The behavior of Shear Connectors in Steel-Normal Concrete Composite Structure under Repeated Loads.

In today's construction industry, the use of composite beams is becoming more and more important, particularly for longspan bridges that must withstand repeated loads from moving automobiles. This work investigates the behavior of composite beams through experimentation. Six push-out steel-concrete specimens are made and tested with various levels of static and repetitive loading applied. The specimens are made of rolled steel sections that are joined to concrete decks on both sides by stud shear connectors. Two approaches—one static and the other repeating—applied a push-out load to two sets of samples. One has a stud shear connector measuring 16 mm, and the other measures 25 mm. Three specimens were made for each group. To determine the final load, one specimen from each group underwent a static push-out test in the first stage. In the subsequent phase, repeated loads of 0-80% and 25-80% of the maximum static load were applied to the remaining ones. The analysis process measured the variation in slip between the concrete decks and the steel section over several load cycles. It was found that the recorded slip values at the ultimate load increased about four times just before the failure. The recorded values of the residual slip at the end of each load cycle decreased with the increase in load cycle numbers. Also, it was found that the values of the residual slip depend on the values of the lower and upper limits of the load level. [ABSTRACT FROM AUTHOR]