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Embedded Connectors to Eliminate Debonding of Steel Plate for Optimal Shear Strengthening of RC Beam

  • Research Article - Civil Engineering
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Abstract

Externally bonded method would be the most potential technique for optimal shear strengthening of deficient reinforced concrete (RC) beam subjected to eliminate premature debonding failure. The main aim of this research was to eliminate debonding failure of steel plate using embedded connector systems for optimal shear strengthening of RC beam. Dimensions of steel plates were optimized based on the proposed design guideline in accordance with EC2. The strengthened beams with connectors were then compared with those of U-jacketing system. Bond strength enhancements of steel plate using connectors were experimentally investigated through pullout test of prisms. The beam specimens were fabricated and tested to investigate the effects of embedded connectors. Result showed that steel bar and adhesive embedded connectors significantly increased the bond strength of externally bonded plates. The connectors completely prevented premature debonding failure of steel plates and allowed the beams to fail by flexure with full ductility and strength, whereas U-jacket showed the premature debonding of plates. The embedded connectors optimized/reduced the dimension of the externally bonded steel plate by 60% as compared to those of arbitrarily strengthened beam. The experimental results satisfactorily verified the proposed design guideline.

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Abbreviations

M :

Moment resisting capacity of beam

T :

Tensile force of flexural reinforcement

Z :

Moment arm

\(A_\mathrm{s}\) :

Cross-sectional area of flexural reinforcement

\(f_\mathrm{tk}\) :

Tensile strength of flexural reinforcement

\(f_\mathrm{ck}\) :

Concrete compressive strength based on cylinder test

b :

Width of beam

x :

Depth of neutral axis

\(V_\mathrm{d}\) :

Design shear force

V :

Shear resisting capacity of beam

\(L_\mathrm{s}\) :

Shear span

N :

Number of shear links that resist shear

\(N_\mathrm{sp}\) :

Number of steel plates that resist shear

\({d}'\) :

Depth of compression reinforcement (top bar)

s :

Spacing of shear link

\(s_\mathrm{sp}\) :

Spacing of steel plate

\(\theta \) :

Inclination of shear crack

\(V_{{\textit{t},\mathrm{link}}(\theta )}\) :

Shear force resisted by shear link

\(A_{{\textit{s},\mathrm{link}}}\) :

Cross-sectional area of shear link

\(f_{{\textit{y},\mathrm{link}}}\) :

Yield strength of shear link

\(f_{{\textit{t},\mathrm{link}}}\) :

Tensile strength of shear link

\(f_{{\textit{y},\mathrm{sp}}}\) :

Yield strength of steel plate

\(f_{{\textit{t},\mathrm{sp}}}\) :

Tensile strength of steel plate

\(V_{{\text {cb}}}\) :

Shear capacity of un-strengthened control beam

\(E_\mathrm{sp}\) :

Modulus of elasticity of steel plate

\(s_\mathrm{sp}\) :

Spacing of steel plate

\(\varepsilon _{{\mathrm{sp}}}\) :

Strain of steel plate

\(A_\mathrm{sp}\) :

Cross-sectional area of the steel plate

\(V_\mathrm{sp}\) :

Shear force resisted by the steel plate

\(V_{\textit{y},\mathrm{link}(45)}\) :

Maximum design shear force resisted by shear link

\(F_\mathrm{bu}\) :

Bond strength of concrete

\(\varepsilon _\mathrm{sp}\) :

Design strain of steel plate

\(\varepsilon _{\text {sp(debonding)}}\) :

Debonding strain of steel plate

\(t_\mathrm{sp}\) :

Thickness of the steel plate

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Acknowledgements

The authors would like to express their gratitude to the Ministry of Higher Education (MOHE) for providing research grant (Grant No. 08012012ERGS) to carry out the project. Thanks are also due to the Department of Civil Engineering and Research Management Centre, Universiti Tenaga Nasional and those who contributed directly or indirectly.

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Authors and Affiliations

  1. Department of Civil Engineering, College of Engineering, Universiti Tenaga Nasional, 43000, Kajang, Selangor, Malaysia

    Md Ashraful Alam, Ali Sami & Kamal Nasaruddin Mustapha

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  1. Md Ashraful Alam
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  2. Ali Sami
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  3. Kamal Nasaruddin Mustapha
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Correspondence to Md Ashraful Alam.

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Alam, M.A., Sami, A. & Mustapha, K.N. Embedded Connectors to Eliminate Debonding of Steel Plate for Optimal Shear Strengthening of RC Beam. Arab J Sci Eng 42, 4053–4068 (2017). https://doi.org/10.1007/s13369-017-2572-5

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