预应力混凝土低温施工材料性能试验分析

发布时间：2018-11-23 11:19

【摘要】：我国寒冷地区地域辽阔,包括了“三北”地区13个省、市、自治区,占全国面积50%以上,黑龙江地区一年的常温施工时间只有4-6个月。对于预应力混凝土简支梁桥而言,低温条件下施工面临的主要问题是混凝土早期冻害和预应力钢绞线冬季张拉问题,由于早期冻害损伤对混凝土的破坏作用极大,这种破坏作用即使经过后期标准养护也无法恢复,这将给混凝土的后期使用性能带来永久性伤害。低温条件下施工,人们-般用常温下预应力钢绞线的强度与变形理论来进行施工,但是由于低温的影响,其弹性模量和伸长率都会发生变化,如果还是按照规范下伸长值控制,就不能准确的控制张拉控制应力。所以对低温混凝土抗冻临界强度以及影响因素的分析和低温条件下钢绞线力学性能的分析是十分必要的。本文主要研究低温条件下水泥胶砂和不同强度等级混凝土力学性能的变化规律,并根据广义抗冻临界强度的定义,找到不同温度条件下各强度等级混凝土的抗冻临界强度；然后通过混凝土抗冻临界强度影响因素分析,确定混凝土抗冻临界强度的主要影响因素,并借助SPSS统计分析软件进行正交试验,找到各影响因素的主体效应,用于改善并指导低温条件下施工。本文通过低温条件下预应力钢绞线力学性能试验,利用Origin9.0对预应力钢绞线的极限强度、弹性模量以及伸长值进行数理拟合。然后以木兰大桥引桥段40m预应力T梁钢绞线的张拉为例,对钢绞线低温条件下张拉给出了修正公式。
[Abstract]:The cold area of China is vast, including 13 provinces, cities and autonomous regions in the "three north" regions, accounting for more than 50% of the whole country's area. The construction time of the Heilongjiang region is only 4-6 months in a year at room temperature. For prestressed concrete simply supported beam bridge, the main problems in construction under low temperature are early freezing damage of concrete and tension of prestressed steel strand in winter. Due to the damage of early freezing injury to concrete, the damage to concrete is very important. This damage can not be restored even after the later standard maintenance, which will cause permanent damage to the later use performance of concrete. In construction at low temperature, people usually use the strength and deformation theory of prestressed steel strands at room temperature to carry out construction. However, due to the influence of low temperature, the elastic modulus and elongation will change, if the elongation is controlled according to the criterion, Can not accurately control the tension control stress. So it is necessary to analyze the critical strength and influencing factors of low temperature concrete and the mechanical properties of steel strand under low temperature condition. In this paper, the variation law of mechanical properties of cement mortar and concrete of different strength grades under low temperature is studied, and according to the definition of generalized freezing resistance critical strength, the freezing critical strength of concrete of different strength grade under different temperature condition is found. Then through the analysis of the factors affecting the critical strength of concrete frost resistance, the main factors affecting the critical strength of concrete frost resistance are determined, and the main effect of each factor is found by orthogonal test with the help of SPSS statistical analysis software. Used to improve and guide construction under low temperature conditions. In this paper, the mechanical properties of prestressed steel strands at low temperature are tested, and the ultimate strength, elastic modulus and elongation of prestressed steel strands are fitted by Origin9.0. Then taking the 40m prestressed T-beam strands of Mulan Bridge as an example, a modified formula is given for the tensioning of steel strands at low temperature.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U445.57

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