scope:

INTRODUCTION 

Because concrete is relatively weak and brittle in tension, cracking is expected when significant tensile stress is induced in a member. Mild reinforcement and/or prestressing steel can be used to provide the necessary tensile strength of a tension member. However, a number of factors must be considered in both design and construction to insure proper control of cracking that may occur.

A separate report by ACI Committee 224 (ACI 224R) covers control of cracking in concrete members in general, but contains only a brief reference to tension cracking. This report deals specifically with cracking in members subjected to direct tension.

Chapter 2 reviews the primary causes of direct tension cracking, applied loads, and restraint of volume change. Chapter 3 discusses crack mechanisms in tension members and presents methods for predicting crack spacing and width. The effect of cracking on axial stiffness is discussed in Chapter 4. As cracks develop, a progressive reduction in axial stiffness takes place. Methods for estimating the reduced stiffness in the post-cracking range are presented for both one-dimensional members and more complex systems. Chapter 5 reviews measures that should be taken in both design and construction to control cracking in direct tension members.