STUDY ON DRIFT RATIO LIMITS OF 600 MPA GRADE HIGH-STRENGTH STEEL BARS REINFORCED CONCRETE COLUMNS AT DIFFERENT PERFORMANCE LEVELS

Within the context of the performance-based seismic design, the study on drift ratio limits of 600 MPa grade high-strength steel bars reinforced concrete columns is very important to popularize the application of high-strength reinforced concrete columns. The investigation of seismic performance is thusly performed for 17 HTRB630 high-strength steel bars reinforced concrete columns and 3 HRB400 steel bars reinforced concrete columns through quasi-static tests. Compared with the HRB400 steel bars reinforced concrete column, the shape of the hysteresis curve of the HTRB630 high-strength steel bars reinforced concrete column does not change significantly, and the displacement ductility coefficient of the specimen increases. The damage indexes calculated using the Kunnath damage model are compared with the range of damage indexes measured in the test to illustrate that the accuracy of the Kunnath damage model. According to the failure characteristics of HTRB630 high-strength steel bars reinforced concrete columns, the yield point, peak point and limit point are used as the performance level control points of high-strength reinforced concrete columns. Based on the idea of performance-based seismic design, the performance levels of 600 MPa high-strength reinforced concrete columns are divided into five performance levels, namely normal operation performance level, temporary operation performance level, reparable operation performance level, life safety performance level and collapse prevention performance level. Combined with the experimental data of 600 MPa grade high-strength steel bars reinforced concrete columns in the references, the relative frequency statistical analysis is carried out on the drift ratios of each characteristic point of 65 high-strength reinforced concrete columns of 600 MPa grade. The drift ratio limits with more than 90% safety assurance rate at the three performance levels of temporary operation, reparable operation and collapse prevention are 1/150, 1/80 and 1/60, respectively.