Flexural Strengthening of Two-Way RC Slabs with Cut Openings Using Textile-Reinforced Mortar Composites
Publication: Journal of Composites for Construction
Volume 25, Issue 3
Abstract
This paper presents an experimental investigation on the application of textile-reinforced mortar (TRM) layers as a means of increasing the flexural capacity of two-way reinforced concrete (RC) slabs with cut openings. The investigated parameters included the number of TRM layers (one versus two layers), the textile type (two carbon fiber textiles with different weight and geometry), the strengthening configuration (full coverage versus partial coverage via the use of diagonal strips), and the role of the matrix material (mortar versus epoxy resin). For this purpose, six large-scale two-way RC slabs with a central opening were constructed and tested to failure under monotonic loading distributed at four points. It was mainly concluded that TRM substantially enhanced the flexural capacity of the two-way RC slabs with a central cut opening and restored the original capacity of the slab without the opening. The effect of the various investigated parameters is discussed in terms of flexural capacity, post-yielding stiffness, and load resistance at the serviceability limit state. Finally, an already available simple design tool was refined based on the new results of this study. It was found to provide a good estimation of the flexural moment of resistance of the TRM-retrofitted slabs.
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Acknowledgments
The experimental work described in the paper has been conducted at the University of Nottingham. The authors wish to thank Mr. Sultan Alotabi for his assistance in the preparation of the specimens.
Notation
The following symbols are used in this paper:
- d
- effective depth of the slab;
- Ef
- elastic modulus of the textile fibers;
- Ft
- tensile force carried by TRM;
- fc
- concrete compressive strength;
- fte
- TRM effective stress value at the ultimate limit state;
- fted
- design value of TRM effective stress value at the ultimate limit state;
- fy
- steel-reinforcement yield stress;
- h
- section height equal to the slab thickness;
- k
- load-to-moment calibration factor;
- mR
- flexural moment of resistance per unit length;
- mRs
- contribution of the steel reinforcement to the moment of resistance;
- mRt
- contribution of the TRM to the moment of resistance;
- Pmax
- flexural load-bearing capacity;
- tt
- TRM thickness equal to the equivalent thickness of the textile times the number of layers;
- wt/ws
- coverage ratio equal to the area covered by the TRM composite (wt) over the area of the slab's face (ws);
- x
- depth of neutral axis;
- ɛc
- concrete compressive strain;
- ρs
- steel reinforcement ratio equal to the steel area per 1 m divided by the effective depth of the slab; and
- ρt
- textile reinforcement ratio equal to the fibers area per 1 m (per direction) divided by the thickness of the slab (multiplied by the coverage ratio wt/ws for partially covered slabs).
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Published In
Journal of Composites for Construction
Volume 25 • Issue 3 • June 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: Oct 10, 2020
Accepted: Feb 19, 2021
Published online: Mar 30, 2021
Published in print: Jun 1, 2021
Discussion open until: Aug 30, 2021
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