The limit value of plasticity coefficient of reinforcement under seismic loads

Plastic deformations develop in bending reinforced elements under seismic loads. In calculation of concrete constructions by spectral method they are taken into account only at the stage loads determination introduction reducing coefficients. But development plastic strains leads to appearance cracks, which don’t close after changing internal forces sign. Due it work height a section decreases, and strength reduces during subsequent loading cycles. The experimental evaluation influence on stress-strain state beams low-cycle alternating effects high intensity has been carried out. first group beams, considered as reference, was loaded with monotonously increasing load until complete destruction. other groups were monotonically up specified value reached. Then unloaded force opposite sign normal sections all stages studied. It discovered that when through cracks formed later if reinforcement not large. limit plasticity coefficient semi cycle preventing formation non-closing determined.