sbcsbq rc design

8/2/2019 Sbcsbq Rc Design

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SBC1142 / SBQ2122STRUCTURAL DESIGN

by

Ir. Mohamad Salleh YassinDepartment of Structures & Materials

Faculty of Civil Engineering

Universiti Teknologi Malaysia


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OBJECTIVESAfter completing this subject ___ should be able to :

understand the concept, procedure and objective of

structural design

prepare structural layout plan for a typical building floors.

prepare and present a complete design calculations forbeams and slabs.

prepare structural detailing for beams and slabs.


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1. BS 8110: Part 1, 2 and 3 : 1997Structural Use of Concrete.

2. Mac Ginley, T.J., Reinforced ConcreteDesign, Theory and Examples, E & FN

SPON, 1995.3. Allen, A.H., Reinforced Concrete

Design to BS 8110Simply Explained,1988.

4. Mosley, W.H. and Bungey, J.H,Reinforced Concrete Design,MacMillan Education Ltd., 1999.

5. Martin, L.H., Structural Design in

Concrete to BS 8110, Edward Arnold,1989.

6. Higgins and Rogers, Design andDetails: BS 8110, Cement andConcrete Assoc., 1990.

7. Ray, S.S., Reinforced Concrete:Analysis and Design, BlackwellScience, 1995.

8. M. L. Zakaria et al, Rekabentuk konkritPrategasan, DBP, 1990

RM 59.90

RM 10.00

REFERENCES


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INTRODUCTION &

GENERAL DESIGN CONSIDERATIONS

Definition

Purpose of design

Project procedure Design Process

Reinforced concrete

Structural elements

Code of practice

Method of design

Loads

Limit states design

Material strength Partial safety factor

Stress-strain relation

Behavior of beams in

bending

Types of failure


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DESIGN A process of determination of

reliable structural system,selection of suitable materialsand determination of optimummember sizes for the structureto be built.


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PURPOSE OF DESIGN to provide a structure which satisfy the

following criteria :

Fitness for purpose

Safety and reliability

Durability

Economy User comfort

Maintainability


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PROJECT PROCEDUREProject Manager

(Architect or.Engineer, or ..)

Architect

Consultants

Mechanical and

Electrical engineer

(M & E)

Quantity SurveyorCivil and Structuralengineer (C & S)

Contractor

(QS, Project Engineer, SiteSupervisor, Clerk, Construction

workers)


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Client/Project Manager


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Architect Determine the

arrangement and

layout of thestructure to meetthe clients

requirements.

Producearchitecture

drawings


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STRUCTURAL ENGINEER

Determines the best

structural systems orforms to bring thearchitects concept

into being

Analysis and designthe structure

Produce the

structural drawings


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QUANTITY SURVEYOR

Prepare bill of

quantities,specification andcontract

documents.


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CONTRACTOR

Construct the

structure under thesupervision ofengineers and

architects.


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DESIGN PROCESS1. Idealization of the structure into frames

and elements.

2. Estimation of loads.3. Analysis to determine the maximum

moments, shears, etc.

4. Design of sections and reinforcement

for every structural elements.5. Production of arrangement and

detail drawings and bar schedules.


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Architect drawings


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Elevation


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Plan


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Plan


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Structural drawing


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Details


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Construction


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REINFORCED CONCRETE Concrete in which

steel reinforcement

is embedded insuch a manner thatthe two materials

act together inresisting forces.


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CONCRETE STEEL

Strength in tension

Strength in compression

Strength in shear

Durability

Fire resistance

Poor

Good

Fair

Good

Good

Good

Good, but slender bars

will buckle.

Good

Corrodes if unprotected

Poor suffers rapid loss

of strength at high

temperatures


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REINFORCED CONCRETESTRUCTURE

Column

Slab

wall

Ribbed slab Column

Staircase

Landing

Ground floor

Slab

Pad footing

Stripfooting

Beam


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STRUCTURAL ELEMENTS

Beams

Slabs

Columns

Walls

Foundations

Staircases


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The oldest code known

If a builder has built ahouse if the house hehas built falls and killsthe householder, thebuilder shall be slain

- The code of Hammurabi, Kingof Babylon, about 3800 yearsago.


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METHODS OF DESIGN PERMISSIBLE STRESS DESIGN

LOAD FACTOR DESIGN

LIMIT STATE DESIGN

PERFORMANCE BASED DESIGN


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LIMIT STATE DESIGN

The criteria for safe design:

The structure should not become

unfit for use, i.e. that it should not

reach a limit state during itsdesign life


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LIMIT STATES

ULTIMATE LIMIT STATESThe whole structure or its elements shouldnot collapse, overturn or buckle whensubjected to the design loads.

SERVICEABILITY LIMIT STATES

The structure should not become unfit foruse due to excessive deflection, crackingor vibration.


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LOADS

Characteristic load

The actual loads that the structure isdesign to carry i.e. the maximum loadswhich will not be exceeded during the life

of the structure (* 95% probability of not

being exceed)


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Characteristic Imposed Load, QkThe weight of people, furniture, equipment etc. on thefloors. Given in BS 6399: Part 1 for various type of buildings.


