FRP strengthening design
Choose the module, then work through the steps. Product data from the DCP Qatar datasheets of Profiber CP System and Profiber CW System.
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Concrete
Compressive strength
MPa
Steel
Reinforcement properties
MPa
MPa
Beam section
Cross-section shape
Slab (1 m)
Rectangular
T-beam
Inverted T-beam
I-beam
Bottom (tension) reinforcement
mm
mm
Include top (compression) reinforcement
mm
mm
φ — strength reduction factor
ACI 440.2R-17 Eq. 10.2.7: 0.65 where the steel strain εt is at or below yield (εsy), 0.90 at 0.005 or more, linear between.
εty
φ = 0.90 from εt
Loads & unstrengthened capacity
kNm
kNm
kNm
kNm
kNm
value
Neutral axis c
Net tensile strain εt
φ
Mn
φMn
MULS ÷ φMn (unstrengthened section)
FRP strengthening
System
Results
value
Ef
εfu* / ffu*
εfu = CE·εfu*
εbi existing strain from M0
εfd debonding limit
Governing mode
Neutral axis c
Stress block α1 / β1
εfe / ffe
εt (steel) / φ
Mn / φMn strengthened
Development length ldf
MULS ÷ φMn (strengthened section)
Serviceability & damage checks
Load case checks ACI 440.2R-17 §9.2, via ACI 562-16 §5.5.2-5.5.3
Initial and FRP strengthening-limit are checked against the existing section with its own φ; the fire case takes the FRP as lost and compares the fire loads (1.0D + 1.0L) with the nominal strength of the existing member times the temperature factor Rnθ you enter (1.00 if the member stays cool; Eq. 9.2.1a); ULS is the main design check against the strengthened section.
Summary
Before / after
φMn before (kNm)
φMn after (kNm)
Detailed calculation — same figures as the PDF report
Calculation details
How to use this module
1
WhereChoose the Design Desk project and area this design is filed to.
2
Calculation detailsName the element.
3
Concretef'c.
4
SteelStirrup yield strength.
5
Beam sectionShape, cover, longitudinal bars, existing stirrups.
6
LoadsUnstrengthened Vc/Vs capacity.
7
FRP strengtheningWrap scheme + Profiber CW System fabric.
8
SummaryBefore/after and PDF report.
9
DoneThe report is numbered and filed on your Design Desk with the design.
Concrete
MPa
Steel
MPa
MPa
Beam section
Rectangular
Rectangular, unaccessible from top
T-beam
mm
mm
mm
mm
mm
mm
mm
deg
Loads & unstrengthened capacity
kN
kN
kN
kN
Vc ACI 318-19 Table 22.5.5.1
Vs
φ
φVn unstrengthened
VULS ÷ φVn (unstrengthened section)
FRP strengthening
Complete wrap only available for the fully-accessible Rectangular shape.
εfe / ffe
Vf
ψf
φVn strengthened
VULS ÷ φVn (strengthened section)
Load case checks ACI 440.2R-17 §9.2, via ACI 562-16 §5.5.2-5.5.3
Initial and FRP strengthening-limit are checked against the existing section (φ = 0.75); the fire case takes the FRP as lost and compares the fire loads (1.0D + 1.0L) with the nominal strength of the existing member times the temperature factor Rnθ you enter (1.00 if the member stays cool; Eq. 9.2.1a); ULS is the main design check against the strengthened section.
Summary
Before / after
φVn before (kN)
φVn after (kN)
Detailed calculation — same figures as the PDF report
Calculation details
How to use this module
1
WhereChoose the Design Desk project and area this design is filed to.
2
Calculation detailsName the column.
3
Concretef'c.
4
SteelLongitudinal steel yield strength.
5
Column sectionRectangular or circular, plus longitudinal steel.
6
LoadsAxial + biaxial bending, unstrengthened capacity.
7
FRP strengtheningProfiber CW System confinement jacket.
8
SummaryBefore/after and PDF report.
9
DoneThe report is numbered and filed on your Design Desk with the design.
Concrete
MPa
Steel
MPa
MPa
Column section
Rectangular
Circular
mm
mm
Spiral transversal reinforcement (else tied)
Loads & unstrengthened capacity
kN
kN
kNm
kNm
kN
kN
kN
The Initial, Fire and strengthening-limit cases take the ULS moments in proportion to their axial load (same eccentricity).
Ag / As / ρg
Pn,max
φ compression-controlled
φPn,max existing column
P-M interaction, existing column (ACI 318 diagram)
Each axis has its own axial load–moment diagram by strain compatibility (ACI 318). With bending about both axes the moments are combined as Mx/φMnx + My/φMny ≤ 1 at the factored axial load, a conservative load-contour check.
FRP strengthening (confinement)
mm
εfe κε·εfu, κε = 0.55
κa / κb shape factors, Eq. 12.1.2b,c
fl confinement pressure
fl/f'c min. 0.08
f'cc confined strength, Eq. 12.1g
εccu ultimate axial strain, Eq. 12.1j
Pn,max / φPn,max strengthened
P-M interaction, strengthened column (Appendix D, points A, B, C)
Serviceability
Load case checks ACI 440.2R-17 §9.2, via ACI 562-16 §5.5.2-5.5.3
Axial load and bending on the P–M interaction diagram; the other cases use moments in proportion to their axial load. Initial and FRP strengthening-limit are checked against the existing column; the fire case takes the FRP as lost and compares the fire loads (1.0D + 1.0L) with the nominal strength of the existing member times the temperature factor Rnθ you enter (1.00 if the member stays cool; Eq. 9.2.1a); ULS is the main design check against the strengthened (confined) column.
Summary
Before / after
φccPn,c before (kN)
φccPn,cc after (kN)
Detailed calculation — same figures as the PDF report