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PROCEEDINGS OF THE ELEVENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY
Edited by: B.H.V. Topping
Computational Modelling of Deconstructable Composite Steel-Concrete Beams
M.A. Bradford and Y.-L. Pi
Centre for Infrastructure Engineering and Safety, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, Australia
M.A. Bradford, Y.-L. Pi, "Computational Modelling of Deconstructable Composite Steel-Concrete Beams", in B.H.V. Topping, (Editor), "Proceedings of the Eleventh International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 153, 2012. doi:10.4203/ccp.99.153
Keywords: deconstructability, composite beams, high-strength bolts, non-linearity, shear connection.
The implementation of "green" technologies in the building and construction sector is currently being researched and practised with significant fervour in many industrialised nations, with life-cycle issues being critical in the initial design. While low-rise steel framed buildings with composite flooring are extremely popular because of many economic advantages that accrue to their speedy construction, they are somewhat difficult to dismantle and their components cannot be reused without the input of significant and energy-consuming structural modification. It is clear that the fundamental cause of their problematic recyclability after deconstruction is the headed stud shear connector that is embedded in the concrete and welded to the steel top flange. The replacement of headed stud connectors by high strength bolts that can be dismantled easily is an attractive consideration at the design phase. Surprisingly, this form of shear connection has received very little attention in the published literature, despite its benefits being known for many decades [1,2].
As with conventional composite beams, testing of prototype members and structures is expensive and time-consuming, and so recourse to efficient computational algorithms that produce reliable results is important. In response to this, the current paper presents a beam-type finite element, based on that developed elsewhere by the authors , to analyse the response of composite beams for which a solid concrete slab is connected to the steel beam with high-strength bolts. The model incorporates material non-linearity, including post-yield of the steel beam and plasticity in the concrete in tension and compression. It also uses an empirical curve for the load-slip behaviour of the bolted shear connection, based on less-expensive conventional push test results. An algebraic representation of this is proposed, and which can be fitted to push test data using three empirical parameters. Geometric non-linearity is included using vector analysis and differential geometry to formulate correctly the relationship between the strains and displacements, and in particular this is able to capture the effect of interface slip whose modelling in the non-linear range of geometric response is complex. The numerical model is then calibrated with full-scale tests reported elsewhere [1, 2], with good agreement being obtained. The proposed finite element modelling provides an efficacious technique for investigating the use of bolted shear connectors, which seemingly possess the very advantageous characteristic of ductility in the shear connection as well as being deconstructable at the life-end of the structure.
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