| Summary: | 碩士 === 國立成功大學 === 土木工程學系碩博士班 === 95 === This research is to compare the behavior of reinforced concrete beams subjected to the combined loading of bending,shear and torsion.
In the experimental work, we extuced ten reinforced concrete beams with the same cross section of 250×350mm. Two types of beam length 1.5 and 2.1m were used. The main variables include the ratio of torsion to bending(T/M), and torsion to shear(T/V) ratios 0, 1/10, 1/8, were used.The specimens of 2.1m length were used for reference.
The main results of our research are:(1) The beams with hollow section subjected to T/M=1/10 had pronounced reduction in ductility, than subjected to T/M=0.(2) Pronounced reduction in ultimate strength was found in specimens having T/M=10. For specimens with hollow section the reduction was about 10.01%.(3) The prediction of cracking strength according to Collin’s theory for hollow section beams is very close to the test result. The flexural cracking strength Mcr decreased as the T/M ratio increased. Both the hollow and solid section beams had the same trend.
(4)Comparing the principal tensile strains in the four sides of a cross section, beams subjected to torsion had higher value which led to easier softening of concrete. It is found as the main reason for specimens subjected to torsion had less flexural ductility.
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