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Characteristic Wind

Load, WkDepends on thelocation,shape anddimensions of thebuildings. Wind loads

are estimated using CP3:Chapter V : Part 2.


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Design Load= Characteristic load

x partialsafety factor

= (Gk, Qk, Wk) x gf


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Characteristic strength of concrete, fcu

= the 28 day cube strength in N/mm2

* The grade recommended by BS 8110 are 25,

30, 35, 40, 45 and 50 N/mm

2

for normalweight concrete.


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Characteristic strength of steel

reinforcement, fy

= the yield or proof stress in N/mm2

The specified strength given in BS 8110 are,

fy = 250 N/mm2 for mild steel (R)

fy = 460 N/mm2 for high yield steel (T)


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Design strength

= Characteristic strength

Partial safety factor for strength

= fk/ gm


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PARTIAL SAFETY FACTOR

The partial safety factor for load gf takes accountof

possible increases in load

inaccurate assessment of the effect of loads

unforeseen stress distributions in members

the importance of the limit state beingconsidered

Construction inaccuracies


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The partial safety factor for load, gf

Loadcombination

Load type

Dead load Imposed load Earth, wind

& waterpressureAdverse Beneficial Adverse Beneficial

Dead andImposed (andearth andwater)

1.4 1.0 1.6 0 1.4

Dead and Wind(and earth andwater)

1.4 1.0 - - 1.4

Dead, windand imposed(and earth and

water)

1.2 1.2 1.2 1.2 1.2


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The partial safety factor for strength gm takesaccount of

Uncertainties in strength of materials in thestructure

Uncertainties in the accuracy of method usedto predict the behavior of material

Variations in member sizes and buildingdimensions.


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Values of gm for the ultimate limit states

ReinforcementConcrete in flexure or axial load

Shear strength

Bond strengthOthers, e.g. bearing strength

1.151.5

1.25

1.4> 1.5


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STRESS STRAIN CURVE


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STRESS-STRAIN CURVE- for concrete

Actual curve Design curve


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STRESS STRAIN CURVES


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STRESS-STRAIN CURVES

- for reinforcement

Actual curve Design curve


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Important notes :

Yielding commences at the design

strength of fy/gm The modulus of elasticity is 200 kN/mm2

The behavior and strength of

reinforcement are taken to be the samein tension and compression


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Assumptions in definingthe behavior of section

Strain distribution is assumed to be linear. This isbased on hypothesis that the plane sectionsbefore bending remain plane and perpendicular

to the neutral axis after bending.

Strain in steel and the surrounding concrete is thesame prior to cracking of the concrete oryielding of the steel.

Concrete is weak in tension. So concrete in thetension zone of the section is neglected andreinforcement is assumed to take total tensileforce.


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DEPTH OF NEUTRAL AXIS, X

From strain diagram,

ecc/x = est/(d-x)x = d/[1 + (est/ecc)]

At the ultimate limit states, where concrete fails andsteel yield simultaneously,

ecc = 0.0035est = 0.87fy/Es = 0.87fy/200 x 103

For fy= 500 N/mm2, est = 0.002175

So, x = d/[(1 + (0.002175/0.003500] = 0.617d


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2. UNDER REINFORCED

If less steel is provided than in case 1 the steel has reachyield and continues yielding before the concrete fails atultimate load. Cracks appear giving warning of failure.Neutral axis depth,x < 0.617d


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3. OVER REINFORCED

If more steel is provided than in case 1, the concrete failssuddenly without warning before the steel reaches yield.Neutral axis depth, x > 0.617d


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A man was strolling on the beach when he saw a fisherman fishing onthe cliff. He went up and asked the fisherman how was his catch. Thefisherman replied there wasn't many fishes but he was contented and

happy with his catch. The man went on and told the fisherman that heshould go out into the ocean, that way he would get more fishes tosell. If the fisherman was really good, he could set up a company andbuy up trawlers, catch even more fishes and earn even more money.Having achieved all these, the fisherman could buy all the things hewanted, that including a beach resort, do the things he wanted like

relaxing down at the beach eg. fishing recreationally.The fisherman looked puzzled, "I don't understand this, you aresuggesting that I should go one big loop so as to end up where I amtoday, happily fishing on the cliff?"

The Fisherman


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***PENGAJARAN DARIPADA CERITA DI ATAS*****

Almost everyone here is constantly working to achieve happiness. We all

work hard, trying to earn more money. What is the point of all this when

we are not happy? Afterall, we are forcing ourselves to work harder just toobtain happiness. Are we all trying to be like the man above, going a

full circle to end up being at the same place.

Your parents have been telling you, study hard get a good job, work hard

and earn your keep, only then you would be happy. We have to realise

that the key to happiness is to appreciate yourself and Life. It is not

about working yourself to death and getting no where. We all want the same

goal, to be happy. Basic happiness is to look introspective. Success dependsheavily on yourself, your innerself.

sbcsbq rc design

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