Sputo, Thomas

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Missouri University of Science and Technology (Missouri S&T): Scholars' Mine

Missouri University of Science and Technology Scholars' Mine International Specialty Conference on Cold-Formed Steel Structures Wei-Wen Yu International Specialty Conference on Cold-Formed Steel Structures 2018 Nov 7th, 12:00 AM - Nov 8th, 12:00 AM SDI Steel Deck on Cold-Formed Steel Framing Design Manual Thomas Sputo Follow this and additional works at: https://scholarsmine.mst.edu/isccss  Part of the Structural Engineering Commons Recommended Citation Sputo, Thomas, "SDI Steel Deck on Cold-Formed Steel Framing Design Manual" (2018). International Specialty Conference on Cold-Formed Steel Structures. 1. https://scholarsmine.mst.edu/isccss/24iccfss/session6/1 This Article - Conference proceedings is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in International Specialty Conference on Cold-Formed Steel Structures by an authorized administrator of Scholars' Mine. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact scholarsmine@mst.edu.  SDI Steel Deck on Cold-Formed Steel Framing Design Manual Thomas Sputo, Ph.D., P.E., S.E.1 Introduction The First Edition of the SDI Steel Deck on Cold-Formed Steel Framing Design Manual is the first design manual that specifically addresses the design of steel deck on cold-formed framing.  The design of the steel deck is similar to deck on heavier rolled beams or open web steel joists, but it requires attention to some different detailing and fastening methods.  This Manual concentrates on these differences. The Manual Section contains and introduction to the topic, and sections specific to roof deck, floor deck, and fasteners.  The roof and floor deck sections include diaphragm applications.  The Manual contains tables for fasteners and diaphragms, and also includes 7 design examples specific to deck on cold-formed framing. The Manual makes use of an on-line design tool, the SDI Diaphragm Interaction Calculator, which develops diaphragm tables for the situation where the diaphragm capacity is reduced by wind uplift. This Manual conforms to the ANSI/SDI RD-2017 Standard for Steel Roof Deck, the ANSI/SDI NC-2017 Standard for Non-Composite Steel Floor Deck, ANSI/SDI C-2017 Standard for Composite Steel Floor Deck-Slabs, the AISI S100-16 North American Specification for the Design of Cold-Formed Steel Structural Members and the AISI S310-13 and -16 editions of the North American Standard for the Design of Profiled Steel Diaphragm Panels. 1 Technical Director, Steel Deck Institute; and Consulting Structural Engineer, Sputo and Lammert Engineering, LLC (tsputo50@gmail.com). Wei-Wen Yu International Specialty Conference on Cold-Formed Steel Structures St. Louis, Missouri, U.S.A., November 7 & 8, 2018397Manual Format and Coverage  The SDI Steel Deck on Cold-Formed Steel Framing Design Manual is divided into a Forward and eight sections as follows:  Section 1 Introduction Section 2 Roof Deck  Section 3 Floor Deck Section 4 Fasteners Section 5 Examples Section 6 Fastener Tables Section 7 Diaphragm Tables Section 8 References   This new Manual provides information on how the use of steel  floor and roof deck  on  cold-formed steel framing differ from when supported  on open web steel joists or rolled beams,.  1. The Manual complies with the analysis and design methods contained within the AISI S100 and S310 Standards, taking into account the more flexible behavior of strew fasteners in cold-formed supports.  2. The Manual contains seven design examples illustrating the design and analysis of steel deck on cold-formed steel framing, both roof and floor deck, and diaphragms.  3. Examples also show the calculation of diaphragm strength and stiffness using the AISI S310 provisions when supported by cold-formed steel framing.  4. Examples include expanded discussion of the interaction of wind uplift with diaphragm strength.  5. Fasteners included in the Manual include generic screws in accordance with the strength and flexibility provisions of AISI S100 and S310  6. Diaphragm load tables are calculated using the generic AISI S310 weld and screw provisions, and calculated using the previous 3rd Edition DDM fastener equations and proprietary fasteners. The same resistance and safety factors apply to both methods. 398Section 1 - Introduction  Section 1 introduces the general differences when designing deck to be supported on cold-formed framing.  The Manual supposes that the user is already conversant with designing deck on open web steel joists and rolled beams.   