Proof of concept of a demountable steel‐concrete composite flooring system

Abstract

Environmental concerns steer the construction industry towards more sustainable developments such as demountable and reusable structures. Composite structures are a frequent solution for multi-story buildings and bridges, however the use of welded shear connectors requires labour and energy intensive disassembly. Two bays of a demountable flooring system for a multi-storey car park building were erected in the laboratory. The flooring system consists of large prefabricated concrete decks connected to tapered steel beams. The feasibility of assembly and disassembly of the flooring system was tested under laboratory condition. Shear interaction was achieved by an embedded bolt and coupler which are connected to the top flange of the steel beam by an external injection bolt. Oversized holes are used in the top flange of the steel beam to accommodate fabrication and execution deviations and the deformations occurring during construction. Extensive imperfection measurements and finite element models were used to design the oversized hole diameter to 32 mm. The hole clearance must be compensated either by pretensioning or injecting the bolt-to-hole clearance with an epoxy resin to enable instantaneous composite action under live loads. Experimental injection of 150 injection bolts confirms that epoxy resin can reliably fill the hole clearance, and that the injection process takes 30 seconds per bolt. Various non-uniform shear connector arrangements were considered to minimize construction costs and maximize the speed of execution. The mechanical behaviour of the demountable composite beam was tested experimentally and numerically.

Towards a demountable composite slab floor system

“…However, to successfully re-use the composite slab in combination with an arbitrary steel beam, the hole clearance has to be increased in the second life cycle. Similar finding was confirmed in a feasibility study by (11) on a demountable composite flooring system with large prefabricated decks.…”

Requirements for oversized holes for reusable steel-concrete composite floor systems

“…The results of the Monte Carlo analysis are based on the assumption that the floor elements do not exhibit geometrical and dimensional deviations. Gîrbacea [8] has identified the deviations in terms of longitudinal and transversal spacing of the embedded demountable shear connectors for the composite floor system executed by Nijgh et al [4]. The maximum transversal deviations of the spacing of the demountable shear connectors were +2.6 and −2.8 mm.…”

“…A tight control over the dimensional and geometrical deviations of the prefabricated concrete floor elements would have mitigated the experimentally required nominal hole clearances. In addition, the floor elements could be designed slightly narrower than the nominal centre-to-centre distance of the steel beams to allow for minor deviations in floor element width [8]. This strategy cannot be used longitudinally, because direct contact of the floor elements is necessary to generate composite interaction during the functional lifetime.…”

“…The tapered steel beams were braced at five locations along their span, reducing their out-ofstraightness, which had a beneficial effect the observed geometrical deviations. On the other hand, the prefabricated floor elements used in the experiments [4] exhibited relatively large geometrical and dimensional deviations [8], which is discussed later in this paper.…”

Experimental and numerical study on the in-plane behaviour of a new long-span assembly composite floor system under lateral load

“…commonly used floor structure in steel structure engineering, and it is widely used in large-span floor structures [32][33][34]. With the continuous improvement of the industrialization of buildings, the prefabricated steel-concrete composite floor system has gradually attracted the attention of the engineering community, especially the application of steel-concrete composite steel beams with precast concrete hollow-core slabs [35][36][37] and the application of the slim-floor system [38][39][40][41].Both are beneficial to promote the development of prefabrication of steel-concrete floor systems [42,43].However,the current research on prefabricated assembled steel-concrete composite floors has basically focused on the vertical mechanical behavior, and less attention has been paid to the in-plane mechanical behavior of this type of floor.…”