Wind tipping curves - assessing the anchorage and wind load of urban trees by motion monitoring.
To date, the anchorage and wind load of urban trees can only be assessed in static load tests. These are complex and expensive, and the reliability of wind load estimates has been questioned. Monitoring the basal inclination of trees in natural winds yields a wind tipping curve, which can be used to inexpensively assess anchorage. Combining this with static load test allows to estimate real wind loads, which can be used to assess the conventionally used wind load estimates. Our analyses show that wind speed data can be taken from weather stations several kilometers away from the tree. The quality of the wind speed-tilt correlation does vary, depending on local conditions and topography. The differences between measured and estimated wind loads were rather modest between 4% and 31%. Thus, our results show that dynamic loads in gusts are comparable to the results of a wind load analysis. They cause a maximum reaction that can be reproduced in static load tests.