COMBINED TENSION AND SHEAR LOAD
Tri-Linear
Calculations Utilization β N , V
[%]
Calculations 318-14 Chapter 17 Provision Comments for PROFIS Engineering Utilization β N , V
[%]
17.6 – Interaction of tensile and shear forces
Unless determined in accordance with 17.3.1.3 , anchors or groups of anchors that are subjected to both shear and axial loads shall be designed to satisfy the requirements of 17.6.1 through 17.6.3 . The values of ϕN n and ϕV n shall be the required strengths as determined from 17.3.1.1 or from
17.2.3 . 17.6.1 If V ua
/( ϕV n ) ≤ 0.2 for the governing strength in shear , then full strength in tension shall be permitted : ϕN n ≥ N ua
.
17.6 . 2 If N ua /( ϕN n
) ≤ 0.2 for the governing strength in tension , then full strength in shear shall be permitted : ϕV n ≥ V ua
.
17.6.3 If V ua /( ϕVn ) > 0.2 for the governing strength in shear and N ua
/( ϕN n ) > 0.2 for the governing strength in tension , then
N ua + V ua ≤ 1 . 2 ( 17 . 6 . 3 ) ϕN n ϕV n
The failure mode for a given tension or shear load condition can be expressed as a ratio of factored load to design strength :
• Factored tension load / tension design strength = ( N ua / ϕN N
)
• Factored shear load / shear design strength = ( V ua / ϕV N
)
PROFIS Engineering references these ratios as “ utilizations ”, and shows them in the report as a percentage .
Part 3 of the PROFIS Engineering report shows the utilizations for each tension failure mode being considered and designates “ tension utilizations ” via the parameter “ β N
”. 3 Tension load
Load N ua [ lb ]
Capacity
ϕN n
[ lb ]
Utilization
β N
= N ua / ϕN n
Status
Steel strength * 5,000 14,550 35 OK Bond strength ** 10,000 31,564 32 OK Sustained tension load bond strength * 3,450 16,800 21 OK Concrete breakout Failure ** 10,000 19,971 51 OK
* highest loaded anchor ** Anchor group ( anchors in tension )
Part 4 of the PROFIS Engineering report shows the utilizations for each shear failure mode being considered and designates “ shear utilizations ” via the parameter “ β V
”.
4 Shear load
Load V ua [ lb ]
Capacity
ϕV n
[ lb ]
Utilization
β N
= V ua / ϕV n
Status
Steel strength * 1,500 4,540 33 OK Steel failure with lever arm * N / A N / A N / A N / A Pryout ( bond strength controls )* 6,000 52,765 12 OK Concrete edge failure in direction x + ** 6,000 10,080 60 OK
* highest loaded anchor ** Anchor group ( relevant anchors )
364 NORTH AMERICAN PROFIS ENGINEERING ANCHORING TO CONCRETE DESIGN GUIDE — ACI 318-14 Provisions