Title: Reinforced Concrete Design for Thermal Effects on Nuclear Power Plant Structures

Author(s): ACI Committee 349

Publication: Journal Proceedings

Volume: 77

Issue: 6

Appears on pages(s): 399-428

Keywords: cracking (fracturing); frames; nuclear power plants; reinforced concrete; shells (structural forms); structural analysis; structural design; tem-perature;thermal gradient; thermal properties; thermal stresses.

DOI: 10.14359/7017

Date: 11/1/1980

Abstract:
This report presents a design-oriented approach for considering thermal loads on reinforced concrete structures. Although the approach is intended to conform to the general provisions of Appendix A of ACI 349-76, it is not restricted to nuclear power plant structures. Two types of structures, frames and axisymmetric shells, are addressed. For frame structures, a rationale is described for determining the extent of member cracking which can be assumed for purposes of obtaining the cracked structure thermal forces and moments. Stiffness coefficients and carry-over factors are presented in graphical form as a function of the extent of member cracking along its length and the reinforcement ratio. Fixed-end thermal moments for cracked members are expressed in terms of these factors for (1) a temperature gradient across the depth of the member, and (2) end displacements due to a uniform temperature change along the axes of adjacent members. For the axisymmetric shells, normalized cracked section thermal moments are presented in graphical form. These moments are normalized with respect to the cross section dimensions and the temperature gradient across the section. The normalized moments are presented as a function of the internal axial forces and moments acting on the section and the reinforcement ratio. Use of the graphical information is illustrated by examples.