2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference


Title
FLEXURAL BEHAVIOR OF RECTANGULAR CONCRETE FILLED FRP TUBES (CFFT) BEAMS POST TENSIONNED WITH STEEL CABLES

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Author(s)
Ms. Asmaa Ahmed, Université de Sherbrooke (Presenter)
Dr. Mohamed Hassan, Université de Sherbrooke
Mr. Radhouane Masmoudi, Université de Sherbrooke
Abstract

The concept of concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) is promising for a variety of structural applications and a good alternative for innovative constructions because of numerous attractive features, including durability and concrete confinement. In applications where the design of a structural member is governed by large flexural loads, such as in the case of marine (fender) piles and bridge girders, laboratory and field bending tests have shown that CFFTs can match the bending strength of similarly sized conventional prestressed and reinforced concrete (RC) members. After cracking, however, CFFTs have lower flexural stiffness, which results in large deflections. The lower flexural stiffness is due to the low Young’s modulus of the FRP tubes. One way to counteract the effects of this lack of flexural stiffness is to apply longitudinal post-tensioning, which will also activate the confinement mechanism induced by the FRP tube and would lead to considerable enhancement. Also, the using post-tensioning in combination with FRP Tube confinement may lead to a better control of service limit states and reduce the size of the structural member. This paper presents the test results of an experimental study aimed at investigating the flexural behaviour of rectangular post-tensioned concrete filled FRP tubes (PCFFTs) beams. A total of three full-scale PCFFT and one control conventional RC CFFT beams with 3300 mm long and 305×406 mm2 cross section were constructed, instrumented and tested under a four-point bending load. The test parameters are: the level of post-tension in the steel cables and the FRP tube thicknesses. The experimental results showed that introducing post-tensioning to the CFFT beams substantially enhanced the flexural strength as well as the serviceability requirements of the tested beams. In addition, the flexural mode (tension or compression failure) was finally governed by the FRP tube thickness.