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
Strength and Ductility of Reinforced Concrete Beams Externally Reinforced with Carbon Fiber Fabric
This paper presents results obtained from an experimental study of reinforced concrete beams strengthened in flexure and shear using externally epoxy-bonded bidirectional carbon fiber fabric. Two series of 3 large-scale concrete beam models were built and tested under 4-point bending. The beams of the 2 series were internally reinforced with high-tensile steel for both shear and flexure. One beam for each series was used as a control beam without external reinforcement. The difference between the 2 series related to the amount of internal stirrups and concrete strength. To study effects of external composite reinforcement, variations in the number of layers applied and in the external end arrangements were made. One type of external reinforcement consisted of 2 layers of fabric bonded to the tension face of the beam and partly extended up to the vertical sides. The second arrangement consisted of 4 layers of fabric and supplementary end anchorages. The composite reinforcement led to an increase both in the load-carrying capacity at ultimate and flexural stiffness as compared with control beams. Significant reductions in deflection, curvature, and structural ductility were observed.
Heat Recovery Systems
Geothermal energy is recovered from an underground zone of relatively hot strata via a borehole into which is inserted a heat pipe system containing a working fluid, the heat pipe system comprising an assembly of two tubes in concentric relation, the inner tube being constituted by a relatively small diameter capillary for the return of working fluid to the vicinity of the zone of the relatively hot strata. The working fluid is preferably assisted in its return under gravity by means of a pump. The system includes heat exchange means operable to recover thermal energy from the working fluid. A third and outermost tube may be used to reduce heat losses, this third tube enclosing the two tubes over all but that part of their length which is in the zone of relatively hot strata.