An investigation on the application of hybrid glass fibre reinforced polymer
(GFRP) and steel bars bars as longitudinal reinforcement for simple and
continuous concrete beams is presented. Three simply and eleven multi-spans
continuous reinforced concrete beams were constructed and tested to failure.
Nine continuous and two simply supported beams were reinforced with a
hybrid combination of both GFRP and steel re-bars at mid spans and internal
support regions. In addition, two continuous concrete beams reinforced with
either GFRP or steel bars and one simply supported beam reinforced with
GFRP bars were tested as control beams. The beams were classified into two
groups according to the reinforcement configurations. All specimens tested
were 200 mm in width and 300 mm in depth. The continuous beams comprised
of two equal spans, each of 2600 mm, while the simply supported beams had
a span of 2600 mm.
Unlike GFRP reinforced concrete beams, the hybrid and steel reinforced
concrete beams failed in a favourable ductile manner and demonstrated
narrow cracks and smaller deflections compared to the GFRP-reinforced
control beam. The lower stiffness and higher deflection of GFRP reinforced
concrete beams can be controlled and improved by the use of steel
reinforcement in combination with GFRP re-bars. However, the ratio of GFRP
to steel reinforcement is a key factor to ensure sufficient ductility and stiffness
beyond the first cracking stage. The experimental results showed that the
extent of moment redistribution in hybrid reinforced continuous beams
depends mainly on the amount of hybrid reinforcement ratio in critical sections.
Similar area of steel and GFRP bars in critical sections leads to limited moment
redistribution whereas different amount of steel and FRP bars in critical
sections leads to a remarkable moment redistribution.
Design guidelines and formulas have been validated against experimental
results of hybrid GFRP/steel reinforced concrete beams tested. The Yoon’s
equation reasonably predicted the deflections of the hybrid beams tested
whereas Qu’s model which is based on ACI 440.1R-15 underestimated the
deflections of hybrid beams tested at all stage of loading after cracking. The
ACI 440.2R-08 and Pang et al., (2015) equations reasonably predicted the
sagging failure moment in most continuous hybrid reinforced concrete beams,
whereas they underestimated the hogging flexural strength at failure of most
hybrid continuous beams. On the other hand, the formulas proposed by
Yinghao et al., (2013) was very conservative in predicting the failure moment
at the critical sagging and hogging sections.
On the analytical side, a numerical technique consisting of sectional analyses
has been developed to predict the moment–curvature relationship and
moment capacity of hybrid FRP/ steel reinforced concrete members. The
numerical technique has been validated against the experimental test results
obtained from the current research and those reported in the literature. In
addition, a two-dimensional nonlinear finite element model was proposed
using ABAQUS package. The proposed model was validated against the
experimental results of the beams tested in the present research. / Higher Education Institute in the Libyan Government
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/16920 |
| Date | January 2017 |
| Creators | Araba, Almahdi M.A.A. |
| Contributors | Ashour, Ashraf, Lam, Dennis |
| Publisher | University of Bradford, Faculty of Engineering and Informatics |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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