Circularity of Composite Structures
The demountability and reusability of composite structures is assessed in the RFCS project REDUCE. The project aim is to provide technical solutions, tools and guidance to assist in design for deconstruction as well as reuse, in particular of multi-storey steel-composite structures. Important goals in the project are to determine whole-life benefits of reusable structures through LCA and Circular Economy indictors, as well as to develop a demountable composite construction system.
Within the REDUCE-project, our group is mainly focusing on technical solutions and is working together with the Steel Construction Institute (UK) (project coordinator), University of Luxembourg (Luxembourg), Tata Steel (NL), AEC3 (UK, Germany), Bouwen met Staal (NL), University of Bradford (UK) and Lindab S.A. (Luxembourg) on variety of very actual issues for the future of construction.
TU Delft research staff involved in the project:
ir. M.P. Nijgh (contact person)
prof. dr. M. Veljkovic
The REDUCE-project addresses the increasingly important requirements for design to facilitate reuse of structures, which is an important part of the circular economy initiative that underpins the sustainability and environmental impact of the built environment within the European Union. The main application of the project is in multi-storey steel framed buildings, which often use composite construction for structural efficiency, speed of construction, and cost efficiency. A key focus of the project is to develop and test efficient demountable composite construction systems that are key to retaining and growing market share for steel construction. An important step is to develop demountable shear connectors, since structures with welded headed studs cannot be demounted without damaging the concrete deck. An example of a demountable shear connectors are embedded bolted shear connectors, which are used connect the prefabricate deck and the top flange whilst allowing for demountability. Within the project an innovative demountable shear connector has been developed, consisting of an external (injection) bolt which connects to a coupler and bolt embedded in the concrete deck. Given the needs for larger execution tolerances of steel and concrete products, oversize holes are used in the beam flange to allow for rapid execution and easy demounting of the composite floor system. The void between the bolt and bolt hole in the top flange is filled using epoxy resin, to achieve composite action under live loading.
Feasibility and structural tests were carried out on demountable and reusable composite floor systems. The concept of demountable and reusable composite structures was proven by designing and execution two bays (at 90% scale) of a 16 m span building, which is a typical span for a multi-storey car park building. The composite floor system consists of tapered steel beams and prefabricated concrete decks with cast-in shear connectors, consisting of a coupler and bolt. After placing the prefabricated concrete decks on the steel beams the connection is made by installing external injection bolts. Composite interaction is achieved by filling the bolt-to-hole clearance with epoxy resin.
After the proof-of-concept stage, the composite floor system was subjected to point loads and the mechanical response was evaluated. Several shear connector arrangements were studied to find the optimal number of shear connectors to balance structural and economic benefits.
The experimental set-up resembles a typical span for a multi-storey car park building. The video below gives an indication of how the execution and demounting process of a demountable and reusable composite structures would look like in case of an actual structure.
Nijgh, M., Gîrbacea, A., & Veljkovic, M. (2019). Elastic behaviour of a tapered steel-concrete composite beam optimized for reuse. Engineering Structures, 183, 366-374. DOI: 10.1016/j.engstruct.2019.01.022
Xin, H., Nijgh, M., & Veljkovic, M. (2019). Computational homogenization simulation on steel reinforced resin used in the injected bolted connections. Composite Structures, 210, 942-957. DOI: 10.1016/j.compstruct.2018.11.069
Nijgh, M., Gîrbacea, A., & Veljkovic, M. (2018). Optimization of a composite (steel-concrete) floor system for fast execution and easy demolition. Proceedings of iNDiS 2018.
Gritsenko, A. (2018). Towards a demountable composite slab floor system (Master’s thesis). Delft University of Technology.
Gîrbacea, A. (2018). Assessment of demountable steel-concrete composite flooring systems (Master’s thesis). Delft University of Technology.
Kozma, A., Odenbreit, C., Volker Braun, M., Veljkovic, M., & Nijgh, M. (2018). Push-out tests on demountable shear connectors of steel-concrete composite structures. In V. Albero, A. Espinos, C. Ibabez, A. Lapuebla, & M. L. Romero (Eds.), Proceedings 12th international conference on Advances in Steel-Concrete Composite Structures - ASCCS 2018 (pp. 549-556). Valencia: Universitat Politecnica de Valencia. DOI: 10.4995/ASCCS2018.2018.7155
Nijgh, M., Xin, H., & Veljkovic, M. (2018). Non-linear hybrid homogenization method for steel-reinforced resin. Construction and Building Materials, 182, 324-333. DOI: 10.1016/j.conbuildmat.2018.06.111
Nijgh, M., Veljkovic, M., Oly, R. & Pavlovic, M. (2018). Flexible shear connectors in a tapered composite beam optimized for reuse. In M. S. T. Anderson, & P. Anderson (Eds.), Annual International Conference Proceedings 6th Annual International Conference on Architecture and Civil Engineering (ACE 2018) (pp. 32-39). Singapore: Global Science and Technology Forum. DOI: 10.5176/2301-394X_ACE18.49
Arnim, M. von (2017). Demountable composite steel-concrete flooring system for reuse (Master’s thesis). Karlsruhe Institute of Technology / Delft University of Technology.
Pavlovic, M. & Veljkovic, M. (2017). Prefabricated demountable concrete and FRP decks in composite structures. Proceedings of Eurosteel 2017. Copenhagen.
Nijgh, M. P., Arnim, M. von, Pavlovic, M. & Veljkovic, M. (2017). Preliminary assessment of a composite flooring system for reuse, Proceedings of the 8th International Conference on Composite Construction in Steel and Concrete. Jackson (WY).
Braendstrup, C. (2017). Conceptual design of a demountable, reusable composite flooring system: Structural behaviour and environmental advantages (Master’s thesis). Delft University of Technology.
Maheninggalih, G. (2017). A demountable structural system of multi-storey buildings: Case study of a car park building (Master’s thesis). Delft University of Technology.
Nijgh, M. P. (2017). New materials for injected bolted connections: A feasibility study for demountable connections (Master’s thesis). Delft University of Technology.