Investigation in reusable composite flooring systems in steel and concrete based on composite behaviour by friction

Doctoral thesis (2022)

The steel-concrete composite systems proved to be very efficient structural solution in terms of material consumption and mechanical response regarding the construction of the structural floor systems ... [more ▼]

The steel-concrete composite systems proved to be very efficient structural solution in terms of material consumption and mechanical response regarding the construction of the structural floor systems whether in the case of industrial and residential buildings or especially in the case of car parks. However, their contemporary application that relies on the utilization of the welded headed studs as a mean to provide the shear connection between the steel section and the concrete chord renders the system unable to be disassembled (in the best case its steel and concrete parts are recycled). Considering the ongoing push from the linear to circular economical models and the application of 3R principle (Reduce, Reuse & Recycle) such systems are unable to furtherly improve their environmental and economic efficiency through reuse schemes. The profound task in this research is development and the verification of the new demountable shear connector solutions that could allow modularity and demountability (hence reusability) of the steel-concrete composite floor systems while retaining their inherent structural advantages. Based on the previous investigations of the demountable shear connector systems (at the first-place bolted solutions) and investigations of mechanical components that were not strictly related to the shear connectors, four demountable shear connector devices were developed. Having in mind the drawbacks of the earlier solutions, adequate detailing and structural measures were applied and the ease of assembly and disassembly was proved on the constructed prototypes. Afterwards, the mechanical properties of devised demountable connector systems were investigated thoroughly through experimental campaign (push tests) and numerical investigation. Based on the experimental and numerical results of the shear connector behaviour it is concluded that the proposed shear connector device Type B possess adequate strength and stiffness and might be considered ductile in accordance with the EN 1994-1-1 allowing for the application of existent design strategies in accordance with the same design code. The force-slip behaviour of the proposed shear connector is explained and adequate analytic model is proposed. Based on the force-slip behaviour model the applicability of the shear connector is verified on a range of composite beams that represent the demountable floor. [less ▲]

Non-linear design for composite structures in steel and concrete in reference to Eurocode 4, Part 1-1

Learning material (2021)

The design of composite structures in steel and concrete for buildings follows the rules according to Eurocode 4: EN 1994-1-1. In the last years more and more individual composite members and cross ... [more ▼]

The design of composite structures in steel and concrete for buildings follows the rules according to Eurocode 4: EN 1994-1-1. In the last years more and more individual composite members and cross-section types have been developed. Those sections are not always fulfilling the requirements for the application of simplified design methods given by EN 1994-1-1 and therefore plastic resistance cannot always be applied. Furthermore there is an increasing demand for optimization in the design by using more advanced design methods. This optimization is concentrating on the use of individual shaped cross-sections and their efficiency, the composite shear connectors and consideration of their ductility and flexibility, investigation in the sequence of loading, time effects as well as concrete cracking and yielding of steel within the analysis. In addition it is to be mentioned that the draft for the second generation of Eurocode 4 provides more opportunities for advanced numerical methods. At least, the demand for more advanced numerical design methods is permanently increasing also due to the availability of powerful hardware and software applications. The target of this chapter is to introduce the advanced numerical design for composite structural members in steel and concrete and to explain the boundary conditions given by Eurocode 4 and related Eurocodes. Thereby the focus is more on the member and not on the global analysis. The computer-aided global analyses for the determination of action effects are well-known for years while the possibilities for nonlinear analysis based on shell and volume elements considering physical and geometrical nonlinearity becoming more important and will be further developed in future. However, there is not so much information available explaining the application of e.g. the general method in detail and guidance is missing by the code. Therefore the general method acc. to EN 1994-1-1/prEN1994-1-1 is the main focus of this contribution. In the following, some principles for the design according to EN 1994-1-1 are explained. Thereby the basics for the classification of cross-sections as well as the determination of inner forces for continuous beams will be pointed out. However, the focus is on the general method for the design of composite compression members. While in the case studies additional information for the structural analysis and the numerical investigation in composite beams is provided. This chapter will not repeat well-known explanations from the literature, which have been published many times but limits itself to the most important normative fundamentals, rather concentrate on the application of numerical methods for the design of composite structures. More details for global structural analysis and the design according to EN 1994-1-1 [1] are provided by the literature, e.g. [8], [40] and will not be further commented here. It should be noted that the here referred methods according to prEN 1994-1-1, prEN 1993-1-14 and prEN 1992-1-1 do not represent officially introduced design standards, until the introduction of the second generation of Eurocodes modification is not finalized. Therefore this references are to be understood as informative. Until the introduction of the second generation of Eurocodes further changes and adjustments may also to be expected. [less ▲]