Behaviour of pultruded GFRP truss system connected using through-bolt with mechanical insert

Abstract

This paper presents the experimental and analytical studies of double-chorded composite truss system connected using stainless steel through-bolts with mechanical inserts. The composite trusses were assembled using rectangular hollow sections of pultruded glass fibre reinforced polymer (GFRP) where adhesively bonded mechanical inserts were introduced at the vicinity of the joining areas. The trusses were tested under 4-point bending (Load Case 1) and 3-point bending (Load Case 2). From this experimental program, the load-vertical deflection behaviour of the truss, internal forces distribution in the members and joint behaviour were investigated. The pultruded GFRP truss under Load Case 1 was capable of resisting the maximum load capacity of the testing equipment at 450 kN with the lowest factor of safety of 1.10 was attained by the external diagonal members. High axial compression forces experienced by the external diagonal members has exceeded the American pre-standard theoretical joint bearing capacity by 2%, and this was reflected by the minor bearing damage observed on the joints of these members. Meanwhile, the truss under Load Case 2 failed at 160 kN with the continuous top chords ruptured in flexural bending manner. The satisfactory comparisons between the Strand 7 truss model and experimental results demonstrated the validity of the adopted simplified numerical model. Additionally, the theoretical strength limits of pultruded GFRP truss members in tension, compression and flexural according to American pre-standard are in close agreement with the experimental results.