高性能水泥复合砂浆钢筋网薄层二次受力加固RC偏压柱试验及承载力计算方法研究

采用自主研发的工作性能良好的柱二次受力加固试验装置，对4根近似足尺偏压柱进行了用高性能水泥复合砂浆钢筋网薄层（HPFL）作二次受力加固的试验测试，将其试验结果与同参数的未加固柱和一次受力加固柱试验结果进行了比较和分析，研究了二次受力加固前应力水平指标β（定义为加固前柱所受轴向荷载与理论轴向极限荷载之比）对加固柱承载力、延性、刚度以及开裂模式的影响规律，并进行了徐变影响分析。结果表明,β越小，其承载力提高幅度越大，当β≤0.7时，二次受力加固柱比一次受力加固柱的延性改善效果更好，但对刚度的改善效果不明显。在试验研究和理论分析的基础上，建立的加固柱承载力计算式明确反应了HPFL加固层的工作机制，对二次受力加固柱中加固层比原柱应变滞后问题有具体反应，计算值与实测值符合程度较高。提出的加固构造措施能保证加固层充分有效工作。

Experimental investigation and research on calculation method of load-carrying capacity for eccentrically compressed RC columns strengthened by high performance ferrocement laminates under twice loading

This research developed the test setup for the twice-loading for columns strengthening. With which four approximately full-size eccentric columns strengthened by high performance ferrocement laminates (HPFL) under twice loading were tested. The test results were compared and analyzed with the columns without strengthening as well as one-time-loading strengthened ones with the same test parameters. The influences of the stress level factor β（the ratio of the actual axial load and theoretical ultimate axial load of the column before strengthening）before twice-loading strengthening on the load-bearing capacity, ductility, stiffness, cracking mode of the strengthened columns were researched, the creeping influence of the test columns during test process was analyzed. The results show that the smaller β is, the higher the increase of load-bearing capacity is. When β≤0.7, the ductility improvement effect of twice-loading strengthening columns is more obvious than that of one-time-loading strengthening columns, while the stiffness improvement effect isn't distinct. Based on the experimental investigation and theoretical analysis, the formulas were concluded for calculating the load-bearing capacity, which explicitly reflected the work mechanism of the HPFL strengthening jacket and also concretely reflected the problem of strain lag of strengthening jacket from the column. The calculated values by the formulas agreed well with the test values. The corresponding strengthening construction measures proposed can ensure the effective function of strengthening jacket.