This is an academic presentation based on literature review of various research papers on Bolt-Steel Plated Beam. It was presented in regular seminar session held in the department of Civil Engineering, Kasetsart University.

1. Use of bolted-steel plate (BSP)) to
strengthen r.c beam
Pramod Rai
Structural Engineering
Kasetsart University, Thailand
1
NOVEMBER 30, 2017

2. OUTLINE
1. Failure mechanisms in rc beam
2. Failure MECHANISMS in bsp beams
3. CONTRIBUTING PARAMETERS
4. EXPERIMENT test for this kind of research
5. ANALYTICAL MODELs by baglin Et al. and Li et al.
6. Comparison of STRENGTH, STIFFNESS, AND DUCTILITY
7. Other important observations
8. FINDINGS AND CONCLUSION
2

3. 1. BEAMS FAILURE MECHANISM
FAILURE
SHEAR
COMPRESSION
CRUSHING
COMPRESSION
SHEAR
FLEXURE
TENSILE
YIELDING OF
STEEL PLATE
BUCKLING IN
COMPRESSION
3

4. Bsp BEAMS FAILURE MECHANISM
FAILURE
SHEAR
COMPRESSION
CRUSHING
COMPRESSION
SHEAR
FLEXURE
TENSILE
YIELDING OF
STEEL PLATE
BUCKLING IN
COMPRESSION
4

5. 1. flexural failure
• preceded by the yielding of the
tensile reinforcement
• The strain of the outermost
tensile-reinforcement-layer
reaches its yield strain εst >
εy.
5

6. • caused by crushingofthe concrete
• the maximum compressive strainofthe
concreteexceeds its crushingstrain εcc
> εc0.
2. SHEAR failure
6

7. • diagonalsplitting tension crackinthe web.
• tensile capacityof the‘web’ is sufficient
• tension crackextends alongthediagonal
• crushing ofconcrete takesplace.
2.1. Compression zone crushing mechanism
7

8. 2.2. Compression zone shear mechanism (
• differs from thecompression zonecrushingmechanismonly at the final
stages offailure.
• compression hasreachedits critical value failure ofthe concretein the
compression zone in shearand underthe biaxial State ofstress.
8

9. 2. Bsp BEAMS FAILURE MECHANISM
FAILURE
SHEAR
COMPRESSION
CRUSHING
COMPRESSION
SHEAR
FLEXURE
TENSILE
YIELDING OF
STEEL PLATE
BUCKLING IN
COMPRESSION
9

10. BSP BEAMS
1. flexural failure:
yielding of the tensile regions of the steel plates
2. brittle failure:
buckling of the compressive regions of the steel plates
10

11. bsp flexural failure
• themaximum tensile strainof the
steel plates reachesits yield strain
εpt > εpy
11

12. Bsp brittle failure
• the maximumcompressive strain onthe
outer face of the steel plates decreases
suddenly ∆εpc < 0
12

13. 3. OTHER LOCAL FAILURES
3.1 Bearing failure
3.2 Plate anchorage failure
3.3 Plate buckling
13

14. Bearing failure
• caused by localized crushing of
concrete
• can occur both under the load
and above the support
• allowable limitsdepend on
boththe biaxialstress
condition and the adopted
detailing.
14

15. Plate anchorage failure
• breakdown of composite
interaction between the plate and
concrete
• This leads to sudden and brittle
failure of the beam.
• Ideally the anchorage capacity
should be sufficient to allow tensile
yielding of the plate along the full
length of the failure plane.
15

16. Plate buckling
• sudden failure
• possible small torsional effects
induced by the loading
arrangement
16

17. 4. Contributing parameters
• Thicknessofplate
• Spacing ofbolt anchorage
• Depth ofPlate
• Provision ofstiffeners
• Transverseand longitudinal slip
17

18. 5. EXPERIMENTAL PROGRAM
1. SpecimenDetails
2. Strengthening Procedure
3. Material Properties andBolt Test
4. Test Set-Up
5. Instrumentation
18

19. 6. observations
19

20. The two stage behavior
(1) The linear growth stage
• the loadwasless than75%ofthe peak loads
(0.75Pu)
• linear growth
• generally integralcross-section
(2) The stiffness decreasing stage
• non-linear behaviors
• yieldingoflongitudinalandtransverse
reinforcements aswellas thepropagationof
cracks.
20