First, the user is introduced to the thinner supporting material, as shown in Table 1.  Not all base steel thicknesses are available from all suppliers, and 27 mil material is rarely used for floor and roof joists, while 118 mil material is rarely used in trusses.   Thickness Designation (mils) Minimum Thickness (inches) Design Thickness (inches) Reference Gage (Not Used for Specifying) 27 0.0269 0.0283 22 33 0.0329 0.0346 20 43 0.0428 0.0451 18 54 0.0538 0.0566 16 68 0.0677 0.0713 14 97 0.0966 0.1017 12 118 0.1180 0.1242 10  Table 1.  Structural Cold-Formed Framing Base Steel Thickness Floor and roof framing can be constructed either of trusses or of individual members.  The design of the framing is beyond the scope of this manual, and the user is referred to any of several publications that are listed in the General References section of this Manual.  However, it is important that the designer be cognizant of the limitations that the shape of the supporting framing imposes on the design of the steel deck.  Individual members used as floor joists or roof rafters are usually lipped channels, as shown in Figure 1.  There are industry standard cross sections that are available from many manufacturers.   399 Figure 1.  Lipped Channel The flange width is important to consider when designing the bearing and attachment of the steel deck to the flange.  Typical standard flange widths for structural cross sections are 1-5/8 inch (S162), 2 inch (S200) and 2-1/2 inch (S250).  Also available, but not as commonly used in this application are 3 inch (S300) and 3-1/2 inch (S350).  Cold-formed steel trusses are commonly used for both floor and roof applications.  Trusses are usually designed by the manufacturer as a specialty engineered item.  Trusses can use lipped channels for top chords (referred to as C-Section Trusses), however there are proprietary sections used by some truss manufacturers, as shown in Figure 2.        Figure 2.  Proprietary Truss Chords (Courtesy of Aegis and Alpine Trussteel)  The Chapter closes out by reminding users that specific responsibilities for design are laid out in two Code of Standard Practice publications;  the AISI Code of Standard Practice for Cold-Formed Steel Structural Framing (AISI S202) and the SDI Code of Standard Practice (SDI-COSP).     400Section 2 - Roof Deck  Any of the roof deck profiles shown in the SDI Roof Deck Design Manual  (RDDM) can be used on cold-formed steel roof trusses or rafters, with 1-1/2 inch Wide Rib (WR) deck (Figure 2.1) being the most common for spans of up to 8 feet.  Engineering information, including section properties and span tables, can be found in the RDDM and in manufacturers literature.  This section provides an extensive development of sloped roof diaphragms, including monoslope, gable, and hipped roofs, as shown in Figures 3 and 4.       Figure 3.  Monoslope Diaphragm, Laterally Loaded  401 Figure 4.  Monoslope Diaphragm Transverse Collectors  Roof diaphragms that are loaded by wind must resist both in plane shear and uplift.  There are two loading conditions that must be considered:  A. The roof deck is designed as the sheathing for the roof.  For this case,  the wind uplift on the deck and fasteners is calculated using component  and cladding (C&C) wind pressures.  B. The roof deck is designed as a diaphragm.  For this case, the wind  uplift and in plane diaphragm shear are both calculated using main  wind force resisting system (MWFRS) wind pressures.  The application of combined wind uplift and diaphragm shear is covered in the manual, along with the accompanying "Diaphragm Interaction Calculator."  Section 3 - Floor Deck  Any of the floor deck profiles shown in the SDI Floor Deck Design Manual  (FDDM) can be used on cold-formed steel floor trusses or joists.  Engineering information, including section properties and span tables, can be found in the RDDM and in manufacturers literature.  For closely spaced trusses or joists (48 402inches or less on center), form deck of 9/16 inch to 1 inch in depth  can also be used.  For longer spans, deeper form deck or composite deck can be used.  Form deck is most often galvanized, and if galvanized, it is permitted to be considered to be a permanent form that supports the weight of the concrete slab, with the concrete slab designed to support the weight of the superimposed loads.  Alternately, it is allowed to use bare or painted deck as permitted by the applicable SDI Specification (SDI C or SDI NC).  There are some design considerations that are common to both composite and non-composite (form) deck used for floors.  Refer to Figure 5.  