hello everyone
i am design the steel building i staad pro . now if the beam is continuous say 10 m and i am having the node at the ends. the say i'm getting the beam section as pass with iswb 450 and if i am inserting the node in between the beam say one at mid point the the staad gives beam as pass with value less than the above written value. say ismb 400 what is the reason. i have check all the parameters and they are ok . but design is not sufficient as per requirement.
Yours is not a case of unsupported i.e. UNB and UNT.
Dear Arun,
I once again bother you if you do not mind. Now I have partially understood your posting dated 15/5/2011. You have proposed to divide the 10 meter length of beam in two pieces of 4m and 6m each. You propose to have a uniform factor of 0.85 for the beam member. I understand from your posting that you would have assigned the factor 0.85 to the10 meter long beam even if the beam was not divided in two parts.Is my understanding correct? I further understand that the factor 0.85 would not be applied to column members. This is purely my understanding. Please clarify whether I have understood the matter correctly
Dear Sir,
The factor 0.85 would be applicable to the 10m beam. Hence, the effective length would be 0.85 x 10 or 8.5 m. Since we are dividing the beam into 4m component and 6 m component, if we do not give Ky/Kz/LY/LZ factors, their effective lengths would have been 4m and 6m respectively. Hence, for the two members we can give LY and LZ 8.5m as you have suggested. Alternatively, for the 4m member, we can assign KY and KZ of 8.5/4 and for the 6m member, we can assign 8.5/6...
The factor is applicable to all beams and columns depending on the type of connection (pinned/fixed/free) on each end. This is from Table 5.2 of old code or Table 11 of new code.
Arun
A lot many thanks to you for the quick response. You have referred to Table 11 of the new code. I suppose by new code you mean IS 456 - 2000. But Table 11 of the above code refers to Characteristic compressive strength of concrete. It does consist of the factor i.e. 0.85 that you have stated. Please also clarify whether the factor 0.85 is applicable to the frame members or it is meant only individual beam and individual column. Please.
Both new and old code refers to steel sections. From first post it was mentioned as steel section, so I have been talking with steel only in mind... In case of concrete also ELY and ELZ are applicable instead of KY and KZ but only for columns.