@phdthesis{,
    author = {Xiao, Weifang },
    title = {Experimental and Numerical Investigations on the Effectiveness of Protective Barriers against Air Blast},
    editor = {},
    booktitle = {},
    series = {},
    journal = {},
    address = {},
    publisher = {},
    edition = {},
    year = {2019},
    isbn = {},
    volume = {},
    number =  {},
    pages = {},
    url = {},
    doi = {},
    keywords = {Protective barriers; Air blast; Shock wave attenuation; Overpressure; Impulse; Canopy; Steel posts; Arbitrary-Lagrangian-Eulerian (ALE)},
    abstract = {Protective barriers are often proposed in order to protect buildings and their properties against air blast. On the one hand, they act as stand-off barriers, on the other hand as obstacles in the propagation path of the shock wave. If properly designed, they can also act as barriers in order to stop vehicles. This Dissertation analyses experimentally and numerically the effectiveness of protective barriers in attenuating the shock wave. While the distribution of blast loads from explosions in the free field is well understood, only limited information is available on the blast loads behind non-conventional walls or barriers, especially if the wall or parts of it do not behave rigidly or if the barrier has a surface containing openings. In this context, two different types of protective barriers are investigated, i.e. blast walls with a canopy on top and protective barriers made of steel posts. New experimental results of these protective barriers are provided, i.e. the overpressure-time histories at the gauges both in front of and behind the barriers. Numerical simulations using the software LS-DYNA are performed to complement and / or to substitute the experiments. Prior to the experiments, numerical models are developed in order to predict the blast loads numerically. The numerical simulations use the approach proposed by Slavik to couple empirical blast loads to Arbitrary-Lagrangian-Eulerian (ALE) air domains. The numerical simulation is subdivided into two stages. In the first stage, the empirical formulae of Kingery and Bulmash are used to calculate the blast loads on a layer of ambient ALE air elements, which is situated at the front face of the air domain facing the charge. The front face of the air domain is located 2m in front of the barrier. In the second stage, the shock wave propagation is simulated by using the ALE formulation with a multi-material option, where the results from the first stage are used as input for the ambient ALE air elements. Applying this coupled approach combines the advantages of both the empirical method and the ALE method. For blast walls with a canopy, the solid blast wall is considered as a rigid body. The canopy is modelled applying two assumptions: firstly as a rigid structure, secondly as a flexible bending plate. For protective barriers made of steel posts, the steel posts are modelled with two assumptions: firstly as rigid structures, secondly as flexible structures. Using the Fluid-Structure-Interaction (FSI), the shock wave and the barrier are coupled in the numerical analysis. The coupling algorithm of FSI utilizes the ALE air mesh to derive the dynamic forces on the barrier. Meanwhile, the barrier provides a dynamic constraint to the shock wave propagating through the air domain. The influence of the structural flexibility on the blast load distribution behind the barriers is investigated by comparing the numerical results based on the rigid and flexible assumptions. The experimental data is used to validate the developed numerical models. After validation, they are applied to carry out parametric studies in order to explore the influence of further parameters of the barriers on the shock wave attenuation performance. Based on the overpressure-time histories at the gauges, both the peak overpressures and the maximum impulses can be calculated. They are employed to estimate the effectiveness of protective barriers by means of overpressure and impulse reduction factors. This research contributes to the blast-resistant design of blast walls with a canopy and protective barriers made of steel posts.},
    note = {},
    
    school = {Universität der Bundeswehr München},
    
}