Impact resistance of pre-damaged ultra-high performance fibre reinforced concrete (UHPFRC) slabs

Zaini, Shaharudin
(2015) Impact resistance of pre-damaged ultra-high performance fibre reinforced concrete (UHPFRC) slabs. Doctor of Philosophy thesis, University of Liverpool.

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This research aims to gain deeper insight and understanding into the behaviour of scaled pre-damaged UHPFRC slabs under the combined loading effect of static pressure followed by low velocity impact loading. The intension is to simulate impact from failed columns onto a damaged UHPFRC slab, as a result of an explosion. The context of these studies is the prevention of progressive collapse of a building through the contribution from using UHPFRC slabs. A static pressure device was used to create the initial damage with low velocity drop tests carried out subsequently. The interest is focused on ability of the pre-damaged UHPFRC slabs to withstand cumulative impact energy, manifested via the measurement of the impact resistance, deformations and stiffness degradation compared to the undamaged slabs. The sensitivity of the impact locations were also investigated by setting the impact locations to be at the centre, edge and corner of the slab. Impact at an oblique angle of 10° was also included. The results showed that the impact resistance of the pre-damaged slabs were substantially high, approximately 50 - 85% of the undamaged slab. Similarly, the high residual strength of the pre-damaged slabs was also reflected in the pattern of the deformations and stiffness degradation where in most cases, the patterns were found to be relatively similar to the undamaged slabs. Their high strength reserves after initial damage make them appealing as a construction material to withstand abnormal loading and mitigate progressive collapse of a structure. On the other hand, the slabs subjected to the asymmetrical impact showed lower impact resistance and therefore possessed higher risk towards initiating a progressive collapse failure. On the contrary, tilting the slabs to 10° only exhibited higher impact resistance. To predict the response of slabs, FE models were developed using ANSYS Explicit Dynamics Release 13.0 software. RHT concrete formulation was used to represent the dynamic properties of UHPFRC materials. A new technique was also introduced to model the pre-damaged slabs. Although showing scattered results, the FE models were able to predict the response with reasonable accuracy ranging from 3%-52% in the majority of the cases. Finally, the results from the analytical simulations using an SDOF model were also able to produce a reasonably close agreement with the experimental data and particularly true when the resistance functions were derived from the static tests. Therefore, SDOF modelling can be considered as a credible method to predict the deformation of UHPFRC slabs.

Item Type: Thesis (Doctor of Philosophy)
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Divisions: Fac of Science & Engineering > School of Engineering
Depositing User: Symplectic Admin
Date Deposited: 22 Aug 2016 07:53
Last Modified: 22 Aug 2016 07:53
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