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Dr. Mom MonyManaging Director, Mony Engineering Consultants Ltd

Director, MonyAkademiaM:+855-69-816 888

E:monystructural@gmail.com

Design of Reinforced Concrete StructuresAccording to ACI 318M-11

Academic Year 2014-2015

mailto:monystructural@gmail.commailto:monystructural@gmail.com

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Lecture 1: Introduction

RC Design: IntroductionDr. Mom Mony 2

Terminology and unitsHistorical background

Advantage and disadvantage of reinforced concretestructuresCement, Concrete, reinforcement, and admixture

Design loadsDesign methods

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Terminology and Units

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SI Metric Unit

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Conversion US Customary to SI Units

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History of the Development ofReinforced Concrete

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History of Concrete/Reinforced Concrete asStructural Materials

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Cement and ConcreteVolcanic ash mixed with lime (pozzolana) byRomans, called Roman cement

Panthoen in Rome, Italy (AD 126)Limestone mixed with clay by John SmeatonEddystone Lighthouse, south coast of England (AD 1800

Limestone mixed with clay and heated in a kiln by Joseph Aspdin in England (1824), the inventor ofPortland cement

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RC Design: IntroductionDr. Mom Mony 10

Volcanic ashmixed with lime(pozzolana) byRomans, calledRoman cement

Panthoen in Rome, Italy (AD 126)

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Limestone mixedwith clay by John Smeaton,English Engineer

Eddystone Lighthouse, south coast of England (AD1800)

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Portland CementLimestone mixed withclay and heated in Kiln

by Joseph Aspdin inEngland (1824)

Portland stone quarry in Isle of Portland, England

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History of Concrete/Reinforced Concrete asStructural Materials (cont )

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Reinforced Concrete Tub(~1850) Joseph Monier, French gardener, inventedconcrete tub with iron for his garden usePatents

Pipes & tanksFlat plates

BridgesStairs

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Reinforced Concrete Boat

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1848, Joseph-Louis Lambot , French Engineer, builtRC boat.

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Reinforced Concrete Beam, Floor

RC Design: IntroductionDr. Mom Mony 15

RC Beam1850, Thaddeus Hyatt, American Lawyer and Engine built a RC beam with longitudinal bars in tension zoand vertical stirrups for shear.

RC Floor1854, William BoutlandWilkinson, Enland, built a Rfloor deck.

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Reinforced Concrete Theory

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Theory of Flexure1886, Mathias Koenen, German engineer, developedmethod computing the strength of reinforced concre

called Theory of FlexureWorking Stressed Design for Flexure1894, Coignet de Tedeskko, France, extendedKoenen

theory of flexure1928,Prestressed Concretewas pioneered byEugene Freyssinet, French civil/structural engin

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Advantage and Disadvantage ofReinforced Concrete Structures

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Advantage vs Disadvantage

AdvantageAvailability of local materialsLess labor skills requiredCast-in-place for any shape in comparison with steelfabricationEconomical materials for footings, basement walls,piers, floor slabs and similar applicationsGreat resistance to fire and waterLow maintenanceLonger lifespan as the strength of RC concrete does decrease with time but increasing

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Advantage vs Disadvantage (cont..)

Rigidity of RC structuresConsiderable compressive strength per unit wei

DisadvantageLow tensile strength (1/10 of compressivestrength), is that, requiring to use reinforcing steRequire forms to hold structural elements untilthe hardening of concrete is sufficiently hard

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Advantage vs Disadvantage (cont )

Low strength per unit weight => heavyLow strength per unit volume => largeProperties of concrete vary widely due to itsmixing and proportions.

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Cement, Concrete, Reinforcement,Admixture

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Types of Portland Cement (ASTM)

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Type I : normal cementUse for general purpose of construction works

Type II : modified cement Type IUse for lower heat hydration and minor exposure to sulfate attack

Type III : high early strength cementIn 24hrs, double strength of Type I but higher heat of hydrationType IV : low-heat cement

Generates heat very slowly, use for very large concrete structures

Type V : sulfate resistant cementUse for high concentration of sulfate*ASTM: American Society for Testing and Materials

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Admixture

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Air-entraining admixture- Increase concrete resistance to freeze and thaw- Better resistance to deicing saltThe air-entraining agents cause the mixing water to foWhen the concrete freezes, the water moves into the a bubbles, relieving the pressure in concrete. When theconcrete thaws, the water moves out of the bubbles, lecracking the concrete.

