Previous Work
So that the objectives of the topic can be suitably analysed, previous sensitivity work conducted by Thornsteinsson will be used (Thornsteinsson, A. "Punching shear of flat slabs in fire conditions" 2012). This will provide the following benefits:
- The use of the same dimensions, material parameters at ambient temperature and other relevant characteristics will allow for comparisons between the simplified material behaviour using the Isotherm method as presented by Thornsteinsson and a more complex behaviour analysis that will be conducted in this work.
- It will allow for more time to be spent on completing the objectives, initial modelling steps such as mesh sensitivity can be carried across to this project and do not need to be done again.
- A standard ISO fire will also be used for the heat transfer analysis. At this stage in the research, investigating "real fire" behaviour isn't seen as an effective use of time as the behaviour of the slab first needs to be properly understood. In future work, the behaviour of slabs in real fires may be of more interest if this project is successful.
- An axi-symmetric model will continue to be used, this allows the analysis to be simplified to a 2 dimensional problem which significantly reduces computing time. This method has been proven to give similar results to analytical methods and also to the limited experimental data.
ABAQUS
All modelling will be done using ABAQUS, this Finite Element programme allows the user to perform both a heat transfer and thermo-mechanical analysis which is required for the scope of works proposed. ABAQUS also provides suitable concrete models to be used to assess the tangential and radial cracks that will appear in the lead up to punching shear.
Title Image Source: Thornsteinsson, A. "Punching shear of flat slabs in fire conditions" 2012