Crack Control through Bar Spacing Requirements

In the ACI 318-99 building code, new design provisions were introduced for the control of cracking through reinforcing bar spacing requirements. With the introduction of the ACI 318-05 code, the direction of controlling cracking through reinforcement spacing with be further extended. The new provisions provide for the control of flexural cracking along both the tension and side faces through a unified design approach. The presentation will provide an overview of the background regarding the control of cracking through reinforcing spacing as well as the development of the new specifications. In particular, effects of changes in the load and resistance factors on crack control and the resulting specifications will be discussed. Finally, design examples will be presented illustrating the use of the new design provisions.