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A. Preliminary OUTLINE
B. C. D. IntroductionSingly ReinforcedDoubly Reinforced Beam ( Beam (Working Stress Design)WSD) E. F. G. T BeamSingly Reinforced Beam (Ultimate Strength Design)Doubly - ReinforcedSingly Reinforced ( Beam (USD)WSD) H. I. J. T Beams (SR and DR USD)One Way SlabTwo Way Slab K. L. M. Shear ReinforcementTorsional ReinforcementShort Columns N. O. Long ColumnsServiceability Requirement
ReviewT.O.S.
Introduction Concrete
Concrete carefully proportional mixture of cement, sand and gravel or Is a stone-like material obtained by permitting a
other aggregate, and water to harden in forms of the shape and dimension of the desired structure Material used in Concrete.
Cement two weeks to achieve a sufficient strength to permit the removal of Concrete : made with normal Portland cement require about forms and the application of moderate loads. Such concrete reach their design strengths after 28 days and continue to gain strength at a slower rate thereafter. On some occasions, if it is desired to speed up construction, the use of โhigh in 3 to 7 days rather than the normal 28 days.-early-strength cementsโ is used. Desired strengths are obtained
There are several special types of Portland cement available. The American Society for Testing Material (ASTM) recognizes five types of Portland and cement. A brief description of these cement types follows Type I construction work. Type II-the common all-a modified cement which has a lower heat of-purpose cement used for general hydration than does Type I cement and which can withstand some exposure to sulfate attack. Types III-a high-early-strength cement which will produce in the first 24 hours a concrete with a strength about twice that of type I cement. This cement does have a much higher heat of hydration. Type IV exposed to high concentrations of sulfate.-a cement used for concrete which are to be
Aggregates three-fourths of the concrete volume. They must be the aggregates used in concrete occupy about strong, durable and clean. Should dust or other particles be present, they may interfere with the bond between the cement paste and aggregate. The maximum reinforced concrete are specified in Section 3.3.2 of the ACI Code. These limiting values are as follows:-size aggregates that can be used in
- of their form - oneone--fifth of the narrowest dimension between the sidesthird of the depth of slabs, or
- reinforcing.three-fourth of the minimum clear spacing between
Water concrete. When the water is mixed in mortar, it reacts with Water is an important component for mortar or cement and forms a binding paste which fills small voids in the sand. This creates a close cohesion of sand particles and cement. In case of cement concrete the voids formed between sand and coarse aggregate gets filled with the paste forming a cohesive substance/concrete. Note: The quantity and quality of water have vital effect on the strength of the concrete mix. Too much water will lessen the concrete strength while too little amount of water makes the workability of the mix difficult.
Admixtures: mixing are referred to as admixtures. They are used to materials added to concrete during or before improve the performance of concrete in certain situations as well as to lower the cost. Several of the most common types of admixtures: 1.) Air requirements of ASTM C260 and C618)-entraining admixtures (Conforming to the thawing^ - - to increase concreteโs resistance to freezing andto provide better resistance to the deteriorating action of de 2.) accelerating admixtures (i.e. calcium chloride) - accelerate early strength development-icing salt the concrete and early removal of forms.^ - reduce time required for curing and protection of
3.) Retarding admixtures (various acids and sugar derivatives) temperature - slow the setting of concrete and retard the increase of blending in successive pours 4.) Superplasticizers (Organic sulfonates)^ - prolong the plasticity of the concrete enabling a better while at the same time increasing the slump^ - - enables the reduction of the water content in concretekeep constant water-cement ratio while using less cement to produce workable concrete with considerable higher strength 5.) Water proofing material (petroleum products) - hardened concrete surface Curing - the process of controlling the conditions of humidity and^ - retard the penetration of water into porous concrete temperature.
419.1 Scope 419.1.1 this section shall apply to concrete including a.) Properties to be used for design b.) Durability requirements
Section 419;NSCP 2015 Concrete: Design and Durability Requirements
Steel
Steel Any of various modified forms of iron, artificially
produced, having a carbon content less than that of pig iron and more than that of wrought iron, and having qualities of hardness, elasticity, and strength varying according to composition and heat treatment: generally categorized as having a high, medium, or low-carbon content.
