Behaviour and strength of shear connectors utilising blind bolting for composite steel-concrete beams

The paper herein describes the experimental investigation and numerical modelling of the behaviour and strength of different shear connectors for composite steel-concrete beams. Three types of shear connectors were used. They included headed stud shear connectors, blind bolt type I and type 2. The blind bolts are used because portable and recyclable structures can be developed, hence contributing to significant sustainability benefits. The experimental studies were designed according to the standard Eurocode 4 push tests. Special attention was given to the modelling of the geometric and mechanical characteristics of the bolts including the shank, head and nut. For headed stud shear connectors, the failure mode observed was stud fracture. This is because the ultimate stress of the stud was achieved before the crushing stress of the concrete was reached. For blind bolt type I, cracks started to appear from the middle of the bottom bolt and concrete around the bottom bolts started to crush and fell off. It was observed in all the specimens that failure was due to concrete cracking and crushing. For blind bolt type 2, it was observed that crack formation and concrete crushing were due to pulling out of the bolts away from the concrete. The expansion of the sleeve of blind bolt type 2 was the major cause of the cracks. The load-slip relationship for the three different shear connectors demonstrated that the ultimate strength achieved by all the connectors were well above 90kN per connector. The pertinent results obtained from the finite element analysis were verified against experimental results. Based on the experimental investigation and finite element analysis, the blind bolts were significantly appropriate to be used as shear connectors. It can be concluded that in order to construct portable composite steel-concrete structures, blind bolts could be utilised in lieu of welded headed stud shear connectors