### Significance

Have you ever wondered how buildings are designed to withstand impacts, like a car crashing into them or a boat colliding with a bridge? Well, engineers use a lot of complicated math and computer simulations to figure out how strong a building needs to be and how it will behave under different types of stress. Simulating the impact loading of reinforced concrete structures involves using computer models to replicate the effects of sudden loads, such as those resulting from explosions or vehicle collisions, on concrete structures. This simulation process allows engineers to analyze the behavior of the structure under extreme loading conditions, such as the formation of cracks, shear failure, or collapse.

There are various methods used to simulate impact loading, such as finite element analysis (FEA), computational fluid dynamics (CFD), and empirical models. FEA is a widely used method that divides the structure into small elements and solves equations to predict the response of each element under load. CFD is used to analyze the fluid flow around the structure, which can help predict the pressure and force exerted on the structure during an impact. Empirical models, on the other hand, use experimental data to develop mathematical relationships that can be used to predict the behavior of the structure under impact loading.

To test the strength of these buildings under impact, the researchers used two different computer programs: LS-DYNA and VecTor2. LS-DYNA is a program that can simulate how an impact will affect a building by analyzing things like the force and speed of the impact, the shape of the object hitting the building, and the materials that the building is made of. VecTor2, on the other hand, is a program that can create a detailed model of the building and how it’s put together. The researchers wanted to combine these two programs so that they could get a more accurate picture of how a building would behave under impact loading. However, there was one obstacle: the two programs were for different shapes and sizes. LS-DYNA works in three dimensions (meaning it can create models of things in three-dimensional space), while VecTor2 only works in two dimensions. To get around this problem, the authors came up with an inovative way to connect the two programs using a special communication protocol. This protocol allowed the two programs to exchange information with each other during the simulation so that they could work together seamlessly.

Once they had the two programs working together, the authors tested their method by simulating a vehicle-bridge head-on collision. They found that using just LS-DYNA to model the impact could overestimate the crashworthiness of the reinforced concrete structure. However, when they combined LS-DYNA with VecTor2, they were able to get a much more accurate picture of how the building would behave under impact loading.

So, why is this important? Well, there are a lot of situations where engineers need to know how strong a building needs to be to withstand impacts. For example, if you’re building a bridge, you need to know how it will hold up if a boat collides with it. If you’re designing a parking garage, you need to know how it will hold up if a car crashes into one of the support columns. By using computer simulations like the ones used in this study, engineers can design buildings that are stronger and safer for everyone.

Overall, the research team presented a new method for simulating the impact loading of reinforced concrete structures. By combining two different computer programs, the researchers were able to get a more accurate picture of how these structures would behave under stress. While this may sound complicated, the end result is that engineers can design buildings that are safer and more resilient in the face of unexpected events.

Wei FAN, Professor of Hunan University, deputy director of the Department of bridge engineering, deputy director of the Key Laboratory of building safety and energy conservation of the Ministry of education, deputy director of the Hunan Provincial Key Laboratory of wind engineering and bridge engineering, young editorial board member of China Journal of highways, etc. He has been committed to the research of bridge structures against impact and vibration loads for over fifteen years and has published over 60 papers (about 50 SCI-indexed papers, H-index=22). His research outcomings have been gradually applied to engineering practices.

Zhengwu Zhong, PhD student of Hunan University, his recent research interests primarily lie in the field of impact engineering of bridge. To date, he has published three articles.

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Dr. Xu Huang is currently a research associate in the Construction Research Centre at the National Research Council, Canada. Dr. Huang received his Bachelor of Engineering and Master of Science degrees from Hunan University, China, in 2009 and 2012, respectively. He earned his second Master’s degree and Ph.D. degree from the University of Toronto in 2012 and 2019, respectively. He developed a generalized integrated simulation framework (UT-SIM: www.ut-sim.ca) that allowed pseudo-dynamic hybrid simulations, as well as coupling of dynamic systems modelled with different software. The framework has been used by various institutions in Canada, the U.S., South Korea, China, and several European countries. His research interests include performance assessment of structural systems against natural hazards, finite element modelling, and structural health monitoring. He has published 29 academic papers including 20 peer-reviewed journal papers and 9 conference papers.

Wenbiao Sun, PhD student of Hunan University, his research focuses on the study of impact resistance and protection of bridge structures. To date, he has published about 10 research papers.

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Wei Mao, earned master degree in Civil Engineering from Hunan University in 2021. Her research focuses on impact engineering with hybrid simulation method. To date, she has published two articles.

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### Reference

Wei Fan, Zhengwu Zhong, Xu Huang, Wenbiao Sun, Wei Mao, Multi-platform simulation of reinforced concrete structures under impact loading. Engineering Structures (2022), 266, 2022,114523.