1

Analysis of Test Results

2

What we’ll have to do:

• Load-Deflection curve.

• Load Vs Strain curve for steel and concrete

• Find yield load (εs = 0.002) for flexural rebar and strain at failure load for concrete and rebar.

• First yield load for flexural reinforcement.

• Ductility of the slab.

• Energy absorption.

• Deflection profile.

3

• Calculate flexural strength and Punching shear capacity of the slab.

• Compare test result with predicted result.

• Show a photograph depicting the crack pattern at failure.

• Make comment on the mode of failure of the slab.

4

Tension Reinforcement and Strain gauges arrangement

T1(1050,845);T2(1260,1020);T3(1460,845);T4(1590,1020);T5(810,1080)

T1

T2

T3

T4T5

1900

1900

5

Compression Reinforcement and Strain gauges arrangement

C9

C8

C7C6

C6(820,770); C7(1090,820); C8(820,580); C9(820,400)

6

Concrete Strain gauge locations

5

4

3

2

1

30, 70, 100, 100

7

Load-Deflection curve

Load vs Central Deflection

0.0

50.0

100.0

150.0

200.0

250.0

-40.0 -30.0 -20.0 -10.0 0.0 10.0 20.0 30.0 40.0

Deflection (mm)

Load

(KN

)

8

Load-Deflection curve

Load vs Central Deflection

0.0

50.0

100.0

150.0

200.0

250.0

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0

Deflection (mm)

Load

(NK

)

9

Load-Deflection curveLoad vs Central deflection

0.0

50.0

100.0

150.0

200.0

250.0

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0

Deflection (mm)

Load

(KN

)

10

Load vs Strain curve for steel and concreteLoad vs Strain in Steel (T2)

0.0

50.0

100.0

150.0

200.0

250.0

-500 0 500 1000 1500 2000 2500

Micro-Strain

Load

(KN

)

11

Load vs Strain curve for steel and concrete

Load vs Strain in steel (T2)

0.0

50.0

100.0

150.0

200.0

250.0

-500 0 500 1000 1500 2000 2500

Micro-Strain

Load

(KN

)

12

Load vs Strain curve for steel and concrete

Load vs Strain in steer (T2)

0.0

50.0

100.0

150.0

200.0

250.0

-500 0 500 1000 1500 2000 2500

Mocro-Strain

Load

(KN

)

13

Load vs Strain curve for steel and concreteLoad vs Strain in Concrete(3)

0.0

50.0

100.0

150.0

200.0

250.0

-2500 -2000 -1500 -1000 -500 0

Mocro-strain

Load

(KN

)

14

Load vs Strain curve for steel and concrete

Load vs Strain in Concrete (3)

0.0

50.0

100.0

150.0

200.0

250.0

-2500 -2000 -1500 -1000 -500 0

Micro-Strain

Load

(KN

)

15

Load vs Strain curve for steel and concreteLoad vs Strain in Concrete (3)

0.0

50.0

100.0

150.0

200.0

250.0

-2500 -2000 -1500 -1000 -500 0

Micro-Strain

Load

(KN

)

16

Steel Strain Distribution

100 KN

150 KN

200 KN

17

Concrete Strain Distribution

50 KN

100 KN

150 KN

200 KN

18

• Find yield load (εs = 0.002) for flexural rebar and strain at failure load for concrete and rebar.

• First yield load for flexural reinforcement.

19

Ductility and Energy Absorption of the Slab

Ductility = Ratio of the deflection at 25% of maximum load (after reaching the maximum load) to the deflection at the first yielding of flexural reinforcement.

Energy Absorption = Area under the load deflection curve up to 25 % maximum load (after reaching the maximum load)

20

Ductility and Energy Absorption of the Slab

21

Deflection Profile

1 division = 0.01 mm

1 cycle = 1 mm

22

Calculation of Flexural strength

( )( )cyyo

oflex

ffdfMca

sK

KMP

'2 /59.01

172.08

ρρ −=

⎟⎠⎞

⎜⎝⎛ −−

=

=

tesrcylinderfromfmmd

MPafor

c

y

__120

4000.15.0

' =

=

==ρ

23

Calculation of Punching Shear Capacity

( )dccbdbfV

o

occu

224.0

21

'

++=

= λφ

24

Compare Test result with Predicted result

Pflex Pv Ppred. Ptest Ptest/Ppred.

25

Show a photograph depicting the crack pattern at failure and Make

comment on the mode of failure of the slab

flex

test

PP

=φ If φ ≥ 1 , Flexural failure

If φ < 1 , Punching Shear failure→

→ From crack pattern

Make comment on mode of failure