Reinforced Concrete Design-4
Design of T beams
By
Dr. Attaullah Shah
Swedish College of Engineering and Technology
Wah Cantt.
Quick 30 minutes- Open Book Quiz
− Compare WSD and USD methods. (5 min)
− Design a simply supported singly reinforced concrete
beam of span 15 ft having a superimposed dead load
of 1K/ft and live load of 1.5K/ft. fc’ = 4000 psi and fy=
60000psi (15min)
− Determine the moment capacity of doubly reinforced
beam of size 12inx18in having 6#8 bars in the bottom
and 2#8 bars at the top. Use the above material
stresses. (10min).
T Beams
Case 1: Compression area in Flange a<t
− If the depth of equivalent stress block is equal or less than flange depth,
the beam may be designed as rectangular beam.
−
In such case
− Nominal moment Capacity
− If the thickness of a > t, then T beam analysis will be required
Case 1: Compression area in web a>t
− The tensile force in steel T is resisted by two components one
C1corresponding to A1 and other C2 corresponding to A2
Compression
− Area of steel corresponding to compression in Flange is given as
− The nominal resisting moment by flange is given as
− The remaining steel area ( As-Asf) is compensated by the compression in
web.
− The additional resisting moment is given as
− The total nominal resisting moment is given as:
−
Maximum and Minimum Steel
-
For Case
-
The area of steel reinforcement As is given as
-
The balanced steel ratio is given as
-
The balanced steel ratio is given as
-
-
For Case 2
(87000/(87000+fy))
Design Steps for T-beam