Near‐field blast behavior of ultra‐high‐performance concrete slabs: Parametric analysis and calibration of the UFC ‐3‐340 predictive model

Abstract Blast loads impose extreme, short‐duration pressures that can cause severe structural damage and compromise safety, a crucial aspect in critical infrastructure, including nuclear facilities. Whereas ultra‐high‐performance concrete (UHPC) offers superior blast resistance compared to conventional concrete (CC) and high‐performance concrete (HPC), the parameters underpinning such improved capacity remain insufficiently understood. Existing popular blast‐prediction models (e.g., the U.S. Department of Defense's Unified Facilities Criteria [UFC] 3–340 design guide), derived from CC data, fail to accurately predict UHPC's response to blast. Given the exorbitant cost, potential safety hazards, and limited access to certified blast‐testing facilities, it is imperative to develop reliable blast‐predictive models for UHPC to improve the blast resistance of critical structures. In this study, a 3D finite element model was developed and validated against an existing experimental blast study on UHPC slabs. The validated model was then used to perform a multi‐dimensional parametric analysis on the blast performance of UHPC slabs, considering the compressive strength, tensile capacity, reinforcement grade and ratio, slab thickness, and blast charge mass. Results show that UHPC slabs exhibit significantly enhanced blast resistance, primarily due to UHPC's exceptional tensile properties and fracture energy, while compressive strength plays a limited role. Reinforcement grade and ratio have a strong linear effect on blast resistance, which highlights a critical limitation of existing models that neglect both parameters. An extensive database of simulated blast scenarios was developed and used to calibrate the UFC 3–340 blast prediction model—the most widely referenced model in blast design manuals. This calibration yielded a new model better suited for UHPC slabs, while introducing, for the first time, a parameter that captures the combined effects of reinforcement grade and ratio, thereby establishing a foundation for the efficient design of blast‐resistant UHPC structures.