Outline of Specification for Composite SC Walls in Nuclear Facilities

Abstract

Appendix N9 to AISC N690s1 presents the design provisions for steel-plate composite (SC) walls in safety related nuclear facilities. AISC N690s1 is Supplement No. 1 to AISC N690-12 specification for safety related steel structures in nuclear facilities and was published in October 2015. This paper discusses the outline of Appendix N9 as well as how the appendix can be used for the design of SC wall structures. Appendix N9 establishes the minimum requirements that SC walls need to meet in order for the specification to be applicable. The requirements include minimum and maximum wall thickness and steel reinforcement ratio. Detailing requirements for SC wall panel sections are also discussed. The faceplate slenderness requirement to prevent the limit state of buckling before yielding is provided. Steel anchor requirements are based on developing adequate composite action, and preventing interfacial shear failure. Requirements for tie bars connecting the steel plates (faceplates) are provided to prevent splitting failure and out-of-plane shear failure. The detailing and design provisions for regions around openings in SC walls are also included. Appendix N9 provides a method of checking the design of SC walls for impactive and impulsive loads. A discussion of the analysis requirements for SC walls is presented. The provisions include effective stiffnesses, accident thermal loading and model parameters for analysis. The design strength equations for axial tension, axial compression, out-of-plane shear, out-of-plane flexure, in-plane shear, and for combined in-plane forces and out-of-plane moment demands are parts of the provisions of the appendix. The provisions also include interaction equations for evaluating tie bars resisting demands due to combination of out-of-plane and interfacial shear forces. Performance requirements for the anchorage of SC walls to concrete basemat, SC wall-to-wall connections and SC walls to floor slab connections are given in the appendix. The provisions also include requirements for fabrication, inspection, and quality control of SC walls constructed for safety-related nuclear facilities.