TY JOUR TI EVALUATION OF THE CROSS-SECTION AREA OF WORKING REINFORCEMENT IN CONCRETE BEAMS BY THE VIBRATION TESTING RESULTS KW cross-sectional area of the working reinforcement KW main frequency KW longitudinal vibrations KW transverse vibrations KW reinforced concrete beam JO Bulletin of Belgorod State Technological University named after. V. G. Shukhov AU Abashin, E.G. PY 2018 IS 3 PB Belgorod State Technological University named after V.G. Shukhov