Title:
Tension Stiffening and Cracking of High-Strength Reinforced Concrete Tension Members
Author(s):
Kelvin Fields and Peter H. Bischoff
Publication:
Structural Journal
Volume:
101
Issue:
4
Appears on pages(s):
447-456
Keywords:
cracking; high-strength concrete; reinforced concrete; shrinkage; tension
DOI:
10.14359/13330
Date:
7/1/2004
Abstract:
Axial tension members made of both normal- and high-strength concrete are used to investigate tension stiffening and cracking of reinforced concrete to determine experimentally if any relationship exists between concrete strength and post-cracking behavior. Tension stiffening represents the tensile strength of concrete between cracks in a reinforced concrete member and can significantly affect member stiffness, deflection, and crack widths under service loads. Large-scale specimens using 40 and 80 MPa concrete were reinforced with either 15M or 20M bars to give a corresponding reinforcing percentage of 1.3 and 2%, respectively. An empirical model is proposed to predict the average tensile response of concrete after cracking. When this relationship is expressed as a normalized stress-strain response, it is independent of concrete strength and the reinforcing steel ratio as long as shrinkage is included in analysis of the member response. When shrinkage is ignored, the higher-strength concrete exhibits a corresponding greater decrease in tension stiffening because of the higher shrinkage values that developed in this concrete. Crack spacing is not affected by the strength of concrete for the type of specimens tested. Hence, any decrease in crack width for a given load level occurs because of the increase in tension stiffening attributed to a concrete having a higher tensile cracking strength.