Anchor Bolt Calculator

Cast-in-Place Anchors

1. Position anchor bolts before concrete pour
2. Use templates or fixtures for alignment
3. Secure bolts to prevent movement during pour
4. Allow concrete to cure per specifications (28 days minimum)
5. No wait time before installation of equipment

Wedge Anchors

1. Drill hole to proper diameter and depth
2. Clean hole thoroughly with brush and air
3. Insert anchor bolt with washer and nut hand-tight
4. Drive bolt with hammer to set wedge
5. Torque nut per specifications (typically 25-50 ft-lbs)

Epoxy Adhesive Anchors

1. Drill hole to proper diameter and depth
2. Clean hole with brush, follow with air flush
3. Mix epoxy per manufacturer instructions
4. Inject epoxy into hole, insert bolt, rotate bolt
5. Allow 24-hour cure before loading
6. Torque bolt per specifications

What is the difference between tensile and shear capacity?

Tensile capacity is the maximum pulling force an anchor can withstand (perpendicular to concrete surface), while shear capacity is the maximum lateral or sliding force. Combined loads require consideration of both types.

What does ACI 318 specify for anchor design?

ACI 318 is the Building Code Requirements for Structural Concrete. It provides design provisions for anchors including strength calculations, spacing requirements, edge distances, and embedment depths to ensure safe performance under loads.

How do I know if my anchor installation meets code?

Verify that embedment depth, edge distance, and spacing meet minimum requirements. Use proper installation methods (torque specifications for mechanical anchors, cure time for epoxy). Follow manufacturer instructions and have a professional engineer review critical applications.

Can I use cast-in-place anchors if the concrete is already cured?

No. Cast-in-place anchors must be installed during the concrete pour. For existing concrete, use mechanical anchors (wedge, sleeve) or epoxy adhesive anchors instead.

What is the typical safety factor for anchor design?

A safety factor of 3.0 is commonly used for static loads. Higher factors (4-5) may be required for dynamic or vibratory loads, and for critical applications like falls protection or seismic design.

How does concrete strength affect anchor capacity?

Anchor capacity increases with concrete strength. The relationship is proportional to the square root of concrete compressive strength (f'c). Higher strength concrete provides greater load capacity, especially for tensile loads.

Why is edge distance important?

Edge distance prevents concrete breakout failures where a cone of concrete around the anchor pulls away. Insufficient edge distance significantly reduces anchor capacity and can cause sudden failure.

How should I maintain anchor bolts over time?

Periodically inspect bolts for corrosion, looseness, or damage. Re-torque bolts if needed (consult manufacturer specs). Apply rust preventative if exposed to weather. Replace any damaged or corroded bolts to maintain safe load capacity.