Because HRB500E (steel bar with "e")

The (strength-to-yield ratio) of reinforcement shall not be less than 1. 25. After plastic deformation or plastic hinge occurs in a certain part of the structure, the steel bar has the necessary strength under the condition of large deformation to ensure the basic seismic bearing capacity of the component; (Yield) should not be greater than 1. 3. It ensures that the design requirements of "strong column and weak beam" and "strong shear and weak bending" will not be disturbed by excessive dispersion of yield strength of steel bars; (elongation) should not be less than 9%, to ensure that the steel bar has sufficient plastic deformation capacity under the condition of large earthquake deformation.

Therefore, "E" brand steel bars are suitable for concrete structures with high seismic ductility requirements.

(Seismic grade I, II and III, beams, columns and supports of frame structure, edge members of shear wall).

1 1.2.3 For frames and braced members designed according to the first, second and third seismic grades, the longitudinal stress of ordinary steel bars shall meet the following requirements:

1 The ratio between the measured tensile strength and the measured yield strength of steel bars should not be less than 1. 25;

2 The ratio of the measured yield strength of steel bars to the standard yield strength should not be greater than 1. 30;

3 The measured total elongation of steel bars under the maximum tension should not be less than 9%.

"Other requirements in Article 7.3.3 are the same as the corresponding existing steel grade reinforcement." The strength index and elastic modulus of the reinforcement with "E" are the same as those of the same brand of hot-rolled ribbed reinforcement without "E".

References:

Code for design of concrete structures GB 50010-2010 (2015)? 、《? Steel for reinforced concrete Part 2: Hot rolled ribbed bars GB 1499.2-2007