A new concept in composite construction has been developed at the University of Salford, involving the use of fibre-reinforced cement channels, combined structurally with partially prestressed composite concrete T-beams. The British Standards Institution Code of Practice, CP110: 1972, "The Structural Use of Concrete", permits the use of Class 2 and Class 3 (partially prestressed) concrete members in structural design'. The limiting design criteria for such members are usually the limit'states of deflection and cracking and therefore, an improvement in their flexural behaviour would be beneficial. This improvement may be brought about by the addition of fibre-reinforcement, in the form of two or three dimensionally randomly distributed fibres. The Code of Practice, CP110: 1972, does hot, however, give any guidance on the use of fibres in structural members and it is also apl. arent that the methods outlined in the code for the calculation of the limit states are limited and can be improved. The flexural behaviour of twenty-two partially prestressed composite concrete T-beams was investigated. Each beam consisted of a precast partially prestressed X-joist web, combined with a cast-insitu lightweight aggregate concrete flange. Alkali-resistant glass fibrereinforced cement channels were placed at the soffits of six beams and steel fibre-reinforced concrete was used in the webs of two beams. The T-beams were subjected toshort-term, long-term and fatigue loading and their structural performance was considered in terms of strength, cracking and deformation. Theoretical relationships are derived between the applied moment and the depths of the neutral axes of stress and bending, enabling a design equation relating applied moment to the steel stress to be developed. Subsequently, design equations for the calculation of the limit states of deflection and cracking are developed, which are directly applicable to both conventional and fibre-reinforced structural members. The use of a fibre-reinforced cement channel as an integral structural part of a concrete member results in many important advantages when compared with conventional concrete members and the test results show that they considerably improve the structural performance of the partially prestressed composite concrete T-beams.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:471671 |
| Date | January 1976 |
| Creators | Saunders, J. |
| Publisher | University of Salford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://usir.salford.ac.uk/2120/ |
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