Reinforced Concrete Beam Design
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Related DefinitionAggregate A granular material, such as sand, gravel, crushed stone and iron-blast furnace slag, and when used with a cementing medium forms a hydraulic cement concrete or mortar.Balanced DesignA design so proportioned that the maximum stresses in concrete (with strain of 0.003) and steel (with strain of fy/Es) are reached simultaneously once the ultimate load is reached, causing them to fail simultaneously.Cementitious materials Materials with cementing value when used in concrete either by themselves, such as  Portland cement, blended hydraulic cement, or such materials in combination with fly ash, raw or other calcined natural pozzolans, silica fume, or ground granulated blast-furnace slag.Concrete Mixture of water, cement, sand, gravel, crushed rock, or other aggregates.Dead LoadLoads of constant magnitude that remains in one position.Design The determination of general shape and all specific dimensions of a particular structure so that it will perform the function for which it is created and will safely withstand the influences that will act on it throughout its useful life.Design Load CombinationsCombination of factored loads and forces.Design StrengthThe nominal strength multiplied by a strength-reduction factor, ø.Effective Depth of Section, dThe distance measured from extreme compression fiber to centroid of tension reinforcement.Extreme Tension SteelThe reinforcement (prestressed or nonprestressed) that is the farthest from the extreme compression fiber.Live LoadLoads that may change in magnitude and position. Modulus of Elasticity The ratio of normal stress to corresponding strain for tensile or compressive stresses below proportional limit of material. Nominal StrengthThe strength of a member or cross section calculated in accordance with provisions and assumptions of the strength design method before application of any strength-reduction factors.Over Reinforced DesignA design in which the steel reinforcement is more than what is required for balanced design.Plain concrete Structural concrete with no reinforcement or with less reinforcement than the minimum amount specified for reinforced concrete. Reinforced concrete Concrete in which reinforcing bars or other types of reinforcement have been integrated to improve one or more properties of concrete.Required StrengthThe strength of a member or cross section required to resist factored loads or related internal moments and forces.
StressThe intensity of force per unit area. Specified Compressive Strength of Concrete, f’cThe compressive strength of concrete used in design of reinforced concrete members in MPa.Under Reinforced DesignA design in which the steel reinforcement is lesser than what is required for balanced design.Water Used in mixing concrete that should be clean and free from injurious amounts of oils, acids, alkalis, salts, organic materials, or other substances that may be deleterious to concrete or reinforcement. Concrete Proportion (NSCP Section 405.3)Proportions of materials for concrete shall be established by:Workability and consistency to permit concrete to be worked readily into form and around reinforcement under conditions of placement to be employed without segregation or excessive bleeding.Resistance to special exposures.Conformance with strength test requirement.Basic Components of ConcreteThe basic components of concrete are cement, water and aggregates (sand and gravel). Cement and water form a paste that fills the space between the aggregates and binds them together. Chapter 3 of the ACI Code and Section 403 of Nationals Structural Code of the Philippines (2010) contains the minimum requirements for these components and other materials that are commonly used in concrete.Cementitious MaterialsCement shall conform to one of the following specifications:Specifications for Portland Cement (ASTM C150-05)Specifications  for Blended Hydraulic Cements (ASTM C595-07)Specifications  for Expansive Hydraulic Cements (ASTM C845-04)Specifications  for Hydraulic Cements (ASTM C1157-03)Fly ash and natural pozzolans (ASTM C618-05)Ground–granulated blast-furnace slag (ASTM C989-06)Silica fume (ASTM C1240-05)The eight different types of Portland cement referenced in ASTM C150 and their typical applications are summarized below.  Cement TypeApplicationType I – normal General purpose cement commonly used in all types of structuresType IA – normal, air-entrainingUsed in the same structures as Type I where air entrainment is desiredType II – moderate sulfate resistanceGeneral purpose cement used in structures where protection against moderate sulfate attack is important or where moderate heat of hydration is desired.Type IIA – moderate sulfate resistance, air-entrainingUsed in the same structures as Type II where air entrainment is desiredType III – high early strengthUsed in structures where high early strength of the concrete is desired or where structures must be put into service quicklyType IIIA – high early strength, air-entrainingUsed in the same structures as Type III where air entrainment is desiredType IV – low heat of hydrationUsed in structures where a low heat of hydration is required, such as massive concrete structures like damsType V – high sulfate resistanceUsed in structures where high sulfate resistance is required, such as elements in direct contact with soils or ground waters that have high sulfate content