Torsional capacity of SHS/RHS Section
Torsional capacity of SHS/RHS Section
(OP)
Can anyone tell me how I can approximate with reasonable accuracy the torsional capacity of a SHS/RHS Section?
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join EngTips Forums!
*EngTips's functionality depends on members receiving email. By joining you are opting in to receive email. Posting GuidelinesJobs 

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.
Here's Why Members Love EngTips Forums:
Register now while it's still free!
Already a member? Close this window and log in.
RE: Torsional capacity of SHS/RHS Section
In Australian practice, the design torsional moment section capacity is calculated thus:
phi*M_z = phi*0.6*f_y*C
where:
 ‘phi’ is the capacity factor, equal to 0.9 [dimensionless]
 ‘M_z’ is the unfactored torsional moment section capacity [kNm]
 ‘f_y’ is the yield stress used in design [MPa]
 ‘C’ is the torsional section modulus [mm3]
For rectangular and square hollow sections:
C = (t^3*h/3 + 2*k*A_h)/(t + k/t)
where:
 ‘t’ is the wall thickness of the section [mm]
 ‘h’ is the length of the midcontour, h = 2*[(b  t) + (d  t)] – 2*R_c*(4pi) [mm]
 ‘A_h' is the area enclosed by ‘h’, A_h = (b – t)*(d – t) – R_c^2*(4pi) [mm^2]
 ‘k’ is the integration constant, k = 2*A_h*t/h [mm^2]
 ‘b’ is the overall width of the section [mm]
 ‘d’ is the overall depth of the section [mm]
 ‘R_c’ is the mean corner radius, R_c = (R_o + R_i)/2 [mm]
 ‘R_o’ is the outer corner radius [mm]
 ‘R_i’ is the inner corner radius [mm]
 pi = 3.142
The design check is:
M_z* < phi*M_z
where:
 'M_z*' is the design torsional moment (ultimate limit state)
RE: Torsional capacity of SHS/RHS Section
AISC also has desin guide for torsion availble
RE: Torsional capacity of SHS/RHS Section
Check it out at
www.enercalc.com
They have a full function demo you can try before you buy.
It is definitely worth its cost to any practicing structural engineer.