Design of impulse loaded concrete structures: a comparison of FKR 2011 with various design regulations

Report, 2017

The Swedish Fortifications Agency has a long history in the design and maintenance of military fortifications and recently published a revised version of their design regulations; FKR 2011. These regulations can be said to represent the traditional Swedish view of the design of impulse loaded concrete structures and differs from the regulations normally used (i.e. Eurocode) for static design in Sweden today. Further, even though many parts of the content of FKR 2011 are similar to that of corresponding regulations in other countries it is not identical. The purpose of this project was to assess different regulations for the design of reinforced concrete structures subjected to impulse loading. The focus was on FKR 2011 and its applicability for some common design criteria. One aim was to compare FKR 2011 with other similar regulations in order to identify similarities and differences to these; and if necessary, recommend possible improvements. Another aim was to provide an improved basis in order to give general recommendations of further investigations that is deemed necessary. The main subjects compared were how the different regulations treated material strength, bending moment, shear and spalling/breaching. The comparisons were made based on the concept/expressions used in the respective regulations, and using several case studies of a simply supported slab strip of different geometry, concrete strength and reinforcement amount. Based on this it was concluded that the concept used for bending stiffness and moment capacity was similar in all the recommendations compared. Further, the method used in FKR for plastic deformation capacity is based on an older, today non-existing, reinforcement type and there is a need of further comparisons of the method used. The concept used in FKR for shear differs much compared with the regulations compared and it is suggested that further development of it should be made. Finally, the concept used for spalling and breaching is deemed to be okay to use.