Serviceability behaviour of ultra-high performance fibre-reinforced concrete composite slabs
Date
2023
Authors
Chen, Sirui
Editors
Advisors
Visintin, Phillip
Oehlers, Deric John
Oehlers, Deric John
Journal Title
Journal ISSN
Volume Title
Type:
Thesis
Citation
Statement of Responsibility
Conference Name
Abstract
This thesis presents a comprehensive study of composite slabs comprised of a steel profiled deck and ultra-high-performance fibre-reinforced concrete (UHPFRC). The study begins by examining the local bond properties of composite slabs at the contact surface, investigating the impact of concrete mix designs and profiled deck rib openings on the longitudinal bond behaviour. Subsequently, an experimental study is conducted to analyse the behaviour of simply-supported and continuous composite slabs with varying fibre content, focusing on flexural behaviour, load-slip performance and cracking resistance at both the serviceability and ultimate limit states. These experimental results are then used to validate a new numerical model that allows for changing fibre contents and time-dependent behaviour as well as the partial interaction (PI) behaviour between concrete and steel components (for both internal reinforcements and profiled deck). This numerical model is a displacement-based approach that models the serviceability flexural behaviour of simply-supported composite slabs. Finally, based on the same theory as numerical model, an analytical solution which considers non-linear shrinkage strains is developed to provide a quick and rational solution for predicting the load-deflection behaviour of composite slabs at the serviceability limit state. In the first chapter, the characteristics of UHPFRC and the significant benefits of its application as part of steel concrete composites are introduced. The current studies that investigate the behaviour of steel concrete composite structures in experimental and numerical studies and approaches used to evaluate the performance of composites are summarised. Learning from these studies, research gaps and significances of these studies covered in this thesis are identified. The second chapter focuses on the study of local bond properties conducting by a new single-lap test apparatus. This new test apparatus is designed to avoid material pre-failure (such as buckling of profiled deck and concrete crushing) and reduce the friction impact from additional clamping force. Six trial tests are conducted to study the impact of various bonded length and then the shortest one is selected for the following 48 tests to study bond behaviour of steel concrete composites in terms of two different steel decks (dove-tailed and trapezoidal types), varying fibre contents and the presence/absence of coarse aggregate in concrete mixing. This interfacial bond-slip property is important because longitudinal shear transfer dominates the behaviour of composites such as ultimate capacity and flexural stiffness. The third chapter reports on an experimental investigation aimed at quantifying the benefits of application of UHPFRC to composite slabs with profiled steel decks. Steel concrete composites comprising of steel fibre reinforced concrete (SFRC) and high strength concrete (HSC) have been extensively investigated in the previous studies while the application of UHPFRC as potential substitute because of its high compressive strength and ductility, tensile strain-hardening behaviour and superior post-crack characteristics as one component of composite structures have not been given enough attention. This experimental study focuses on the performance of six simply-supported composite slabs and three continuous composite slabs with fibre content of 0%, 1% and 2%. These tests aims to evaluate the influence of fibre content on the behaviour of composite slabs in terms of deformation, stiffness, crack control and moment redistribution. Furthermore, a rotational displacement-based numerical model is proposed to evaluate the behaviour of composite slab in serviceability with considering long-term effects. The development of this unified approach is necessary because there are numerous combinations for fibre contents and fibre types in cementitious matrix when designing a composite slab. Therefore, a general and applicable model for predicting behaviour of different composite slab designs is required. This model only requires fundamental material properties obtained from small scale tests instead of full-scale slabs loading test results which provides a financial benefit. With application of PI theory in a tension stiffening analysis to determine relative slip between concrete and steel components (local behaviour) and in a mechanics segmental analysis to determine moment/rotation/strain (M//ɛ) properties (global behaviour) for the non-debonded and debonded region, this model predicts crack behaviour, longitudinal slip and flexural performance of profiled slab at the serviceability limit state. This numerical model is validated by comparing with a total of six simply-supported experimental test results with applying their corresponding tested material properties as shown in Chapter 3. Finally, on the basis of numerical model, in order to allow for realistic nonlinear shrinkage strains and relative slip occurring between concrete and steel decking, a closed-form analytical solution is developed to estimate the load-deflection behaviour of composites slab at the serviceability limit state up until the formation of macro-cracking. In this approach, two loading configurations are considered, a central point load and uniform distributed load (UDL), and their corresponding elemental curvature expressions in segmental analysis are demonstrated separately. To simplify the process, all the material properties are assumed to be linear-elastic while concrete tensile strain-stress relationship is bi-linear. This approach is validated by comparing with numerical model results. Therefore, this analytical solutions can be used as design guideline for evaluating the load-deflection performance of profiled slabs in serviceability behaviour.
School/Discipline
School of Architecture and Civil Engineering
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Architecture and Civil Engineering, 2023
Provenance
This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals