( w 2 )
( w 2 )
3.5.1.7 DIAPHRAGM SHEAR AND STIFFNESS CALCULATIONS
Background : An extensive independent laboratory test program was conducted investigating the performance of steel deck diaphragms attached with Hilti fasteners . The program test scope consisted of full scale diaphragm system tests conducted in accordance with ICC-ES AC43 and AISI S907 , as well as comparative small element lap-joint shear tests conducted in accordance with AISI S905 Test Methods for Mechanically Fastened Cold-Formed Steel Connections . The resulting full scale and small element test data was analyzed and predictive equations were developed for the steel deck diaphragm system strength and stiffness using specific combinations of Hilti fasteners .
The American Iron and Steel Institute ( AISI ) Standard for the Design of Profiled Steel Diaphragm Panels ( S310 ) method equations are used as the basis for determining the steel deck diaphragm strength and stiffness . Specific Hilti fastener strength and stiffness values and test data correlation adjustment factors were developed to provide 95 % or greater accuracy with test results per ICC-ES AC43 requirements .
The resulting design information is documented in this section and in ICC-ES ESR-2776 and ESR-2197 .
Design : Design equations for calculating steel deck diaphragm strength ( S ) and stiffness ( G ') or flexibility factor ( F ) with Hilti X-HSN 24 , X-ENP-19 L15 or S-MD 12-24x1-5 / 8 M HWH5 ( RT5 ) frame fasteners and Hilti Sidelap Connectors ( SLC ) are provided . The equation numbers in parenthesis correspond to the equation numbers provided in the AISI S310 . The design equation variables needed for common steel deck diaphragm applications are found in Tables 7 through 9 . The conversion factors for Allowable Stress Design ( ASD ), Load Resistance Factor Design ( LRFD ) and Limit States Design ( LSD ) provided in Table 11 shall be applied to the values determined from the design equations in order to produce the final Allowable Diaphragm Shear , S ASD or Factored
Resistance Diaphragm Shear , S LRFD or S LSD , respectively .
The calculated S ASD , S LRFD or S LSD
Diaphragm Shear values do not take into account steel deck buckling and must be checked against the appropriate buckling diaphragm shear value , S buckling
, found in Table 12 . Reference Sections 3.5.2 , 3.5.3 , 3.5.4 and 3.5.5 for pre-calculated diaphragm shear and stiffness tables for the X-HSN 24 , X-ENP-19 , S-RT5 +, and S-MD 12-24x1-5 / 8 M HWH5 fasteners , respectively .
The design equations and load values in this section are for 36 " wide , 1-1 / 2 " deep wide rib steel deck panels ( B-Deck or BI-Deck types ) and are limited to the fastener patterns shown in Figure 16 and sidelap connector spacings greater than 3 " and in accordance with Table 10 .
Direct Fastening Technical Guide , Edition 24
For other steel deck diaphragm conditions ( e . g . deck profile , deck gauge , concrete-filled , etc .) not represented in the tables found in this section , use Hilti Profis DF Diaphragm software or reference ICC-ES ESR-2197 .
AISI S310 steel deck diaphragm strength design equation
S ni
= [ 2 x A x ( λ- 1 ) + ß ] x P nf , plf Eq . D1-1
L
S nc
= P nf x
S ne
=
N 2 x ß 2 , plf Eq . D1-2 L 2 x N 2 + ß 2
( 2 x α 1 x n p x α 2 ) P nf
+ n e P nfs , plf Eq . D1-3
S nf
= min ( S ni , S nc
, and S ne ), plf
S nf
= c x S nf
, plf with : ß = n s x α s + 2n p
X p
2
+ 4 X e
2
X p
2
=
X p
2
=
1
( w 2 )
1
( w 2 )
Σ x p
2
Σ x e
2
D λ = 1- d
L v ≥ 0 . 7 αs = P ns 240 x t P nf where :
L
t = nominal steel deck thickness , in . ( Reference Table 6 ) w = deck width N = number of fasteners per unit length across the width , ft -1
x e
= x p
= distance from panel centerline to any fastener in a panel at the end ( x e
) or purlin ( x p
) supports S = nominal diaphragm shear strength , plf L = span , ft
L = panel length = 3 x L , ft n e
= n s
= 3 x L x 12 ÷ ( sidelap connector spacing in inches ) c = correlation factor for diaphragm system effect
Reference Tables 7 and 8 for description and values of other variables for common conditions .
Uplift and combined loading : Allowable loads to resist uplift forces are provided in the individual sections for each frame fastener . Reference SDI DDM04 Section 4.7 or Section D3 of AISI S310 for combined tension uplift and diaphragm shear interaction .
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