PART 4 SHEAR LOAD
Stand-off Failure Mode
Results V ua
Results 318-14 Chapter 17 Provision Comments for PROFIS Engineering
V ua
5.2.3.2 Steel failure b ) Shear load with lever arm
The characteristic resistance of an anchor , VRk , s , is given by Equation ( 5.5 ).
ACI 318-14 Section 17.3.1.1
V Rk , s
= α M M Rk , s [ N ] ( 5.5 ) l
17.3.1.1 The design of anchors shall be in accordance with Table 17.3.1.1 . In addition , the design of anchors shall satisfy 17.2.3 for earthquake loading and 17.3.1.2 for adhesive anchors subject to sustained tensile loading .
Excerpt from ACI 318-14 Table 17.3.1.1 showing provisions for shear calculations . Table 17.3.1.1 — Required strength of anchors , except as noted in 17.2.3
Failure Mode Single Anchor
Individual anchor in a Group
Steel strength in shear ( 17.5.1 ) ϕ steel
V sa
≥ V ua ϕ steel
V sa
≥ V ua , i
Concrete breakout strength in shear ( 17.5 . 2 )
Concrete pryout strength in shear ( 17.5.3 ) ϕ concrete
V cb
≥ V ua ϕ concrete
V cp
≥ V ua
Anchor Group
Anchors as a group
ϕ concrete
V cbg
≥ V ua , g ϕ concrete
V ag
≥ V ua , g
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 . 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 resistance ; however , the calculations are based on ACI 318-14 strength design provisions . Therefore , PROFIS Engineering calculates a “ design strength ” with respect to bending , which it designates “ ϕV sM
”, using values for the parameters α M , M s
, L b and a strength reduction factor ( ϕ steel
) for steel failure in shear .
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 “ ϕV sM
” in PROFIS Engineering corresponds to the design shear strength with respect to bending , and is calculated as follows :
ϕV s
M
= ϕ steel [( α M
M s
)/ L b ].
The PROFIS Engineering parameter “ ϕ VsM ”, therefore , corresponds to the parameter “ V Rk , s
” in
Equation ( 5.5 ). PROFIS Engineering calculates ϕV s
M for a single anchor and checks this “ design strength ” against a factored shear load ( V ua ). If the application consists of a single anchor in shear , ϕV s
M is checked against the factored shear load acting on the anchor . If the application consists of a group of anchors in shear , ϕV s
M is checked against the highest individually loaded anchor in shear . The PROFIS Engineering report uses the generic designation “ V ua
” to reference either the only shear load acting on an anchor in shear , or the highest shear load acting on an individual anchor within an anchor group in shear . PROFIS Engineering considers the provisions for steel failure in shear with respect to bolt bending to have been satisfied if
ϕV s
M
≥ V ua
.
The PROFIS Engineering Load Engine permits users to input service loads that will then be factored per IBC factored load equations . Users can also import factored load combinations via a spreadsheet , or input factored load combinations directly on the main screen . PROFIS Engineering users are responsible for inputting shear loads . If a single anchor in shear is being modeled , PROFIS Engineering calculates ϕV sM
, and checks this value against either ( a ) the factored shear load acting on the anchor , which has been calculated using the loads input via the Load Engine , ( b ) the factored shear load acting on the anchor , which has been calculated using the loads imported from a spreadsheet or ( c ) the factored shear load acting on the anchor , which has been calculated using the loads input in the matrix on the main screen . The value for V ua shown in the report corresponds to the factored shear load determined to be acting on the anchor . If a group of anchors in shear is being modeled , PROFIS Engineering calculates ϕV sM
, and checks this value against either ( a ) the highest factored shear load acting on an individual anchor that is calculated with the Load Engine , ( b ) the highest factored shear load acting on an individual anchor that is determined from the loads imported from a spreadsheet or ( c ) the highest factored shear load acting on an individual anchor that is determined from the loads input in the matrix on the main screen . The value for V ua shown in the report corresponds to the highest factored shear load determined to be acting on an individual anchor within the group of anchors that are in shear .
Reference the Equations section of the report for more information on :
ϕV s
M
≥ V ua
: ACI 318-14 design check for bending
Reference the Results section of the report for more information on the following PROFIS Engineering parameters .
ϕ steel
: Strength reduction factor for steel failure in shear
ϕV sM
: Design shear strength ( resistance ) for bending
346 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions