Research Output
Articles
Publication Date: 2025
Structures (23520124)72
Composite beams consisting of precast concrete slabs and steel beams connected by deconstructable high-strength friction-grip bolts (HSFGB) have recently attracted much research attention due to their compatibility with sustainable construction. However, studies on the behavior of these composite beams have been entirely deterministic, with no consideration for uncertainty in the governing parameters, especially for the bolted shear connector varieties. In this paper, a three-dimensional finite element model is developed to investigate the behavior of this type composite beam considering the nonlinearities of the geometry, materials, and component interfaces. Nonlinear springs with zero length are utilized to model the HSFGB shear connectors, and then the complete beam model is embedded in a Monte Carlo-based probabilistic assessment approach. The results show that the simplified spring model is reliable in predicting the behavior of composite beams while being efficient in terms of computational efficiency and time savings for conducting probabilistic analyses. The probabilistic analysis finds that Monte Carlo simulation is a useful method for identifying probabilistic trend behaviors with acceptable accuracy to quantify the effect of structural parameter uncertainties. The composite beam with a partial shear connection shows a greater variety of beam responses than the composite beam with a full shear connection. © 2025 Institution of Structural Engineers
Publication Date: 2025
Structures (23520124)75
Eccentrically braced frames (EBFs) are widely recognized as effective seismic resisting systems for buildings and other structures due to their high ductility and stiffness. The performance of EBFs heavily relies on the behaviour of the critical component known as the link, which governs the system's ductility, strength, and overall response. While the link is typically subjected to high shear force and bending moment, the significance of axial force in certain EBF configurations has received limited attention in previous studies and design codes. This research aims to investigate the effects of high axial load on the reliability and performance of EBF links using the finite element method. Experimental data is utilized to validate numerical models, ensuring the accuracy of the subsequent reliability analysis. The assessment of link reliability under high axial force is conducted within the framework of Eurocode 8 (EC8), employing the first-order reliability method (FORM). The results demonstrate that EBF links with very short lengths exhibit acceptable levels of reliability. However, as the link length increases, the target reliability index is not met. To address this challenge, a modification factor is proposed based on the Rackwitz–Fiessler iterative procedure, enabling adjustments to the link shear design. Furthermore, a sensitivity analysis is performed to evaluate the influence of random variables on the reliability analysis. © 2025 Institution of Structural Engineers
Publication Date: 2025
Structures (23520124)80
In this study, a novel method termed the Optimum Stiffness Finder (OSF) is introduced to determine the equivalent stiffness matrix for sandwich beams with lattice cores. The OSF method utilizes the Particle Swarm Optimization (PSO) algorithm to simplify the calculation of equivalent stiffness, addressing the challenges posed by the geometric complexity of lattice cores. This equivalent stiffness matrix is crucial for dynamic instability analysis, enabling the determination of dynamic instability regions that conventional finite element software does not calculate. For validation of the proposed method, the free vibration results of both three-dimensional finite element models developed in ABAQUS and OSF method are compared with results from the literature, confirming the accuracy of the finite element modeling. First, the free vibration results of three-dimensional finite element models developed in ABAQUS were compared with results from the literature, confirming the accuracy of the finite element modeling. Once validated, the ABAQUS models are used to obtain displacement values under uniform loading, which served as target data for the OSF algorithm. The OSF algorithm then optimized the stiffness matrix for Timoshenko beam theory in one-dimensional finite element analysis. The equivalent beam's vibration results are subsequently compared with those from the literature to ensure consistency and accuracy. The findings demonstrate the potential of the OSF method to streamline the dynamic stability analysis of lattice core sandwich beams, providing an efficient and accurate approach for engineering applications. © 2025 Institution of Structural Engineers
Publication Date: 2025
Steel and Composite Structures (15986233)56(1)pp. 49-65
The combination of precast concrete slabs and steel beams connected by deconstructable high-strength friction-grip bolts has emerged as a promising solution for sustainable construction. However, the lack of design guidelines and r egulations has restricted its widespread use. This study aims to conduct a reliability analysis to evaluate the flexural resistance factor (φ) for composite beams with HSFGB shear connectors, as the AISC Specifications incorporate the shear connector resistance factor as part of the overall resistance factor of the composite beam. To analyze the behavior of the composite beam, a three-dimensional finite element model was developed and validated. Additionally, a sensitivity analysis was performed to investigate the impact of various parameters on the flexural strength of the composite beam. The flexural resistance factor for this type of composite beam with varying degrees of connection was evaluated providing an acceptable level of safety. The variability and uncertainty in connectors were determined based on existing push-out tests using statistical analysis. A reliability study found that the reduction factor of flexural resistance for this type of composite beam is dependent on the degree of shear connection. Additionally, using the flexural resistance factor recommended for conventional composite beams with welded shear connectors in the AISC code is unconservative for deconstructable composite beams. © 2025 Techno-Press, Ltd.
Publication Date: 2024
World Conference on Earthquake Engineering proceedings (30065933)2024
Direct displacement-based design (DDBD) method as one of the new performance-based earthquake engineering methods has been developed widely in the recent years. Although DDBD method provides a suitable framework for seismic design, it is not economically viable in some cases. In this paper, the assumptions used in DDBD method are assessed and their effects on the results are discussed. Seismic performance of 6, 10, 12, 15 and 20-story steel moment resisting frames designed based on force-based design (FBD) and DDBD methods is compared using pushover analysis and nonlinear time history analysis first. In addition, the material usage of the designed frames are compared. Using the results of nonlinear time history analyses, important parameters that affect the structural performance of DDBD frames have been identified using sensitivity analysis. Results show that although DDBD method has been able to improve the seismic performance of the designed frames, it is not economically efficient for short and medium-rise frames compared to FBD method. On the other hand, not all the assumptions used in DDBD method agree with the nonlinear time history analyses results. Also, based on sensitivity analysis results, higher mode drift amplification, beam depth, yield displacement, equivalent viscous damping ratio and dynamic amplification of column moments have the greatest effect on the frame weight respectively. Results clarify that DDBD method assumptions need some improvement to optimize its results. © 2024, International Association for Earthquake Engineering. All rights reserved.
