Dynamic assessment of shear connection conditions in steel-concrete composite structures

Composite slabs are widely used in bridges that consist of a reinforced-concrete slab supported on steel or concrete girders, Their behaviour is highly affected by the level of interaction that occurs between the reinforced concrete slab and the steel or concrete girders joints, which is usually provided by the presence of the shear connectors. Damage or failure of the shear connectors will affect the composite action of the bridge girders and slab, and therefore reduce the bridge load-carrying capacity and the horizontal shear resistance. The inaccessibility of the connection system makes direct inspection difficult. On the other hand, the huge number of shear connectors prevents any local non-destructive testing methods to access the connectors one by one. It is of practical importance to develop a new non-destructive assessment technique to detect the integrity of shear connectors. This paper presents an experimental study on condition assessment of the shear connectors in the steel-concrete composite structures. Some removable anchors were specially designed and fabricated to link the beams and slab that cast separately. Each anchor consists of a threaded bar that penetrates through the soffit of the beam and ties up into an embedded nut cap to simulate a shear connector in the real bridges. Different damage scenarios were introduced by pulling out some connectors. Vibration tests were carried out in each damage scenario. Various damage detection methods have been developed and results show that the method was able to detect all the damage successfully and consistently.