Experimental and parametric studies of SCFs in FRP strengthened tubular T-joints under axially loaded brace

摘要

An experimental program was carried out on an axially loaded steel welded tubular T-joint made of circular hollow sections and strengthened with Glass/vinyl ester to study the effect of Glass Fiber Reinforced Polymer (GFRP) material on the Stress Concentration Factors (SCF) at both crown and saddle points on the chord member. Four tests were executed. The first test was performed on the plain joint which served as the reference for comparison, and the remaining three tests were performed on the strengthened joints with various FRP strengthening schemes. The arrangement of tests as well as specimen details together with most pertinent results are discussed. A significant drop in SCF values was observed for the FRP-strengthened T-joint as compared to the SCFs of the corresponding un-strengthened joint. The finite element model of the T-joint specimens were made and verified against the experimental data. Furthermore, extensive numerical analyses comprising of 1188 finite element models were performed to achieve a better understanding of the effect of the FRP parameters as well as the joint's geometric parameters on the chord's SCFs. Additionally, through nonlinear regression analysis, SCF design equations were proposed for the fatigue design of axially loaded FRP strengthened tubular T-joints.