Flexural Behaviour of Composite High Strength Concrete – Fibre Reinforced Polymer Beams
This paper presents the results of an experimental study conducted to examine the effectiveness of Glass Fibre Reinforced Polymer (GFRP) laminates in enhancing the flexural capacity of high strength concrete beams. In this study, a total of ten beams of size 150 mm x 250 mm in crosssection with a total length of 3000 mm were cast and tested. Eight beams were strengthened with chopped strand mat glass fibre reinforced polymer and uni-directional cloth glass fibre reinforced polymer of 3mm and 5mm thickness. The study parameters included the reinforcement ratio, GFRP laminate material and their thickness. All the beam specimens were subjected to four-point bending test in a loading frame. Deflection and strain measurements have been made through appropriate instrumentation. The results show that the GFRP strengthened beams exhibit increased strength, flexural stiffness and composite action until failure. Keywords— GFRP, HSC beams, laminates, strengthened
CONCRETE BEAMS STRENGTHENED WITH EXTERNALLY BONDED FRP PLATES
The structural behavior of reinforced concrete beams strengthened with adhesively bonded fiber-reinforced plastics (FRP) is presented. The experimental work included flexural testing of 2.3-m-long concrete beams with bonded external reinforcements. The test variables included the amount of conventional (internal) reinforcement and also the type and amount of external reinforcement. For comparison, some of the beams were strengthened with bonded steel plates. Theoretical analyses included 2D nonlinear finite-element modeling incorporating a “damage” material model for concrete. In general there were reasonably good correlations between the experimental results and nonlinear finite-element models. It is suggested that the detachment of bonded external plates from the concrete, at ultimate loads, is governed by a limiting principal stress value at the concrete/external plate interface.
A rapid on-filter immunoassay screen for dexamethasone in equine urine
A simple on-filter immunoassay screen has been developed for the detection and semi-quantification of dexamethasone in equine urine samples. The assay consists of an indirect competitive ELISA in which dexamethasone in standards or samples competes with an immobilised dexamethasone–protein conjugate for binding to a complex of sheep anti-dexamethasone antibodies complexed with alkaline phosphatase-labelled second antibody. The drug–protein conjugate is immobilised as a spot on the surface of a cellulose nitrate filter and the assay is performed with the filter retained within a filtration port. The assay involves two incubation steps, firstly a ten minute competitive step and secondly a five minute step to generate via an enzyme-catalysed reaction an insoluble coloured dye as a spot on the filter at the site of the immobilised drug–protein conjugate. Rapid washing is achieved through use of the filtration system. The assay has a limit of detection of 10–6 M (390 ng ml–1) for a visual end point in which the colour intensity of spots developed in the presence of samples is compared with those of standards. Twelve filters can be processed in a single batch consisting of two standards and ten samples. The assay has been optimised for equine samples and dexamethasone in the urine of a race horse following injection of 20 mg of drug has been detected for 23 h post administration.