Document: NUREG-0800
Document ID: 786da65a-4915-4af3-afb3-678b7df5bea7
Document Type: srp
Title: OTHER SEISMIC CATEGORY I STRUCTURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070327.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.8.4
CFR Part: 
CFR Title: 

Content:
or being completely absent should be checked. 3. Allowable Stresses Allowable stresses provided in ACI-531-79, as supplemented by the following modifications/exceptions, shall apply. (a) When wind or seismic loads (OBE) are considered in the loading combinations, no increase in the allowable stresses is permitted. (b) Use of allowable stresses corresponding to special inspection category shall be substantiated by demonstration of compliance with the inspection requirements of the NRC criteria. DRAFT Rev. 2 - April 1996 3.8.4-26 (c) When tension perpendicular to bed joints is used in qualifying the unreinforced masonry walls, the allowable value will be justified by test program or other means pertinent to the plant and loading conditions. For reinforced masonry walls, All the tensile stresses will be resisted by reinforcement. 112 (d) For load conditions which represent extreme environmental, abnormal, abnormal/severe environmental, and abnormal/extreme environmental conditions, the allowable working stress may be multiplied by the factors shown in the following table: Type of Stress Factor Axial or Flexural Compression 2.5 1 Bearing 2.5 Reinforcement stress except shear 2.0 but not to exceed 0.9 fy Shear reinforcement and/or bolts 1.5 Masonry tension parallel to bed joint 1.5 Shear carried by masonry 1.3 Masonry tension perpendicular to bed joint for reinforced masonry 0 for unreinforced masonry 1.3 2 113 Notes: (1) When anchor bolts are used, the design should prevent facial 114 spalling of masonry unit. (2) See 3(c). 115 4. Design and Analysis Considerations (a) The analysis should follow established principles of engineering mechanics and take into account sound engineering practices. (b) Assumptions and modeling techniques used shall give proper considerations to boundary conditions, cracking of sections, if any, and the dynamic behavior of masonry walls. (c) Damping values to be used for dynamic analysis shall be those for reinforced concrete given in