Concrete Material Properties

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Material Properties and Behavior

• Poisson's Ratio is the ratio of lateral strain to axial strain when a material is stressed.
• Elastic Modulus measures a material's resistance to deformation under stress.
• Shrinkage signifies the reduction in concrete volume as it loses moisture.
• Creep refers to the slow deformation of concrete under sustained load over time.
• Spalling occurs when surface layers of concrete break off due to freeze-thaw cycles or fire.
• Segregation describes the separation of coarse aggregates from cement paste in fresh concrete.
• Bleeding is the upward migration of water in fresh concrete, leading to weak surface layers.
• Bulk Density is the mass per unit volume of a material, including voids.
• Plastic Shrinkage Cracking appears in fresh concrete caused by rapid moisture loss.
• Concrete Maturity measures concrete strength development based on time and temperature.
• Strain Compatibility assumes plane sections remain plane after bending, which allows for strain analysis.
• Elastic behavior is defined as the reversible deformation of a material under applied loads.
• Plastic behavior is permanent deformation beyond the elastic limit.
• Stiffness measures a structural member's resistance to deformation under load.

Reinforced Concrete Design

• A Tension-Controlled Section is a beam section where steel yields before concrete crushing, ensuring ductile failure.
• A Compression-Controlled Section is where concrete reaches its compressive strain limit before steel yields.
• A Balanced Strain Condition is when steel and concrete reach their strain limits simultaneously.
• Crack Control are methods to minimize cracking in reinforced concrete structures, such as proper reinforcement spacing.
• A Doubly Reinforced Beam contains reinforcement in both tension and compression zones. It can resist high bending moments.
• Modular Ratio is the ratio of the modulus of elasticity of steel to that of concrete and is used in transformed section analysis.
• Serviceability Limit State is the condition where a structure no longer meets functional requirements due to deflection, cracking, or vibration.
• Ultimate Limit State is the condition where a structure reaches its maximum load-carrying capacity before failure.
• Residual Stress is an internal stress remaining in a material after external forces are removed.
• An Overreinforced Beam has excessive reinforcement. It leads to brittle concrete failure before steel yields.
• An Underreinforced Beam has less reinforcement, ensuring ductile failure because steel yields before concrete failure.
• Development Length is the required length of embedded reinforcement to develop its full strength in concrete.
• A Lap Splice involves overlapping reinforcing bars to transfer load between them.
• Anchorage methods secure reinforcement to prevent slippage.
• A Hooked Bar is a reinforcement bar bent at the ends to improve anchorage and bond strength.
• Couplers are mechanical connectors to join two reinforcing bars.
• Deflection Control minimizes excessive bending displacement in structural members.
• Longitudinal Reinforcement are steel bars placed along the length of a beam or column to resist bending.
• Transverse Reinforcement is reinforcement placed perpendicular to the main reinforcement to resist shear forces.
• The Flange Contribution is the portion of a T-beam's strength that comes from the slab flange.
• Web Shear refers to shear forces acting within the web portion of a beam.
• Slenderness Ratio is the ratio of effective length to the least lateral dimension of a column or beam.
• Cracked Moment of Inertia is the moment of inertia of a beam section after cracks have formed.
• Uncracked Moment of Inertia is the moment of inertia of a beam section before cracking occurs.
• Neutral Axis Shift refers to the movement of the neutral axis due to changes in loading or reinforcement.
• Effective Depth measures the distance from the extreme compression fiber to the centroid of tensile reinforcement.

Pre-stressed Concrete

• Post-Tensioned Slab: Tendons are stressed after the concrete has hardened.
• Transfer Length is the length over which prestress force is transferred to concrete.
• Transfer Strength is the concrete strength required before prestressing force is applied.
• Prestress Losses are reductions in prestress force due to creep, shrinkage, and relaxation.
• Elastic Shortening is the shortening of concrete due to immediate prestress application.
• Creep Loss is the reduction in prestress due to long-term deformation under sustained load.
• Shrinkage Loss is the reduction in prestress force due to drying and shrinkage of concrete.
• Relaxation refers to the gradual reduction of stress in prestressing steel over time.
• Friction Loss is the loss of prestress due to friction between tendons and ducts.
• The End Block is the zone near anchorage in prestressed concrete where forces are transferred.
• Stress Transfer involves transferring force from tendons to concrete.
• Bursting Stress are tensile stresses that develop near anchorages in prestressed concrete.

Structural Elements and Systems

• A Precast Slab is factory-made and transported for on-site assembly.
• A Hollow Core Slab is a precast slab with voids to reduce weight and material use.
• Bonded Reinforcement is steel reinforcement fully embedded in concrete, ensuring a strong bond.
• A Construction Joint is placed in concrete structures to control cracking due to shrinkage or expansion.
• An Isolation Joint separates structural elements for independent movement.
• A Control Joint is a planned groove in concrete to control crack formation.
• Thermal Expansion describes the expansion of concrete due to temperature changes.
• The Vibration Method compacts concrete and removes trapped air.
• Formwork are temporary molds used to shape and support concrete until it hardens.
• A Shear Key increases shear resistance at joints.
• Shear Lag is the delay in stress distribution between different sections of a beam.
• Shear Friction uses friction to prevent slip along a shear plane.
• Bearing Stress is the stress between two contacting surfaces under load.
• Diagonal Tension refers to tensile stresses induced by shear forces in concrete.
• Inclined Stirrups are shear reinforcement placed at an angle to resist diagonal tension.
• The Load Path is the route through which loads travel through a structure to reach the ground.
• Reinforcement Anchorage secures reinforcement to ensure force transfer.
• Hook Length is the extra length of a reinforcing bar beyond a bend or hook.

Structural Behavior and Dynamics

• Damping involves dissipating energy in a structure via internal resistance.
• Lateral Load consists of forces acting horizontally on a structure, such as wind and seismic forces.
• Resonance is the amplification of vibrations when a structure's natural frequency matches an external force.
• Base Shear is the total lateral force at the base of a building due to seismic loads.
• Drift reflects the lateral displacement of a structure under lateral loads.
• A Bracing System uses diagonal members to resist lateral forces in buildings.
• An Infill Wall is a non-structural wall that provides stiffness/resists lateral loads.
• Seismic Retrofitting upgrades existing structures to improve their earthquake resistance.
• A Moment Frame resists lateral forces through bending of beams and columns.
• A Seismic Gap is a space left between structures to prevent collisions during an earthquake.