钢纤维聚合物结构混凝土环境疲劳性能的实验研究

发布时间：2018-04-28 04:21

  本文选题：钢纤维聚合物结构混凝土 + 环境疲劳　； 参考：《华南理工大学》2014年硕士论文

【摘要】：工程实践表明，采用普通的高强混凝土材料，，虽然提高了混凝土结构的强度，却使其脆性问题更加突出。为了改善普通高强混凝土的韧性及抗裂性能，本课题组以在建的某高速公路某特大桥为工程依托，从材料的力学性能着手，对已有自主知识产权的“钢纤维增强聚合物改性混凝土”进行二次开发，研发了一种能够应用于大跨度桥梁上部结构的新型结构材料——钢纤维聚合物结构混凝土（SFPSC）。为了进一步探讨该类新材料的耐久性能，本文考虑我国南方和沿海地区桥梁实际服役时的湿热环境影响，对其环境疲劳性能进行了实验研究，研究成果对于提高大跨度混凝土桥梁结构的耐久性具有重要的科学意义和工程应用价值。本文的主要研究内容和结论如下： 1)“钢纤维聚合物结构混凝土（SFPSC）”的研制。根据某高速公路桥梁建设的实际需求，通过配合比设计、材料组分分析及基本力学性能实验，研制出一种与现有高强混凝土（例如C55混凝土）的强度相仿，但具有更优越的抗裂、抗疲劳性能的改性混凝土材料。 2)在不同湿热条件下对SFPSC试件预处理后（50℃和80%RH；50℃和90%RH；50℃和95%RH），实施了三点弯曲疲劳实验，获得了SFPSC梁的S~N曲线；根据疲劳强度理论及假定，推导了SFPSC的环境疲劳寿命表达式。对于该表达式中的常系数，由环境疲劳实验数据来确定。研究结果表明，利用该公式可有效地、方便地推定在亚热带地区湿热气候条件下SFPSC的疲劳寿命及其疲劳极限。 3)分析了环境疲劳实验中SFPSC试件的载荷～跨中挠度曲线和疲劳寿命～跨中挠度曲线，发现了SFPSC三点弯曲梁跨中挠度的三阶段式变化规律。通过对实验数据进行无量纲处理，得到了各实验梁的相对循环次数～相对挠度曲线，并探讨了应力水平和不同湿热环境预处理对试件挠度曲线影响的规律。 4)利用跨中挠度对试件损伤变量D进行描述，并推导出基于损伤变量D的疲劳寿命预测公式。研究结果表明，SFPSC梁疲劳破坏时损伤量的推定值为0.85。在此基础上，通过少量非破坏性疲劳实验数据就可方便地对SFPSC梁的疲劳寿命进行预测。
[Abstract]:The engineering practice shows that the brittleness of concrete structure is more prominent though the strength of concrete structure is improved by using ordinary high strength concrete material. In order to improve the toughness and crack resistance of ordinary high strength concrete, our group based on a large bridge of a highway under construction, started from the mechanical properties of the material. Based on the secondary development of "steel fiber reinforced polymer modified concrete", a new structural material, steel fiber polymer structure concrete, which can be applied to the superstructure of long-span bridges, is developed. In order to further study the durability of the new materials, the environmental fatigue properties of bridges in southern and coastal areas of China are studied experimentally, considering the effect of wet and thermal environment on the actual service. The research results have important scientific significance and engineering application value for improving the durability of long span concrete bridge structure. The main contents and conclusions of this paper are as follows: 1. Development of Steel Fiber Polymer structure concrete (SFPSC). According to the actual demand of a highway bridge construction, through mix ratio design, material component analysis and basic mechanical performance experiment, a kind of strength of high strength concrete (such as C55 concrete) is developed, which is similar to that of the existing high strength concrete (for example, C55 concrete). But with better crack resistance, fatigue resistance of modified concrete materials. 2) SFPSC specimens were pretreated at 50 鈩

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