Assessment of shear connection condition in slab-girder bridges by wavelet based Kullback-Leibler distance

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 the application of any local non-destructive testing methods to identify their conditions. It is of practical importance to develop a new non-destructive assessment technique to detect the integrity of shear connectors. In this study, a method based on wavelet Kullback-Leibler distance was developed to assess the integrity of the shear connectors. Some removable bolts are specially designed and fabricated to link the beams and slab that cast separately. Different damage scenarios were introduced by pulling out some connectors. Vibration tests were carried out in each damage scenario. The results show that the method was able to detect all the damage successfully and consistently.