Selecting a Suitable S275 Steel Universal Beam Section

[thebest99]

steel floor beams span 7.0m and are at 4.2m spacing. the beams are fully laterally restrained by precast concrete floor slabs, 180mm thick, which they support. the floor has to support a speciified imposed load of 5.0 kNm-2.

determine a suitable grade S275 steel universal beam section

From what i have worked out so far:

imposed load = 5.0kNm-2 x 4.2m
=21kN/m

dead load = 4.2m x 0.18m x 24kN/m3
=18.14kN/m
to select a suitable UB section:
214x1.6x7+18.14x1.4x7
=413kN

design shear force:
413/2= 206.5

desing BM:
m=wl sqaured / 8 =

18.14x1.4+21x1.6 x 7sqaured / 8 = 361.4

section selection:
S=m/py

=361.4/275

=1314cm cubed

this is where I am lost need to find UB with plastic section modulus

do i use UB 406 x 178 x 67

if someone could help me with this question and make sure I am doing this example right

thank you

 

[nvn]

thebest99: I currently think your answer looks correct.

 

[pongo38]

I don't see where you have taken account of the self-weight of the steel beam (small as it is).

 

[nvn]

Good catch, pongo38.