Abstract
Three RC slabs were cut out from an existing composite girder bridge used for about 24 years. The two slabs among them were devoted to fatigue test using a wheel tracking machine with a pneumatic tire in a laboratory, and the remaining one slab was devoted to statically loading test. The fatigue test was carried out under a constant load of 11tf, 13tf, and 15tf respectively, and one slab collapsed in punching shear mode at 30×104 in the total repetition of wheel tracking. On the other hand, the statically loading capacity of the slab was found about 79tf in punching shear mode. Based on the data obtained here and referring the past studies on similar problems, a relationship between damage degrees of the slab and the repetition of wheel tracking was discussed. The vertical shear slip on cracked sections of the slab was found an important factor as damage index in addition to deflection, crack density and crack width.