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Accelerating Admixture

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Accelerating admixture- Accelerates early strength development in concrete- Reduces curing times and early removal of formwor- Good for cold climate- Agents contains such as Cacium Chloride (CaCl),

soluble salt and other organic compound

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Retarding Admixture

RC Design: IntroductionDr. Mom Mony 25

Retarding admixture-Slow the setting time of concrete hardening-Retard the temperature increases

-Prolong the plasticity of concrete, enabling better bending or bonding-Slow the hydration of cement on exposed concretesurfaces-Useful for large pour of concreting-Agents contain acids, sugars or sugar derivatives

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Superplasticizers

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Superplasticizer admixture- Reduce water content in W/C ratio in concrete mixin

while increasing slump- Good for workability of concrete or against segrega

of concrete during pouring- Useful for self-consolidating concrete (no vibration

required)- Agents contain organic sulfonates

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Water Proof Materials

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Water proofing admixtures-Retard the penetration of water into porous concrete-It may be applied to hardened concrete surfaces or adto concrete mixes-Agents contain some type of soaps or petroleumproducts (such as asphalt emulsion)

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Concrete/Reinforced Concrete

Concrete= cement (+inert materials)+ aggregate(coarse gravel/crushed rock+ sand) + water(+admixture)

Reinforced Concrete= reinforcement (reinforcing bar)+ concreteConcreteis strong in compression, but weak in tensioReinforcementis good in tension.Reinforced concreteacts as the result of couplinginteraction tension-compression of the reinforcemeand concrete.

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Strength of Concrete

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Compressive strengthtested by cylinder modeldiameter:150 mm, height: 300 mm

Normal Strength Concrete

-Compressive strength, 17 MPa

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Strength of Concrete (cont..)

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Gain of Compressive Strength with Age (Type I)fc(t)

=fc(28)

[t/(4 + 0.85t)]

Tensile strength of concrete (modulus of rupture)Beam specimen (150mmx150mmx750mm)fr = 6M/bh2 , where M: moment, b: width (150mm), hheight (150mm)Cylinder specimen (150mmx300mm)splitting tensile strength (fct) = 2P/ ld, where P:applied load, l:length (300mm), d: diameter(150mm)

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Strength of Concrete (cont..)

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Relationship between Compressive Strength and TenStrength (10 times less)

fr = minimum (0.7fc , 0.5fc)Factors affecting compressive strength-water/cement ratio-types of cement-cementitious materials (fly ash, slag, silica fume)-aggregates (sand, crushed stone,..)-temperature conditions

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Stress-Strain Curve in Concrete

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Tangent

Modulus of

Elasticity(Ec)

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Grades of Reinforcement (ASTM)

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ASTM A615(designated letter S): plain and deformed barsGrade 40(280 MPa) represents minimum yield strength 40,000 psi, Grade 60(420 MPa), Grade 75(520 MPa),Grade 80(550 MPa)

ASTM A706 (designated letter W): low-alloy plain adeformed bars, special use for welding

Grade 60(420 MPa), Grade 80(550 MPa)ASTM A996 (designated letter R): deformed rail steaxle steel bars

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Grades of Reinforcement (ASTM)

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Bar sizes

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RC Design: IntroductionDr. Mom Mony 36

Design Loads (ASCE 7-10)

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Factor Loads and Load Combination(ASCE 7-10)

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Gravity loadsD: dead load; L: live load; Lr: roof live load; S: snowload; R: rain load; F:fluid load

Lateral loadsW: wind load; E: earthquake load; F: fluid load; H: lodue to earth pressure

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Dead Loads

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MaterialsSteel 78.5 kN/m3Aluminum 25.9 kN/m3

Reinforced concrete (normal weight) 23.6 kN/m3Reinforced concrete (light weight) (14.1-18.9) kN/m3Brick 18.9 kN/m3

Wood (5.3-5.8) kN/m3

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Dead Loads (cont..)

