# Numerical Identification of Material Model Parameters of UHPFRC Slab under Blast Loading
The effects of blast and penetration as prevailing sources of material and structural damage to the elements of protective structures and infrastructure are investigated in [31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46]. Concrete structural elements are experimentally tested to the dynamic loading and subsequently modelled using a variety of material models implemented into the software environment of hydrocodes. Both during the testing and modelling, a large volume of datasets is obtained and further analysed. In [31; 32], the deflection was selected as a parameter that is used to assess the behaviour of concrete elements under blast load while considering scaling as a factor influencing the results [31; 33]. Among other parameters that are frequently examined because they alter the behaviour of concrete specimens is the thickness of panels [34]. Another factor that is closely observed is the spalling [35], especially when using RC for protective structures, as the spalls could have a negative secondary impact on the sheltered personnel. Concrete as a composite material offers almost endless possibilities in adding different components into the concrete mixture and thus influencing its properties. In [36], the polyurea is added to increase blast resistance of the specimens. During the modelling phase, the focus is on the different parameters to make the process more reliable and accurate [37; 38]. Large attention is dedicated to the material models themselves with the aim of improving their material properties and structural behaviour under blast loading [39; 40; 41]. The comparison of material models and their behaviour using the program ABAQUS/Explicit and the hydrocode AUTODYN is investigated in [42]. [PERSON] et al. [43] are focused on the simulation of the fragment creation of concrete slabs and their comparison with data from experiments. [PERSON] et al. [44] extensively review the field of transient dynamics of concrete under blast load from several point of views, whilst the paper [45] closely investigates parameters such as thickness of the specimen and weight of the charge. In this paper, the Winfrith concrete material model is employed, but other models are also used and tested [46] to achieve the highest possible level of accuracy in the numerical simulation to precisely predict the behaviour of the concrete elements under blast load. As the aim of this work is the numerical calibration of the concrete material model according to the experimental results of blast loading of the Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) slab, the state-of-the-art review of research dealing with experimental and numerical assessments of the concrete structural elements under blast loading using constitutive concrete material models implemented into the software environment LS-Dyna [38; 39], has shown the necessity of carrying out material testing of used concrete composite [44; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54], the experimental measurements of response of the specimen under blast loading [29; 31; 40] and the connection of the material model parameters obtained from the inverse identification with the creation of the computational model [27; 40; 45]. Results presented in this paper, together with work of the authors, aim to enable and improve the assessment of the response of blast loaded structures and structural elements used for building protective [33] and UHPFRC structures of critical infrastructure, as well as other civilian and industrial objects that can be intentionally targeted [16].