Anchor Spacing, Edge Distance & Embedment Depth Flashcards
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Read the first 7 Anchor Spacing, Edge Distance & Embedment Depth flashcards as text
What is the primary reason minimum edge distance requirements exist for adhesive anchor installations?
Answer: To prevent concrete splitting or breakout failure near the edge
Minimum edge distances prevent concrete splitting and edge breakout failure modes that occur when anchors are placed too close to a free surface.
The effective embedment depth (h_ef) of an adhesive anchor is measured from:
Answer: The concrete surface to the tip of the adhesive-bonded portion of the anchor
Effective embedment depth (h_ef) is the depth of the bond zone, measured from the concrete surface to the bottom of the adhesive-bonded length of the anchor.
When adhesive anchors are installed in a group, the minimum center-to-center spacing requirement is intended to prevent:
Answer: Overlapping bond stress zones that would reduce individual anchor capacity
When anchor spacing is too small, the bond stress zones overlap, reducing the effective load transfer area and lowering the capacity of each anchor in the group.
According to ACI 318, what term describes the minimum edge distance below which the anchor capacity must be reduced due to proximity to a free edge?
Answer: Critical edge distance (c_ac)
The critical edge distance (c_ac) is the ACI 318 term for the minimum edge distance at which the full anchor capacity can be achieved without reduction.
If an adhesive anchor is installed with an embedment depth less than the minimum specified in the MPII, the installer should:
Answer: Stop work and consult the engineer of record before proceeding
Installing below the minimum specified embedment depth compromises structural integrity, requiring an engineer of record to evaluate and approve a corrective action.
The minimum concrete member thickness for adhesive anchor installation is typically specified as a function of:
Answer: The embedment depth and anchor diameter as specified in the MPII or evaluation report
Minimum member thickness is typically specified as a multiple of embedment depth (e.g., h_ef + some clearance) and anchor diameter per the product's evaluation report or MPII.
When an adhesive anchor must be placed closer to an edge than the critical edge distance but farther than the minimum edge distance, the design approach is to:
Answer: Apply a reduction factor to the anchor's tensile and shear capacity
When the edge distance falls between the minimum and critical values, ACI 318 requires applying edge distance modification factors that reduce the calculated anchor capacity.