high-temperature environments such as geothermal tunnels.
Key Words
compressive strength; drying shrinkage; geopolymer composites; nanotubes; scanning electron microscopy; thermal curing
Address
Umara Nasir: Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan
Nejib Ghazouani: Mining Research Center, Northern Border University, Arar, 73213, Saudi Arabia
Mohd Ahmed: Department of Civil Engineering, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia; Center for Engineering and Technology Innovations, King Khalid University, Abha 61421, Saudi Arabia
Abstract
Under the evolution of traffic flow, Modular Expansion Joints (MEJs) needs to meet the needs of adapting to constrained deformation on both sides while bearing direct vehicular loads. This operational state results in continuous non-uniform spatial coupling of multiple internal components under time-varying load, making the wear assessment of inter-component connecting materials both complex and essential. Firstly, based on the spatial movement patterns of the internal components and the locations of connecting materials in MEJs, the wear forms of the connecting material between the components are determined and the indicators are parameterized, and the spatial index system for wear in MEJs is proposed. Secondly, simulate the evolution of operational traffic flow, establish a bridge-expansion joint orthogonal model at the same scale, solve the switching and allocation of vehicle load forms on the model, and improve the traffic-bridge-expansion joint analysis system. Finally, taking a typical cable-stayed bridge equipped with MEJs as the engineering background, the wear indicators of MEJs under the evolution of traffic flow are analyzed. The results show that: (1) the patterns of wear of connecting materials in the MEJs is different from the rule of absolute displacement of center beam commonly used in the evaluation of MEJs, and there is also a multiple difference in the value. The absolute displacement of center beam cannot be used for the evaluation of wear of MEJs; (2) the cumulative relative displacements between adjacent center beams and between upper/lower beams all exhibit monotonically decreasing trends from both sides toward the middle of the MEJs structure. The minimum and maximum wear indicators of shear springs show a difference of approximately 9.2 times, while the wear indicators of bearing between upper/lower beams demonstrate a difference reaching 21.24 times. The shear springs and connecting materials between upper/lower beams require differentiated parameter designs. Connecting materials within the same-side displacement box may adopt identical parameters, whereas those on different sides require differentiated designs.
Address
Ning Liu: School of Civil Engineering, Hebei University of Engineering, Handan, 056038, China; Key Laboratory of Transport Industry of Bridge Detection Reinforcement Technology (Chang'an University), Xi'an, 710000, China
Huanju Liu: School of Civil Engineering, Hebei University of Engineering, Handan, 056038, China; Civil Engineering Department, Faculty of Engineering, Universiti Malaya, Kuala Lumpur, 50603, Malaysia
Suhana Binti Koting: Civil Engineering Department, Faculty of Engineering, Universiti Malaya, Kuala Lumpur, 50603, Malaysia
Xiangqun Hu: School of Civil Engineering, Hebei University of Engineering, Handan, 056038, China
Yu'ang Zhan: School of Civil Engineering, Hebei University of Engineering, Handan, 056038, China
Abstract
The design of slender reinforced concrete columns using the Finite Element Method (FEM) typically requires a full nonlinear analysis. Such analysis demands refined discretization, and the element formulation must account for both geometric and material nonlinearities, implemented within a robust solver using incrementaliterative methods. In this context, this paper proposes a one-element formulation for the design of slender reinforced concrete columns, based on analytical interpolation functions associated with the moment-curvature relationship and the Two Cycles Iterative Method. The results demonstrate that the proposed formulation can efficiently capture the P-
o effect and accurately compute the bending moment distribution along slender columns using a single element per member, eliminating the need for structural discretization and complex nonlinear solution schemes.
Key Words
analytical interpolation functions; moment-curvature relationship; one-element formulation; slender reinforced concrete columns; two cycles iterative method
Address
Marcos Antonio Campos Rodrigues: Department of Civil Engineering, Federal University of Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil
Sara de Jesus Bulhosa: Department of Civil Engineering, Federal University of Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, Vitória, ES 29075-910, Brazil
Rodrigo Bird Burgos: Department of Structures and Foundations, Rio de Janeiro State University, St. São Francisco Xavier, 524, Maracanã Rio de Janeiro, RJ 20550-900, Brazil
Luiz Fernando Martha: Department of Civil and Environmental Engineering, Pontifical Catholic University of Rio de Janeiro, St. Marques de São Vicente, 225, Gávea, Rio de Janeiro, RJ 22451-900, Brazil
Abstract
For concrete beams reinforced with hybrid fiber reinforced polymer (FRP)–steel bars, prevailing codes typically employ the neutral axis depth (c/d) to quantify the degree of moment redistribution (B). Nonetheless, this parameter predominantly reflects sectional behavior and may not accurately capture global structural response. Furthermore, the inherent bond–slip between FRP and concrete significantly influences the moment redistribution characteristics of the structure. To address these deficiencies, this research develops a finite element (FE) model that explicitly incorporates bond–slip effects. An improved simplified model for predicting moment redistribution is also proposed, highlighting the influence of relative stiffness, expressed as pt1/pt2, where pt1 and pt2 represent the effective reinforcement ratios in the sagging and hogging moment regions, respectively. Numerical analyses demonstrate that the B is dictated not only by c/d, but is also strongly governed by pt1/pt2. Accordingly, the BSI model is modified to incorporate both c/d and pt1/pt2 as key parameters within the redistribution assessment framework. Comparative evaluation against FE model results confirms that the proposed simplified model significantly improves prediction accuracy for B, affirming its applicability and reliability for this class of beams.
Key Words
bond–slip; finite element model; hybrid FRP–steel bars; moment redistribution; simplified model
Address
Yanan Wu: Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, 572000, China; School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China
Bo Chen: Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, 572000, China; School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China
Sergio M.R. Lopes: CEMMPRE, ARISE, Faculty of Sciences and Technology, University of Coimbra, Coimbra 3030-788, Portugal
Adelino V. Lopes: INESC Coimbra, Department of Civil Engineering, University of Coimbra, Coimbra 3030-788, Portugal
Yi Dong: School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China
Tiejiong Lou: Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, 572000, China; School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China; CEMMPRE, ARISE, Faculty of Sciences and Technology, University of Coimbra, Coimbra 3030-788, Portugal
