Prying model and mechanism for circular all-FRP flange integrally formed with tube

Abstract

This paper focuses on prying action of integrally-formed circular all-FRP flanges intended for assembly of FRP members. The connection is manufactured by prepreg hand-work layup and compression moulding process. Tensile tests have been performed on three connections of different flange thickness (2.2 mm, 3.0 mm, 3.8 mm). The influences of flange thickness and bolt preloads on prying force have been investigated. Corresponding displacements and strains on tube and flange plate were also analyzed. Then, an analytical model for prying force as well as displacement, strain and stress fields is developed based on the lamination theory of circular shells and plates and the compatibility equations. Quite good agreement is obtained when predicting prying effect factor and fairly good agreement is achieved for flange separation and strains. The experimental and theoretical results indicate that prying force has negative correlation with flange thickness when flange is thick enough, but contrary when flange is very thin. Further theoretical analysis shows that reducing bolt stiffness by BFRP bolts will significantly reduce prying force, by the maximum 39.06% for the connection with 23 mm-thick flange.