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aluminum slenderness - 1997 UBC

Thread starter nongamer12
Start date Mar 31, 2010

Status: Not open for further replies.

Mar 31, 2010

nongamer12

Structural

I am evaluating an aluminum truss canopy that was built based on the 1997 UBC. I know member sizes and aluminum grade, but am having trouble evaluating the allowable compressive stress. The aluminum is 6063-T5, and I was using the welded aluminum properties. I'm using Table 20-I-C and specification #7 to evaluate the compression members of the truss. When I try to evaluate S1 and S2 slenderness limits, I am getting a nonsense number for S1 (I get -30.64). The terms of the slenderness equation appear to all be based soley on aluminum grade, yet I get a negative number. Can anyone help me figure out what I'm doing wrong? Thanks!