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In typical square tubular joints, the most common failure mode is local yielding or buckling of the chord at the brace/chord intersection. Thus, in the current paper, a collar-plate, as external reinforcement, is welded around the weld toe to increase the stiffness of the chord surface. Firstly, theoretical formulas, based on the yield line principle which is often used to examine thin-walled members suffering from local collapse mechanisms, for calculating the capacities of the collar-plate-reinforced square tubular T-joints under axial compression and in-plane bending are deduced. Then, experimental tests and finite element (FE) simulations are carried out on square tubular T-joints reinforced with collar-plates. The experimental results showed an improvement in the bearing capacity of SHS joints reinforced with collar-plate by 78 and 89% compared with the corresponding un-reinforcement joints. The FE results, as well, proved that using the collar-plate reinforcement is an efficient method to improve the static strength of a square tubular T-joint under either axial compression or in-plane bending. Finally, through the comparison between the FE results and the theoretical formulas, the validation range of the formulas for predicting the strengths of the collar-plate-reinforced square tubular T-joints is specified. For the joints under axial pressure, the validation range of the proposed formula is 0.45 ≤ βc ≤ 0.8, 2γ ≥ 20 and τc ≥ 1.5, while for the joints under in-plane bending is βc ≤ 0.8, 15 ≤ 2γ ≤ 30 and τc ≥ 1.50. [ABSTRACT FROM AUTHOR]

In recent years, high-strength steel (HSS) has been widely used in many applications due to its high shear strength, low material consumption and lightweight. Due to the need for the installation of pipelines and mechanical equipment, the use of web opening is necessary in such structures. Therefore, this study aims to investigate the shear strength of HSB800 corrugated web girders (HSB800-CWGs) with circular opening. Firstly, a finite element (FE) model was established by ABAQUS and verified through the existing experimental results found in the literature. Thereafter, 742 FE models were established to investigate the shear strength and failure characteristics of the HSB800 corrugated web girders (HSB800-CWGs) with circular opening. The results show that the presence of an opening in the HSB800-CWGs reduces the shear strength. Furthermore, HSB800-CWGs with circular opening tend to experience failure under global buckling rather than local of intermediate buckling at the vicinity of the opening. As the opening position shifts longitudinally, the shear strength varies significantly according to the opening's location on the corrugated web waves. While, when the opening position changes laterally, the shear strength increases gradually if | e y / h w | > 0.2. Finally, a calculation formula for the elastic–plastic shear strength of HSB800-CWGs with an opening is proposed by regression analysis using MATLAB programing language. • Using ABAQUS, 742 finite element models of HSB800-CWGs with circular opening were generated. • The effects of opening on shear strength of HSB800-CWGs with circular opening were investigated. • The most unfavorable opening position in CWGs were put forward. • A new design equation for HSB800-CWGs with circular opening was proposed. [ABSTRACT FROM AUTHOR]

The current study focuses on estimating the fatigue life of circular hollow section (CHS) gap TT-joints reinforced with carbon fibre reinforced polymer (CFRP) sheets based on S–N curve method. In the S–N curve, the fatigue life of a tubular joint can be predicted from the hot spot stress (HSS) which can be easily calculated from the stress concentration factor (SCF) of the tubular joint. The SCF and the fatigue life of the CFRP-reinforced and unreinforced TT-joints under axial loads were experimentally measured. The experimental results show that the maximum SCF of CHS TT-joints reinforced with CFRP sheets decreases by 14%, and the fatigue life increases by 47%. Thereafter, finite element (FE) models for both CFRP-reinforced and unreinforced TT-joints were established and verified by the experimental results. A parametric study is also carried out to investigate the effects of the number of CFRP layers and the geometrical parameters on the SCF. Finally, through regression analysis on the numerical SCF results of 704 FE models, parametric equations are proposed to estimate the SCFs at the saddle and at the crown of CFRP reinforced CHS gap TT-joints. • Fatigue test on CFRP-strengthened CHS TT-joint was conducted. • Finite element model of CFRP-strengthened CHS TT-joint was built. • Parametric study of SCF for CFRP-strengthened CHS TT-joint was carried out. • Equations for predicting SCFs at critical positions of CFRP-strengthened CHS TT-joint was presented. [ABSTRACT FROM AUTHOR]