A. Available flat bearing width of the framing top flange may not permit the use of butted deck ends once the required deck bearing length (minimum of 3/4 inch per AISI S100) is taken into account.  Also, minimum fastener end distance in the deck (1.5 times the screw diameter per AISI S100) may not be able to be met (for instance, minimum end distance for a #12 framing screw would be 0.324 inches or more than 5/16 inch).  Deck panel underlength within SDI Standards tolerance of 1/2 inch per deck sheet and tolerance for framing placement and straightness needs to also be factored into this consideration.  B. Minimum fastener spacing (3 times the screw diameter per AISI S100) may control the number of fasteners per deck rib.  For instance, the minimum center to center spacing for a #12 support screw is 0.648 or over 5/8 inches.  This, combined with end distance limits, will most likely limit the number of screws to two per deck rib for the most common framing flange widths.       Figure 5  Butted and Lapped Deck Ends  403Section 4 - Fasteners  Fasteners for attachment of steel deck to cold-formed steel framing are limited to screws, as shown in Figures 6 and 7.  The application of screws in this use is similar to when attaching to heavier supporting steel, except that the additional limit states of tilting in shear, and pullout in tension, which do not normally control in heavier supporting steel, may govern design.   Figure 6.  Support, Side-lap, and Edge Screws     Figure 7  Nested and Interlocking Side-lap Screw Connections   Welded connections for either support attachment is NOT RECOMMENDED due to the difficulty in making acceptable welds between two or more layers of sheet steel.  Burn-through damage to truss chords and rafter and joists flanges 404often results and repairs to the supporting framing may not be possible.  Any welding related damage to the support framing is not the responsibility of the framing supplier, deck supplier, or deck installer.  Welded side-laps are possible, but limitations on welding imposed by roof slope, burn through, and the cost effectiveness of screwed side-laps make welded side-laps undesirable.  Power-actuated fasteners are commonly used for steel roof deck attachment to support framing of 1/8 inch and thicker.  At the time of publication of this Manual, no power actuated fasteners were available for connecting steel deck to cold-formed steel support framing.  For additional information on these fasteners, refer to the SDI Roof Deck Design Manual and the literature of the product manufacturers.  As an alternative to screws, side-lap connections can be formed by crimping the upstanding edge of the deck, where provided.  Crimps can only be made with deck that is designed with the upstanding edge to receive them and not all deck has upstanding edges that will accept crimps.  Crimping can be categorized as either generic “button punching” or one of several proprietary mechanically formed connection systems.  Generic button punches serve only to align the deck side-laps but provide little resistance to shear at the panel edge.  Proprietary mechanically formed connection systems are tested connections formed using specific tools for a specific deck.  These proprietary systems have defined shear strength and stiffness values that are contained within research and acceptance reports.  Information on these proprietary systems can be obtained from specific manufacturers.  Strict consideration also needs to be paid to the number of screws that are used at a single rib at a support.  Minimum spacing per AISI S100 is 3 times the screw diameter, or approximately 5/8" for a No. 12 screw.  That practically limits the number of screws per rib to 2 in most practical cases.  At deck ends or butt joints, the minimum end distance is 1.5 times the screw diameter, which also limits the number of screws to 2 in a rib.       405 Section 5 - Examples  Section 5 consists of seven design examples which illustrate the differences between installing steel deck on cold-formed steel framing versus heavier steel supporting framing.  Example 1 Available Diaphragm Shear Strength in the Absence    of Uplift Where the Support is Cold-Formed Steel    Framing Example 2 Stiffness of the Configuration in Example 1 Example 3 Available Diaphragm Shear Strength With Wind    Uplift Where the Support is Cold-Formed Steel    Framing Example 4 Roof Deck (ASD) Example 5 Floor Deck (ASD) Example 6 Gable Roof with Open Ridge Example 7 Loads on Diaphragm  - Gable Roof Loaded on    Endwall  Example 3 is a rigorous development of the interaction of shear and uplift in a wind loaded roof.  