Browsing by Author "Ariyachandra, MREF"

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item: Conference-Full-text
ACI guidelines to assess the performance of CFRP-strengthened concrete beams with transverse end U wraps
(2016-01-06) Ariyachandra, MREF; Gamage, JCPH
In this comprehensive study, firstly, the theoretical model described in ACI 440 committee report to calculate the area of transverse U wraps provided for anchored CFRP-strengthened concrete beams was examined. Then, an experimental study was carried out with a total of 10 small-scale test specimens and test parameters were set to inspect the validity of the limitations given in the above theoretical model. Theoretical calculations were performed in accordance with ACI guidelines for the above test specimens as well as for the previous research studies. Finally, the constraints of applicability of the theoretical model given in ACI 440 committee report was discussed presenting new recommendations for different scenarios.
item: Article-Full-text
Bond characteristics of CFRP-strengthened concrete members subjected to cyclic temperature and mechanical stress at low humidity
(Elsevier, 2017) Gamage, JCPH; Al-Mahaidi, R; Wong, B; Ariyachandra, MREF
A total of fifty two CFRP strengthened concrete specimens were tested. In preliminary investigation, ten specimens were tested at ambient conditions with varying bond length. This indicated the effective bond length is in the range between 100 mm and 150 mm. The bond length of 150 mm was considered and fourty two specimens were prepared for detailed investigation. Thirty of them were conditioned under a range (0% - 50%) of sustained loading. All specimens were subjected to the temperature cycles of 20oC–50oC and constant relative humidity (30%) during conditioning. These specimens were tested using the singlelap shear test method at ambient conditions after 1800 hrs and 2250 hrs exposure for accelerated aging. The conditioned specimens showed the maximum strength reduction of 24%. The test results indicate that the concrete/epoxy interface as the weakest part of the composite in service life. Reduction in peak bond stress was noted from conditioned specimens with exposed level of sustained loading.
item: Article-Full-text
Effects of surface roughness and bond enhancing techniques on flexural performance of CFRP/concrete composites
(Elsevier, 2017) Ariyachandra, MREF; Gamage, JCPH; Al-Mahaidi, R; Kalfat, R
This paper reports a detailed test programme conducted on enhancing the flexural performance of Carbon Fiber Reinforced Polymer (CFRP) strengthened reinforced concrete beams to ensure prolonged composite action between CFRP laminate and concrete. The effects of surface preparation and alternative bonding techniques on the composite performance were investigated. In this regards, a total of 28 small-scale CFRP strengthened and non-strengthened reinforced concrete beams were tested using the three-point bending test method. This study clearly shows the importance of surface preparation and level of roughness on bond performance of CFRP/Concrete composites. The results also indicate the better performance in CFRP/epoxy/Polyester mesh hybrid arrangement when compare with CFRP strengthened concrete beams.
item: Conference-Abstract
Effects of surface roughness on flexural performance of CFRP/concrete composites
Ariyachandra, MREF; Gamage, JCPH
Carbon Fibre Reinforced Polymer (CFRP) composites have been progressively more utilized to strengthen the concrete members to improve its flexural performance. Flexural capacity of CFRP strengthened concrete members mainly hinge on controlling probable failure modes. The interfacial bond failure takes place owing poor surface preparation for FRP application which grounds a bond failure between concrete and adhesive eventually. Preparation of concrete substrate plays a significant role in terms of engendering strong bond between FRP - concrete interface. Achieving uniform surface roughness all through the concrete substrates is the major issue in surface preparation procedure since the uniformity of the roughened concrete substrates totally depends on the human skills and experience. Existing surface roughness quantification methods have a substantial discrepancy although a unique quantification method is essential more imperatively. In the present study, experimental investigation was focused on the flexural performance of the externally strengthened CFRP concrete beams with different types of surface preparation levels. The surface roughness of the concrete substrates was determined by means of a stan.dard quantification method. Concrete beams were subjected to three point bending test and failure modes were observed. The test results point out a significant effect on the flexural capacity of CFRP strengthened concrete beams with the surface roughness levels.
item: Article-Abstract
Investigation on enhancing flexural p erformance of CFRP strengthened concrete beams
Gamage, JCPH; Ariyachandra, MREF
Strengthening of reinforced concrete structures is inevitable to preserve structural integrity and protracted service life due to the effects of numerous elements contained within the natural or artificial environment surrounding it. Carbon Fibre Reinforced Polymer (CFRP) composites have been progressively more utilized for decades as a strengthening material due to its outstanding characteristics such as high strength to weight ratio, reduced weight, excellent resistance to corrosion and environmental degradation and ease of handling during construction which have distinguished it well apart from the other strengthening techniques. However, the ultimate load capacity of CFRP strengthened concrete composites is comparatively lower than CFRP material due to premature debonding which reported as the most frequently observed failure mode in CFRP/concrete composites. In the current study, alternative bonding techniques were investigated to achieve enhanced bond performance by delaying premature debonding failure. A total of 18 CFRP strengthened concrete beams with different bonding techniques were tested using three point bending test. The test results show convincing evidence on strength enhancements. Moreover, a numerical model was also developed to inspect the performance of existing CFRP anchors. Finally, a parametric study was carried out and a new type of anchor; “Tri-leg anchor” is introduced. This paper summarizes the overview of the test programme, finite element modeling, results and analysis.
item: Conference-Abstract
A Review on fracture-mechanics based models on debonding nature of CFRP/Concrete composites
Ariyachandra, MREF; Gamage, JCPH
Debonding failure of externally strengthened CFRP/concrete composites is the most critical failure mode which needs to prevent to achieve a beneficial strengthening solution. Many theoretical and numerical models have been developed to predict the failure load of CFRP/concrete composites. Existing theoretical models are grounded on strength-based and fracture-mechanics based approaches. The use of strength-based models is obsolete due to their inability to estimate the failure behaviour throughout the debonding process. By means of fracture-mechanics based models, both the initiation and propagation of cracks can be explored in terms of interface fracture energy. In the present study, existing fracture-mechanics based models are evaluated using a database and the reliability of the models are analyzed using statistical parameters and suggests best models which can accurately quantify the debonding failure load of CFRP/concrete composites. In addition, a new reduction factor aGF is introduced for interfacial fracture energy for the debonding failure mode which takes place along the CFRP/concrete interface.