TY JOUR TI CRACKING WIDTH OF REINFORCED CONCRETE BEAMS TRAPEZOIDAL CROSS SECTION KW crack opening width KW reinforced concrete KW bending reinforced concrete element KW trapezoidal section KW experiment JO Bulletin of Belgorod State Technological University named after. V. G. Shukhov AU Obernikhin, D.V. AU Nikulin, A.I. PY 2022 IS 7 PB Belgorod State Technological University named after V.G. Shukhov