Structural performance of CFRP strengthened SHS beam-column connections subjected to monotonic loading: A numerical simulation

Square hollow sections (SHS) have been extensively utilised for welded steel beam-column connections in various structural applications. The performance of these connections can degrade over time due to the degradation of material, fatigue and fabrication as well as construction errors, which can lead to failure. Reinforcing i.e., strengthening SHS beam-column connections can play an important role in enhancing the safety of a wide range of new and existing steel structures. The current study reports a detailed parametric study using a recently developed numerical model and investigates the effects of employing carbon fibre-reinforced polymer (CFRP) composite wrap as a strengthening method for SHS beam-column connections under monotonic loading. A finite element (FE) based numerical model, verified against laboratory test results is used in the study. The influence of key parameters such as the thickness of the beam and column section, steel grade, CFRP modulus and strengthening scheme, on the structural performance of the SHS beam-column connections with and without CFRP is investigated. It is identified that the thicknesses of the beam and column section, steel grade and the modulus of elasticity of CFRP have a notable impact on the moment capacity, secant stiffness, energy dissipation and ductility factor of the connection. It is also found that partial strengthening by wrapping the beam region on three sides with CFRP sheets can increase their moment capacity by 41% compared to the bare connection. The full strengthening of the connection with CFRP recorded a higher increase in the moment capacity of 43%.