Direct Fastening Technical Guide , Edition 22
3.5.1.2 STEEL DECK DIAPHRAGM DESIGN AND THEORY
3.5.1.2.1 General discussion A steel deck diaphragm is a horizontal assembly that resists wind , seismic and other lateral forces . A diaphragm can be modeled as a horizontal beam with interconnected floor and roof deck units that act as the beam web . Intermediate joists or beams act as web stiffeners and perimeter beams or reinforcement on the diaphragm perimeter act as the beam flanges . Figure 1 , based on graphics from the Steel Deck Institute ( SDI ) Diaphragm Design Manual ( DDM ), depicts a roof deck diaphragm model .
Design of steel deck diaphragms can be done using the Steel Deck Institute ( SDI ) Diaphragm Design Manual ( DDM ) or American Iron and Steel Institute ( AISI ) S310 . These methods provide the basic equations for determining the strength and stiffness of the diaphragm considering the following parameters :
1 . Steel Deck Profile Type and Thickness 2 . Supporting Steel Frame Spacing or Deck Span
3 . Frame Fastener Type and Spacing ( connector for steel deck to steel frame )
4 . Sidelap Fastener Type and Spacing ( connector for steel deck panel edge to edge )
5 . Safety Factors ( ASD ) or Resistance Factors ( LRFD / LSD ) based on load type ( wind , seismic , other ) and fastening type ( mechanical , weld )
ICC Evaluation Services ( ICC-ES ) recognizes the AISI S310 design methods as acceptable in AC43 , “ Acceptance Criteria for Steel Deck Roof and Floor Systems ”. An ICC Evaluation Service Report ( ESR ) based on ICC-ES AC43 provides recognition for use with the IBC . Hilti deck fasteners are currently listed in the SDI Deck Design Manual Version 04 ( DDM04 ) and were evaluated in ICC-ES ESR-3693 , ESR- 2776 and ESR-2197 . Hilti deck fastener performance with decking systems is also documented in ICC-ES ESR-1169 , ESR-2635 , ESR-2657 and IAPMO ER-0217 , ER-2018 , and ER-0329 . Additional industry research has shown that metal deck systems , bare and filled , provide a high level of ductility and overstrength , when tested as part of a horizontal diaphragm . Metal deck fastened to the structure using specially designed Power-actuated fasteners perform especially well in absorbing excess energy in the inelastic range . The Steel Diaphragm Innovation Initiative , www . steeli . org , has compiled a comprehensive report containing a database of small element and full scale static and cyclic tests .
Figure 1 : diaphragm model
3.5.1.2.2 Fastener test programs
Many small element and full scale test programs have been conducted using Hilti deck fasteners to evaluate their performance .
1 . Small element connection tests
Small element connection tests are used to determine fastener pullout , pullover and lap-joint shear strength and stiffness with sheet steel and base steel representative of typical construction . The data is analyzed and used in a predictive model to calculate the performance of the larger steel deck diaphragm assembly or system . These tests are conducted in accordance with the following standards , and shown in Figure 2 .
• AISI S905 Test Methods for Mechanically Fastened Cold- Formed Steel Connections
• ASTM E1190 Standard Test Methods for Strength of Power- Actuated Fasteners Installed In Structural Members
• ICC-ES AC70 Acceptance Criteria for Fasteners Power Driven Into Concrete , Steel and Masonry Elements
• ICC-ES AC118 Acceptance Criteria for Tapping Screw Fasteners
155