钢管约束钢筋混凝土压弯构件滞回性能试验研究与分析

进行了4个圆钢管约束钢筋混凝土(CTRC)和4个方钢管约束钢筋混凝土(STRC)压弯构件滞回性能的试验研究,并进行了两个钢筋混凝土(RC)对比试件的试验研究。试验中的主要参数为轴压比(0.34、0.65和0.80)和混凝土强度等级(C30和C60)。试验结果表明,由于钢管对核心混凝土的有效约束,核心高强混凝土柱的承载力、延性和耗能能力得到了显著提高。随轴压比和混凝土强度的提高,CTRC压弯构件的受弯承载力提高;但轴压比和混凝土强度对试件的延性无明显影响。随轴压比和混凝土强度的提高,STRC压弯构件的受弯承载力提高,但延性下降。相同轴压比条件下,CTRC压弯构件的受弯承载力和延性明显优于STRC构件。根据试验结果,建议了钢管约束钢筋混凝土柱截面受弯承载力的计算方法。建立了钢管约束钢筋混凝土压弯构件的纤维模型数值计算方法,计算中采用随荷载的增加而不断增大钢管对核心混凝土的约束效应的方法,数值计算结果与试验结果吻合良好。

Seismic behavior of steel tube confined reinforced concrete (RC) beam-columns

The sesimic behavior of steel tube confined RC beam-columns was studied by testing four circular tube confined RC (CTRC) columns, four square tube confined RC (STRC) columns as well as two conventional RC columns under combined constant axial compression and lateral cyclic load. The experimental parameters were axial load ratio (n0=0.34、0.65、0.80) and compressive strength of concrete (C30 and C60). The test results indicate that the steel tube confined RC columns with high axial load ratio exhibite much higher flexural strength, displacement ductility and greater energy dissipation ability than common RC columns in respect of the effective confining effect of the tube to the core concrete. The flexural strength increases as the axial load ratio or concrete compressive strength increases for CTRC columns, while the ductility is barely affected by the increase in axial load or concrete compressive strength. The flexural strength increases as the axial load ratio or concrete compressive strength increases for STRC columns, while the ductility decreases with an increment on axial load or concrete compressive strength. The moment strength and ductility of CTRC columns are higher than that of STRC columns under the condition that the axial load ratio is the same. It was proposed that the flexural strength of the cross-section of CTRC and STRC columns be calculated using the modified ACI code method. Fiber models were developed for the CTRC and STRC beam-columns. The confining effect increasing with an increment on the moment of the cross-section was considered during the fiber model analysis procedure. Excellent agreement was observed between the results from fiber model analysis and the experimental results.