420.1 Scope 420.1.1 this section shall apply to steel reinforcement and shall govern (a) through (b) a.) Materials properties b.) Properties to be used for design c.) Durability requirements, including minimum specified cover requirements
Section 420;NSCP 2015 Steel Reinforcement Properties, Durability, and Embedment Steel Grades 1.) Grade 33
2.) 3.) GradeGrade 4060
fy 228 MPa
275 MPa 414 MPa
fs 124 MPa
138 MPa 207 MPa
fy fu== yield strength of steelultimate/tensile strength of steel
fs= allowable/actual strength of steel
Maximum Strength of Steel
Constant Values of Steel
- โข โข Coefficient of thermal expansionModulus ofModulus of ElasticityRigidity- - 77 200,000- 78 GPa MPa - 11.6x10-6/ยฐC
- โข PoissonUnit Weightยดs Ratio- 7850 - 0.3 kg/cu.m.
Steel Bar Designation Bar English Metric Designation No.2 No.3 Size Diameter 1/4"3/8" Size Diameter 10mm8mm No.4 No.5 No.6 1/2"5/8"3/4" 12mm16mm20mm No.10 No.12^ No.8^11 - -1"1/4"1/2"^ 25mm32mm40mm No.16 2" 50mm
Specified Concrete Cover for Cast^ (Section 420.6.1; NSCP 2015)^ Specified Concrete CoverTable 420.6.1.3.1-in-Place Non Prestressed Concrete Members
Concrete exposure Cast against and permanently in Member Reinforcement Specified cover, mm. contact with ground Exposed to weather or in contact with^ All^ All^75 ground^ All^ 20 mm dia. through MW200 or MD200 wire, and smaller^ 58 mm dia. Bars^ 16 mm dia. Bar,^5040 weather or in contact^ Not exposed to with ground pedestals, and tension^ Slabs, joists, and Beams, columns,^ walls^ 36 mm dia. Bar and^ 40 mm dia. And 58^ mm dia. Bars^ smaller^4020 ties^ stirrups, ties, spirals,^ reinforcement, and hoops^ Primary^40 Reinforcement Details (NSCP 2015-Section 425)
425.1 Scope 425.1.1 This Section shall apply to reinforcement details, including: a.) minimum spacing b.) standard hooks, seismic hooks and crossties c.) development of reinforcement d.) splices e.) bundled reinforcement f.) transverse reinforcement g.) Post-tensioning anchorages and couplers
425.2 Minimum Spacing of Reinforcement 425.2.1 For parallel non-prestressed reinforcement in a horizontal layer, clear spacing shall be at least the greatest of 425.2.2 For parallel non-prestressed reinforcement placed in two or more 50 mm , ๐
๐ and ๐/๐ ๐
๐๐๐. horizontal layers, reinforcement in the upper layers shall be placed directly above reinforcement in the bottom layer with a clear spacing between layers of at least 425.2.3 For longitudinal reinforcement in columns, pedestals, struts, and 25 mm. boundary elements in walls, clear spacing between bars shall be at least the greatest of 40 mm , 1.5 ๐
๐ and ๐/๐ ๐
๐๐๐.
Advantages of reinforced concrete as structural material
1.) considerable compressive strength as compared to most other material
2.) great resistance to the actions of fire and water
3.) very rigid 4.) low-maintenance material
5.) has a very long service life (due to solidification of the cement paste)
Disadvantage of reinforced concrete as structural material 1.) very low tensile strength, require the use of tensile
reinforcement 2.) needs forms, place until it hardens sufficiently falsework or shoring to hold concrete in 3.) low strength per unit of weight of concrete leads to heavy members (very important matter for long span members where dead weight has great effect on bending moments) 4.) low strength per unit of volume of concrete means members will be relatively large (important consideration for tall buildings and long span members) 5.) properties vary wildly due to variations in its proportioning or mixing 6.) placing and curing is not as carefully controlled as is the production of other material
Limit State Design/Load and Resistance Factor Design (LSD/LRFD) separate load uncertainty from material uncertainty. This method of design is called limit state design or more specifically, in United States In structural engineering there has been an increasing trend to it is called load and resistance factor design (LRFD). Load Factors Various types of loads can act on a structure or structural member, and each is multiplied by a load factor that accounts for its variability. The loads include dead load, which is fixed weight of the structure, and live loads, which about. Other types of live loads include wind, earthquake, and snow involve people or vehicles that move loads. Resistance/Reduction Factors Are determined from the probability of material failure as it relates to the material These factors will differ for different types of materials. concrete has smaller factors than steel because engineers have more confidence about the behaviour of steel under load than they do aboutยดs quality and the consistency of its strength. For example, concrete.
