L3 Behaviour of Prestressed Concrete PDF

BICOL UNIVERSITY COLLEGE OF ENGINEERING LEGAZPI CITY CE 414 PRESTRESSED CONCRETE DESIGN...

BICOL UNIVERSITY COLLEGE OF ENGINEERING LEGAZPI CITY CE 414 PRESTRESSED CONCRETE DESIGN LESSON 3: BEHAVIOUR PRESTRESSED CONCRETE PREPARED BY: HANA MYKA C. GATON, MSCE FACULTY HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN  BEHAVIOUR OF PRESTRESSED CONCRETE BEAMS HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION Load-carrying capacity: Prestressed concrete beams have a higher load-carrying capacity than ordinary concrete beams. Deflection resistance: Prestressed concrete beams have a better deflection resistance than ordinary concrete beams. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION Crack control: Prestressed concrete beams are less likely to crack than ordinary concrete beams. Durability: Prestressed concrete beams are durable and can withstand a variety of environmental conditions. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION Methods of analyzing deformation Elastic theory of bending assumes that the concrete and steel in the beam behave elastically. Plastic theory of bending assumes that the concrete in the beam behaves plastically after it reaches its yield strength. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION Methods of analyzing deformation Finite element method is a more sophisticated method that can account for the non-linear behavior of concrete and steel. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION 1. Crack control: The deformation of reinforced concrete beams can be controlled by using a variety of techniques, such as using high-strength concrete, using closely spaced reinforcement, and using stirrups. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION 2. Deflection control: The deflection of reinforced concrete beams can be controlled by using a variety of techniques, such as using a deeper beam, using a smaller load, and using prestressing. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION 3. Durability: The durability of reinforced concrete beams can be improved by using a variety of techniques, such as using high-quality concrete, using corrosion-resistant reinforcement, and protecting the concrete from the environment. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN DEFORMATION HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN CRACKING Common causes of cracks Loading: Concrete is strong in compression but weak in tension. Shrinkage: Concrete shrinks as it dries. Corrosion of reinforcement: The steel reinforcement in concrete can corrode if it is exposed to moisture and oxygen. Defects in the concrete HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN CRACKING How to prevent cracking? Using high-quality concrete Properly curing the concrete Protecting the concrete from moisture and oxygen Using corrosion-resistant reinforcement Minimizing defects in the concrete HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN CRACKING Types of cracks Hairline cracks: Hairline cracks are small, narrow cracks that are typically less than 0.1 mm wide. Wide cracks: Wide cracks are more than 0.1 mm wide. Delamination: Delamination is the separation of the concrete from the reinforcement. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN WELL-BONDED STEEL SECTION Factors that affect the bond between steel and concrete Surface profile of the steel reinforcement Thickness of the concrete cover Quality of the concrete Construction practices HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN UNBONDED STEEL SECTION Advantages of using unbonded steel sections Reduce the weight of the structure Allow for thermal expansion and contraction Allow for the use of different materials HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN UNBONDED STEEL SECTION Disadvantages of using unbonded steel sections Reduced strength and durability Increased risk of corrosion Increased maintenance requirements HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN SHEAR RESISTANCE Shear resistance is the ability of a material to resist forces that tend to cause two parts of the material to slide past each other. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN SHEAR RESISTANCE Factors that affect shear resistance Type of material Thickness of the material Presence of reinforcement Angle of the forces HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN SHEAR RESISTANCE Mohr-Coulomb failure criterion - a material will fail in shear when the shear stress reaches a critical value. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN IMPACT RESISTANCE Impact resistance is the ability of a material to resist sudden forces without breaking or deforming. Factors that affect impact resistance Type of material Thickness of the material Presence of reinforcement Shape of the material HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN VIBRATION Effects of vibration Low-intensity vibration: Low-intensity vibration is typically not harmful to humans or structures. Moderate-intensity vibration: Moderate-intensity vibration can cause discomfort and fatigue in humans. High-intensity vibration: High-intensity vibration can cause serious injuries to humans. HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN VIBRATION Methods to lessen vibration Isolating the source of vibration Absorbing vibration Dampening vibration Designing structures to resist vibration HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN  THANK YOU FOR LISTENING HANA MYKA C. GATON, MSCE FACULTY CE 414 – PRESTRESSED CONCRETE DESIGN