AAI AAI Load Calculations & Structural Requirements

Question 1

In ACI 318 anchor design, what does the term 'characteristic bond strength' (τk) represent?

Accepted Answer

The 5th percentile bond strength from testing used as the basis for design

Answer

The characteristic value is the 5th percentile of the test population, meaning 95% of tested anchors will meet or exceed this strength, providing a conservative design basis.

Question 2

Which failure mode for adhesive anchors involves pulling out a cone of concrete around the anchor?

Accepted Answer

Concrete cone breakout

Answer

Concrete cone breakout occurs when tensile stress radiates out from the anchor head and fractures the concrete in a conical shape, governed by ACI 318 equations based on embedded depth and concrete strength.

Question 3

How does increasing the embedment depth of an adhesive anchor affect its tensile bond capacity?

Accepted Answer

It increases capacity because a larger bonded surface area develops greater total bond force

Answer

Bond capacity is proportional to the bonded perimeter (π × diameter) times embedment depth; doubling the depth approximately doubles the bonded area and total bond force.

Question 4

When adhesive anchors are installed in a group, what design reduction factor must be applied?

Accepted Answer

A group effect factor (ψg) that accounts for overlapping stress cones

Answer

Overlapping stress cones in anchor groups reduce the effective breakout area, captured by the group factor ψg in ACI 318 Chapter 17 calculations.

Question 5

What is the significance of the sustained load reduction factor for adhesive anchors under long-term tension?

Accepted Answer

Bond strength can creep under sustained tension, so a reduction factor lowers allowable sustained loads

Answer

Polymeric adhesives can exhibit creep (slow deformation) under constant tension, so ACI 318 and ICC-ES reports require a sustained load reduction to prevent progressive failure.

AAI - American Concrete Institute Adhesive Anchor Installer Certification Practice Test

AAI - American Concrete Institute Adhesive Anchor Installer Certification Practice Test

AAI AAI Load Calculations & Structural Requirements