I think Ex8, Ex5, and Ex12 were probably provided by clients. The examples provided with PLS-Tower are meant to show the program functionality and some modeling concepts and are not meant to be 100% correct. They opened an office in Houston, Texas a couple of years ago and I know their Vice President of Engineering. I believe they started out in Italy and operate in Brazil and Mexico.
#Pls cadd tower samples full#
They said that SAE Towers used this staggered leg bracing after much full scale testing, so you may be able to contact them and ask about it. I talked to PLS-TOWER tech support and they feel that Ex8 bracing ratios are probably not correct and should be 2.4/1.2/1.2 for the staggered leg bracing which makes some sense to me after reading ASCE 10 and thinking about it for a while. RE: Angles welded in TOWER transmissiontowers (Structural) 25 Jul 12 08:06 I have been called "A storehouse of worthless information" many times. I have attached a marked up screen shot with a few redundants added that would stabilize the legs and allow K=1 for them. The bridge and building engineers that have to consider human occupancy would faint if they had to deal with the factors of safety we use all the time. Our T-Line industry is fairly unique in that we will accept occasional failure in order to put up cost effective lines. In the strictest sense, a truss member analysis of the staggered leg bracing is unstable and a normal FEA program will never solve the stiffness matrix because of the instability that you see. The program takes into account some bending stiffness of the legs so that it is mathematically stable. The legs are continuous but are usually analyzed as truss members with pinned joints.
At its compression limit, the leg may try to twist but the equations were developed with lots of full scale testing and are conservative. The tower uses a staggered bracing pattern and the KL/r is adjusted for the leg. I look at these pictures daily so it is not too foreign to me. I'm not sure what you meant by no diaphragms, but his picture is the output from PLS-Tower showing his 4 sided tower with the 4 sides color coded. RE: Angles welded in TOWER rubenpezu (Industrial)
If they choose to ignore the failure and risk the potential damages, you can point to your results that predicted failure in the event the towers collapse.
There is a saying, "the loss of human life will be more than offset by the cost savings". As members get close to their capacity in a lattice tower, the load path can redistribute and the tower will remain standing while the computer will predict failure.Ībout the only thing you can do is report your results to your management and recommend that the tower be modified or replaced and let them make the economic decision. If the computer says something like 112% and the real test showed the tower passed, then you may have some rationalization that the computer under-predicted the capacity. The computer says it fails and the testing says it was fine, so which do you believe? I would suggest that you try to put in a load case that is exactly what was tested and look at the results in PLS-TOWER to compare the computer results to the real test.
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