Experimental and numerical investigations of the compressive behavior of carbon fiber-reinforced polymer-strengthened tu
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RESEARCH ARTICLE
Experimental and numerical investigations of the compressive behavior of carbon fiber-reinforced polymerstrengthened tubular steel T-joints Peng DENGa,b* , Boyi YANGb, Xiulong CHENb, Yan LIUa,b a
Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation, Shandong University of Science and Technology, Qingdao 266590, China b College of Civil Engineering and Architecture, Shandong University of Science and Technology, Qingdao 266590, China *
Corresponding author. E-mail: [email protected]
© Higher Education Press 2020
ABSTRACT A method for strengthening damaged tubular steel T-joints under axial compression by wrapping them with carbon fiber-reinforced polymer (CFRP) sheets was proposed and evaluated. The influence of the CFRP strengthening on the failure mode and load capacity of T-joints with different degrees of damage was investigated using experiments and finite element analyses. Five T-joints were physically tested: one bare joint to obtain the peak load and corresponding displacement (D1m), two reinforced joints to provide a reference, and two pre-damaged then retrofitted joints to serve as the primary research objects. The ratio of the pre-loaded specimen chord displacement to the value of D1m was considered to be the degree of damage of the two retrofitted joints, and was set to 0.80 and 1.20. The results demonstrate that the maximum capacity of the retrofitted specimen was increased by 0.83%–15.06% over the corresponding unreinforced specimens. However, the capacity of the retrofitted specimen was 2.51%–22.77% lesser compared with that of the directly reinforced specimens. Next, 111 numerical analysis models (0.63£b£0.76, 9.70£g£16.92) were established to parametrically evaluate the effects of different geometric and strengthening parameters on the load capacity of strengthened tubular T-joints under different degrees of damage. The numerical analysis results revealed that the development of equivalent plastic strain at the selected measuring points was moderated by strengthening with CFRP wrapping, and indicated the optimal CFRP strengthening thickness and wrapping orientation according to tubular T-joint parameters. Finally, reasonable equations for calculating the load capacity of CFRPstrengthened joints were proposed and demonstrated to provide accurate results. The findings of this study can be used to inform improved CFRP strengthening of damaged tubular steel structures. KEYWORDS
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tubular T-joint, carbon fiber-reinforced polymer, degree of damage, numerical analysis, equivalent plastic strain
Introduction
Tubular steel structures have been rapidly developed and widely applied in stadiums, bridges, offshore platforms, and other types of structural engineering projects due to their excellent mechanical properties, aesthetic appearance, and cost effectiveness. Due to the thin wall thickness of tubular chords and the complex stress distribution in their joints, tubular chord members often fail in local buckling [1] or yielding [1,2], which can in
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