Assessment of Dynamic Response of 3D Ultra High Performance Concrete Frame Structure under High Explosion Using Johnson-Holmquist 2 Model

Most of the 3D frame structures are not initially designed to resist blast loads. Due to the limitation of financial resources as well as the complex technical requirements, study the dynamic behavior of 3D frame structure under blast load, particularly for advanced materials like Ultra High Performance Concrete (UHPC), faces many challenges. Therefore, numerical simulation can be a good alternative. The objective of the research is to investigate the dynamic behavior of a UHPC building subjected to blast loading through a 3-D numerical model with the direct simulation of blast load. This building studied in this paper is a real, 6-story office building in Vietnam, which was originally designed for dead load, live load, wind, and earthquake. The building is subjected to surface blast of 500kg Trinitrotoluen (TNT) equivalent charge weight with close-in distance and a variable height of blast source. In this study, Johnson-Holmquist 2 damage model (JH-2) model is implemented to simulate the UHPC structures subjected to blast loading. Base on the theory of the JH-2 model, a subroutine, integrated with Abaqus software, is designed by the authors to calibrate the input parameters of UHPC material. A total of 8 cases of the explosion scenario are considered, in which the design of the original column is revised by using UHPC composite structure in external columns. The results indicate that there is a tremendous increase in response when the blast occurs at the mid-height of the building and the severe damage is observed in the external column in front of the explosion. The obtained result in terms of blast wave pressure during time history as well as peak deflections and damage of building under blast loading is assessed. The blast loading resistance effect of the revised design compared to the original design is also demonstrated as a beneficial alternative in blasting condition.