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

Abstract

The design of sustainable structures is increasingly gaining attention in the construction sector as a societal and technological challenge. Demountability and reuse of structures contributes to the reduction of the environmental impact of the built environment. Welded headed studs used in traditional steel-concrete composite floor systems need to be replaced by demountable shear connectors to enable the transition of the construction sector to a circular business model. The demountable shear connectors are embedded in large prefabricated concrete floor elements and connected to steel beams by bolts. The holes in the beam flange are oversized to account for geometrical and dimensional deviations of all members and to facilitate rapid execution and easy demounting. The goal of this paper is to present a methodology that quantifies the required nominal hole clearance for reusable composite floor systems. Statistical characteristics of dimensional and geometrical deviations serve as input for Monte-Carlo simulations. The aggregated results of the Monte Carlo simulations are used to determine the required nominal hole clearance for a specified probability of successful installation of the demountable shear connectors. The proposed methodology is applied to the composite floor system of a demountable and reusable car park building. The contradicting requirement of oversized holes and composite interaction is solved by injecting the hole clearance with a (steel-reinforced) epoxy resin. The bearing resistance of the (steel-reinforced) epoxy resin is addressed based on preliminary results of creep experiments on resin-injected bolted connections.

Mechanical Performance of Injected Steel‐reinforced Resin Connectors Under Different Confined Conditions for Reusable Composite Structures

“…Push-out experiments on iSRR connectors with the injected piece under different confined conditions and different volumes were carried out in [16] and [30] and their mechanical properties and failure mechanisms are presented in this paper. The difference in confinement was a result of the different materials that were investigated for the deck.…”

“…Although the initial investigation of the injected bolt with SRR was done in a steel-to-steel double lap geometry, Nijgh [16] explored its applicability on composite floor systems between concrete and steel elements. The shear connector comprises a bolt with a coupler embedded in a thick concrete element.…”

Steel-reinforced resin for bolted shear connectors: Confined behaviour under quasi-static cyclic loading

“…However, using resin injections in bolted connections with oversized holes requires additional attention since the load-bearing resin volume is larger and deformations will increase. Such oversized holes are crucial when using resin-injected bolted shear connectors in demountable steel-concrete composite floor systems: Nijgh et al [16,17] conducted scientific investigations on the demountability and reusability of a tapered steel-concrete composite beam whose dimensions replicate typical dimensions of a multi-storey car park building. Demountable resin-injected shear connectors were proposedsee schematic representation in Fig.…”

“…To account for tolerances in the construction process, the hole clearance is 4 times larger than normalized hole dimensions. In accordance with these dimensions, a set of creep tests was conducted by Nijgh [16] using double-lap shear connections with M20 bolts in oversized holes with 32 mm of diameter. Results for a normal bearing stress of 175 MPa are presented in Fig.…”

Fracture simulation of a demountable steel-concrete bolted connector in push-out tests

“…Kozma et al [10] also performed push-out tests on the "bolt-coupler" connector and some improvements, such as using epoxy resin injection bolts, were made to enhance the initial shear stiffness of the connector. Nijgh et al [11,12] tested a tapered steel-concrete composite beam connected by resininjected bolt-coupler connectors to investigate its disassembly and reuse abilities. Besides, requirements for oversized bolt hole in reusable composite floor systems using the resin-injected bolt-coupler connectors were studied, since the oversized holes in top flange of beams can facilitate rapid erection and easy disassembly.…”