I'm putting up a new design free-standing lattice tower that will replace one of my old angle iron towers. The angle iron towers have proven to be too flexible and exhibit natural frequency problems at certain rotor rpm ranges. This new tower is designed to address and rectify both of those issues.
The new tower is 71 feet to the top of the lattice with a 8 foot 8" diameter mast so it's 79 feet to the top of the tower and 80 feet from grade to the turbine hub. The columns are 2.5" x 1/4" wall 55Kpsi mechanical tubing on section #1, section #2 is 2.5" x 3/16" wall 55Kpsi, the top section is 2.5" x 1/8" wall 55Kpsi. The lattice is 1.25" x 3/16" angle. Base spread on the tower is 7 feet.
The tower and foundation is designed, certified and built to meet TIA/EIA-222 Revision G with 114 ft
2 flat plate loading, 90 mph survival, 3 second gust, Category B Exposure zone.
The foundation is 5 feet deep, 10 feet square x 1 foot thick at the base. The tower pier is 8 feet square. The foundation is basically an inverted "tee" poured in two lifts. I has ~1,600 lbs of rebar in it and 52,740 lbs of 5Kpsi concrete.
The gin is 30 feet and the gin attachment that bolts on the base of the tower has a provision for side guy cable braces on the gin to prevent it from buckling sideways when the tower is first started on its raise. But the side braces are not needed for just the base section so they are not pictured in the photos. In fact, the gin is so heavy I had to use a floor jack to start the tower on its tip in order to lay it down with just one section standing.
I got the base section of the tower standing on the pier, and leveled. I lowered the tower late this afternoon to put the next three sections on it. But I have to wait 3 weeks for the concrete to reach full strength before putting the turbine on it.
One of my 3.5 meter high voltage MPPT turbines is going on the tower.
Lots of turbine builds get posted, but not too many free-standing lattice tower builds. Thought folks might be interested in seeing how it's done. This tower is not cheap - about $12 Grand with excavator time, all the rebar work, concrete work and steel. But I hate guyed towers with a passion (plus guyed towers can't be erected in our township) so this is the way I do 'em.
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Chris