高强箍筋约束混凝土柱抗震性能和累积损伤分析

Seismic Performance and Cumulative Damage Analysis of Concrete Columns Confined by High-Strength Stirrups

损伤指标可以量化结构或构件在地震作用下的损伤程度,为震后结构损伤评估及结构抗震设计提供重要的理论依据。因此,开展了15个配置高强箍筋的约束混凝土柱抗震性能试验研究和累积损伤分析。试验结果表明:达到峰值点时,约束箍筋尚未屈服,约束箍筋拉应力为屈服强度的56%~91%,达到极限位移时,约束箍筋屈服但仍未被拉断;配置高强箍筋的约束混凝土在整个受力过程中展现出良好的承载力和变形能力。针对混凝土强度等级为C50、配置HRB500纵筋的高强箍筋约束混凝土柱,不同损伤模型的计算结果与试验结果表明:Chai模型能够较为准确地预测损伤程度。对于剪跨比为3、配筋率和配箍率较大的试件,在轻微破坏和中等破坏阶段,Kunnath模型计算的损伤指数稍微偏小。付国模型在各阶段均能较好地预测损伤程度,但损伤指数计算值大于1,计算结果不收敛。剪跨比较大的约束混凝土柱会降低其损伤发展速度,轴压比的增加会加剧约束混凝土的损伤程度。高配筋率和高体积配箍率的约束混凝土柱损伤发展速度较慢,相同循环次数下,损伤程度较低。在约束混凝土柱设计中,可通过合理配置纵向钢筋和约束箍筋,降低和延缓约束混凝土柱的累积损伤。

The damage index can quantify the damage degree of structures and components under earthquake,and provide an important theoretical basis for the post-seismic damage assessment and design of structures.For this reason,this paper conducted on the experiments of seismic performance and cumulative damage analysis about 15 concrete columns confined by high-strength stirrups.The test results showed that the stirrup did not yield at the peak point and the tensile stress of stirrup was 56%–91%of the yield strength.The stirrup could yield at the ultimate displacement but did not break.The concrete columns confined by high-strength stirrups showed good bearing capacity and deformation capacity in the whole loading process.For concrete columns confined by high-strength stirrups whose concrete grade is C50 and longitudinal reinforcement strength grade is HRB500,the comparison between calculated results of different damage models and test results showed that the Chai model could accurately predict the damage degree.For specimens with a shear-span ratio of 3,larger reinforcement ratio and stirrup ratio,the damage index calculated by Kunnath model was slightly smaller at the stage of minor damage and moderate failure.The Fu model could predict the damage degree of confined concrete columns at five stages,but the calculated values were greater than 1 and did not converge.Confined concrete columns with larger shear-span ratio would decrease the development rate of damage,and the increase in axial compression ratio would aggravate the damage degree of confined concrete columns.With high reinforcement ratio and stirrup ratio,the damage development rate was slower and the damage degree was relatively lower with the same cyclic times.In the stirrup design of confined concrete columns,the cumulative damage can be decreased and delayed based on a rational configuration of longitudinal rebar sand stirrups.