Strengthening of RC beams using bottom and side NSM reinforcement

Cristian Sabau; Cosmin Popescu; Gabriel Sas; Jacob Wittrup Schmidt; Thomas Blanksvärd; Björn Täljsten

doi:10.1016/j.compositesb.2018.05.011

Strengthening of RC beams using bottom and side NSM reinforcement

Cristian Sabau^*, Cosmin Popescu, Gabriel Sas, Jacob Wittrup Schmidt, Thomas Blanksvärd, Björn Täljsten

^*Corresponding author for this work

Research output: Contribution to journal › Journal article › Research › peer-review

Abstract

The allowable strain in fibre reinforced polymers reinforcement is limited by design codes to avoid debonding. The near-surface mounted (NSM) reinforcement technique has been proven to produce better anchorage behaviour compared to externally bonded reinforcement solutions. However, NSM solutions do not always eliminate debonding issues, with concrete cover detachment (CCD) typically occurring in RC beams strengthened for flexure. This experimental study investigated the efficiency of side mounted (S) compared to bottom mounted (B) NSM bars to prevent CCD. The experimental results were compared to models available in the literature that predict the observed failure modes and the crack spacing in the NSM anchorage zone. Compared to B-NSM, the S-NSM solution was successful in avoiding brittle CCD failure and showed increased rotational capacity and energy dissipation at failure. Existing CCD debonding models were found to be conservative.

Original language	English
Journal	Composites Part B: Engineering
Volume	149
Pages (from-to)	82-91
ISSN	1359-8368
DOIs	https://doi.org/10.1016/j.compositesb.2018.05.011
Publication status	Published - 2018

Keywords

Debonding
Concrete cover detachment
Crack spacing
Non-contact optical measurements
Strain analysis
CFRP
NSM

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@article{e063852b3295445ea37464b5bbb845b9,

title = "Strengthening of RC beams using bottom and side NSM reinforcement",

abstract = "The allowable strain in fibre reinforced polymers reinforcement is limited by design codes to avoid debonding. The near-surface mounted (NSM) reinforcement technique has been proven to produce better anchorage behaviour compared to externally bonded reinforcement solutions. However, NSM solutions do not always eliminate debonding issues, with concrete cover detachment (CCD) typically occurring in RC beams strengthened for flexure. This experimental study investigated the efficiency of side mounted (S) compared to bottom mounted (B) NSM bars to prevent CCD. The experimental results were compared to models available in the literature that predict the observed failure modes and the crack spacing in the NSM anchorage zone. Compared to B-NSM, the S-NSM solution was successful in avoiding brittle CCD failure and showed increased rotational capacity and energy dissipation at failure. Existing CCD debonding models were found to be conservative.",

keywords = "Debonding, Concrete cover detachment, Crack spacing, Non-contact optical measurements, Strain analysis, CFRP, NSM",

author = "Cristian Sabau and Cosmin Popescu and Gabriel Sas and Schmidt, {Jacob Wittrup} and Thomas Blanksv{\"a}rd and Bj{\"o}rn T{\"a}ljsten",

year = "2018",

doi = "10.1016/j.compositesb.2018.05.011",

language = "English",

volume = "149",

pages = "82--91",

journal = "Composites Part B: Engineering",

issn = "1359-8368",

publisher = "Pergamon Press",

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TY - JOUR

T1 - Strengthening of RC beams using bottom and side NSM reinforcement

AU - Sabau, Cristian

AU - Popescu, Cosmin

AU - Sas, Gabriel

AU - Schmidt, Jacob Wittrup

AU - Blanksvärd, Thomas

AU - Täljsten, Björn

PY - 2018

Y1 - 2018

N2 - The allowable strain in fibre reinforced polymers reinforcement is limited by design codes to avoid debonding. The near-surface mounted (NSM) reinforcement technique has been proven to produce better anchorage behaviour compared to externally bonded reinforcement solutions. However, NSM solutions do not always eliminate debonding issues, with concrete cover detachment (CCD) typically occurring in RC beams strengthened for flexure. This experimental study investigated the efficiency of side mounted (S) compared to bottom mounted (B) NSM bars to prevent CCD. The experimental results were compared to models available in the literature that predict the observed failure modes and the crack spacing in the NSM anchorage zone. Compared to B-NSM, the S-NSM solution was successful in avoiding brittle CCD failure and showed increased rotational capacity and energy dissipation at failure. Existing CCD debonding models were found to be conservative.

AB - The allowable strain in fibre reinforced polymers reinforcement is limited by design codes to avoid debonding. The near-surface mounted (NSM) reinforcement technique has been proven to produce better anchorage behaviour compared to externally bonded reinforcement solutions. However, NSM solutions do not always eliminate debonding issues, with concrete cover detachment (CCD) typically occurring in RC beams strengthened for flexure. This experimental study investigated the efficiency of side mounted (S) compared to bottom mounted (B) NSM bars to prevent CCD. The experimental results were compared to models available in the literature that predict the observed failure modes and the crack spacing in the NSM anchorage zone. Compared to B-NSM, the S-NSM solution was successful in avoiding brittle CCD failure and showed increased rotational capacity and energy dissipation at failure. Existing CCD debonding models were found to be conservative.

KW - Debonding

KW - Concrete cover detachment

KW - Crack spacing

KW - Non-contact optical measurements

KW - Strain analysis

KW - CFRP

KW - NSM

U2 - 10.1016/j.compositesb.2018.05.011

DO - 10.1016/j.compositesb.2018.05.011

M3 - Journal article

SN - 1359-8368

VL - 149

SP - 82

EP - 91

JO - Composites Part B: Engineering

JF - Composites Part B: Engineering

ER -

Strengthening of RC beams using bottom and side NSM reinforcement

Abstract

Keywords

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