Title: Tests of Column-Flat Plate Connections

Author(s): Scott D. B. Alexander and Sidney H. Simmonds

Publication: Structural Journal

Volume: 89

Issue: 5

Appears on pages(s): 495-502

Keywords: anchorage; punching shear; reinforced concrete; slabs; tests; steel strains; truss model; ultimate strength; Structural Research

DOI: 10.14359/2948

Date: 9/1/1992

Abstract:
A test program designed to evaluate the straight-line strut-and-tie model for predicting punching shear capacity is described. Eight isolated column-flat plate connections were loaded to failure. The primary variables were clear cover, spacing of reinforcement through the column, and boundary restraint. Measurements of strain were made along reinforcement passing through and immediately adjacent to the column. The measurements do not support the concept of an inclined straight-line compression strut as assumed in the strut-and-tie model, but indicate that the compression strut is more in the form of an arch. The beneficial effects of increased cover in improving the shear capacity and connection ductility are demonstrated. Increasing the amount of slab reinforcement passing through the column can lead to anchorage failures. An anchorage failure of this reinforcement is not distinguishable from a punching failure on the basis of external appearances during or after a test and it is concluded that many punching failures reported in the literature were limited by anchorage capacity.