Introduction to RCC.pdf
- 1. Chapter 1 INTRODUCTION Asst. Prof. Sushil Adhikari
- 2. Plain Cement Concrete Structures • Plain concrete is defined as the mixture of cement (including mineral admixtures), water (including chemical admixtures), fine aggregate and coarse aggregate, which is obtained by mixing these ingredients in certain proportion in order to achieve required properties in fresh and hardened state as well as durability requirement.
- 3. Limitation of PCC • Concrete is Quasi-brittle Material. • Low Tensile Strength. • Concrete has Low Toughness. • Concrete has Low specific strength. • Formwork is Required. • Long curing time. • Working with cracks. • Demands Strict Quality Control.
- 4. RCC • Reinforced Cement Concrete is a composite material in which concrete's relatively low tensile strength and ductility are counteracted by the inclusion of reinforcement having higher tensile strength and/or ductility.
- 5. Requirement Properties of Reinforcement • High relative strength • High toleration of tensile strain • Good bond to the concrete, irrespective of pH, moisture, and similar factors • Thermal compatibility, not causing unacceptable stresses in response to changing temperatures. • Durability in the concrete environment, irrespective of corrosion or sustained stress for example.
- 6. Advantages of RCC i. It has relatively high compressive strength. ii. It has better resistance to fire than steel. iii. It has long service life with low maintenance cost. iv. In some types of structures, such as dams, piers and footings, it is most economical structural material. v. It can be cast to take the shape required , making it widely used in pre-cast structural components. vi. It yields rigid members with minimum apparent deflection. vii.Yield strength of steel is about 15 times the compressive strength of structural concrete and well over 100 times its tensile strength
- 7. Mechanism of composite action of reinforcement and concrete • The reinforcement in a RC structure, such as a steel bar, has to undergo the same strain or deformation as the surrounding concrete in order to prevent discontinuity, slip or separation of the two materials under load. • Maintaining composite action requires transfer of load between the concrete and steel.
- 8. Types of Loads • Dead Loads • Super Imposed Loads(Live Load) • Wind Loads • Snow Loads • Seismic Loads • Shrinkage, Creep and Temperature Effects
- 9. • Other Loads and Effects – Foundation movement – Elastic axial shortening – Soil and fluid pressures – Vibration – Fatigue – Impact – Erection loads – Stress concentration effect due to point of application of load and the like
- 10. Types of Stresses i. Compressive Stress ii. Shear Stress iii.Flexural Stress iv.Tensile Stress v. Bearing Stress vi.Torsional Stress vii.Thermal Stress viii.Fatigue Stresses
- 11. Design Methods • Design Steps: – Idealization of Structure for analysis – Estimation of Loads – Analysis of structure to determine axial compression, shears, bending moments and deflection – Design of structural elements – Check for strength and serviceability – Detail structural drawings and schedule of reinforcement bars Philosophies for the design of RCC, pre-stressed and steel structures – The working stress method – The ultimate load method – The Limit State Method – Performance Based Design Method