The analysis of unanchored brms considering a velocity-dependent friction model and soil-structure interaction effects

Abstract

Blast-resistant Modular Buildings (BRMB) are multiple-purpose structures that are used in many different areas including in petrochemical facilities, in blast zones near mining fields, in military industries to shelter personnel, etc. Since these modular buildings are prefabricated and are manufactured off-site, they are cost-effective, have better quality compared to on-site manufactured structures, and are built within the construction schedule. Due to the mentioned reasons, they have become more popular, recently. Although extensive studies regarding the dynamic behavior of these buildings have been done over time, there are still gaps that need to be filled. Especially, regarding the unanchored modular buildings since they are relatively a recent trend. The modular buildings which are not anchored to the foundation are more cost-effective in comparison to the typically anchored modular buildings because the anchorage to the foundation requires costly installation of anchorages and building of larger foundations. Additionally, the maximum deflection demands for the structural members of the unanchored buildings are significantly smaller. In this study, the behavior of an un-anchored blast-resistant modular building under blast loads has been studied for two different cases: In the first case, the blast-resistant modular building is placed on a reinforced concrete foundation, un-anchored and freely sliding. In this case, the response of the building is calculated using a relative-velocity-dependent friction model which is based on the Stribeck curve. For a realistically representative friction model to be used in this case, a review of the existing static and dynamic friction models is carried out. In the second case, the behavior of a blast-resistant modular building is studied with the effects of the soil-structure interaction being included. In this case, the building is placed directly on silty-sand soil. The soil-structure interaction effects are calculated in the time domain using dynamic impedance functions which were proposed by Pais and Kausel (1988). Additionally, the accelerations and forces impacting the inhabitants of the BRMB have been calculated for a test dummy assumed to be positioned in the building using the provisions in the literature regarding human injury criteria. In this part, a brief description of the head injury criteria, the neck injury criteria, the chest, and femur injury criteria is provided according to the existent literature on the topic and later the calculations are carried out. The results of the first and second cases and the human response are later validated against the results of a series of blast tests. The comparisons of the test results and the calculated results seem to be approximate enough, in order for the methods which are used in this study to be verified.