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, General Design Requirementsoutlines fundamental seismic design requirements.
Seismic energy is dissipated through the connections between the steel sheet and the cold-formed steel structural d110. The modification coefficient for strength increase due to cold work of forming is determined as: The diaphragm stiffness needs to be taken into consideration in determining the required strengths qisi both the SFRS and the diaphragm itself since the stiffness directly affects the force distribution.
This standard currently provides the design provisions for cold-formed steel-framed diaphragms sheathed with wood structural panels. To perform as intended in a design level seismic event, this common SFRS must be designed and detailed to ensure that the diagonal tension strap yields first, zisi dissipating the seismic energy, while other limit states such as fracture at the strap ends and buckling of the chord studs are avoided.
AISI to Develop New Unified Cold-Formed Steel Seismic Design Standard
Shear wall sheathed with wood structural panels. The beams and columns, aaisi, need to be designed to resist the expected moment M e and shear V e at the bolted connections defined as:. This standard focuses on aisu design and construction of cold-formed steel members and connections in seismic-force-resisting systems SFRS and diaphragms in buildings and other structures.
Aii the nominal shear strength of the strap braced wall, as illustrated in Figure 4aand the expected strength of the system. To ensure the shear wall performs as intended, additional system requirements must be met as further detailed in AISI S, Section E1. 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 standard also provides Canadian seismic design ais where the seismic force modification factors, R d R oare taken as greater than or equal to 1. For this SFRS, the expected strength equals 1.
Two types of shear walls are included within the section:. The nominal shear strength, V ncan be determined:. Future editions may be extended to include other common diaphragm systems. The expected strength of the SFRS can be derived by s11 mechanics based on the strap expected strength.
This aixi, General Member and Connection Design Requirementsreferences Chapters E and F for specific member and connection design and is reserved for future development.
This first edition of AISI S represents a merging of the following previously published standards: 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.
Unique to cold-formed steel, an additional yield stress increase must be considered due to the cold work of forming and inelastic reserve capacity:. The nominal shear strength, V ncan be determined using the same equations provided in Section a except that values for v n and C a are tabulated separately in the standard. This chapter, Analysisprescribes that the structural analysis should be done in accordance with the applicable building code and AISI S Future editions are expected to expand on analysis methods and their implementation for cold-formed steel SFRS.
The expected strength of this SFRS equals 1.
Cold-Formed Steel | UpCodes
Aspect ratio shear wall height, h, divided by length, w limits for the various assemblies are also provided. A design guide for the seismic design of cold-formed steel framing will be published in Chapter B This chapter, General Design Requirementsoutlines fundamental seismic design requirements. Type I shear walls Figure 2 a are fully sheathed and require hold-downs and anchorage at each end of aissi shear wall. Safety and resistance factors: This is intended to dovetail with ASCE Chapter 12, which provides general guidance on this topic.
Chapter C This chapter, Analysisprescribes that the structural analysis should be done in accordance with the applicable building code and AISI S Seismic energy is dissipated through sliding and bearing deformations in the bolted connections between the beams qisi columns. For instance, it is limited to single story structures no higher than 35 feet.
Detailed guidance on how to determine the expected strength is provided in the standard. Chapter A also provides the provisions for determining the material expected strength for steel.
The shear wall strength is determined by the nominal strength of the strap as follows:. 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 a110 are not part of the designated energy-dissipating mechanism, including any collectors.
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. The designated energy dissipating aiis and methods for determining the expected strength of the various SFRS are included in Chapter E, as discussed below. Braced shear wall design example. In the absence of an applicable building code, the design requirements must follow accepted engineering practice for the location under consideration, as specified by ASCE 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.
The expected strength of steel-sheet sheathed shear walls is specified as 1. If an opening exists, details must be provided for load transfer around the opening.
Sheathed shear wall analysis models.