EXPERIMENTAL STUDY ON THE SEISMIC BEHAVIOR OF RC BEAMS OF LOW SHEAR-SPAN RATIOS SUBJECTED TO FREEZE-THAW CYCLES

An artificial climate simulation laboratory was used to perform an accelerated freeze-thaw cycle test on six reinforced concrete (RC) beam specimens with a shear-span ratio of 2.6, which were then subjected to quasi-static loading. According to the test results, the effects of the freeze-thaw cycles and concrete strength grades on the seismic performance indicators of RC beam specimens such as the failure mode, hysteretic curve, strength, deformation capacity and energy dissipation were analyzed. The results show that after the freeze-thaw cycles, the compressive strength of the concrete decreased, the internal porosity of the concrete became larger, the micro-cracks were increased, and cracks appeared on the surface of the beam specimens. Six beam specimens exhibited a flexure-shear failure mode after the quasi-static test. With the increase in the number of freeze-thaw cycles, the strength and energy dissipation capacity degraded, and ductility first increased slightly and then decreased greatly. With the increase in the concrete strength grade, the degree of damage caused by the freeze-thaw cycle of the beam specimens was reduced, the yield, peak and ultimate strengths of specimens were increased, the energy dissipation capacity was enhanced, and the ductility was not significantly changed.