Trellis Wire Tension Estimate

Infer ideal parabolic span tension from declared uniform gravity line load and measured small sag, retaining horizontal/endpoint forces; not generic stress or real catenary/temperature/anchor capacity certification.

Description

A lightly sagging wire under uniform gravity load can be approximated by a parabola.

A lightly sagging wire under uniform gravity load can be approximated by a parabola. Horizontal tension differs from endpoint resultant tension.

When to use Trellis Wire Tension Estimate

Use this tool to infer ideal parabolic span tension from declared uniform gravity line load and measured small sag, retaining horizontal/endpoint forces; not generic stress or real catenary/temperature/anchor capacity certification.

Prepare vineyard measurements, dates or block records for the intended growing period. Keep weights, counts and weather observations in the stated units.

How to use Trellis Wire Tension Estimate and understand its results

Prepare vineyard measurements, dates or block records for the intended growing period. Keep weights, counts and weather observations in the stated units.
Enter wireSpanM, declaredDistributedGravityLoadNPerM, measuredMidspanSagM, callerWireTensionLimitN using the field table and calculation rules, then run the tool.
Read parabolicHorizontalWireTensionN, parabolicEndpointWireTensionN, aboveCallerWireTensionLimit. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
wireSpanM	Wire span m	number	Required
declaredDistributedGravityLoadNPerM	Declared distributed gravity load n per m	number	Required
measuredMidspanSagM	Measured midspan sag m	number	Required
callerWireTensionLimitN	Caller wire tension limit n	number	Required

Use positive span, sag and caller tension limit with nonnegative N/m load. Require sag/span at most 0.2. Flag endpoint tension strictly above the limit.^[1]

horizontal tension = load × span²/(8sag); endpoint tension = hypot(horizontal,load × span/2)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
parabolicHorizontalWireTensionN	Parabolic horizontal wire tension n	number
parabolicEndpointWireTensionN	Parabolic endpoint wire tension n	number
aboveCallerWireTensionLimit	Above caller wire tension limit	boolean

json

{
  "input": {
    "wireSpanM": 10,
    "declaredDistributedGravityLoadNPerM": 2,
    "measuredMidspanSagM": 1,
    "callerWireTensionLimitN": 30
  },
  "output": {
    "parabolicHorizontalWireTensionN": 25,
    "parabolicEndpointWireTensionN": 26.925824035672523,
    "aboveCallerWireTensionLimit": false
  }
}

Limitations and assumptions

Temperature, actual catenary behavior and anchor capacity are excluded; this is not structural approval.

Numbers and computed results must be finite; overflow produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Trellis Post Spacing Load: Screen interior post tributary reactions from caller uniform transverse line load and unequal adjacent bay lengths; simplified statics excludes wire dynamics, soils/wind/design factors and does not approve trellis spacing/safety. For a complementary task, use End Post Anchor Angle Leaning: Balance declared horizontal end-wire overturning moment with supplied ideal anchor lever height/angle and tension limit; ignores post lean, foundation/soil capacity and transient loads, not a construction/safety recommendation.

References

Trellis Wire Tension Estimate — tool.io

Similar or alternative tools

Trellis Post Spacing Load
Screen interior post tributary reactions from caller uniform transverse line load and unequal adjacent bay lengths; simplified statics excludes wire dynamics, soils/wind/design factors and does not approve trellis spacing/safety.
End Post Anchor Angle Leaning
Balance declared horizontal end-wire overturning moment with supplied ideal anchor lever height/angle and tension limit; ignores post lean, foundation/soil capacity and transient loads, not a construction/safety recommendation.