How to Use Anchor Bolt Calculator
The Anchor Bolt Calculator provides structural and mechanical estimates for anchor bolt design in concrete. Enter the bolt diameter, embedment depth, concrete strength, edge distances, and acting design loads. The calculator instantly evaluates the governing failure modes and utilization ratios.
- Enter Anchor Geometry & Steel Grade — Select the bolt diameter, steel grade (e.g., 8.8, 5.8, A4-70), and effective embedment depth $h_{ef}$.
- Specify Concrete Properties & Boundary Conditions — Choose the concrete strength class (e.g., C20/25 to C50/60), whether the concrete is cracked or uncracked, and define edge distances and spacing.
- Apply Design Loads & Check Interaction — Input the applied tensile load $N_{Ed}$ and shear load $V_{Ed}$ to evaluate individual utilization and combined interaction ratios.
Formula & Theory — Anchor Bolt Calculator
The Anchor Bolt Calculator calculates resistances based on established design provisions from DIN EN 1992-4 / ETAG 001 and ACI 318:
1. Steel Tension Resistance ($N_{Rd,s}$)
$$N_{Rd,s} = \frac{A_s \cdot f_{uk}}{\gamma_{Ms}}$$
Where $A_s$ is the tensile stress area, $f_{uk}$ is the nominal tensile strength of the steel, and $\gamma_{Ms}$ is the partial safety factor for steel failure.
2. Concrete Cone Breakout Resistance ($N_{Rd,c}$)
$$N_{Rk,c}^0 = k_{cr} \cdot \sqrt{f_{ck}} \cdot h_{ef}^{1.5}$$
$$N_{Rd,c} = \frac{N_{Rk,c}^0 \cdot \psi_{s,N} \cdot \psi_{re,N} \cdot \psi_{ec,N}}{\gamma_{Mc}}$$
Where $k_{cr}$ is $7.7$ for cracked concrete and $11.0$ for uncracked concrete, $f_{ck}$ is characteristic cylinder compressive strength, and $h_{ef}$ is the effective embedment depth.
3. Combined Tension and Shear Interaction
$$\left( \frac{N_{Ed}}{N_{Rd}} \right)^{1.5} + \left( \frac{V_{Ed}}{V_{Rd}} \right)^{1.5} \leq 1.0 \quad \text{or} \quad \left( \frac{N_{Ed}}{N_{Rd}} \right) + \left( \frac{V_{Ed}}{V_{Rd}} \right) \leq 1.2$$
Use Cases for Anchor Bolt Calculator
- Structural Steel Baseplate Fastening — Verify anchor bolt capacities for column baseplates, portal frames, and structural brackets.
- Heavy Machinery & Equipment Anchorage — Check pull-out and shear resistance under dynamic or static operating loads.
- Facade & Railing Attachments — Ensure anchor safety with edge distance checks to prevent concrete edge blowout.
- Retrofit & Structural Renovation — Quickly verify existing anchor bolt embedment depths and load capacities for new structural loads.