SHEAR STRESS TRANSFER ACROSS CONCRETE TO CONCRETE AND STEEL TO CONCRETE INTERFACES

Abstract

Abstract This research project investigates shear transfer across concrete-to-concrete and steel-to-concrete interfaces where “sliding shear” failure is critical. Experimental data available in the literature were collected and statistically analyzed. Based on the experimental data available for concrete-to-concrete interfaces, a strength prediction model was calibrated and proposed. The performance of this new model, built on the framework of the model proposed by Mattock (2001), was compared against current design code provisions and some of the available models proposed by others over the years. The database assembled for steel-to concrete interfaces was also used to examine the performance of some of the existing design equations and strength models. In addition, the analysis of the database led to the identification of a number of important gaps in the literature. Amongst those, the lack of tests on embed plates subjected to combined shear and bending actions was of particular concern. Thus, an experimental program involving a total of five specimens was planned and conducted. The main variables considered were the load eccentricity and the stud distribution across the embed plate. The results of the experiments shed some light on the complex mechanisms that contribute to the interface strength, providing some preliminary insight and qualitative information on the aspects that should be incorporated in a rational design model. In the sub-discipline of concrete engineering, shear transfer across both concrete-to-concrete and steel-to-concrete interfaces is treated as a frictional phenomenon, whereas, in the steel sub-discipline, shear transfer across steel-to-concrete interfaces is treated as a dowel action phenomenon. Both approaches can predict similar strengths if they are suitably calibrated, but some of the subtleties of the behavior of steel-to-concrete interfaces appear to be better modeled using the dowel action approach.