Strategic slab–column joint details for improved transmission of HSC column loads Available to Purchase

In typical construction, the slab is made of normal-strength concrete (NSC) and is cast in a continuous fashion through the slab–column joint. For the case of high-strength concrete (HSC) columns, this results in a layer of lower-strength concrete between the upper and lower columns at the floor levels. Since this lower-strength concrete layer can limit the capacity of the column, it is necessary to provide alternative design or construction strategies for the transmission of column loads through slab–column connections. The current paper presents the structural characteristics of slab–column connections by using full-scale tests and non-linear three-dimensional finite-element analyses. Finite-element analyses considering material non-linearity were performed to investigate the axial load plotted against average column strain responses, the type of failure, the principal stress distribution and the reinforcement yielding conditions for various slab–column members. The puddled HSC in the joint, the HSC core, the use of high-strength steel for the column longitudinal reinforcement, and the additional vertical compression reinforcement through the joint were investigated. The alternative reinforcement methods in the slab–column joints significantly improved the performance of the joints—that is, higher axial compressive strength, greater loading stiffness and higher ductility.