Hey,
Looking at all the skyscrapers going up these days around the world, i was wondering how they control the verticality of them. I understand the traditional methods used in buildings up to 100m using laser plummets and Total Stations but skyscrapers are huge(One World Trade Center-541m,Burj Khalifa-830m). So many factors have to be taken into consideration Wind (Resonance), Solar Energy (heating and shrinking), Random movement from cranes etc.
It's blows my mind even thinking about how the surveyors would meet the building specifications.:-S
It's impossible. I don't know how they do the really tall ones either. I've done control on several short towers, and I always got bitched at for my "lousy" control. Even just the second floor of a steel structure will move as much as a tenth throughout the day. And after about the fifth floor, the building is swaying so bad that you can't use an autolevel. I swore I'd never do another tower.
Dave
Search this forum for Scott Zelenak's posts. He mentioned the difficulty of maintaining verticality several times.
Please contact Joel van Cranenbroeck of Leica (Heerbrugg, Switzerland). To my knowledge, he was the one who devised the technique of controlling/monitoring erection/construction verticality of Burj Khalifa. I personally met him in HK during an event/workshop on high rise structures construction monitoring conducted in The Hong Kong Polytechnic University in November last year.
According to him, it is possible.
Obviously, it's not impossible. Just above my pay grade or I missed that class or something.:-S
Dave
Leica Geosystems Core Wall Survey Control System seems to be the system of choice in skyscrapers today and of the future (planned for several projects in the Arabian Gulf with heights in excess of 1000m). The Developments of GNSS and Total Stations have made this possible. I think this is what made the leap in building structures so high now. Taipei 101 was the biggest building at 509m then the Burj was built at 828m, that is a big increase.
Anyone have any ideas what methods were used in older skyscrapers such as the Petronas Towers-452m built in 1998 and Sears Tower-442m built in 1973.
Piano wire and a plumb bob in a 50-gallon barrel of oil?
Dave
There's a lengthy article hidden away somewhere on the fig website. A Google search takes you directly to the downloadable pdf.
Copy and paste this into a search engine to access the pdf:
Advanced Surveying Control Services for Building the Vertical Cities. Joël VAN CRANENBROECK, Switzerland
The answer would appear to be lots of hardware, lots of software, lots of money.
Ask the guy on the job known as "Six Pack".