wijgeng
Structural
- Dec 23, 2014
- 27
My company is currently constructing a wind farm next to one of our existing wind farms. My question is about the foundation anchor rods. The rods are typically #11 Grade 150 threaded rods (different turbine types may use different sized bolts such as #10, but that is not related to my question).
Typically, the anchor rods are post-tensioned, then 10% of the bolts are checked after initial torque, 10% of the bolts are tested again after the turbines operate for 500 hours, and 10% of the bolts are checked again after 1 year of operation. At our existing wind farm, the design engineers have signed off stating that no further testing is required. This is not typical as the engineers at our new wind farm are taking the more common approach of having 10% of the bolts being checked every other year for the life of the plant.
I am curious as to why the engineers at the first wind farm have decided that the bolts do not need to be tested throughout the life of the project, but the others require bi-annual testing? I am a young engineer and will not be making the decision on when rods should be tested, but some day I hope to get to that point in my career. The two issues I can think of which could require re-tensioning are relaxation of the post-tensioned rods and "rattling" loose of the bolts due to turbine vibration. Are these the two major factors requiring re-tensioning of a post-tensioned rod? Am I missing anything?
Thanks!
Typically, the anchor rods are post-tensioned, then 10% of the bolts are checked after initial torque, 10% of the bolts are tested again after the turbines operate for 500 hours, and 10% of the bolts are checked again after 1 year of operation. At our existing wind farm, the design engineers have signed off stating that no further testing is required. This is not typical as the engineers at our new wind farm are taking the more common approach of having 10% of the bolts being checked every other year for the life of the plant.
I am curious as to why the engineers at the first wind farm have decided that the bolts do not need to be tested throughout the life of the project, but the others require bi-annual testing? I am a young engineer and will not be making the decision on when rods should be tested, but some day I hope to get to that point in my career. The two issues I can think of which could require re-tensioning are relaxation of the post-tensioned rods and "rattling" loose of the bolts due to turbine vibration. Are these the two major factors requiring re-tensioning of a post-tensioned rod? Am I missing anything?
Thanks!
