steel and concrete composite section
steel and concrete composite section
(OP)
Hi, all. I am doing a dynamic modelling of a building. SOme of the beams are made up with 2 W-sections side by side encased in concrete. ANy suggestion on how to model the equivalent section? I suppose the total area of section can be calc by Ac+As(Es/Ec), but what E do you use? Ec or an equivalent E? how would you calculate the equivalent E?
Thanks in advance for all suggestion.
Peter Lee
www.neillandgunter.com
Thanks in advance for all suggestion.
Peter Lee
www.neillandgunter.com
Peter Lee
www.neillandgunter.com





RE: steel and concrete composite section
Correct me if I am wrong as I am no civil or structural engineer but for a beam of two materials I would proceed as
follows:- Assuming that the steel and concrete are connected
ridgidly together the bending moment:-
M=Mc + Ms
M= Ec*Ic/(R) + Es*Is/(R)
but Es/Ec = m = modular ratio
M= (Ic/(R) + m*Is/(R))*Ec
divide thru by R
M=(Ic+m*Is)*Ec/R and Ec/R= fc/y
: M=(Ic+m*Is)*(fc/y)
where fc=stress
Is,Ic= second moments of area for steel
and concrete beam.
R = radius of curvature of beam
Ec,Es = modulus of elasticity of materials
y = distance to neutral axis
By using this method I have found the equivalent
second moment of area of a complete concrete beam by
using the modular ratio and converting the steel part
into a equivalent concrete part.So you can now
calculate stress using Ec only. Alternatively you can
turn the concrete portion into an equivalent steel beam
if you desire again using m however the formula would
look like this:-
M=(Ic/(m))+Is)*(fs/y)
hope this helps
regards desertfox