21. 21
7.
strength, stiffness, and ductility

22. performance
PARAMETERS
1. Strength
2. Stiffness
3. Ductility
22

23. Strength and
stiffness
• Increasing platedepthandthickness
• ReducingBoltSpacing
• Providing Stiffeners
23

24. Ductility
• Decreasingbolt spacing
• Increasing Platedepth and thickness
• Stiffener doesn’t much affect
24

25. 25
Other significant observations

26. three typical linear segments
• The first turningpointreferred to the
occurrence of the diagonal cracks
• The second indicated the yieldingof
stirrups..
• The Last, the stirrup strains increased
rapidly and beganto yield after they
reached about 2000 le.
26
Strains developed in
the shear stirrups

27. • Linear straindevelopment
• sharedthe tensile force once
borne by the tensile
reinforcement
• Severaldidn’t reachthe yield
strain
Strains developed in the tensile reinforcement
27

28. Longitudinal strains in
the steel plates
• increased asthe increasing
distance from thesupport
• Meanwhile, compressive strain<
thetensile strain
• Whenthe BSPbeam reachedthe
ultimate limit state, the
longitudinal tensile strainat the
bottom edge > the yield strain
28

29. Principal strains in
the steel plates
• the principal strainsat the middle
level did not change
• becausethe shearforcesin the
shearspanis kept constant along
the beam axes.
29

30. Longitudinal and
transverse slips
• shear force wastransferred fromthe RCbeamstothe
bolted steel plates throughtheanchor bolts
• thedisplacement ofthe steel plates laggedbehind
thatof theRCbeams, thusrelative slipsoccurred.
30

31. Longitudinal slip
• Same variation trend
• Magnitudes of Slip and slopes of
curveincreased with increasing load
• Direction consistent
• Slips at top edge were largerthan
slips at the bottom
31

32. P100B300 P100B450
P250B300R P250B450R
Increasingplate depth
Decreasing BoltSpacing
Provisionof Stiffener
• Proportional to
squareofstiffness
ratio
• Inversely
proportional tobolt
spacing
• Full depth plate has
minimal effect on
flexure
Longitudinal
slip
33

33. Transverse slip
• Negative nearthe plate ends and
positive with greater value near
the loading points
• Comparatively, smaller than
longitudinal slip
• controlled by theflexural
stiffnessratio βfand the
stiffnessofthe connecting media
km.
34

34. Magnitudes of
transverseslipis
proportional to depth
of plate,the
flexural stiffness
ratioβf
35
P100B300 P100B450
P250B300R P250B450R

35. • Magnitudes of slip are small, but due to higher value of E, their
effect cannot be ignored in design.
• Longitudinal Slip is no longer a dominant factor for evaluating the
performanceofBSPbeams with deep steel Plates.
• Transverseslip is proportional todepth of plate. So it cannotbe ignored in
evaluating the performanceofBSPbeams with deep steelplates.
36

36. Plate Behavior
(1) behaving as additional tensile reinforcement-providingan additional
coupling moment
(2) providing an additional bending moment duetotheir flexural stiffness
37

37. 38
ANALYTICAL MODELING

38. Baglin et al.- 2000
39
COMPATIBILITY
SHEAR
CAPACITY

39. 40
Li et al.-2017
COMPATIBILITY
SHEAR
CAPACITY

40. 41
conclusions

41. Tensile failure shifted to shear
compression failure.
1
(a)thebrittle shear–tension (ST)failure
causedbystirrupyielding andpropagationofamain diagonalcrack
(b) theshear–compression (SC)failures
causedbyconcretecrushing combinedwithdevelopment
ofmultiple diagonalshearcracks
42

42. The flexural strength can only be
improved by adding deep bolted-side
steel plates
2
• Theexperimental results reveal thatunlike the lightlyreinforced RCbeams,whose strength
andstiffness canbe increased significantlywith asmallsacrifice ofductility byattachingsteel
plates to thebeam soffitor thetensile region of theside faces.
43

43. The steel plates in BSP beams
contribute to the overall flexural
strength by
3
• thecouplingmomentprovided bytheir axialtensile forces
• thebending momentprovided bytheir flexural stiffness.
Shallow steel plates contribute mainly tothe former, whereasdeep plates
contribute mainly to the latter
44

44. Uniform distribution of Bolts
4
• BSPbeams require auniform distribution of anchorbolts over theentirespan;otherwise,
enormoustransverseslipswill occuratmid-spanandjeopardizethe load-carryingcapacityofthe
beam.
45

45. 1. Increasing Plate thickness
2. Increasing Plate depth
3. Decreasing Bolt Spacing
4. Provision of Stiffeners
Strength and Stiffness Ductility
1. Increasing Plate
thickness
2. Increasing Plate depth
3. Decreasing Bolt Spacing
5
46

46. The end
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