for allowable slenderness of a member, which is more decisive, compression member or tension ?
i think compression member is more decisive because the allowable slenderness is 200 (tension 300).
my intention is, when a member experiencing all compress in all load case, so the member is a compression member which allowable slenderness is 200.
and vice versa, if a member experiencing all tension in all load case, so the member is a tension member which allowable slenderness is 300.
but how about if a member experiencing compress and tension in all load case ?
in my staad 2010, i check the member 509 experience the compress and tension.
tension for load comb 101 to 104 and 106. compression for load comb 105.
but in output report, the staad consider the slenderness by using load 101 so the allowable is 300.
here's my parameter
CODE AISC UNIFIED 2005
TRACK 2 ALL
RATIO 1 ALL
MAIN 200 ALL
LOAD LIST 101 TO 106
*LOAD LIST 105
CHECK CODE MEMB 509
when i used AISC 360-05 code, the staad contain error. due to slenderness (FAIL).
so in my opinion, for 360-05 code, the logic will be check the slenderness first, and then the ratio. if slenderness is exceed, and then staad give us ERROR. if slenderness is ok, then staad will check the strength.
but in 360-10 code, the slenderness is checked using the first load case even it is tension or compress (?) instead of the load case which make the member compressed and the output is just like the mention above (only shows the stress ratio).
i do try check the member only use the load list 105 (compression) and the staad give us correct answer.
SLENDERNESS, AND COMPRESSION, AND ALLOWABLE ARE CORRECT.