This document summarizes the seminar work on the analysis and design of reinforced concrete curved beams. It discusses that curved beams experience both bending moments and torsional moments due to loads acting outside the line of supports. The document outlines the methodology used, which includes manual design using limit state method according to Indian code IS 456 and software analysis and design using ETABS. It presents the important equations for calculating bending moments and torsion in circular beams. A design example is included to demonstrate and compare the manual and software based designs. The conclusion indicates that manual design considers the combined effect of bending and twisting better than software.

1. OF RCC BEAM
CURVED IN PLAN
SEMINAR PHASE – I
BY VINAYAK SURESH PATIL
Reg. No. 18221222
Under Guidance of
Mrs V. M. Bogar

2. Contents :
Introduction
Methodology
Analysis Methods
Design
Literature Review
Results
Conclusion
References
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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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4. Methodology
Analysis Design
Comparison
between
MANUAL &
SOFTWARE
results
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Linear
Analysis
• Classical
Method
Manual Design
• LSM
Software
• ETABS

5. Important values
•Support Moment = kwR2
•Mid-span Moment=k’wR2
•Maximum Torsion=k”wR2
•Shear Force = wR/2
In general,
•Bending Moment=wR2[-1+ 0.5**sin  +0.5*  *cot(/2)*cos]
•Twisting Moment=wR2[ - 0.5 + 0.5**cos +0.5*  *cot(/2)*sin]
k, k’, k” are values depending on no. of supports
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6. Coefficient for B.M. & Torsion
in Circular Beams
No. of Supports  k k’ k”

4 90ᵒ 0.137 0.070 0.021 19.25ᵒ
5 72ᵒ 0.108 0.054 0.014 15.25ᵒ
6 60ᵒ 0.089 0.045 0.009 12.75ᵒ
7 51.42ᵒ 0.077 0.037 0.007 10.75ᵒ
8 45ᵒ 0.066 0.030 0.005 9.33ᵒ
9 40ᵒ 0.0663 0.027 0.004 8ᵒ
10 36ᵒ 0.054 0.023 0.003 7.5ᵒ
12 30ᵒ 0.045 0 0.002 6.25ᵒ
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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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10. ETABS Design
•Modelling
•Material Specification
•Support Condition
•Load cases
•Analysis
•Results
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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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12. Design by Manual Method
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13. Design by Software
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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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17. THANK YOU
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