Dynamic Analysis of Reinforced Concrete Beams on Yielding Supports

Abstract

AbstractBearing structures of buildings and constructions can be subjected to short-term dynamic loads. These loads characterized by high intensity and short duration of action can lead not only to significant damage of structures but also to the death of people. The paper considers one of the methods of active safety of structures based on the use of yielding supports in the form of crushable inserts of an annular section. The use of yielding supports allows to reduce the intensity of the dynamic impact. As a result, the material consumption and labor intensity of the restoration of structures are reduced. The influence of the compliance of the support connections on the dynamic factor of structures and consequently on displacements, forces and stresses is considered. The influence of support compliance on the stress–strain state of structures under short-term dynamic loading is considered by a numerical-analytical method. On the basis of theoretical research an algorithm for dynamic calculation of reinforced concrete beams in a conditionally elastic stage has been developed. The calculation of structures is carried out at various ratios of the stiffness of the structure and the yielding supports, the stages of deformation of the yielding supports and the laws of changing of the dynamical load. Calculations have shown that the use of yielding supports that deforming only in the elastic stage does not lead in all cases to a decrease in the dynamic factor. In this case ranges of values ωΘ may arise for which there is a negative effect of yielding supports on the dynamic factor. The greatest efficiency of the use of yielding supports is achieved when they are deformed in the plastic stage without going into the stage of hardening. The degree of reduction of efforts and displacements is determined by the time of transition of the yielding support from the elastic stage to the plastic one tSY, el.KeywordsEquation of motionReinforced concrete beamDynamic factorYielding supportNatural frequencyShort-term dynamic loadDisplacementsEfforts