Posts Tagged Guide to design of Doubly reinforced beams
7 step procedure for “Design of Doubly reinforced sections”
In our article series for “Design of Doubly reinforced sections”, we covered the following:
In our previous article, we discussed a detailed 6 step procedure for determining stresses in steel and concrete followed by a numerical example. Now we shall move on with the “design procedure for doubly reinforced sections”.
Generally the following data are given:
Breadth of the beam = b
Effective depth of the beam = d
Permissible stress in concrete = σcbc
Permissible stress in steel = σst
Modular ratio = m
Bending moment = M
To solve a problem, the following procedure may be followed.
Design the beam as a singly reinforced one (balanced section)
Find xc by
σcbc/ (σst/m) = xc/(d – xc)
Moment of Resistance calculations | Doubly reinforced sections
In our article series for “Doubly reinforced sections”, we have covered the following:
Now we shall move on with a solved example. This will help you understand the methods in a better way. I suggest that you do them yourselves too. Practice will help you make your concepts more concrete and clear.
An reinforced concrete 300mm x 600mm effective dimensions is provided with tensile and compressive reinforcement of 1256mm2 each. The compressive steel is placed 30mm from the top edge of the beam. If σcbc = 7N/mm2, σst = 190N/mm2 and m = 13.33, find the moment of resistance of beam by following two methods:
1) Elastic theory method
2) Steel beam theory method