Title:
Span-Depth Ratios for One-Way Members Based on ACI 318 Deflection Limits
Author(s):
Peter H. Bischoff and Andrew Scanlon
Publication:
Structural Journal
Volume:
106
Issue:
5
Appears on pages(s):
617-626
Keywords:
beams; concrete; deflection; slabs; span-depth ratio
DOI:
10.14359/51663102
Date:
9/1/2009
Abstract:
Span-depth ratio (l/h) expressions are developed for steel-reinforced concrete one-way slabs and beams to satisfy deflection control and flexural strength requirements. The expressions are presented as functions of reinforcement ratio and specified deflection-to-span limit. A comparative study is performed to evaluate the effects of effective moment of inertia, shrinkage restraint, construction loads, sustained live load, long-time deflection multiplier, support conditions, and deflection limits on the resulting span-depth ratios. A comparison is also made with minimum thickness values prescribed by ACI 318 that are a function of span and support conditions only. Effects of various input parameters are considered in examples involving a simply supported rectangular beam and an interior span of a continuous one-way slab. The results of the study indicate some of the limitations associated with the ACI 318 minimum thickness requirements.