This paper describes the work conducted by the Canadian Nuclear Safety Commission (CNSC) related to the influence of concrete pre-stressing on perforation capacity of reinforced concrete (RC) slabs under "hard" missile impact (impact with negligible missile deformations). The paper presents the results of simulation of three tests on reinforced concrete slabs conducted at VTT Technical Research Centre (Finland), along with related sensitivity studies. The baseline setup (the first test) was slab (2.1m*2.1m*0.25 m) with longitudinal reinforcement only. In the second and third tests the specimens have been cast with DYWIDAG bars placed in PVC sleeves in order to avoid the contact between the bars and the concrete. In the second test the Dywidag bars are without initial pre-tensioning and in the third test they were pre-tensioned in order to to introduce 10 MPa pre-stressing in the concrete slab. The impact missile velocity was selected using empirical formulas for just perforation as presented in Orbovic et al. (2015). Non-linear dynamic behavior of reinforced concrete slabs was analyzed using commercial Finite Element (FE) code LS-DYNA. Explicit version was selected for the entire modelling. FE predictions based on Winfrith MAT084 concrete material model without strain-rate were compared with tests results. Concrete erosion criteria as well as other "non-physical" parameters of FE model were selected identical to earlier authors work on modelling concrete slab without pre-stressing. The behaviour of Dywidag bars was also examined. FE predictions obtained are in good agreement with tests, showing similar trend for concrete damage patterns at both front and back sides of the slab. Subsequently, it was concluded that FE model developed earlier for slabs without pre-stressing could be successfully used for pre-stressed concrete structures as well.
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