“Analysis and Design of T-Beam Girder and Box Girder Bridge”
Submitted by
Under the Guidance of
AMIT SAXENA (0701CE08ME01)
Dr. (Ms) SAVITA MARU Prof. in (Civil Engg. Dept.)
Department of Civil Engineering, Ujjain Engineering Collage, Ujjain (M.P.) 2012-2013
Contents •
Introduction
•
Bridge
•
Superstructure
•
Design
•
Results and Discussion
•
Conclusions
Introduction Bridge - life line of road network. Importance. Design of 25 m span two lane simply supported bridge super structure Suitable choice for 25m span- T- Beam and Box Girder bridge T-Beam girder bridge construction – easy Box girder sophisticated and costly formwork. Analysis for dead load and IRC moving load. Dead load calculation – manually Live load - linear analysis by software Staad Pro.
Bridge Definition – structure that crosses over a river, bay, or other obstruction. Purpose - Permits the smooth and safe passage of vehicles, trains, and pedestrians. Bridge parts - Upper part - the superstructure- deck, floor system, and the main trusses Lower part – substructure- piers, columns, footings, piles, and abutments.
Elevation view of a typical Bridge
Superstructure “Structural parts of the bridge that provide the horizontal span.“ The portion of the bridge above the bridge bearings.
Simple RCC Bridge
Cable Stayed Bridge
Arch Bridge
T-Beam Girder Bridge
Box Girder Bridge
Suspension Bridge
Superstructure Cont…. Type of superstructure and Suitable span(IRC:SP:54-2000) Type of superstructure
Span length
(i)
RCC single or multiple box
1.5 to 15 m
(ii)
Simply supported RCC slabs
3 to 10 m
(iii)
Simply supported RCC T -Beam
10 to 25 m
(iv)
Simply supported PSC Girder bridge
25 to 45 m
(v)
Simply supported RCC voided slabs
10 to 15 m
(vi)
Continuous RCC voided slabs
10 to 20 m
(vii) Continuous PCC voided slabs
15 to 30 m
(viii) RCC box section : Simply supported/ balanced cantilever
25 to 50 m
continuous (ix)
PSC box section : Simply supported/ balanced cantilever
35 to 75 m
(x)
PSC cantilever construction/ continuous
75 to 100 m
(xi)
Cable stayed bridge
200 to 500 m
(xii) Suspension bridge
500 m
Superstructure Cont…. T-Beam Girder
POSITIVE POINTS Simple geometry. Easy to cast at site. Most widely adopted. Slab acts monolithically with beams. NEGATIVE POINTS Cross - beam requirement gives less clean appearance.
Main Components of T-Beam Girder
Superstructure Cont…. Box Girder
POSITIVE POINTS High torsional strength. Suitable for curved bridges. Minimal maintenance problems. Good appearance. NEGATIVE POINTS Heavy units for erection. Inefficient at short spans.
Main Components of Box Girder
Design
Longitudinal section of T-Beam Girder Bridge
Plan of T-Beam Girder Bridge
Design Cont…
Cross section of T-Beam Girder Bridge at 0.25L, 0.50L and 0.75L
Cross section of T-Beam Girder Bridge at 0.0L and 1.0L
Design Cont…
Longitudinal section of Box Girder Bridge
Plan of Box Girder Bridge
Design Cont…
Cross section of Box Girder Bridge at 0.25L, 0.50L and 0.75L
Cross section of Box Girder Bridge at 0.0L and 1.0L
Design Cont… Dead Load : Self weight of Superstructure + load of railing, kerb, and wearing coat. Superstructure dead load = • cross sectional area of concrete section x density of concrete (IRC: 62010) • Dead Load of kerb and wearing coat - same procedure as above • weight of railing - 0.3 T/m as per IRC: 6-2010 Clause 206. Philosophy - working stress method of design Bending moments = [wl/4{l-(x\2)}] Shear forces = [w{(l/2)-x}] at each one tenth of effective span.
Showing tenth effective span
Design Cont…. Live Load : As per IRC:6-2010
Class A Loading
Class 70R Loading
Design Cont….
Staad model : • Linear model on Staad Pro. • Member property • Support
• Live load bending moments & shear forces
Class A Forward Direction
Class 70R Forward Direction
Design Cont…. Impact factor : •As per IRC-6:2010 For IRC Class A loading If = Where If A B L
= = = =
A B+L
impact factor constant, 4.5 for RCC bridges, 9.0 for steel bridges constant, 6.00 for RCC bridges, 13.50 for steel bridges span in m.
