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Shear and anchorage behaviour of fire exposed hollow core slabs

Author: Fellinger, J.H.H. · Stark, J. · Walraven, J.C.
Type:article
Date:2005
Institution: TNO Bouw en Ondergrond
Source:Syllabus. International Symposium on Fire Safety Research. On the occasion of the retirement of Leen Twilt in cooperation with EGOLF, Delft, the Netherlands, 14 March, 95-117
Identifier: 331076
Keywords: Architecture and Building

Abstract

The fire resistance of hollow core slabs is currently assessed considering flexural failure only. However, fire tests showed that shear or anchorage failure can also govern the load bearing behaviour. As the shear and anchorage capacity of these slabs rely on the tensile strength of the concrete, the load bearing capacity with respect to these failure modes decreases dramatically during fire due to the impact of thermal stresses. This paper presents a FE model for the shear and anchorage behaviour of fire exposed hollow core slabs, comprising new constitutive models for concrete and bond of prestressing strands at high temperatures. The constitutive models were calibrated with 60 new small scale tests carried out at elevated temperatures up to 600 °C. The FE model was validated on the basis of 25 full scale fire tests on hollow core slabs loaded in shear. Finally, a parameter study was carried out with the FE model. The results showed that the thermal expansion of concrete, the ductility of concrete in tension and the restraint against thermal expansion by the supports are the main influencing factors. It is recommended to control these factors in design in order to improve the safety level. This paper is an extended summary of the dissertation by the first author [10].