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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
RC_RCSD_1 2
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
RC_RCSD_1 3
• .....
• 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
RC_RCSD_1 4
• 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
RC_RCSD_1 5
• 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
RC_RCSD_1 8
REINFORCED CONCRETE
RC_RCSD_1 9
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)
RC_RCSD_1 10
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
RC_RCSD_1 11
• 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
RC_RCSD_1 12
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
RC_RCSD_1 13
• 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
RC_RCSD_1 14
• 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
RC_RCSD_1 15
http://mmf2.ogu.edu.tr/atopcu/index.htm
Loads Load types and effects
RC_RCSD_1 16
http://mmf2.ogu.edu.tr/atopcu/index.htm
Loads Load types and effects
RC_RCSD_1 17
http://mmf2.ogu.edu.tr/atopcu/index.htm
Loads Load types and effects
RC_RCSD_1 18
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
RC_RCSD_1 19
TS 498
Design Loads for
Buildings
TS 500 Specifications for buildings to be built in seismic zones (2007)
Specifictions TS498, TS500, Seismic Code
RC_RCSD_1 20
SpecifictionsTS498
Value of Loads is given
Live load
Dead load
RC_RCSD_1 21
Vertical live load values
SpecifictionsTS498
Value of Loads Usage
RC_RCSD_1 22
SpecifictionsTS500
Turkish Standard
RC_RCSD_1 23
SpecifictionsTS500- safety of structures
Structural safety
Ultimate strength limit
RC_RCSD_1 24
Material Coefficients
Concrete:
Steel:
SpecifictionsTS500- safety of structures
RC_RCSD_1 25
Load coefficients and load combinations
Vertical loads
SpecifictionsTS500- safety of structures
RC_RCSD_1 26
wind
EQ
Lateral soil effect
Structural analysis
SpecifictionsTS500- safety of structures
RC_RCSD_1 27