Advantages of continous members
- 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