3. Introduction
Curved beams are used to support circular reservoir, curved balconies
and curved ramps.
In curved beams the centre of gravity of loads acting on a span lies
outside the lines joining supports.
This will cause torsional moments in addition to bending moment and
shear force.
Therefore one need to consider torsion reinforcement while designing
beam curved in plan.
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7. • Design
MANUAL DESIGN
LSM
IS 456:2000 (PLAIN AND
REINFORCED CONCRETE) –
Provides the design method for
curved beam.
Check for combined action of
shear and maximum torsion.
SOFTWARE DESIGN
ETABS
ETABS gives the analysis and
design based on linear analysis of
curved beam.
Software design is based on same
IS code which can be compared
with manual result.
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8. LSM Design(Manual)
• Size of beam
•Material
•Load calculation
•Design Bending Moment & Shear Force
•Design of Support Section
•Design of Mid-Section
•Design of Section Subjected to Maximum Torsion & Shear
•Reinforcement Details
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9. IS 456 (Steps)
•Critical Section
•Shear and Torsion
•Reinforcement in Members subjected to Torsion
•Requirements of Reinforcement
Tension reinforcement
Compression reinforcement
Side face reinforcement
Transverse reinforcement
Maximum spacing of shear reinforcement
Minimum shear reinforcement
Distribution of torsion reinforcement
Reinforcement in flanges of T- and L-beams
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11. Design Example
Determine the reinforcement required of a ring beam (Fig.6.16.3) of b =
400 mm, d = 650 mm, D = 700 mm and subjected to factored Mu = 200
kNm, factored Tu = 50 kNm and factored Vu = 100 kN. Use M 20 and Fe
415 for the design.
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14. Comparison
• Software can design straight beam precisely and accuracy will be
similar to manual method but for curved beam software is unable to
give results similar to manual method.
• Besides % of steel in both results longitudinal reinforcement ,
transverse reinforcement and side face reinforcement is considered.
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15. Conclusion
• In curved beam torsional reinforcement must be provided as torsional
moment are generated.
• Software can not provide precise design as torsional moments are not
considered properly.
• Use of IS 456 & manual design ensures safety as effect of both bending
& twisting moments are considered along with shear force.
•Aside from aesthetic view curved beam should be avoid as these are
not economical.
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16. Refrences
• Analysis of Structures Vol. II Theory, Design and Details of Structures by
Prof. V. N. Vazirani, Dr. M. M. Ratwani, Dr. S. K. Duggal
•Advanced Reinforced Concrete Design by N. Krishna Raju
•www.sciencedirect.com
•https://www.researchgate.net
• www.ijera.com
•www.iiste.org
•www.icontrolpollution.com
•www.google.com
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