Design Criteria
Where ๐พ = ๐ฟ๐๐๐: ๐น๐๐๐ก๐๐ ๐
โ
(^) == ๐ฟ๐๐๐๐ ๐
๐๐๐ข๐๐ก๐๐๐ ๐ก๐ ๐๐ ๐น๐๐๐ก๐๐ ๐๐๐๐๐๐๐ ๐๐ฆ ๐กโ๐ ๐ ๐ก๐๐ข๐๐ก๐ข๐๐ ๐
๐
๐ข๐ == ๐ข๐๐ก๐๐๐๐ก๐๐๐๐๐๐๐๐ ๐ฟ๐๐๐๐ฟ๐๐๐
External and Internal Actions
Types of Applied
Loadings
203.2 Symbols and NotationsSection 203 (NSCP 2015)-Load Combination
D= E=earthquake load set forth in Section 208.6.1 Em=estimated maximum earthqauke force that can be developed in the structure as set forthdead load in Section 208.6.1 F=load due to fulids with well defined pressures and maximum heights H=load due to lateral pressure of soil and water in soil L=live load, except roof live load, including any permitted live load reduction Lr=roof live load, including any permitted live load reduction P=ponding load R=rain load on the undeflected roof T=self temperature change, shrinkage, moisture change, creep in component materials, movement-straining force and effects arising from contraction or expansion resulting from due to differential settlement, or combinations theroef W=load due to wind load
Load
Combinations
203.4 Load Combinations Using Allowable Stress or Allowable Strength Design 203.4.1 Basic Load Combinations D+F ( 203 - 8) D+H+F+L+T D+H+F+(Lr or R) ((203 203 - -9)10) D+H+F+0.75(L+T(Lr or R)) D+H+F+(0.6W or (E/1.4)) (( 203203 - -11)12)
203.3 Load Combination using Strength Design or Load and Resistance Factor Design 203.1 Basic Load Combinations 1.4(D+F) 1.2(D+F+T)+1.6(L+H)+0.5(Lr or R) 1.2D+1.6(Lr or R)+(f1L or 0.5W) (203(203( 203 - --1)2)3) 1.2D+1.0W+f1L+0.5(Lr or R) 1.2D+1.0E+f1L 0.9D+1.0W+1.6H (((203 203203 - --4)5)6) Where f 1 0.9D+1.0E+1.6H =1.0 for floors in places of public assembly, for live loads in excess of^ (^203 - 7) 4.8kPa, and for garage live load, or 203.2 Other =0.5 for other live Loads loads Where โPโ is to be considered in design, the applicable load shall be added to Section 203.3.1 factored as 1.2P.
Letโs Get Started
P Cross Section h (^) b NA 3 Stages the member will encounter 1.) 2.) Concrete Cracked Elastic Stress Stage Uncracked Concrete Stage 3.) Ultimate Strength Stage
L
Uncracked
Concrete Stage
b h NA
Stress Diagram fc
Note:^ ft๐๐ก<^ ๐๐ Flexural Tensile Strength of Concrete /Modulus of Rupture ๐๐ = ๐๐๐ ๐ผ๐๐ฆ๐ก^ ; ;^ ๐๐๐๐^ ==^00 ..62๐7๐ ๐๐โฒ๐โฒ๐^ (Section 419.2.3.1 (2001 NSCP) NSCP)^ ;^2015
โWithout rebar^ installedโ
Strain Diagram ๐๐
๐๐
