In ultimate strength design (USD), the Designer must size the anchorage such that the required strength (i.e. factored load) does not exceed the lowest design strength of the anchor or anchor group considering all possible failure modes.

N_ua ≤ N_n
V_ua ≤ V_n

Calculations are performed in accordance with the applicable design standards: ICC-ES AC193 and ACI 318 Appendix D for mechanical anchors and ICC-ES AC308 for adhesive and torque-controlled adhesive anchors. The additional design provisions of AC308 are shown elsewhere on this website.

The nominal strengths and design data throughout this website are derived from full-scale testing and calculations in accordance with ACI 355.2, ICC-ES AC193 and ICC-ES AC308. In general, nominal strengths are 5% fractile strengths calculated using the average ultimate load, and standard deviation of full scale test results. A 5% fractile strength is the nominal strength for which there is a 90% confidence that there is a 95% probability of the actual strength exceeding the nominal strength.

For anchors that are designed using ACI 318 Appendix D, AC193, or AC308, it is possible to convert design strengths (i.e. N_n or V_n) to allowable loads using the following approach from AC193 (dated February 2008) and AC308 (dated February 2008):

Tallowable,ASD =	Nn	and    Vallowable,ASD =	Vn
	α		α

where:

T_{allowable,ASD}= Allowable tension load

V_{allowable,ASD} = Allowable shear load

N_n = Lowest design strength of an anchor or anchor group in tension as determined per ACI 318 Appendix D, AC193, AC308 and IBC Section 1908.1.16.

V_n = Lowest design strength of an anchor or anchor group in shear as determined per ACI 318 Appendix D, AC193, AC308 and IBC Section 1908.1.16.

α = Conversion factor calculated as a weighted average of the load factors for the controlling load combination. In addition, α shall include all applicable factors to account for non-ductile failure modes and required over-strength.

Interaction shall be calculated as follows:

For tension loads, T ≤ 0.2T_allowable, the full allowable load in shear shall be permitted.

For shear loads, V ≤ 0.2V_allowable, the full allowable load in tension shall be permitted.

For all other cases:	T	+	V	≤ 1.2
	Tallowable		Vallowable

ICC-ES AC308 ULTIMATE STRENGTH DESIGN METHOD FOR ADHESIVE AND TORQUE-CONTROLLED ADHESIVE ANCHORS