DYNAMIC CALCULATION OF REINFORCED CONCRETE BEAMS ON YIELDING SUPPORT BEYOND THE LIMITS OF ELASTICITY

Protective structures of civil defense are designed from the condition of perception of short-term dynamic loads. In this case, the supporting structures can be deformed in the plastic stage. To reduce the forces and displacements of the bearing elements under intense dynamic loading, the active methods of protecting structures are used. The flexible supports in the form of collapsible inserts of annular section is one of such methods. The paper considers the change in displacements and forces of the elastic-plastic reinforced concrete beams, depending on the compliance of support fastenings. Based on the theoretical studies, an algorithm for the dynamic calculation of reinforced concrete beams with cracks was developed, with which the calculation of structures was performed under various conditions of deformation of yielding supports. The calculations showed that the use of yielding supports deformed only in the elastic stage can have both a positive and a negative effect on the operation of structures. In this case, there may be the areas of ωθ values in which there is an increase in the dynamic coefficient of the structure on yielding supports relative to the beams on non-displaceable supports. The greatest efficiency of using the yielding supports is achieved when they work at the plastic stage without transition to the hardening stage.