EXPERIMENT STUDY ON FLEXURAL AND TORSION PROPERTIES OF STEEL REINFORCED CONCRETE BEAMS

In order to study the mechanic properties of steel reinforced concrete beams under flexural-torsional condition, the monotonic loading tests of 12 steel reinforced concrete beams and 1 reinforced concrete beam were conducted. The failure patterns and torque-torsion ratio curves were studied and damage evolution was analyzed under bending and torsion. The results showed that the entire process of load-bearing in all specimens under bending and torsion could be divided into three stages which were elastic, elasto-plastic and failure stages. The smaller torsion-bending ratio were, the earlier the cracks appeared in the solid-web steel reinforced concrete beams. Stirrup ratio had no significant effect on the increase of cracking torque. The failure patterns of angle steel truss reinforced concrete beams had two types:failure with flexural feature and failure with torsional feature. Before cracking, the torsional resistance performance of the specimens under bending and torsion depended not only on the tensile strength of the concrete, but also on the torsional rigidity of the steel. The damage degree of specimens also presented three stage features, and the damage degree of reinforced concrete beams was larger than that of steel reinforced concrete beams. The influence of concrete strength on the later damage of the specimen was very small. With the increase of the Ι-steel model, the constraint on the surrounding concrete became smaller and more unfavorable to torsion.