锈蚀混凝土梁桥承载性能准动态计算模型及高效增延补强方法研究

The failure mechanism of severe corroded concrete beam bridges may vary from a ductile manner to a brittle type. However, exsiting theoretical analysis for the residual strength of corroded members is based on the qualitative model which could not reveal the time-dependent characteristics of failure mechanism. In addtion, the ductility of the corroded members strengthened using general techniques usually is not of promise. Therefore, it is a great threat to the safety of exsiting structures located in Xinjiang cold area. Aiming at these problems, the strength deterioration and performance improvement of corroded structures is selected as the leading clue, the high efficient strengthening method with high strength aluminium alloy and residual strength of corroded reinforced concrete beam bridges will be addressed systemically by introducing high strength aluminium alloy bars with excellent corrosion resistance, low temperature performance, and high ductility. Firstly, the calculation method of the section loss for the corroded reinforcement will be put forward based on the accelerated corrosion expriment. Then, the bond-slip degradation model of corroded steel bar will be established. Moreover, the residual strength model of corroded beam bridge will be put forward to analyze multiple failure modes including concrete crush, reinforcement rupture and shear failure based on truss model with struts at various angles, and the calculation theory of residual strength of corroded beam bridges will be put forward based on the time similarity relation between accelerated corrosion and actual exposure of bridge structures. Afterward, the suggested model will be modified by load test resluts of the corroded reinforced concrete beam bridges. Finally, the strengthening method of near surface mounted high strength aluminium alloy will be given after checking the load bearing capacity of the corroded beam bridges, the failure mechanism of strengthened corroded beam bridges will be analyzed based on test results, and the design method of strengthening corroded concrete beam bridges using near surface mounted high strength aluminium alloy bars is presented.

在役混凝土梁桥锈蚀严重时其失效机理将由延性破坏诱变为脆性破坏，已有锈蚀构件剩余承载力的定性分析模型不能反映破坏机理的时变特性，按常规方法加固后锈蚀构件延性较差，对新疆寒区既有结构存在安全隐患。本项目拟将耐腐蚀和低温韧性好的高强铝合金引入既有梁桥修复中，以结构强度退化和性能提升为主线，深入研究锈蚀混凝土梁桥的承载力计算模型和嵌入式增延补强方法。首先通过加速腐蚀试验提出锈蚀钢筋几何损伤计算方法，建立粘结滑移退化模型；基于变角桁架理论提出分析锈蚀梁桥发生混凝土压溃、钢筋断裂和斜截面破坏等多种失效模式的承载力计算模型，根据加速腐蚀和自然腐蚀的时间相似关系，建立锈蚀混凝土梁桥剩余承载力计算理论，并通过锈蚀梁桥荷载试验对建议模型进行修正；基于承载能力验算结果，提出确保锈蚀梁桥延性提升的高强铝合金嵌入式补强方法，通过试验分析加固后梁桥的破坏机理，建立锈蚀钢筋混凝土梁桥高强铝合金嵌入式补强的实用设计方法。

已有锈蚀钢筋混凝土构件剩余承载力的定性分析模型不能反映破坏机理的时变特性，常规方法加固后锈蚀构件的延性不足，不利于结构的可持续使用。针对此问题，本项目以混凝土结构为对象，采用试验研究和理论分析相结合的方法，对锈蚀钢筋混凝土构件承载性能、锈蚀梁剩余承载力准动态计算模型与高强铝合金嵌入式补强混凝土结构设计方法进行了系统研究，取得了如下研究成果：（1）建立了锈蚀钢筋混凝土梁承载力变角桁架模型，通过国内外49根锈蚀钢筋混凝土梁的试验结果对建议模型进行了验证，并推导了考虑钢筋粘结性能退化影响的锈蚀钢筋混凝土其它构件的承载力计算模型；（2）以集中荷载作用下锈蚀预应力混凝土梁为研究对象，基于桁架-拱模型给出了桁架作用与拱作用的荷载分配系数，建立了考虑破坏模式演变的预应力混凝土梁剩余承载力准动态计算模型，对25根锈蚀预应力混凝土梁的承载性能进行了预测分析；（3）通过22个高强铝合金筋嵌入式加固试件的拉拔试验，分析试件的破坏形态、荷载-位移曲线，研究粘结长度、铝合金筋表面形态和直径等参数对粘结性能的影响，提出适用于嵌入式铝合金筋-混凝土的粘结本构模型；（4）完成了18根高强铝合金筋嵌入式加固混凝土梁单调静载试验，重点分析了破坏形态、荷载-挠度关系、荷载-应变曲线等性能，研究了铝合金加固量、梁端锚固形式、嵌入式填充材料等参变量对嵌入式加固梁受力性能的影响，建立了不同破坏模式下嵌入式加固混凝土梁的承载力计算模型；（5）完成了7根预应力高强铝合金筋嵌入式加固混凝土梁的静载试验，研究了铝合金加固量与预应力等级等参数对加固梁破坏模式、承载力、延性等力学性能的影响，提出了考虑预应力反拱作用的嵌入式加固混凝土梁受弯全过程曲线计算模型；（6）进行了6根高强铝合金筋嵌入式加固混凝土梁的低周反复荷载试验，分析铝合金筋表面形态、加固量等参数对加固梁受力性能的影响，建立了嵌入式加固混凝土梁骨架曲线预测模型。