Title:
Bearing Strength of Compressive Struts Confined by Plain Concrete
Author(s):
Perry Adebar and Zongyu Zhou
Publication:
Structural Journal
Volume:
90
Issue:
5
Appears on pages(s):
534-541
Keywords:
building codes; caps (supports); cracking (fracturing); deep beams; footings; piles; plain concrete; reinforced concrete; shear strength; structural design; tests; Structural Research
DOI:
10.14359/3948
Date:
9/1/1993
Abstract:
To study transverse splitting of compression struts due to spreading of compression, concrete cylinders of varying diameters and of varying heights were loaded over a constant-size bearing area. The travel time of an ultrasonic pulse was used to indicate internal cracking and measured cracking loads were compared to finite element predictions. It was found that when compression struts are confined by plain concrete, the maximum bearing stress to cause transverse splitting depends on the amount of confinement, as well as the aspect ratio (height/width) of the compression strut. Design recommendations are given for the maximum nodal zone bearing stress to prevent diagonal tension failure in deep members (disturbed regions) with unreinforced compression struts. A simple example is provided to illustrate the suggested nodal stress limits for the design of a pile cap using a strut-and-tie model.