Design Cont…. For IRC Class 70R loading
Impact percentage for Highway Bridges (Clause 208.2 IRC 6:2010)
Design Cont… Lateral distribution coefficents of live load : • Morrice Little method has been adopted. • Actual bending moments and shear forces.
Case 1
Case 2
Case 3
Design Cont… Design moment and shear force:
Design moment = DLBM + LLBM x IM x LD
Design shear
= DLSF + LLSF x IM x LD
Where , IM= Impact factor LD=Lateral distribution factor
Results and Discussion Dead load
• T-Beam Girder has produced less moment than Box Girder units.
Results and Discussion Cont…. Dead load
• T-Beam Girder has produced less shear than Box Girder
Results and Discussion Cont…. Live load
• Bending moment on T-Beam Girder formed more.
Results and Discussion Cont…. Live load
• Live load shear forces for Box Girder is less
Results and Discussion Cont…. Dead Load and Live Load
• Bending moment due to combine load of Box Girder is less.
Results and Discussion Cont…. Dead Load and Live Load
• Shear force due to combine load of T-Beam Girder is more.
Results and Discussion Cont…. Moment capacity and Shear resistance
• T-Beam girder are more resistance capacity of moment for 25 m span.
Results and Discussion Cont…. Moment capacity and Shear resistance
• T-Beam girder capacities to resist the shear are more.
Results and Discussion Cont…. Quantity Comparison
• Quantity of concrete is almost same • Quantity of steel has more in Box Girder Bridge.
Results and Discussion Cont…. Cost Comparison • Consider local SOR rates • Cost of Box Girder Bridge has more
Conclusion The following conclusion are drawn upon i. Service Dead load bending moments and Shear force for T-beam girder are lesser than two cell Box Girder Bridge. Which allow designer to have lesser heavier section for T-Beam Girder than Box Girder for 25 m span. ii. Moment of resistance of steel for both has been evaluated and conclusions drawn that T-Beam Girder has more capacity for 25 m span. iii. Shear force resistance of T-Beam Girder is more compared to two cell Box Girder for 25 m span. iv. Cost of concrete for T-Beam Girder is less than two cell Box Girder as quantity required by T-beam Girder. v. Quantity of steel for T-beam Girder is less so cost of steel in T-Beam is less as compared to two cells Box Girder Bridge.
References 1.
IRC 6-2010, “Standard Specifications and Code of Practice for Road Bridges”, Section II, loads and stresses, The Indian Roads Congress, New Delhi, India, 2010.
2.
IRC: 21-2000, “Standard Specifications and Code of Practice for Road Bridges, Section III, Cement Concrete (Plain and Reinforced)”, The Indian Roads Congress, New Delhi, India, 2000.
3.
IRC:SP: 54-2000 “Project Preparation Manual for Bridge”, The Indian Roads Congress, New Delhi, India, 2000.
4.
M.G Aswani . (1995), “Design of Concrete Bridges, 2nd edition, Nai Sarak, KHANNA Publishers”
5.
American Association of State Highway Officials. (1998), “LRFD Bridge Design Specification”, 2nd edition, Washington ,AASHTO
6.
D Johnson Victor (2007), “Essential of Bridge Engineering”6th edition
References Cont…. 7.
V. K. Raina, (2007)“Concrete Bridge practice analysis, Design and Economics”, 2nd edition
8.
N. Krishna Raju, (2010), “Design of Bridges”, 4th edition
9.
T. R. Jagadeesh & M. A. Jayaram, (2010), “Design of Bridge Structures”, 2nd edition
10. Structure engineering research center, Roorkee, U.P., “Design tables for concrete bridge deck slabs” 11. S Ramamrutham, “Design of Reinforced Concrete Structures”, 10th edition
Publication IJREAT International Journal of Research in Engineering & Advanced Technology, Volume 1, Issue 2, April-May, 2013 ISSN: 2320 - 8791 www.ijreat.org Comparative Study of the Analysis and Design of T-Beam Girder and Box Girder Superstructure Published by: PIONEER RESEARCH & DEVELOPMENT GROUP (www.prdg.org)
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