Effect of Connection Techniques on the Static and Fatigue Performance of Pultruded Basalt FRP Multibolted Joints
Diana S. E. Abdelkerim, Xin Wang, Haitham A. Ibrahim, Zhishen Wu
Abstract
The loading capacity of pultruded fiber-reinforced polymer (FRP) multibolted joints typically controls the structural design of composite structures. This study focuses on enhancing the low loading capacity of conventional unidirectional pultruded FRP-bolted joints by investigating the efficiency of three types of connection techniques: bonded and bolted joints, resin-injected bolted joints, and bolted joints with additional bidirectional FRP layers. Sixty-eight specimens of double-lap multibolted basalt FRP (BFRP) joints, constructed with stainless steel (SS), BFRP, or hybrid steel-FRP bolts (HSFRP), were tested under static, fatigue, and postfatigue static loadings. The results indicated that an increase of up to 60% in the loading capacity of the conventional bolted connection could be achieved by adopting the aforementioned three techniques. Furthermore, at a targeted fatigue life of two million cycles, the resin-injected bolted joints and bolted joints with additional bidirectional BFRP layers improved the load efficiency of the conventional joints by 24%. Additionally, the proposed BFRP and HSFRP bolts proved their reliability in replacing conventional SS bolts without affecting the loading capacity of the composite joints, regardless of the connection technique used.