Design guidelines and optimization of ultra-high-performance fibre-reinforced concrete blast protection wall panels

Ultra-high-performance fibre-reinforced concrete is the latest generation of structural concrete, having outstanding fresh and hardened properties; this includes the ease of placement and consolidation with ultra-high mechanical properties, as well as toughness, volume stability, durability, higher flexural and tensile strength, and ductility. As more research is being focused on it, the material behaviour and characteristics are getting more understood, and the research demand for the special applications of the ultra-high-performance fibre-reinforced concrete is growing higher. One special application that ultra-high-performance fibre-reinforced concrete is thought to have an outstanding performance at is in the field of protective structures, specifically against blast loads. This article presents part of a study that is concerned with the behaviour and response of ultra-high-performance fibre-reinforced concrete wall panels under blast load. Size and shape optimization techniques were combined in this study to optimize the design of a 200-MPa ultra-high-performance fibre-reinforced concrete under blast loads using finite element modelling. This design optimization aims to maximize stiffness and minimize the cost while satisfying both design stresses and construction requirements. The design variable to be optimized for are the thickness ranging from 100 to 300 mm at 25 mm increments, in addition to the reinforcement ratio of 0%, 0.2%, 1% and 3%, and aspect ratio of 1, 1.5 and 2; the boundary condition is four edges fixed and restrained. The numerical simulation has been performed using an explicate finite element software package. The complete behaviour of an ultra-high-performance fibre-reinforced concrete is defined using the concrete damaged plasticity model. The concrete constitutive model has been developed considering the contribution of tensile hardening response, fracture energy and crack-band width approaches to accurately represent the tensile behaviour and guarantee mesh independence of results. The blast load is applied using the Conventional Weapons method of the US Army Corps of Engineers that is readily available in the finite element software. The validity of the numerical model used is verified by comparing numerical results to experimental data.