Two-Leg Bridle Leg Tension
Leg tensions, angles, and beam reaction for an asymmetric two-leg bridle.
Example
You enter
- Apex load (lb) 1000
- Leg 1 horizontal run (ft) 4
- Leg 1 vertical rise (ft) 8
- Leg 2 horizontal run (ft) 10
- Leg 2 vertical rise (ft) 6
You get
- T1 (lb) 860
- T2 (lb) 449
- Horizontal beam reaction 385
Details, formula, and sources
Each leg's tension and angle and the horizontal beam reaction of an asymmetric two-leg bridle from the apex load and the run/rise to each point. The legs never carry half each -- the steeper leg carries more, and a shallow bridle drives both legs above the hung load.
L = sqrt(run^2 + rise^2) per leg; a = run/L, b = rise/L; den = a2 b1 + a1 b2; T1 = W a2/den, T2 = W a1/den; H = T1 a1 = T2 a2.
Entertainment rigging bridle geometry (asymmetric two-leg static resolution), by name.
Static bridle resolution is a public statics result; ASME B30.9 governs rigging practice. An ESTIMATE only; the hardware ratings and a qualified rigger govern.
Estimate. Head rigger and manufacturer working-load-limit charts govern. Inspect every piece of hardware before the show.
Field names used by the API: apex_load_lb, run1_ft, rise1_ft, run2_ft, rise2_ft, t1_lb, t2_lb, horizontal_lb
- Two-dimensional statics single apex, two legs in one vertical plane; a three-point or out-of-plane bridle differsbridle statics
- Estimate only the hardware working load limits and a qualified rigger govern the actual pickASME B30.9