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Building Component WeightCeiling

Gypsum or suspended metal lath 0.48 kN/m2

Acoustical fiber tile or channel ceiling 0.24 kN/m2Roof

Three-ply felt tar and gravel 0.26 kN/m2

2-in. (50 mm) insulation 0.14 kN/m2

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Dead Loads (cont.)

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Walls and PartitionsGypsum board (1 in. (25mm) thick) 0.19 kN/m2Brick (per inch thickness) 0.48 kN/m2Hollow concrete block (12 in. thick)

Heavy aggregate 2.83 kN/m2Light aggregate 2.63 kN/m2

Clay tile (6 in. thick) 1.44 kN/m2

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Live Loads

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Assembly areas and theatersFixed seats (fastened to floor) 2.87 kN/m2Lobbies 4.79 kN/m2

Stage floors 7.18 kN/m2Libraries

Reading rooms 2.87 kN/m2

Stack rooms 7.18 kN/m2Garage: vehicle passenger garage 1.92 kN/m

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Live Loads (cont..)

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Office BuildingsLobbies 4.79 kN/m2Offices 2.40 kN/m2

ResidentialHabitable attics and sleeping areas 1.44 kN/m2Uninhabitable attics with storage 0.96 kN/m2All other areas 1.92 kN/m2

SchoolsClassrooms 1.92 kN/m2Corridors above the first floor 3.83 kN/m2

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Live Loads (cont..)

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Live Loads (cont..)

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Live Loads (cont..)

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Live Loads (cont..)

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Live Loads (cont..)

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Live Loads (cont..)

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Roof Live Load

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Live Load Reduction

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When influence areas (KLLAT) 37.2 m2L =Lo (0.25 + 4.57/KLLATwhere Lo: Live Load(original)

L: reduced value of live load,AT: tributary area (m2),KLL: live load element factor (4 for columns, 2 for bea

But L 50% of Lo for column or beam susingle floor; L40% of Lo for column or beamsupporting two or more floors

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Live Load Reduction

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Live Load Not To Be Reduced

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Heavy Live LoadLive load that exceeds 4.79 kN/m2 (100 lb/ft2)shallnot be reduced , except live loads for members supporti

two or more floors shall be permitted to be reduced 20%.Passenger Vehicle Garage

The live load (1.92 kN/m2) shall not be reduced,except live loads for members supporting two or mofloors shall be permitted to be reduced by 20%.

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Live Load Not To Be Reduced

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Assembly UsesThe live loads shall not be reduced.

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Rain Loads

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Design rain loads

- R: rain loads on the undeflected roof (kN/m2)- ds: static head (mm), the depth of water up to the

inlet of the secondary drain.

- dh: hydraulic head (mm), additional depth of waabove the inlet of the secondary drain

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Loads Not Specified

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Partition wallPartition can be considered as dead load or liveload.

Live load: >0.72 kN/m2. It is not required if theminimum live load exceeds 3.83 kN/m2.

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Loads Not Specified

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Loads on Handrail and GuardrailNot to be considered for

- One- and two-family dwellings,

- Areas that are not accessible to the publicConcentrated load : 0.89 kN (200 lb) applied in any directioon the handrail or top rail, and 0.22 kN (50 lb) appliedhorizontally normal to the area of rail panel.

Uniform load : 0.73 kN/m (50 lb/ft) applied in any directioalong the handrail or top railAll these loadings need not to be applied concurrently.

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Loads Not Specified

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Load on Grab BarConcentrated load : 1.11 kN (250 lb) applied in any directioon the grab bar.

Load on Fixed Ladder with rungsConcentrated load (live load): 1.33 kN (300 lb) applied at anypoint on the fixed ladder to produce maximum load effeon the element. This loading shall be applied 1 unit (1.3

kN) for every 3 m (10 ft) of ladder height. The extendedpart of the rail above platform, 0.445 kN (100 lb) applieany direction on the top of side rail extension.

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Loads Not Specified

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Load on Vehicle (Passenger) BarrierConcentration load : 26.7 kN (6,000 lb) appliedhorizontally in any direction to the barrier.

The loading is assumed to act at heights between460mm (1 ft 6 in.) and 686 mm (2 ft 3 in.) above thefloor or ramp surface to produce the maximum load

effect.

