自密实混凝土增大截面加固RC梁后可靠指标提高量分析

Analysis on Improvement of Reliability Index of RC Beams after Section-Enlarging Reinforcing with Self-compacting Concrete

为了探究自密实混凝土增大截面加固后可靠指标的提高量,依托RC简支T梁加固试验,建立了自密实混凝土加固前后的承载力模型,基于误差传递公式算出抗力的均值和方差,考虑材料特性、几何参数以及计算模式不确定性,通过JC法确定梁加固前后的可靠指标,讨论了持荷工况以及加固厚度对可靠指标的影响。结果表明:加固厚度相同时,持荷工况越小,可靠指标提升越大;持荷工况相同时,加固厚度的改变对可靠指标的变化较小。加固厚度为100 mm的梁的可靠指标比加固厚度为60 mm的加固梁的可靠指标提高量小于5%。

In order to explore the improvement of the reliability index of self-compacting concrete after section-enlarging reinforcing,the bearing capacity model of self-compacting concrete before and after reinforcement was established based on reinforcement test of simply-supported reinforced concrete T-beam.Using error transfer formula to calculate the mean and variance of resistance and considering uncertainties in material properties,geometric parameters and calculation models,the reliability index before and after the reinforcement was calculated through JC method,and the influence of sustained load conditions and the thickness of reinforcement on the reliability index were discussed.The results show that the lower the sustained load is,the greater the reliability index will be when the thickness of reinforcement is same.The thickness of reinforcement has little influence on the change of the reliability index when sustained load is same.Compared with beams strengthened with thickness of 60 mm,the increment of reliability index of beams strengthened with 100 mm thickness is less than 5%.