Reinforcemet, Loads, Code

Reinforced Concrete StructuresMIM 232E

RCSD-2

Dr. Haluk SesigürI.T.U. Faculty of Architecture

Structural and Earthquake Engineering WG

S420a

Steel (çelik)

yielding

strengthHot benching

(BÇIIIa)

220 I

420 III

500 IV

D: smooth

N : ribbed

P: profile

http://mmf2.ogu.edu.tr/atopcu/index.htm

Smooth bar

Ribbed bar

Reinf. mesh

Reinf. meshReinforcing Bars

Reinforcing steel bar Steel types and class in Turkey

Mech. prop

Min. yielding strength

Min. Ultimate strength

Min. Fracture strain

Min. Fracture strain

Natural hardness Cold process

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Reinforcement mesh:

• Q type (15cm x 15cm)• R type (15cm x 25cm)

• Should be used in slabs, shear walls, retaining walls, tunnel linings, road pavements etc.

http://mmf2.ogu.edu.tr/atopcu/index.htm

Reinforcing steel bar Steel types and class in Turkey

Q type

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• .....

• Hot benching (a) more ductile; cold benching (b) more brittle• (b) is not allowed in seismic zones• Lineer –elastic/Hooke Law is valid up to yielding strength• Es = tan 𝛼 (elastic modulus)

yielding strength: the stress corresponding to yielding treshold (for type a)

http://mmf2.ogu.edu.tr/atopcu/index.htm

Reinforcing steel bar Stress-Strain (σ-𝞮) Relationship

steel yielding strength

Characteristic steel y. strength

steel ultimate strength

steel yielding strain

steel ultimate strain

Stress of steel

Strain of steel

Elastic modulus of steel

steel curves

Str

es

s

Strain

crushing

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• S220 : steel class with the lowest strength and adherence;usage in beam,column and shear walls should be avoided

• Steel with higher diameters are more birittleFor S420a and S500a ; φ<32

• S420a most common and convenient (strength&ductility)

Reinforcing steel bar general

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• ES = 2.1x106 Τkg cm2

• γ = 7850 Τkg cm2

• Lengths; 12m (in gen.)

Diameters;

• S220a (BÇI) : 6,8,.....,22,24,25,26,28mm• S420a,b (BÇIII) and S500a (BÇIV):• 6,8,.....,22,24,25,26,28,30,32,40,50mm• Corrosion protection is needed for storage

Reinforcing steel bar properties

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REINFORCED CONCRETE

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REINFORCED CONCRETE

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REINFORCED CONCRETE

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Bend up rebars

Beam reinf.

Formwork

Plastic spacers for

Concrete covering

slab reinf.

Reinforced Concrete General

Concrete

+ Steel bar (reinforcement)

• Concrete; high compressive strength, poor tensile strength

• To resist the cracking due to tensile stress, steel reinforcing bars are placed inside the sections’ tensile regions. Therefore, RC is constituted.

= Reinforced Concrete (RC)

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The resistence developed on concrete-steel bond that occurs when pull out force applied to steel bar.

Coherence of concrete and steel; working together

Expansion coefficient of steel and concrete similar/same

Adherence; bonding force that resists the shear force developed in between concrete and steel.

Surface roughness, rib of reinforcement is important

Reinforced Concrete Adherence

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• Diameter, surface of bar

• Strength, composition, compaction of concrete

Cement/sand ratio adherence

W/C adherence

In RC; interlocking length of the bar, direction of bar; cover thickness, stirrup effects the adherence.

Adherence depends on;

Reinforced Concrete Adherence

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Reinforced Concrete Adventages

• Ease of formability/workability

• Good in compression but requires steel bar for tension

• Fire-resistant (compared to steel/wood)

• Rigidity,

• less corrosion problem;

• Cheap maintenance, long life

• Economic,

• Workmanship is easy

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• Formwork, scaffold cost

• Relativeley heavy structures, dead loads

• Attentive cure needed

• Damage repairing difficult/expensive

• Mostly non-recyclable

• Non convenient for skyscrapers as only use

• casting depends on wheather

• Concrete production in construction site

Reinforced Concrete Disadventages

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• Dead laods (G): self-weights of RC components such as columns, • slabs, beams etc.• Live loads (Q): the loads that acting betimes • (furniture, snow, people etc.)

• Lateral loads: Earthquake (E), wind (W), soil (H), fluid etc.

• Others: temperature effects, differential settlement, ice load etc.

Vertical / gravity loads

• Load values is not precise, statistically determined and given in codes

TS498, TS ISO9194 :G, Q, W, snow-ice loads

DBYBHY 2007: Earthquake loads

http://mmf2.ogu.edu.tr/atopcu/index.htm

Loads Load types and effects

Lateral loads

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http://mmf2.ogu.edu.tr/atopcu/index.htm

Loads Load types and effects

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http://mmf2.ogu.edu.tr/atopcu/index.htm

Loads Load types and effects

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http://mmf2.ogu.edu.tr/atopcu/index.htm

Loads Load types and effects

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TS500 (6.3.3); to obtain maximum excitations

min B4

min M4max M3min M2max M1

0 1 2 3 4

max X0

1 2 3 4max

max X

1max

2

2 3 40

0 2 431min

min X 0

0 21min

3 4

min X2

max B

0

min X

0

max X

0

0

2 431

min X

2

1 2

1min

1

min3 4

3

3

max

4

max X

1max

1

2

min M

1

1 max M

2

2

3

3

4

3

min M1 max M

4

4

4

0

Ex.

Betonarme, İ.A. -F.K. –F.Ç.-O.C.Ç.

Loads Live load arrangement

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TS 498

Design Loads for

Buildings

TS 500 Specifications for buildings to be built in seismic zones (2007)

Specifictions TS498, TS500, Seismic Code

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SpecifictionsTS498

Value of Loads is given

Live load

Dead load

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Vertical live load values

SpecifictionsTS498

Value of Loads Usage

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SpecifictionsTS500

Turkish Standard

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SpecifictionsTS500- safety of structures

Structural safety

Ultimate strength limit

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Material Coefficients

Concrete:

Steel:

SpecifictionsTS500- safety of structures

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Load coefficients and load combinations

Vertical loads

SpecifictionsTS500- safety of structures

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wind

EQ

Lateral soil effect

Structural analysis

SpecifictionsTS500- safety of structures

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