This document discusses the advantages and methods of achieving continuity in prestressed concrete members. The key advantages are an even distribution of moments, reduced member sizes, higher load carrying capacity, and increased stability. Methods of achieving continuity include using straight cables, curved cables, cap cables, straight tendons, and composite construction. There are two main types of continuity - fully continuous, which uses larger tendons along the entire length, and partially continuous, which uses techniques like cap cables or straight tendons but not along the full length.

1. TOPIC 1
ADVANTAGES OF CONTINOUS
MEMBERS

2. EVEN DISTRIBUTION OF MOMENTS
• Between center of span and supports
• Lesser span moments
• Longer spans

3. REDUCTION OF SIZE
• Vertical load carrying capacity is more
• Lighter structures
• Economical

4. HIGHER LOAD CARRYING CAPACITY
• Redistribution of moments
• Reduced cross sectional dimensions

5. INCREASED STABILITY
• Redundancy in load path
• Formation of hinges in extreme events

6. PRECAST UNITS CONNECTED BY
PRESTRESSED CABLES
• Segmental construction
• Precast units
• Connected by pre-stressed cable

7. SUITABLE POSITIONING OF CURVED
CABLES
• In post tensioned girders
• Resist span and support moments

8. REDUCTION IN NO: OF ANCHORAGES
• One pair of post tensioned anchorages
• A single stressing operation
• Less maintenance

9. SMALLER DEFLECTIONS
• Higher load carrying capacity
• Even distribution of moments
• Safer

10. DISADVANTAGES
• Secondary stresses
• Losses
• Skill of workmanship
• Analysis and design
• Concordant cables

11. TOPIC 2
METHODS OF ACHIEVING
CONTINUITY

12. USING STRAIGHT CABLES
• Wide web necessary
• Large anchorage blocks
• Form work
• Skilled workmen
• High strength threaded
rods

13. USING CURVED CABLES
• Higher resistance to
stress
• Longer spans
• Cracking over piers
eliminated in multistage
post-tensioning

15. USING CAP CABLES
Negative moment taken care of

16. USING STRAIGHT TENDONS
Limited length

17. COMPOSITE CONSTRUCTION
• Beam ends embedded
in cast-in-situ
diaphragms
• Reinforcement for
negative moment
within deck thickness
• SS under major loads

18. COUPLING
• Pre-tensioned precast
members
• Optimized strands
• Top strands at adjacent
interior members
coupled
• Performance of full
length post tensioning
• Lesser cost

19. TWO TYPES
PARTIALLY
FULLY CONTINOUS CONTINOUS
• Using cap cables
• Using straight cables
• Using straight tendons
• Using curved cables • Tendons not used to
• Larger size tendons achieve continuity
• Negative moment at
• Secondary reinforcements supports
• Expensive • Cheaper

24. TOPIC 3
EFFECT OF PRESTRESS