PROFIS Design Guide: US-EN Summer 2021 | Page 341

Stand-off Failure Mode

Results V _S

M

Results 318-14 Chapter 17 Provision Comments for PROFIS Engineering

V _S

M

5.2.3.2 Steel failure b ) Shear load with lever arm

The characteristic resistance of an anchor , V _{Rk , s} , is given by Equation ( 5.5 ). where

V _{Rk , s}

= ^α M ^M Rk , s [ N ] ( 5.5 ) l α _M

= see 4.2.2.4 l = lever arm according to Equation ( 4.2 )

M _{Rk , s}

= M ^{0 ( 1 - N / N} ) [ Nm ] ( 5 . 5a )

Rk , s Sd Rd , s

N _{Rd , s}

= N _{Rk , s} / γ _Ms

N _{Rk , s}

, γ _Ms to be taken from the relevant ETA M ⁰ = characteristic bending resistance of an individual anchor

Rk , s

The value of M ⁰ for anchors according to current experience is obtained from Equation ( 5 . 5b ).

Rk , s

M ⁰ Rk , s ^{= 1 . 2 W} el ^f uk

[ Nm ] ( 5 . 5b )

The figures below illustrate ETAG 001 design assumptions with respect to bolt bending . PROFIS Engineering nomenclature for ACI 318 calculations is used in the illustrations .

Shear and tension load act on an anchor having standoff .

PROFIS Engineering uses the provisions given in the European Technical Approval Guideline ( ETAG ) titled ETAG 001 Metal Anchors for Use in Concrete Annex C : Design Methods for Anchorages to consider bolt bending as a possible shear failure mode . When a standoff condition exists for an anchorage , an applied shear load can create bending in the anchors . An internal bending resistance , designated M ⁰ , can be calculated using the material properties of the anchor

Rk , s element . M ^{0 is designated “} Rk , s ^M0 ” in PROFIS Engineering , and is calculated per s

Equation ( 5.5b ). If tension load also acts on the anchor , M ⁰ is reduced by a

Rk , s factor designated ( 1 – N _sd

/ NRd , s ) per Equation ( 5.5a ), and the resultant design bending resistance is designated “ M _{Rk , s}

” in Equation ( 5.5 ). M _{Rk , s} is designated

“ M _s ” in PROFIS Engineering . The parameter “ α _M

” in Equation ( 5.5 ) corresponds to the amount of rotational restraint acting on the fixture , and the parameter “ l ” ( designated L _b in PROFIS Engineering ) corresponds to distance from where the shear resistance is assumed to act , to the “ point of fixity ” in the concrete where the internal bending resistance is assumed to act .

Reference the figures to the left . The parameter V _{Rk , s} in Equation ( 5.5 ) corresponds to the design shear resistance . Per Equation ( 5.5 ), PROFIS Engineering calculates a design shear strength ( resistance ) with respect to bending using values for the parameters α _M

, M _s , L _b and a strength reduction factor ( ϕ-factor ) for steel failure in shear . PROFIS Engineering designates this design shear strength “ ϕV _sM

”.

ACI 318 anchoring-to-concrete provisions require calculation of a “ nominal strength ” which is then multiplied by a strength reduction factor ( s ) ( ϕ-factors ) to obtain a “ design strength ”. The parameter “ V _sM

” in PROFIS Engineering corresponds to the nominal shear strength with respect to bending , and is calculated as follows :

V _s

M

= ( α _M

M _s

)/ L _b

The parameter “ ϕV _sM

” in PROFIS Engineering corresponds to the design shear strength with respect to bending , and is calculated as follows :

ϕV _s

M

= ϕ [( α _M

M _s

)/ L _b ].

The PROFIS Engineering parameter “ ϕV _sM ”, therefore , corresponds to the parameter “ V _{Rk , s}

” in Equation ( 5.5 ). Per ACI 318 anchoring-to-concrete provisions , ϕV _s

M is checked against the factored shear load ( V _ua ) acting on the anchor .

341 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions