Title: Ultimate Strength Design of Reinforced Concrete Chimneys

Author(s): Wadi S. Rumman and Ru- Tsung Sun

Publication: Journal Proceedings

Volume: 74

Issue: 4

Appears on pages(s): 179-184

Keywords: axial loads; bending moments;chimneys; loads (forces);reinforced concrete; strains;stress-strain relationships;stresses; structural design; ultimate strength method.

DOI: 10.14359/11000

Date: 4/1/1977

Abstract:
There are two main sections in this paper: the first is concerned with determining the ultimate moment capacities of reinforced concrete members of hollow circular sections subjected to axial forces: and the second emphasizes the importance of designing reinforced concrete chimneys to satisfy both a working stress condition and an ultimate strength condition. Hollow circular sections are encountered not only in chimneys but in other structures such as intake-outlet towers, offshore platforms, and hollow circular bridge piers. The ultimate moment charts presented are based on the assumption that failure is reached when the strain in the concrete reaches 0.003 and that the stress-strain relationship for the concrete is the parabolic-declined type as suggested by Hognestad. The importance of designing chimneys to satisfy a working stress as well as an ultimate condition stems from the fact that in both cases the axial load could be the same. This could result in high working stresses in certain sections proportioned only for ultimate capacity. The opposite could also be true whereby a section proportioned for the service loads only could fail due to a relatively small overload.