Contribution to the Determination of the Load-carrying Capacity of Friction Grip Bolts Used as Shear Connections in Composite Steel Beam Structures.

Composite beams with precast slabs in which high-strength friction-grip bolts transmit horizontal shear forces between steel beams and concrete slabs have many advantages. This report introduces tests on this kind of shear connection. During lower loading levels the transmission of horizontal shear is related completely to friction, whereas after exceeding the maximum friction force a combined action of friction and shearing takes place. Neither the size of the hole for the bolts nor eccentrically positioned bolts have much effect on the load-carrying capacity. In the case of fatigue positive behavior was observed. The loss of the initial prestressing forces in high-strength bolts due to creep and shrinkage of the concrete was determined by means of long-term tests.