Steel grades for reinforced concrete have been adjusted
(1) Include 500 MPa steel bar. Considering the actual demand of 500 MPa grade steel bar application, on the basis of a large number of experimental research and pilot project application, 500 MPa grade 500 MPa is included in the Design Code for the first time, and detailed requirements are put forward for its design calculation and reinforcement structure. However, considering the lack of relevant test data, the fatigue design parameters of 500 MPa steel bars have not been included.
(2) Include fine grain reinforced bar. On the basis of previous material and structure studies, three kinds of fine grain reinforced bars, HRBF335. HRBF400 and HRBF500, were included. However, considering the actual problem of welding fine grain steel bar, the Code of Design proposes that the welding of fine grain steel bar should be determined by test.
(3)以HPB300鋼筋替代HPB235鋼筋。根據標準《鋼筋混凝土用鋼 第1部分：熱軋光圓鋼筋》( GB 1499. 1-2008)的規定，考慮到推廣高強鋼筋的需要，建筑工程中淘汰HPB235光圓鋼筋，全面推廣應用HPB300鋼筋。
(3) Replace HPB235 steel bar with HPB300 steel bar. According to the national standard "Steel for Reinforced Concrete Part 1: Hot Rolled Round Reinforcement Bar" (GB 1499.1-2008), considering the need to promote high-strength reinforcement, HPB235 round reinforcement bars were eliminated in construction projects, and HPB300 reinforcing bars were comprehensively promoted and applied.
(4)保留了RRB400鋼筋?！对O計規范》保留了RRB400鋼筋品種，但規定不宜焊接?？衫斫鉃榇虽摻罴礊樾滦抻喌摹朵摻罨炷劣糜酂崽幚礓摻睢? GB 13014-1991)中的不可焊余熱處理鋼筋RRB400，RRB400W鋼筋雖未列入，但如有可靠焊接依據，也可應用。HRB500鋼筋由于（GB 13014-1991）產品標準修訂未及時完成，暫未納入。
(4) RRB400 reinforcing bar was retained. The RRB400 steel bar is retained in the Design Code, but it is not suitable for welding. It can be understood that the reinforcing steel bar is RRB400, which is a non-weldable waste heat treatment reinforcing steel bar in the newly revised GB 13014-1991. Although RRB400W reinforcing steel bar is not included, it can also be applied if there is reliable welding basis. HRB500 reinforcing bar has not been included in the revised product standard (GB 13014-1991).
Note: 1. For stirrups used for calculating shear, torsion and punching shear capacity, the tensile design strength FYV is chosen according to the value of fy, but its value should be smaller than 360N/mm2:
2. As indirect reinforcement for local compression and stirrups for confined coagulation of compressive members, the tensile design strength FY is selected according to the values in the table.
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