Visual Analysis & Lattice Tower 3

[XBLEE]

I'm creating a model in Visual Analysis of a lattice tower, constructed from angle members rivetted to plates at the joints. I'm not sure if I should model the members as having rigid or simple connections. My guess is somewhere in between, which I don't really understand how to do. I'd appreciate any help.

Just another wannabe PE,

 

[JedClampett]

Traditionally, these are designed and modeled as pinned ended members.

 

[Jatfuentes]

Hi, XBLib

To suppose that the joint is a hinge was a simplification in the time of hand calculations. Always exist an restriction to joint rotations( unless a truly pin). Usually when the ratio between the side of an angle to its length was less than 10, was required an secondary stress analysis ( see N. J. Hoff - " The Analysis of Structures"- pag 103), usually painfull done by the Cross method. Today with fast computers you can suppose rigid joints and see what happen. Usually you get very small moments,
regards,
Jatfuentes

 

[transmissiontowers]

ASCE 10 is the guide you need to reference for the analysis of lattice towers, but the compression allowables are adjusted based on the end restraint for KL/r >Cc and connection eccentricity for KL/r < Cc. The formulas are based on many full scale tower tests. I have never used Visual Analysis, so forgive my ignorance if this is covered there.

The free student version of GTStrudl has a transmission tower check module if you can stay under the number of joint limits. I use PLS-CADD software to analyze towers.

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