EXPERIMENTAL STUDY ON MOMENT REDISTRIBUTION IN REINFORCED CONCRETE CONTINUOUS BEAMS WITH HRB500/HRB600 STEEL BARS

HRB500 and HRB600 steel bars have been adopted by ‘Code for design of concrete structures’ (GB 50010-2010) and ‘Steel for the reinforcement of concrete-Part 2: Hot rolled ribbed bars’ (GB/T 1499.2-2018). In order to investigate the moment redistribution in continuous reinforced concrete beams with HRB500 and HRB600 steel bars as tensile longitudinal bars, 24 two-span continuous beams were tested in this study. The test results showed that the moment redistribution occurred not only after the formation of plastic hinge but in the process from plastic development of the tensile concrete to the formation of the plastic hinge. The moment redistribution was investigated in two stages, namely, before and after the appearance of the plastic hinge. The first-stage moment redistribution (β_I) was between 15.28%~24.21% and the second-stage moment redistribution (β_Ⅱ) was between 6.91%~30.3%. It was found that the increase in the yield strength of tensile longitudinal steel bars led to an increase in β_I but a decrease in β_Ⅱ. Moreover,β_I and β_Ⅱ increased with the increase in the width of the mid-support and the decrease in the relative depth of the compressive zone. Formulas for the moment redistribution of two stages considering the effects of the key factors were proposed based on the test results.