Behaviour and modelling of large-scale hybrid FRP-concrete-steel double-skin tubular beams with shear connectors

Pao Yue-kong Library Electronic Theses Database

Behaviour and modelling of large-scale hybrid FRP-concrete-steel double-skin tubular beams with shear connectors

 

Author: Zhao, Jun-liang
Title: Behaviour and modelling of large-scale hybrid FRP-concrete-steel double-skin tubular beams with shear connectors
Degree: Ph.D.
Year: 2017
Subject: Composite construction -- Testing.
Tubular steel structures.
Concrete-filled Tube.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Civil and Environmental Engineering
Pages: xxxii, 329 pages : color illustrations
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2952780
URI: http://theses.lib.polyu.edu.hk/handle/200/8912
Abstract: Hybrid fibre-reinforced polymer (FRP)-concrete-steel double-skin tubular members (DSTMs) are a new form of hybrid members developed at The Hong Kong Polytechnic University (PolyU). A hybrid DSTM consists of an outer tube made of FRP and an inner tube made of steel, with the space between them filled with concrete. The existing studies on hybrid DSTMs have been mainly focused on their use as compression members, with only a very limited number of studies on their use as flexural members [i.e., hybrid double-skin tubular beams (DSTBs)]. The limited existing studies on DSTBs have generally been limited to the testing of small-scale specimens without shear connectors. Against this background, this thesis presents a systematical study, both experimentally and theoretically, aimed at the development of an in-depth understanding of the structural behaviour of large-scale DSTBs with headed stud shear connectors. The research project mainly consisted of two parts: the first part was on the behaviour and modelling of headed stud shear connectors in hybrid DSTBs and the second part was on the behaviour and modelling of large-scale hybrid DSTBs with headed stud shear connectors. In the first part, the behaviour of headed stud shear connectors was investigated experimentally using a modified push-out test set-up. A three-dimensional (3D) finite element (FE) approach using ABAQUS was developed to predict the behaviour of headed stud shear connectors. The main advantage of the proposed FE approach over existing approaches lies in the use of a reliable constitutive model for confined concrete under a general state of multiaxial stresses. The effectiveness and accuracy of the proposed FE approach were demonstrated by comparing its predictions with the test results. A parametric study was then carried out using the verified FE approach to clarify the effects of various parameters on the behaviour of headed stud shear connectors. Based on the parametric study, new equations for the load-slip behaviour of headed stud shear connectors were proposed.
In the second part, four large-scale hybrid DSTBs with headed stud shear connectors under three-point/four-point bending were first tested. Four different cross-sectional configurations, including a DSTB/FRP-reinforced deck unit, were included in the tests. A 3D FE approach with ABAQUS/Explicit was then proposed for the modelling of hybrid DSTBs, in which the relative slips between the concrete and the steel tube were duly considered. The bond mechanisms in hybrid DSTBs were investigated using the FE approach to clarify the effects of key parameters. The FE approach was shown to be able to accurately predict both the global load-deflection response and the local relative slips between steel and concrete in hybrid DSTBs. In addition, a force-based fibre-section beam/column element model, which is capable of accounting for the relative slips between the concrete and the steel tube, was developed to model hybrid DSTBs. The accuracy of the beam/column element model was demonstrated to be comparable to that of the 3D FE approach but the former is much more computationally efficient than the latter.

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