Serviceability of Fabric-Formed Concrete Structures

Authors: Yadgar Tayfur, Antony Darby, Tim Ibell, Mark Evernden, John Orr

Abstract:

Fabric form-work is a technique to cast concrete structures with a great advantage of saving concrete material of up to 40%. This technique is particularly associated with the optimized concrete structures that usually have smaller cross-section dimensions than equivalent prismatic members. However, this can make the structural system produced from these members prone to smaller serviceability safety margins. Therefore, it is very important to understand the serviceability issue of non-prismatic concrete structures. In this paper, an analytical computer-based model to optimize concrete beams and to predict load-deflection behaviour of both prismatic and non-prismatic concrete beams is presented. The model was developed based on the method of sectional analysis and integration of curvatures. Results from the analytical model were compared to load-deflection behaviour of a number of beams with different geometric and material properties from other researchers. The results of the comparison show that the analytical program can accurately predict the load-deflection response of concrete beams with medium reinforcement ratios. However, it over-estimates deflection values for lightly reinforced specimens. Finally, the analytical program acceptably predicted load-deflection behaviour of on-prismatic concrete beams.

Keywords: Concrete beams, deflections, fabric formwork, optimisation, serviceability.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1124075

References:

[1] Orr, J. J., Darby, A., Ibell, T., and Evernden, M., 2011. Fibre Reinforced Polymer Grids as Shear Reinforcement in Fabric Formed Concrete Beams. In: Advanced Composites in Construction 2011, ACIC 2011., 72-83.
[2] Abdalla, H., A., 2002, Evaluation of Deflection in Concrete Members Reinforced with Fibre Reinforced Polymer (FRP) Bars, Composite Structures, Elsevier, 56 (1), 63-71.
[3] West, M. 2001. Fabric formed concrete structures. In: Proceedings of the First International Conference on Concrete and Development. Teheran, Iran, April 30-May 2, 2001., 133-142.
[4] Gilbert, R.I. 2011. The Serviceability Limit States in Reinforced Concrete Design, Procedia Engineering, Elsevier, 14, 385-395.
[5] Kwak, H., and Kim, S. 2010, Simplified monotonic moment–curvature relation considering fixed-end rotation and axial force effect, Engineering Structures, Elsevier, 32 (1), 69-79.
[6] Eurocode 2: Design of Concrete Structures: Part 1-1: General Rules and Rules for Buildings.
[7] Kwak, H., and Kim, S. 2002, Nonlinear Analysis of RC Beams Based on Moment–Curvature Relation, Computers and Structures, Pergamon, 80 (7), 615-628.
[8] Visintin, P., Oehlers, D., J., Muhamad R., and Wu, C., 2013. Partial-interaction short term serviceability deflection of RC beams, Engineering Structures, 56, 993-1006.
[9] Veenendaal, D. Coenders, J, Vambersky, J., West, M. Design and optimization of fabric‐formed beams and trusses: evolutionary algorithms and form-finding, structural concrete, 2011,12 (4), 241-252.
[10] Garbett, J., Darby, A. & Ibell, T. 2010. Technical Papers: Optimized Beam Design Using Innovative Fabric-Formed Concrete. Advances in Structural Engineering, 13, 849-860.
[11] Foster R, Form finding and analysis of fabric formed concrete beams, MEng Thesis, Architecture and Civil Engineering, Bath, University of Bath, 2010.
[12] ACI 318M-11, Building Code Requirements for Structural Concrete and Commentary.
[13] Kalkan, I. 2010, Deflection Prediction for Reinforced Concrete Beams through Different Effective Moment of Inertia Expressions, International journal of engineering research and development, 2 (1), 72-80.
[14] Orr, J., J., 2012, Flexible Formwork for Concrete Structures, PhD Thesis, University of Bath.