發(fā)布時間：2018-11-23 11:19

【摘要】：我國寒冷地區(qū)地域遼闊,包括了“三北”地區(qū)13個省、市、自治區(qū),占全國面積50%以上,黑龍江地區(qū)一年的常溫施工時間只有4-6個月。對于預(yù)應(yīng)力混凝土簡支梁橋而言,低溫條件下施工面臨的主要問題是混凝土早期凍害和預(yù)應(yīng)力鋼絞線冬季張拉問題,由于早期凍害損傷對混凝土的破壞作用極大,這種破壞作用即使經(jīng)過后期標準養(yǎng)護也無法恢復(fù),這將給混凝土的后期使用性能帶來永久性傷害。低溫條件下施工,人們-般用常溫下預(yù)應(yīng)力鋼絞線的強度與變形理論來進行施工,但是由于低溫的影響,其彈性模量和伸長率都會發(fā)生變化,如果還是按照規(guī)范下伸長值控制,就不能準確的控制張拉控制應(yīng)力。所以對低溫混凝土抗凍臨界強度以及影響因素的分析和低溫條件下鋼絞線力學性能的分析是十分必要的。本文主要研究低溫條件下水泥膠砂和不同強度等級混凝土力學性能的變化規(guī)律,并根據(jù)廣義抗凍臨界強度的定義,找到不同溫度條件下各強度等級混凝土的抗凍臨界強度；然后通過混凝土抗凍臨界強度影響因素分析,確定混凝土抗凍臨界強度的主要影響因素,并借助SPSS統(tǒng)計分析軟件進行正交試驗,找到各影響因素的主體效應(yīng),用于改善并指導(dǎo)低溫條件下施工。本文通過低溫條件下預(yù)應(yīng)力鋼絞線力學性能試驗,利用Origin9.0對預(yù)應(yīng)力鋼絞線的極限強度、彈性模量以及伸長值進行數(shù)理擬合。然后以木蘭大橋引橋段40m預(yù)應(yīng)力T梁鋼絞線的張拉為例,對鋼絞線低溫條件下張拉給出了修正公式。
[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.
【學位授予單位】：東北林業(yè)大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：U445.57

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