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Loads Not Specified

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Impact Loads: weight of elements and live or moving loashall be increasedElevators

-increased by 100%

Machinery-Light machinery, shaft, or motor driven: 20%-Reciprocating machinery or power-driven units: 50%-Cab-operated traveling crane support girders and their connect25%Hangers-Hangers supporting floors or balconies: 33%

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Loads Not Specified

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Crane Loads:Maximum wheel load (MWL): weight of bridge (DL) + suof rated capacity and weight of trolley (LL) that indu

maximum load effect on its runway.Vertical impacts or vibration force: increase of MWL

- Monorail cranes (powered), 25%

- Cab-operated or remotely operated bridge cranes(powered), 25 %

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Loads Not Specified

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- Pendant-operated bridge cranes (powered), 10 %- Bridge cranes or monorail cranes with hand-geared (not powe bridge, trolley, and hoist 0%Lateral Force

-20% of the sum of rated capacity of crane, and the weight of trand hoist. It is assumed to act horizontally at the traction surfacrunway beam in either direction perpendicular to the beam.

Longitudinal Force

-10% of MWL. It is assumed to act horizontally at the tractionsurface of a runway beam in either direction parallel to the beam

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Wind Load (Lateral Force)

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Static wind pressure (qs)qs =0.613V 2 (1) where V: basic wind speed (m/s)Velocity wind pressure at height z above groundlevel (qz)qz = q sI K zKzt Kd (2)I: importance factor, Kz: velocity exposure coefficientKzt: topographic factor, Kd: wind direction factor

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Wind Load (cont..)

RC Design I: Introduction 63

Design wind pressure p =q zGC p (3)

p: design wind pressure,G: gust factor,C p: externalpressure coefficient

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Soil Loads and Hydrostatic Pressure

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If the soil load is not given by soil investigation,

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Soil Loads and Hydrostatic Pressure

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Uplift Force: water pressure shall be taken as thefull hydrostatic pressure applied for the entire ar

Factor Loads and Load Combination

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Factor Loads and Load Combination(ASCE 7-10)

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1.4D (1)1.2D + 1.6L +0.5 (Lr, or S or R) (2)1.2D+1.6(Lr or S or R)+(1.0L or 0.5W) (3)

1.2D+1.0W+1.0L+0.5(Lr or S or R) (4)1.2D+1.0E+1.0L+0.2S (5)

Control Overturning or Sliding

0.9D+1.0W (6)0.9D+1.0E (7)

Factor Loads and Load Combination

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Factor Loads and Load Combination(ASCE 7-10) (cont..)

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If fluid load is present: 1.4F to be included in (1)If earth pressure is present: 1.6H to be included in (2,6.7);if it is permanent present: 0.9H in (2,6,7)

If earthquake designed for service-level : 1.4E in (5)If wind is designed for service-level : 1.6W in (4,6) and 0.8Win (3)

If small live loads: 0.5L in (3,4,5) except for garages,areas of public assembly, areas where live loads is grthan 100 psf (4.78 kN/m2)

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Design Methods

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Design Methods

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Working Stress Design (WSD)Based on working loads/service loads/unfactored loDrawbacks

Inability to account properly for the variability of resistanand loadsLack of knowledge of the level of safety (safety factor),

Inability to deal with the effects of variation of loads in gr

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Design Methods (cont..)

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Strength Design (SD)Required strengths (Ru) computed from thecombination of factored loads, and

Design strengths (R)computed as the product ofnominal resistance and strength reduction factors ((also known as resistance factors)

Limit-state design philosophyR Ru

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Design Methods (cont..)

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Performance-Based Design (PBD)Rational methodis employed to provide reliability that isnot less than that expected for with the Strength Design

Uncertainties are considered for loadings and resistanceDesign is carried out by analysis or the combination ofanalysis and testing. The design assumptions are based oapproved test data or referenced standard,Testing used to substantiate the performance capacity,Peer review

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Design Methods (cont..)

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Strength reduction factor ()Tension-controlled sections =0.90Compression-controlled sections

Members with spiral reinforcement =0.70

Other reinforced members =0.65Shear and torsion =0.75Bearing on concrete =0.65

Design Procedure1. Strength design2. Check with working stress design

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Thank You !Q & A ???