Title: An Explanation of Draft Australian Concrete Code Provisions for Deflection and Serviceability

Author(s): P. F. Walsh

Publication: Symposium Paper

Volume: 86

Issue:

Appears on pages(s): 365-376

Keywords: beams (supports); building codes; concrete slabs; cracking (fracturing); deflection; load factors; moments of inertia; prestressed concrete; reinforced concrete; serviceability; span-depth ratio.

DOI: 10.14359/6438

Date: 8/1/1985

Abstract:
The new draft Australian Concrete code contains sub-stantial revisions to the requirements for deflection and cracking of beams and slabs. The author was closely involved in the prepar-ation of this section of the draft code. The principle changes are explained in this paper and include: Load factors are specified for service loads. The adoption of the ACI (Branson) effective moment of inertia for deflection calculations for both reinforced and partially prestressed beams. The replacement of the allowable span-to-depth tables with revised formula consistent with the ACI formula. The method for slab deflection is related to equivalent beams. More stringent requirements are given for cracking in the secondary direction in slabs. Flexural cracking requirements are specified by bar spacing rules or limits on tensile stresses or bar stress increments.