| The crack behavior of concrete bending members with HRB400 steel is experimental studied in this paper. HRB400 steel bar, which is called new Gradeâ…¢steel bar, has been defined the leading steel bar using in building structures by Code for design of concrete structures(GBJ 5002-2002). It has been used widely in these years. HRB400 steel bar is characterized by high parity between strength and price, good ductility and welding quality. It can meet the requirement that high building should use high stress steel bars. By now, few studies are made of the HRB400 reinforced concrete members. Study in this paper can provided theoretic and testing bases for the application.According to test of 6 HRB400 reinforced concrete beams and a HRB335 reinforced concrete beam, the flexural strength of members with different ratio are studied, and the crack and deflection behaviors under the state of serviceability are analyzed. The developments, the fracture intervals and the width of cracks have been observed. The testing results indicated that the HRB400 reinforced concrete members worked well and members have obvious failure marks.The bend behaviors of concrete banding members with HRB400 steel can meet the requirements of the Code. The formula in Code can be used to estimate the width, space between cracks and the deflection. The statistics of crack widths and fracture intervals can satisfy normal distribution. Compared the limitation of crack width of different Codes, suggestion is made that the limitation of Code for design of concrete structure should be broadened.By the vibration tests, the dynamic property before and after the damage obtained in statics tests is tested and analyzed. Testing results indicated that in the state of serviceability, the members'natural frequencies and dynamic-stiffness are descent because of damage. And the degree of damage can be detected by the descent degree of natural frequencies and dynamic-stiffness.
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