Ground Anchor Tieback Capacity Calculator
Geotechnical anchoring & shoring engineering: Determine prestressed ground anchor bond length ($L_b$), unbonded free length ($L_f$), tendon strand capacity, and elastic proof test elongation per FHWA GEC-007.
Design Load & Geometry
Working unfactored anchor tension (~100 kips)
Degrees downward from horizontal (15°–25° standard)
Standard auger / cased hole diameter (6 inches)
FHWA minimum = 4.5 m (15 ft)
Ground Stratum & Grout Bond Stress
FHWA Geotechnical Tieback Rules
- Bond Length ($L_b$): Typically $4.5\,\text{m} \le L_b \le 12\,\text{m}$. Lengths $>12\,\text{m}$ suffer progressive bond debonding.
- Safety Factor: $FS \ge 2.0$ on ultimate ground-grout bond stress.
- Tendon Lock-off: Prestressed to $75\% - 100\%$ of design load; proof-tested to $133\%$.
Bonded Length & Capacity
Required Bond Length (L_b)
--
Total Anchor Length (L_tot)
--
Steel Tendon & Strand Sizing
Required Tendon Strands
--
0.6" (15.2 mm) Gr 270 strands
Proof Test Load (133% T_d)
--
Performance verification load
Proof Test Elastic Elongation
Expected Elastic Elongation (ΔL):
--
Allowable FHWA Acceptance Band:
--
Bond Length Viability:
--
Recommended Tools & Equipment
Tested hardware and components for high reliability
100% Free Tool
Zero Sign-Up