Designing double channel-front to front

javad sanjari — Sun, 25 Dec 2016 11:21:05 GMT

I have a strucrure that has modeled in staad pro and there are some double channels(front to front) for vertical bracing sections. When i want to design structure using AISC-360(ASD) there are some warning that tell me design of section for these members is not supported but when i use double channel(back to back) there is no problem. please someone tell me what's wrong with double channel(front to front) and is there anyway for designing this kind of sections using staad pro?

Decrease load combinations

javad sanjari — Wed, 21 Dec 2016 07:43:57 GMT

I'm learning staad pro and I'm working on staad pro v8i(2007).

I'm trying to model a structure which has following load cases:

-dead

-Live

-snow

-pipe-empty

-pipe-oper

-pipe-test

-thermal-x

-thermal-z

-Temperature

-cable-tray

-equipment-empty

-equipment-oper

-equipment-test

-wind-xp

-wind-xn

-wind-zp

-wind-zn

-quake-x

-quake-z

-quake-y

-crane-dead

-crane-live

-crane-longitudinal

-crane-transverse

Some of above load cases act on positive and negative direction and I should use them in positive and negative form in load combinations. For example for the following load combination

(Dead+live+snow+pipe-oper+pipe-anchor+ cable-tray+ thermal-x+ thermal-z+temperature+equipment-oper+crane-dead+crane-live+ crane-longitudinal+ crane-transverse)

6 of them act on positive and negative and if I want to use them I should use 64 load combinations and since I have a lot of combinations I should use over 1900 load combinations for service and ultimate level and after that the program will inform me that your system is on low memory.

Is there anyway to decrease these load combinations?

For example in SAP2000 there is a way:

At first we combine a load case that acts on positive direction with its negative direction (load combination type should be envelope) and then we use it in load combination so the 64 load combinations will decrease to just 1 load combination.

Please help me?

javad sanjari's Activities

Designing double channel-front to front

Decrease load combinations