Instructions 2 – The measurement
How does it work?
- Accurately determine height of the tree (usually with a tape measure)
- Determine wind load and centre of the surface, direction of tension towards or against the damage
- Attach tilting angle sensors (up to 4) and length measuring sensors (up to 10) towards or against the direction of the tension.
- Attach pull rope at tested tree (stable point, as high as possible)
- Attach pull rope at anchor point (tree, van, rope angle smaller than 45° not admissible)
- Adjust sensors, reset, note down sensor length, sensor positions (form)
- Increase tensile load step by step (100 kg steps with 10 sec. breaks, lead in slowly)
- Maximum tensile load is 39 % of possible wind load
- Tilting angle at tree base may not exceed 0.25°
- Edge fibre strains, compressions depending on sensor length, max. 30% of the maximum possible strain/compression
- Note down measured values of the sensors in each load step (form)
- Evenly, swiftly release after reaching maximum load or maximum limits.
- Note down resetting behaviour, measured values of all sensors (form)
- Enter basic data and measured values in the TSE calculation program and initiate calculation.
- The respective safety values in proportion to the assumed wind load appear in the relevant columns/lines. Values in the lines across the individual load steps have to show approximately the same value. In case of differences or measured values increasing or decreasing heavily, errors in the application (sensor attachment, etc.) are to be checked first. Afterwards the measurement shall be repeated. If the sensors or the measured results are synchronous to the previous measurement it is required to reflect further on the cause. It may be required to use other measuring technologies.
TSE may be loaded with a real example file filling the fields with basic data and measuring results. After initiating the calculations the safety values are displayed. Now certain basic values and measured values may be changed and the resulting effects may be displayed by means of the calculation. For example cutting the tree top may be simulated by decreasing the top sail surface while reducing the load centre at the same time. After calculating the values obtained for stability and safety against fracture are corrected.TOP