Blast performance of ultra-high performance concrete panels under intermediate-to-far-field explosive loading

In order to study the blast performance of ultra-high performance concrete (UHPC) panels under intermedium-to-far-field explosion loading, a series of field blast tests were conducted to systematically analyze the influence of scaled blast distances on the failure modes of the specimens. To evaluate the dynamic response of the panels, post-blast and residual strength were investigated through four-point bending tests. To understand the dynamic response mechanism, an equivalent single-degree-of-freedom (SDOF) model was established to predict the mid-span peak deflection under different scaled blast distances. Finite element simulations of the UHPC panels under blast loading were performed using the continuous surface cap (CSC) model to further explore the failure mechanism. Considering uncertainties in material mechanical properties, a stochastic finite element model was developed by introducing a Gaussian autocorrelated spatial random field. The results indicate that UHPC panels maintain structural integrity under intermedium-to-far-field explosion, exhibiting a typical flexural damage mode; damage on the back surface is concentrated in the mid-span region. As the scaled blast distance increased, the extent of damage in the UHPC panels decreased significantly. The deterministic finite element model accurately predicted the blast response of the UHPC panel. The analysis showed that the SDOF method provided accurate predictions of mid-span peak deflection though it tended to overestimate deflection in cases of minor damage where significant plastic deformation did not occur. The random finite element model, by incorporating Gaussian auto-correlated random fields, accounted for the uncertainty in mechanical properties of the material and demonstrated superior simulation results. An increase in the compressive strength of UHPC gradually reduces the mid-span peak deflection, highlighting the effect of material strength on panel deformation. Furthermore, when the auto-correlation length of the random field is within the range of 10 mm to 20 mm, the damage characteristics predicted by the model are highly consistent with the actual observations. This study verifies the excellent blast resistance of UHPC under intermedium-to-far-range explosions, demonstrates the effectiveness of the random finite element model, and reveals the significant influence of material variability on the blast resistance assessment of UHPC structures.