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A platform for research: civil engineering, architecture and urbanism
Modelling of Unbonded Post-Tensioned Concrete Slabs Under Fire Conditions
This paper investigates the structural behaviour of unbonded post-tensioned one-way spanning concrete slabs in fire conditions. The slabs were simply-supported and reinforced with 15.7mm nominal diameter seven-wire mono-strand tendons. A nonlinear finite element model for the analysis of post-tensioned unbonded concrete slabs at elevated temperatures was developed. The mechanical and thermal material nonlinearities of the concrete, prestressing tendon and anchorages have been carefully inserted into the model. The interface between the tendon and surrounding concrete was also modelled, allowing the tendon to retain its profile shape during the deformation of the slab. The temperature distribution throughout the slab, time-deflection behaviour, time-longitudinal expansion, time-stress behaviour in the tendon, and the failure modes were predicted by the model and verified against test data. The study has shown that the coefficients of thermal expansion currently used in the European Code for calcareous and siliceous concrete can lead to inaccurate predictions of the structural behaviour. A parametric study was conducted to investigate the effects on the global structural behaviour due to the change in the aggregate type, load ratio and boundary conditions. It was shown that by varying the boundary conditions the fire resistance was greatly affected. Although changing the aggregate type and load ratio affected the time-displacement response, the fire resistance defined by failure of the slab was not affected due to the splitting mode of failure above the tendon locations not being affected by these parameters. Comparison with the codes shows that the UK code BS8110 is generally unconservative whereas the Eurocode EN1992-1-2 provides reasonable design rules.
Modelling of Unbonded Post-Tensioned Concrete Slabs Under Fire Conditions
This paper investigates the structural behaviour of unbonded post-tensioned one-way spanning concrete slabs in fire conditions. The slabs were simply-supported and reinforced with 15.7mm nominal diameter seven-wire mono-strand tendons. A nonlinear finite element model for the analysis of post-tensioned unbonded concrete slabs at elevated temperatures was developed. The mechanical and thermal material nonlinearities of the concrete, prestressing tendon and anchorages have been carefully inserted into the model. The interface between the tendon and surrounding concrete was also modelled, allowing the tendon to retain its profile shape during the deformation of the slab. The temperature distribution throughout the slab, time-deflection behaviour, time-longitudinal expansion, time-stress behaviour in the tendon, and the failure modes were predicted by the model and verified against test data. The study has shown that the coefficients of thermal expansion currently used in the European Code for calcareous and siliceous concrete can lead to inaccurate predictions of the structural behaviour. A parametric study was conducted to investigate the effects on the global structural behaviour due to the change in the aggregate type, load ratio and boundary conditions. It was shown that by varying the boundary conditions the fire resistance was greatly affected. Although changing the aggregate type and load ratio affected the time-displacement response, the fire resistance defined by failure of the slab was not affected due to the splitting mode of failure above the tendon locations not being affected by these parameters. Comparison with the codes shows that the UK code BS8110 is generally unconservative whereas the Eurocode EN1992-1-2 provides reasonable design rules.
Modelling of Unbonded Post-Tensioned Concrete Slabs Under Fire Conditions
Bailey, Colin (author) / Ellobody, Ehab (author)
2009-01-01
Bailey , C & Ellobody , E 2009 , ' Modelling of Unbonded Post-Tensioned Concrete Slabs Under Fire Conditions ' Fire Safety Journal , vol 44 , no. 2 , pp. 159-167 . DOI:10.1016/j.firesaf.2008.05.007
Article (Journal)
Electronic Resource
English
Risk , Fire , Safety , /dk/atira/pure/subjectarea/asjc/1600 , /dk/atira/pure/subjectarea/asjc/2200/2213 , /dk/atira/pure/subjectarea/asjc/2500 , Unbonded , Structural and Fire Engineering , Post-tensioned concrete slabs , Finite element modelling , Physics and Astronomy(all) , Chemistry(all) , Materials Science(all) , /dk/atira/pure/core/keywords/library/01/09 , /dk/atira/pure/subjectarea/asjc/3100 , Structural design , Reliability and Quality , Tendon
DDC:
690
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