Behaviour of critical regions of concrete slabs under impulsive loading

An attempt has been made to analyse the local failure of reinforced concrete slabs subjected to soft missile impact by using three-dimensional dynamic finite element analysis in which provision is made for the simulation of impact loads, plasticity and cracking of concrete. An assessment is made for perforation and scabbing.
An attempt has been made to analyse the local failure of reinforced concrete slabs subjected to soft missile impact by using three-dimensional dynamic finite element analysis in which provision is made for the simulation of impact loads, plasticity and cracking of concrete. An assessment is made for perforation and scabbing. Two existing three-dimensional finite element programs are used to carry out the analysis. The program NONSAP is modified to include a four-parameter concrete model based on Ottosen's failure criterion. The reinforcement and concrete are modelled simultaneously by
assuming they act as a composite material. Concrete cracking is modelled based on the smeared crack concept. The Nemnark direct integration scheme is used to carry out the iteration process.
A three-dimensional non-linear dynamic finite element package, MARC is used for comparison. In this analysis the parabolic Mohr-Coulomb yield criterion is adopted to model the concrete while the failure of the reinforcement is predicted using the Von Mises yield criterion. Cracking criteria used by MARC is based on the smeared crack concept. Again the Newmark direction integration scheme is adopted in this analysis.
Two reinforced concrete slabs tested by UKAEA have been examined using the above computer packages and the analytical results are compared with each other and with those of the experiment. Despite slight deviations, the analytical results are in reasonable agreement with those given by experiment.