The results of a repetitive load test conducted on a laboratory model to study the deterioration of connections designed to develop composite behavior in precast-decked steel bridges are presented. Two million sinusoidal load cycles at a frequency of 3.5 Hz at levelsexceeding those of an equivalent hs 20-44 aashto truck were appliedto a 1/3-scale laboratory model of a composite, precast-decked, simple-span bridge. Loads, deflections, strains, and relative deck-beamdisplacements were continuously monitored and recorded at several time windows. The dynamic measurements were approximated to the steady state response by curve-fitting 3.5 Hz sinusoidal wave functions from which the amplitudes of measurements were obtained. The amplitudes of deflections, composite moments of inertia of two sections, andrelative deck displacements were analyzed and graphed versus the cycle number. A statistical test was conducted to establish the significance of the test results. The flexibility of the structure increased by less than 7%. The flexural properties of the two instrumented sections remained constant. The amplitude of relative deck-beam displacements remained negligible throughout the test. No evidence was found of any deterioration of the deck-beam interface connections. This paper appears in transportation research record no. 1268, Highwaymaintenance operations and research 1990.
Abstract