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
Comparative Study on Behaviour of Medium and High Strength Concrete Beam with and Without fiber Under Flexure
An experimental investigation of the behaviour of concrete beams reinforced with conventional steel bars and steel fibers and subjected to flexural loading is presented. An experimental program consisting of tests on steel fiber reinforced concrete (SFRC) beams with conventional reinforcement and reinforced concrete (RC) beams was conducted under flexural loading. SFRC beams include two types of beams containing steel fibers in two different volume fractions i.e. one percent and 1.5 percent. The cross sectional dimensions and span of beams were fixed same for all types of beams. The dimensions of the beams were 125mm x 150mm x11000mm.Tests on conventionally reinforced concrete beam beams showed enhanced properties compared to that of RC beams. The ultimate loads obtained in the experimental investigation were also compared with the theoretical loads for all types of beams specimens, containing steel fibers in different proportions, have been conducted to establish load –deflection curves. The various parameters, such as, first crack load service load ultimate load, of beams with and without steel fibres have been carried out and a quantitative comparison was made on significant stages of loading. Keywords; SFRC beams, RC beams, Steel fibres, Flexural loading.
Design of reinforced concrete lining in pressure tunnels, considering thermal effects and jointed rockmass
Abstract Jaeger's theory (Jaeger, Rock Mechanics and Rock Engineering , Cambridge University Press, 1972) of the design of the lining for a pressure tunnel applies to a tunnel located in an isotropic, homogeneous and elastic medium. The theory is derived from the elasticity equations for the plane stress condition. In this paper, Jaeger's theory is extended to a plane strain situation. Also included is a discussion of the effects of a uniform increase (or decrease) in the lining temperature, jointed rockmass, cracking of the tunnel lining, and cracking of the rockmass around the opening. Tables are presented for the modulus of subgrade reaction for various rockmass conditions and for rock sharing pressures for various lining conditions. The reduction factor to include the effect of joints in rockmass is derived by the analysis of a numerical model of the lined tunnel by the finite-infinite-interface element method.