Is the third-grade seismic reinforcement equipped with E?

All seismic steel bars are marked with E, which is a sign of earthquake resistance.

5.2.2 For structures with seismic fortification requirements, the strength of longitudinal reinforcement shall meet the design requirements; When there are no specific requirements in the design, the frames and diagonal bracing members (including ladder sections) designed according to the first, second and third levels of earthquake resistance shall adopt HRB335E, HRB400E, HRB500E, HRB335e, HRB400e or HRB500e steel bars, and the measured values of the maximum strength and total elongation 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 than1.25;

2 The ratio of the measured yield strength of reinforcement to the standard strength value should not be greater than 1.30.

3. The total elongation of reinforcement under the maximum stress should not be less than 9%.

Extended data:

GB1499.2-2007–2007 "Steel for Reinforced Concrete Part 2: Hot Rolled Ribbed Reinforcement" issued by AQSIQ and National Standardization Committee. It is clearly stipulated in the standard that the sign of seismic strengthening is to add "e" after the brand of seismic structure with high requirements, such as HRB400E and HRB500E. "E" is the first letter of the English word earthquake, which means that steel has reached the "seismic" standard promulgated by the state.

However, judging from the three requirements of the new standard for seismic strengthening, the technical indicators are mainly aimed at the measured values of steel bar strength and elongation.

For example, the first regulation stipulates that seismic reinforcement should bear more than 25% tension from yield to tensile failure; The second is to ensure that the dispersion of yield strength of steel bars will not be too large, which will affect the effect of structural ductility requirements in design; Article 3 The maximum total elongation of ordinary steel bars shall be increased from not less than 7.5% to not less than 9%. With the improvement of these technical indexes, the seismic capacity of steel bars is enhanced, and structural members have better ductility under the action of seismic force.

Therefore, the essential difference between seismic steel bars and ordinary steel bars is to make steel bars have better ductility, so as to better ensure that important structural members have sufficient plastic deformation capacity and energy consumption capacity during earthquakes.

References:

Baidu encyclopedia-seismic reinforcement