Title: Interface Shear Transfer on Composite Concrete Members

Author(s): Pedro M. D. Santos and Eduardo N. B. S. Júlio

Publication: Structural Journal

Volume: 111

Issue: 1

Appears on pages(s): 113-122

Keywords: codes; interface; repair; roughness; shear; shrinkage; standards; stiffness

DOI: 10.14359/51686543

Date: 1/1/2014

Abstract:
The “shear-friction theory” was adopted in design codes to predict the longitudinal shear strength between parts of concrete members cast at different times. This is a relevant subject for different situations, such as the connection between precast members with cast-in-place parts and strengthening of existing reinforced concrete (RC) members with a new concrete layer. The bond strength of the interface is controlled by parameters such as the substrate roughness, curing conditions, and the material strength and stiffness of both concrete layers, among others. Some of these—for example, differential shrinkage due to different curing conditions, and differential stiffness due to the difference in the Young’s modulus of each layer—are not addressed in codes. This paper presents recommendations and proposes an alternative design approach for concrete-to-concrete interfaces that can be adopted in future revisions of ACI 318 and Eurocode 2. A comparison between ACI 318 and Eurocode 2 is presented.