Find the most up-to-date version of AISI S at Engineering 2 to the North American Specification for the Design of Cold-Formed Steel Structural Members, Edition February ; AISI S/S ()AISI . Cold-Formed Steel─Special Bolted Moment Frame (CFS─SBMF) system in the proposed AISI Seismic Standard (AISI S) are developed.
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This chapter, Analysisprescribes that the structural analysis should be done in accordance with the applicable building code and AISI S The nominal shear strength, V ncan be determined:.
The expected strength of the SFRS, capped by the seismic load effects including overstrength, is to be used to design other components in the SFRS that are not part of the designated energy-dissipating mechanism, including any collectors.
Unique to cold-formed steel, an additional yield stress increase must be considered due to the cold work of forming and inelastic reserve capacity:. Braced shear wall design example.
This standard focuses on the design and construction of cold-formed steel members and connections in seismic-force-resisting systems SFRS and diaphragms in buildings and other structures. Chapter D This chapter, General Member and Connection Design Requirementsreferences Chapters E and F for specific member and connection design and is reserved for future development. To ensure the shear wall performs as intended, additional system requirements must be met as further detailed in AISI S, Section E2.
Shear wall sheathed with wood structural panels. For this SFRS, the expected strength equals 1. This is intended to dovetail with ASCE Chapter 12, which provides general guidance on this topic.
The standard also provides Canadian seismic design provisions where the seismic force modification factors, R d R oare taken as greater than or equal aiei 1.
Chapter A also provides the provisions for determining the material expected strength for steel. This first edition of AISI S represents a merging of the following previously published standards: This chapter outlines requirements for Diaphragms.
STRUCTURE magazine | AISI S/S
Seismic energy is dissipated through the connections between the steel sheet and the cold-formed steel structural members. S1100 a Comment Click here to cancel reply. The expected strength of this SFRS equals 1. Cold-formed steel special bolted moment frame. This chapter, General Design Requirementsoutlines fundamental seismic design requirements. Future editions are expected to expand on analysis methods and their implementation for cold-formed steel SFRS. Future editions may be extended to include other common diaphragm systems.
In addition, a new effective strip method has been introduced in this edition, which can be used to determine the nominal shear strength of the shear wall analytically.
Aisl the absence of an applicable building code, the design requirements must follow accepted engineering practice for the location under consideration, as specified by ASCE Aug, By Rob Madsen P. Additional system requirements must be met as further detailed in Section E3. This standard currently provides the design provisions for cold-formed steel-framed diaphragms sheathed with wood structural panels.
The expected strength of the strap equals the expected yield strength of the strap times its gross area.
Type II shear walls Figure 2b permit openings in the wall without specific design for force transfer around the openings. The beams and columns, therefore, need to be designed to resist the expected moment M e and shear V e at the bolted connections defined as:.
Two types of shear walls are included within the section:. Seismic energy is dissipated in wood structural panel shear walls through titling and bearing deformation in the screw connections between the wood structural panel sheathing and the cold-formed steel structural members, and in the wood structural panels themselves. First Name Last Name. Your message Submit Comment. For instance, it is limited to single story structures no higher than 35 feet.
To ensure the shear wall performs as intended, additional system requirements must be met as further detailed in AISI S, Section E1. The shear wall strength is determined by the nominal strength of the strap as follows:.
Expected strength is used to estimate the maximum forces the SFRS is anticipated to resist prior to dissipating energy through yielding.
Seismic Design Of Cold-Formed Structural Systems Covered In New AISI S Standard
Determine the nominal shear strength of the strap braced wall, as illustrated in Figure 4aand the expected strength of the system. Collectors, strap connections, chord studs, other vertical boundary elements, hold-downs and anchorage connected to it and all other components and a110 of the strap braced wall should be designed to resist this force.
The nominal shear strength and detailed requirements are provided in Section E6 of the standard. Safety and resistance factors: The designated energy dissipating mechanism and methods for determining the expected strength of the various SFRS are included in Chapter E, as discussed below.
This consolidated seismic design standard brings together all North American cold-formed steel seismic-force-resisting systems SFRS into one standard, adding a consistent capacity-based design philosophy to each.
The expected strength of steel-sheet sheathed shear walls is specified as 1. The modification coefficient for strength increase due to cold work of forming is determined as: The expected strength of the SFRS can be derived by simple mechanics based on the strap expected strength.
Specifically, the available strength of the SFRS must be greater than or equal to the required strength determined from the applicable load combinations to ensure adequate performance in a design-level seismic-event.
For instance, provisions must be made to guard against loose strap bracing either by pre-tensioning the straps or through other similar methods of installing the tension-only strap bracing.