Experimental Studies On Seismic Behavior Of HRB500 RC Columns

Now there is great demand for steel construction industry, so in order to keep economic continued developing and save resources, The high-strength reinforced HRB500 is made. The high-strength reinforced have advantage of enforcing specimen's strength, decreasing the amount of reinforced and reducing specimen's sectional dimension and so on, but it also have some questions, for example,the ultimate deformation is large. Moreover the non-prestressed reinforced strength of reinforced concrete structure which used in general in China is relatively low compared with that of the developed countries. It is necessary to kown the mechanical behavior of reinforced concrete specimens with HRB500 reinforced for bringing it into specification and promoting its'application in the actural project.In the specifications on detailing of stirrups and Minimum Hoop Characteristic Factors in column hoop densified regions, there exists large difference between Chinese Codes and related codes of other countries. So it is necessary to check the seismic behaviors of columns with different transverse reinforcement schemes in different codes. Moreover, it is also needed to verify the seismic behaviors of columns, designed by Chinese Codes, using HRB500 bars with a higher strength as longitudinal reinforcements. Cyclic loading tests of 9 RC column specimens reinforced with HRB500 steel bar were conducted. The test parameters included the transverse reinforcement ratio, hoop characteristic value, stirrup strength and arrangement of stirrups. The effects of these parameters on the failure mechanism, load-deflection hysteretic-curve, ductility, stiffness degradation and energy-dissipating capacity are analyzed. Different behaviors between the columns with HRB500 bars and those with HRB335 bars are discussed, with other parameters remaining the same.Experimental results show that:①Compared with codes of other countries in the specifications on detailing of stirrups and Minimum Hoop Characteristic Factors in column hoop densified regions, the limit value of hoop characteristic value of Chinese codes is lower,especiclly when axial compression ratio is higher.②The specimens which have high reinfoceing steel indexes own higher ductility, improve its'capacity degradation apparently and have better seismic behaviors.③For HRB500 reinforced concrete column, the specimen with composite stirrups have better ductility compared with the specimen with ordinary stirrups when their reinfoceing steel indexes about the same.④Compared the specimen of""shape closed composite stirrups with the specimen of""shape composite stirrups with tie wire, we can find that there are not apparently difference in the factor of seismic behaviors which conclude hysteretic curve,hysteretic energy dissipation,stiffness degradation and so on.⑤Though the reinforced concrete columns with HRB500reinforced has influence on their ductility, it can satisfied the requirements of deformation and ductility. .