International Journal of Civil Engineering最新文献

Flexible ring nets exhibit complex nonlinear mechanical behaviour when subjected to static and dynamic impact loads. This research presents the development of an efficient numerical model for assessing the performance of flexible netting barriers used in debris flow and rockfall risk mitigation. The model is calibrated through benchmark analyses and based on the equivalent stiffness method. The results demonstrate that the proposed numerical approach offers a significant computational cost reduction of 80% compared to complex numerical models while maintaining high accuracy. The coupled Eulerian–Lagrangian finite element method (CEL) is employed to simulate fluid–debris–structure interaction, showing damage characteristics consistent with flexible ring net barriers. The model is suitable for accurately determining the impact forces acting on the barrier and presents the debris behaviour and movement at various flow velocities. Notably, the results confirm that the presented model is capable of evaluating the interaction between the flexible barrier and debris flow with boulders and is an efficient approach to estimating the performance of flexible protection subjected to impacts.

A new retrofitting technique of CFRP–steel plate was proposed to retrofit the eccentric beam–column joint without sufficient transverse stirrups in the joint panel zone. Four specimens were fabricated with different retrofit techniques. The seismic performance of aforementioned specimens was studied through low-frequency reciprocating cycle load tests. Research shows that the yielding carrying capacity is increased by 24.35–47.65%, while the maximum carrying capacity is increased by 30.65–55.37% for the retrofitted specimen. Besides, the ultimate carrying capacity of the specimen retrofitted with CFRP, steel plate and CFRP–steel plate is increased by 32.26%, 41.08% and 58.41%, respectively. The displacement ductility coefficient of the retrofitted specimen is increased by 12.09–33.02%. The cumulative energy-dissipation capacity of the specimens is sequentially determined by specimen retrofitted with CFRP–steel plate, specimen retrofitted with steel plate, specimen retrofitted with CFRP sheet and specimen without retrofitting. The stiffness of the retrofitted specimen is greater than that of the specimen without retrofitting. The stiffness degradation rate of the specimen without retrofitting is greater than that of the retrofitted specimen. In general, the retrofit effect of steel plate on the eccentric beam–column joint is better than that of CFRP sheet, while the retrofit effect of CFRP–steel plate on the eccentric beam–column joint is most obvious. The calculation method of the shear carrying capacity of retrofitted eccentric beam–column joint was proposed. Comparison results show that the proposed calculation method can effectively predict the shear carrying capacity of retrofitted eccentric beam–column joint.

This study investigated the performance degradation of headed stud shear connectors in composite structures subjected to freeze–thaw cycles (FTCs). Parametric finite-element (FE) analysis was conducted, incorporating damage plasticity models to assess the failure progression of these shear connectors while considering concrete strength, stud dimensions, and FTC number. The parameters under scrutiny have concrete compressive strengths of 30/40/50/60 MPa, stud diameters of 13/16/19/22/25 mm, stud height–diameter ratios of 4/5/6, and FTC numbers of 0/50/100/150. A comprehensive parametric study was carried out to investigate the shear behavior of stud connectors under varying FTC conditions and identify the critical factors affecting their shear resistance. Results demonstrate that, in comparison to experimental findings, the ultimate shear strength obtained through numerical analysis falls within a margin of ± 10%, and the secant shear stiffness remains within ± 15%. Notably, FTCs exert a pronounced influence on ultimate shear strength and shear stiffness, with both parameters experiencing nearly a 20% reduction after 150 FTCs. Based on regression analysis of FE results, a new equation was proposed to determine the ultimate shear strength of headed stud shear connectors, incorporating four parameters: stud diameter, stud height, concrete compressive strength, and FTC number.

This work studies a new 90º connection system based on clamps for a square or rectangular steel profile, which can be used on existing structures without any prior or invasive operations. The main field where this connection system could be used would be in industrial plants, since it allows the reuse of industrial structures as many times as necessary, depending on each layout change, thus obtaining significant economic savings. This work aims to analyse the behaviour of this new type of connection using a 3D FEM-based numerical analysis procedure, previously validated against experimental tests. In this research, it has been possible to identify four behavioural modes, the first of which, linear behaviour, is the most suitable for the operational work of this type of connection. The distance between the bolts, one of the most important variables affecting the mechanical response, is parameterised and analysed in a numerical model. According to the results, the strength of the joint improves as the distance between the bolts increases, but this also means larger clamps and the need for more space.