Bending performance of splice connections for assembly of tubular section FRP members: experimental and numerical study

This paper presents experimental and numerical investigations of the bending performance of innovative splice connections developed for tubular section FRP members. Each of the splice connections consists of a steel bolted flange joint between two tubular steel-FRP bonded sleeve joints. Three connection specimens with different bolt configurations or bond lengths are prepared and tested under four-point bending. Finite element (FE) models are developed featuring a mixed-mode bilinear traction-separation relation for the adhesive bond, the Tsai-Wu failure criterion for the FRP, and yielding of the steel components. The contact behavior and bolt pretensioning are also modeled in detail. All of the connection specimens exhibit excellent ductility through yielding of the steel flange-plate before ultimate failure. The FE modeling, validated by the experimental failure mode, moment-rotation behavior, and strain response, provides insight into the adhesive stress distribution and the yielding mechanism of the steel flange-plates. According to Eurocode 3 for steel structures, the connection specimens are all classified as semirigid and partial-strength connections. The results also show that under flexural loading, the splice connections, which have ductility indices between 5.7 and 8.4, are able to impart ductility to a structure made of brittle FRP members.