This example will prove useful to designers in understanding the interaction that develops in fasteners.  Section 6 - Fastener and Framing Tables  Section 6 contains tables which will assist the user in designing fasteners  Table 1  Screw Dimensional and Tensile Strength Table 2   Screw Nominal Pull-out Strength Table 3  Screw Nominal Pull-over Strength Table 4  Sidelap Screw Nominal Shear Strength Table 5  Support Screw Nominal Shear Strength Table 6  Support Screw Flexibility Table 7  Sidelap Screw Flexibility Table 8  Roof Deck Fastener Patterns Table 9  Spanning Zee Framing   406 Figure 8 - Roof and Form Deck Fastener Patterns    Section 7 - Diaphragm Tables  Section 7 includes tables for both filled and bare deck diaphragms.  For concrete filled floor diaphragms, a simplified table which considers only the contribution of the fill above the top of the deck ribs is included, and is shown as Figure 9. 407 Nominal Diaphragm Shear Strength, Sn, PLF ASD (Ω = 3.25)   LRFD (Φ=0.50)  Concrete Thickness Above Deck (inches) Normalweight  Concrete (145 pcf) Lightweight Concrete (115 pcf) 3000 psi 4000 psi 3000 psi 4000 psi 1.5 2943 3398 2078 2400 2 3923 4530 2771 3200 2.5 4904 5663 3464 4000 3 5885 6796 4157 4800 3.5 6866 7928 4850 5600  Notes: 1. This table considers only the contribution of the concrete to the diaphragm resistance. 2. Per SDI-NC, the minimum thickness of a structural concrete slab is 1-1/2 inches above the top of the non-composite steel deck. 3. Per SDI-C, the minimum thickness of a composite concrete slab is 2 inches above the top of the composite steel deck.  Figure 9 - Concrete Filled Diaphragm Table  For bare deck roof diaphragms, tables which are similar to those in DDM04 are provided for deck on cold-formed supporting framing.  Each different combination of deck thickness , support framing thickness, and  support framing ultimate strength is included.  The tilting behavior of the support fastener screws in different thickness of support framing creates many more tables than are 408found in DDM04, where fastener tilting is not a design limit state.  An example of a typical table is shown in Figure 10.    Figure 10 - Typical Roof Deck Diaphragm Table 409 Section 8 - References  Section 8 contains references used in the Manual, along with general recommended design references for cold-formed steel framing.  Diaphragm Interaction Calculator  To reduce the design effort involved with calculating the reduced diaphragm capacity when wind uplift must be considered in the design, the SDI has provided an on-line tool to assist designers.  This "Diaphragm Interaction Calculator" will calculate the ASD and LRFD diaphragm capacity for an input uplift pressure, given deck profile, material strengths, and fastener pattern and type.  This calculator will provide answers for deck on both cold-formed framing, and open web steel joists and rolled steel beams.    Conclusion  The new SDI Steel Deck on Cold-Formed Steel Framing Design Manual represents a step forward for designers of buildings that incorporate steel deck on cold-formed steel framing.   References  American Iron and Steel Institute (2013).  ANSI/AISI S310-13 North American Standard for the Design of Profiled Steel Diaphragm Panels, Washington, DC  American Iron and Steel Institute (2016).  ANSI/AISI S310-16 North American Standard for the Design of Profiled Steel Diaphragm Panels, Washington, DC  American Iron and Steel Institute (2016).  ANSI/AISI S100-16 North American Standard for the Design of Cold-Formed Steel Structural Members, Washington, DC  Steel Deck Institute (SDI) (2015).  Diaphragm Design Manual, 4th Edition, Glenshaw, PA.  Steel Deck Institute (SDI) (2013).  Roof Deck Design Manual, 1st Edition, Fox River Grove, IL.  410Steel Deck Institute (SDI) (2014).  Floor Deck Design Manual, 1st Edition, Glenshaw, PA.  Steel Deck Institute (SDI) (2017) ANSI/SDI RD-2017 Standard for Steel Roof Deck, Glenshaw, PA.  Steel Deck Institute (SDI) (2017) ANSI/SDI NC-2017 Standard for Non-Composite Steel Floor Deck, Glenshaw, PA.  Steel Deck Institute (SDI) (2017) ANSI/SDI C-2017 Standard for Composite Steel Floor Deck-Slabs, Glenshaw, PA.  Steel Deck Institute (SDI) (2018) SDI Steel Deck on Cold-Formed Steel Framing Design Manual, Glenshaw, PA.  411

SDI Steel Deck on Cold-Formed Steel Framing Design Manual

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SDI Steel Deck on Cold-Formed Steel Framing Design Manual

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Missouri University of Science and Technology (Missouri S&T): Scholars' Mine