Professor Kypros PilakoutasProfessor Peter Waldron, Dr Maurizio Guadagnini

Centre for Cement and ConcreteThe University of Sheffield, UK

Andrew HendersonDirector of World Wide Sales, Concrete Reinforcement Products

ERICO

New Punching Shear Reinforcement for Flat Slabs

Centre for Cement and Concrete

• Problem/Solutions

• Lenton® Shear Fortress

• Experiments

• Results

• Conclusions

OutlineOutline

Shear ReinforcementShear Reinforcement

Conventional Reinforcement Closed

Hoop Sausage Links

Inclined Shear Reinforcement

• Difficult to anchor

• Difficult to install

• Does not facilitate prefabrication

SystemsSystems

Stud-rail Systems

• Priority over flexural re-bar installation• Conceptual issues

•System•Anchorage•Shear design

ΤΤhe he LSF LSF on top of theon top of the uupper pper flexural reinforcementflexural reinforcement

Lenton® Steel FortressLenton® Steel Fortress

s s

depth11””

• Maximum effective depth

• Easy placement/ Adaptability

• Shear design based on Codes (e.g. ACI 318)

• Excellent anchorage

AdvantagesAdvantages

• 1st Series (PSSA-D)• 2nd Series (PSSF-H)• Beam Tests (B1-B10)• Slabs with holes (PSSH1-5)• Slabs with FRP reinforcement• Tests for ICC Certification (California)• Cyclic tests (California)

Testing workTesting work

top #5@8”

bottom #4@8”

links 3#2@20”

Column 4 # 5 8”

6’ 7”

8”

8”

Testing ArrangementTesting Arrangement

Loading Frame

Slab

FLAT SLAB TESTING

Reaction Frame

Load Application

Testing ArrangementTesting Arrangement

Loading Ring Frame

Reaction Ring Frame

Jacks

Column Stub

S1

S2

S3

S4

S5

S6

S7S8S9

S10 S11 S12

D5

D4

D3

D2

D1

D6 D7 D8

R250 mm 10” R400 mm 16”

R600 mm 24” R850 mm 36”

D9

D10

D11

RS5,6

RS3,4

TS1RS7,81

2 RS1TS2

RS2

InstrumentationInstrumentation

Strain gauge location Displacement Measurements

PSSAPSSA

Control Slab PSSAControl Slab PSSA

4685

PSI

0.4511102454PSSAinchesmmKipskN

Maximum DisplacementMaximum LoadSlab

PSSB and PSSCPSSB and PSSC

PSSB,C

PSSB

PSSC

SS1 SS2SS3

SS4

SS5

SS6

SS7

SS8

PSSDPSSD

SS1 SS2

SS3SS4

SS5

SS6

SS7

SS8

PSSD

0

100

200

300

400

500

600

0 5 10 15 20 25

Displacement (mm) at D850

Load

(kN

)

0

20

40

60

80

100

120

PSSA PSSB

PSSC PSSD

Load

Kip

s

Load - DeflectionLoad - Deflection

0

100

200

300

400

500

600

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000Microstrain in Flexural Bar

Load

(kN

)

PSSA

PSSB

PSSCPSSD

Load - StrainLoad - Strain

0

20

40

60

80

100

120

Load

Kip

s

S1S1

PSSA to PSSDPSSA to PSSD

0.8421126560PSSD

0.9524126560PSSC

1.0025126560PSSB

0.4511102454PSSA

inchesmmKipskN

Maximum Displacement

Maximum Load

Slab

4685

PSI

0

100

200

300

400

500

600

0 500 1000 1500 2000 2500 3000Microstrain on shear reinforcement

Load

(kN

)

PSSB

PSSC

0

20

40

60

80

100

120

Load

Kip

s

PSSB versus PSSCPSSB versus PSSC

SS1 SS6

SS7

SS12

PSSE

PSSEPSSE

0

20

40

60

80

100

120

Load

Kip

s

PSSE versus PSSBPSSE versus PSSBL

oad

(kN

)

0

100

200

300

400

500

600

5 1010 15 20 25 30

PSSEPSSBPSSA

Deflection (mm)

D850

SS1 SS6

SS7 SS12

SS1 SS6

SS7 SS12SS9 SS10

PSSF PSSG

PSSF and PSSGPSSF and PSSG

0

100

200

300

400

500

600

0 5 10 15 20 25Displacement (mm) at D850

Load

(kN

)

PSSE

PSSF

PSSG

PSSA

1.0928133590PSSG

1.1930134598PSSF

1.0326129573PSSE

0.4511102454PSSA

inchesmmKipskN

Maximum Displacement

Maximum Load

Slab

Load - DeflectionLoad - Deflection

0

20

40

60

80

100

120

Load

Kip

s

6342

PSI

0

100

200

300

400

500

600

0 2000 4000 6000 8000 10000 12000Microstrain in the Shear Reinforcement

Load

(kN

)

SS3SS9

PSSE

Load - StrainLoad - Strain

SS1 SS6

SS7

SS12

0

1

2

3

4

5

6

7

8

9

0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000Microstrain on the strip

Load

(kN

)

Cross-section with hole

Cross-section without hole

Strain ReadingsStrain Readings

•Strain normally measured at cross-section without hole to avoid recording stress concentration due to hole

SS1 SS6

SS7 SS12

PSSHPSSH

PSSH

More slabs with holesMore slabs with holes

PSSH Load-DeflectionPSSH Load-Deflection

0

100

200

300

400

500

600

700

0 5 10 15 20 25 30Displacement (mm)

Load

(kN

)

PSSG D11

PSSG D8

PSSH D11PSSH D8

D11

•PSSH capacity increased by more than 100%

0

100

200

300

400

500

600

0 1000 2000 3000 4000 5000 6000 7000 8000

Strain on Strip

Load

(kN

)

SS2SS7

PSSH

PSSH Load-StrainPSSH Load-Strain

The LSF:

• Prevents brittle punching shear failure and leads to ductile behavior

• Fast and easy fixing; placed on top of main reinforcement for max anchorage

• Can be designed as conventional shear reinforcement

• Evidence of LSF yielding

ConclusionsConclusions