再生混凝土-钢筋黏结锚固可靠度设计

Reliability of bonding between recycled concrete and steel rebar

通过66个同强度、不同再生粗骨料取代率的钢筋-混凝土中心拉拔试验,研究不同再生粗骨料取代率、相对保护层厚度、配箍率等参数对再生混凝土与钢筋黏结强度的影响。统计目前国内外892个钢筋-再生混凝土中心拉拔试验结果以及336个再生混凝土抗压强度,建立极限黏结强度计算公式。基于与普通混凝土同水灰比和同强度这2种再生混凝土设计标准,采用Monte Carlo法进行再生混凝土-钢筋黏结锚固可靠度计算,并提出相应的锚固长度设计建议。研究结果表明:同强度再生混凝土锚固长度设计可直接按GB50010—2010"普通混凝土结构设计规范"进行,而同水灰比再生混凝土锚固长度则应在普通钢筋混凝土锚固设计长度基础上适当考虑提高10%～15%。

66 pull-out specimens containing different levels of recycled coarse aggregate(RCA)were fabricated to study the effect of RCA replacement,layer thickness,stirrups ratios on the bond strength between recycled concrete(RC)and steel rebar.Results from 892 pull-out tests and 336 compressive tests were statistically analyzed.The formula of ultimate bond strength between RC and steel rebar was established.Two kinds of design standard were considered for RC mixture,i.e.,the mixture of RC was directly designed as conventional concrete(CC),or it was designed to get a comparable compressive strength with CC.The Monte Carlo method was adopted to calculate the reliability and the anchorage length of reinforced RC based on the two kinds of design methods.The results show that the anchorage length of CC suggested in Chinese code GB 50010-2010 is applicable for RC design to get a comparable compressive strength with CC,but the anchorage length of RC designed as CC should be increased by 10%-15%compared with that of CC.