Rehabilitation of insufficient anchorage bar lengths
-
Upload
andreas-kalantzis -
Category
Documents
-
view
147 -
download
1
Transcript of Rehabilitation of insufficient anchorage bar lengths
![Page 1: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/1.jpg)
Rehabilitation of insufficient anchorage bar
lengths according to EN 1998 and the Greek rehabilitation code KAN.EPE
Andreas Kalantzis / Civil Engineer
![Page 2: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/2.jpg)
Anchorage bar length
Is the required reinforcement bar length in order to transfer safely the forces (axial, moment, shear) from one bar to another without failure of the concrete – steel interface.
Imposed: By the steel industry(reinforced bar with length >10 m is
difficult to attach). In order to installed and transferred properly to the site. Usually encountered outside the critical zone of a column .
![Page 3: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/3.jpg)
Rehabilitation of insufficient anchorage bar lengths
Failure mechanism: The concrete is unable to receive and transfer the forces/stresses and it cracks allowing the reinforcement bar to slide (in a non ductile type of failure).
Main object: The enforcement of an outer confinement that will create compression stresses to the element in concretes attempts to enlarge with tensile stresses.
A non destructive method is the use of FRP materials(fibre reinforced polymer).
![Page 4: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/4.jpg)
Fibre Reinforced Polymer materials(F.R.P)
Advance and compose materials that consists of a polymer(epoxy)matrix reinforced with fibers.
Carbon, aramid and glass fibers.
Advantages : extremely high tensile resistance, durability in corrosion, low self weight, easy and rapid attachment.
Disadvantages: notable cost of persuasion, poor performance in high temperatures, zero ductility.
![Page 5: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/5.jpg)
Stress – Deformation Diagram
![Page 6: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/6.jpg)
Composite materials: Carbon, Aramid, Glass
![Page 7: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/7.jpg)
ΚΑΝ.ΕPΕ 2012
ΚΑΝ.ΕPΕ §8.2.1.2
figure. 8.3
In case of a constant cloak made from frp materials the ratioΑj/s is the required thickness tj of the cloak.
![Page 8: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/8.jpg)
ΚΑΝ.ΕPΕ 2012
γrd=1.5 : safety coefficient for the uncertainty of the simulation .
: the total area of reinforcement bar.
: is the enforced design axial stress of the confinement elements.
λs : coefficient that describes the contribution of the all ready attached(the insufficient)anchorage bar length. It is advised to be taken λs = 0.
![Page 9: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/9.jpg)
ΚΑΝ.ΕPΕ 2012
ls : the reinforcement bar length
: bf the wide of friction area along the crack of the
anchorage bars and Β is the wide distribution of the total shear force that delivers the axial force from the frp material material confinement( for c / ds ≤2
the value of β is near 1.0).
μ : friction factor that depends on the magnitude of the compression stresses between the crack interface as well from the acceptable sliding of the bar. μ takes values from 0,4 to 2,0. Luck of data someone can consider μ=1,0 .
![Page 10: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/10.jpg)
Notations of ΚΑΝ.ΕPΕ 2012
Για τη εφαρμογή της τεχνικής πρέπει : The attached(insufficient) anchorage length ls should be grater than
0.30 lso and 15 ds
The length of the element in which we will apply the confinement should have at list the length of the critical zone and no less than 1,3 ls ή 0.60 m .
Thickness t j ≥ 25 mm
εjd= √2 wd / b , where wd =0.6 sd 2/3 while sd 0.3 for performativity level Α and 0.4 for Β while C, b = (b1 +b2)/2 .
![Page 11: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/11.jpg)
Example according to ΚΑΝ.ΕPΕ 2012
Material: Sika Wrap 600C/120 : tj=0.337mm ,E=242GPa , perf. Level Β Φ18 , fyk=330 Mpa , 400mm x 200mm , Ab =π182/4=254.5mm
lso =Φ fyd/4 fbd= 782mm , 0,3x782=234.6mm , at least ls=210mm
ΚΑΝ.ΕPΕ §8.2.1.2 , rel. 8.3
1.61mm/0.337mm=4.77 ≈ 5 layers
Για κ ≥ 4 layers , tj =ψ κ tj με ψ=κ-1/4 where ψ the reduced efficiency coefficient of multi layering. ΚΑΝ.ΕPΕ
We are choosing 8 layers of material § 6.2.3
![Page 12: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/12.jpg)
EN1998-3
According to §Α4.4.4(tightening of the bonds by overlaping the bars )of the Α annex of ΕΝ 1998-3
( ΕΝ1998-3 , §Α.4.4.4 , Α.37 )
σsw=0,001ρwEs
For orthogonical columns D is the wide bW of the cross section§A.4.4.4(2)
Εf is the modulus of elasticity for the frp material
![Page 13: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/13.jpg)
EN1998-3
EN 1998-3 , §Α.4.4.4 , (Α.38)
Α s the area of every reinforced bar that is been overlped.
fyl the yield bound of steel that can be taken equal to the middle value, multiplied properly with the so called trust coefficient CF ( ΕΝ 1998-3 §3.3 )
p the perimeter of the column measured from the inner side of the longitudinal reinforcement bar.
![Page 14: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/14.jpg)
EN1998-3
dbl the maximum diameter of the longitudinal reinforced bars
c thickness of concrete cover.
Ls the anchorage length
n the number of the overlapped bars along p
![Page 15: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/15.jpg)
Example according to EN1998-3
For orthogonical column: CFΕΓ3=1.0, c=30mm, tf=0.337mm , fyk = 330
400 6Φ18, Ef =242GPa
Φ 200
( EN1998-3 A.4.4.4 , A.37 )
1.1mm/0.337mm = 3 layers
![Page 16: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/16.jpg)
Comparison
ΚΑΝ.ΕPΕ , §
8.2.1.2 , (8.3)
EN1998-3 , §A.4.4.4 , A.37
![Page 17: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/17.jpg)
Conclusions The relation8.3 of ΚΑΝ.ΕPΕ proved conservative compared to relation
Α.37 of EN1998-3 and thus it gives grater values of material thickness. Bigger thickness of frp material leads to small number of layers.
Performativity level Β and C ( ΚΑΝ.ΕΠΕ §8.2.1.2 , β , ii ) leads to bigger values of deformation εjd .
![Page 18: Rehabilitation of insufficient anchorage bar lengths](https://reader036.fdocuments.net/reader036/viewer/2022062400/588a34d31a28abc6168b564d/html5/thumbnails/18.jpg)
End of presentation
Thank you