考虑徐变的大跨度混凝土连续刚构桥边中跨比的合理设计
发布时间：2019-01-07 08:23
【摘要】：边中跨比的选取是否合理，不仅会影响到恒载内力分布的合理性，，影响到预应力设计的合理性和经济性，影响到施工难易等，而且还会对桥梁的总造价产生很大的影响，因此选择合理的边中跨比是连续刚构桥总体设计时应重点考虑的内容。 由于边中跨比的大小会影响预应力的布置，继而影响结构内力的分布和徐变量的大小，而徐变又会影响结构内力重分布，并对跨中下挠和开裂产生重要影响。因此，在研究合理边中跨比时，必须考虑徐变的影响。在目前不能精确分析计算徐变的情况下，将徐变当作一个随机变量进行包络设计，估算其对桥梁的影响。并以海心沙大桥及凫洲大桥为工程背景，采用徐变包络设计的方法来分析与研究大跨度三跨和四跨连续刚构桥的合理边中跨比，通过分析与研究得出使结构受力最优且能减少徐变对结构不利影响的合理边中跨比。 本文的主要工作包括： ⑴阅读、总结了近年来国内外混凝土连续刚构桥梁合理边中跨比以及徐变的相关文献，阐述了考虑徐变的合理边中跨比的研究现状，指出了目前研究中存在的局限性。并与课题组共同提出了将徐变当作一个随机变量进行包络设计的方法。 ⑵提出了连续刚构桥合理的内力目标状态，着重论述了合理边中跨比的目标是使得连续刚构桥具有合理的内力，施工简单、经济合理，并采用弯曲能量最小法对现浇三跨和四跨等截面连续梁的合理边中跨比进行研究。 ⑶介绍了混凝土徐变的机理、计算理论及预测模型，并论述了预测模型的差异性，并阐述了其对连续刚构桥的影响。 ⑷以海心沙大桥为工程背景，研究了考虑徐变的三跨混凝土连续刚构桥的合理边中跨比。 ⑸以凫洲大桥为工程背景，研究了考虑徐变的四跨混凝土连续刚构桥的合理边中跨比。 本文研究取得的主要结论有： ⑴只有在合理的边中跨比下，结构的恒载分配才会合理，预应力束布设相对容易，同时使得徐变对结构的影响最小。 ⑵现浇的三跨等截面连续梁的合理边中跨比为0.79，现浇的四跨等截面连续的合理边中跨比为0.81。 ⑶以海心沙特大桥为工程背景和研究对象，得到了考虑徐变的三跨混凝土连续刚构桥的合理边中跨比值的区间为0.552～0.576。 ⑷以凫洲大桥为工程背景和研究对象，得到了考虑徐变四跨混凝土连续刚构桥的合理边中跨比值的区间为0.577～0.6。
[Abstract]:Whether the ratio of side to middle span is reasonable or not will not only affect the rationality of the distribution of internal forces under dead load, the rationality and economy of prestressed design, and the difficulty of construction, but also have a great impact on the total cost of the bridge. Therefore, it is important to choose a reasonable ratio of side to middle span in the overall design of continuous rigid frame bridge. Because the ratio of side to middle span will affect the arrangement of prestress, and then influence the distribution of internal force and the size of creep variable, creep will affect the redistribution of internal force of the structure, and it will have an important effect on the deflection and cracking in the span. Therefore, the effect of creep must be considered when studying the reasonable ratio of middle to middle span. Under the condition that the creep can not be accurately analyzed and calculated at present, the envelope design is carried out with the creep as a random variable to estimate the influence of the creep on the bridge. Taking Haixinsha Bridge and Fuzhou Bridge as engineering background, the paper analyzes and studies the reasonable ratio of middle to middle span of long-span three-span and four-span continuous rigid frame bridge by using creep envelope design method. Through the analysis and research, it is concluded that the optimum stress of the structure can reduce the adverse effect of creep on the structure, and the reasonable mid-span ratio can be obtained. The main work of this paper is as follows: 1 Reading, summarizing the relevant literature on the reasonable mid-span ratio and creep of concrete continuous rigid frame bridges at home and abroad in recent years, and expounding the research status of the reasonable mid-span ratio of concrete continuous rigid frame bridges considering creep. The limitations of current research are pointed out. A method of envelope design is proposed by using creep as a random variable. 2. The reasonable target state of internal force of continuous rigid frame bridge is put forward, and the objective of reasonable ratio of side to middle span is discussed emphatically, which makes continuous rigid frame bridge have reasonable internal force, simple construction and reasonable economy. The reasonable mid-span ratio of cast-in-place three-span and four-span continuous beams with equal cross-section is studied by means of bending energy minimization method. 3. The mechanism, calculation theory and prediction model of concrete creep are introduced, the difference of prediction model is discussed, and its influence on continuous rigid frame bridge is expounded. 4 taking Haixinsha Bridge as the engineering background, the reasonable mid-span ratio of three span concrete continuous rigid frame bridge considering creep is studied. 5 taking the Fuzhou Bridge as the engineering background, the reasonable mid-span ratio of four span concrete continuous rigid frame bridge considering creep is studied. The main conclusions obtained in this paper are as follows: 1 the distribution of dead load of the structure is reasonable only under the reasonable ratio of side to middle span, and the placement of prestressing tendons is relatively easy, and at the same time, the influence of creep on the structure is minimized. 2 the reasonable ratio of middle to middle span of three-span continuous beam with equal cross-section is 0.79, and that of four-span continuous beam of cast-in-place is 0.81. (3) taking the Haixin Saudi Bridge as the engineering background and the research object, the reasonable mid-span ratio of the three-span concrete continuous rigid frame bridge considering creep is obtained, which is 0.552n0.576. 4 taking the Fuzhou Bridge as the engineering background and the research object, the reasonable mid-span ratio of side to middle span of the concrete continuous rigid frame bridge with four spans considering creep is obtained, which is 0.5770.6.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.23;U442.5
本文编号：2403441
[Abstract]:Whether the ratio of side to middle span is reasonable or not will not only affect the rationality of the distribution of internal forces under dead load, the rationality and economy of prestressed design, and the difficulty of construction, but also have a great impact on the total cost of the bridge. Therefore, it is important to choose a reasonable ratio of side to middle span in the overall design of continuous rigid frame bridge. Because the ratio of side to middle span will affect the arrangement of prestress, and then influence the distribution of internal force and the size of creep variable, creep will affect the redistribution of internal force of the structure, and it will have an important effect on the deflection and cracking in the span. Therefore, the effect of creep must be considered when studying the reasonable ratio of middle to middle span. Under the condition that the creep can not be accurately analyzed and calculated at present, the envelope design is carried out with the creep as a random variable to estimate the influence of the creep on the bridge. Taking Haixinsha Bridge and Fuzhou Bridge as engineering background, the paper analyzes and studies the reasonable ratio of middle to middle span of long-span three-span and four-span continuous rigid frame bridge by using creep envelope design method. Through the analysis and research, it is concluded that the optimum stress of the structure can reduce the adverse effect of creep on the structure, and the reasonable mid-span ratio can be obtained. The main work of this paper is as follows: 1 Reading, summarizing the relevant literature on the reasonable mid-span ratio and creep of concrete continuous rigid frame bridges at home and abroad in recent years, and expounding the research status of the reasonable mid-span ratio of concrete continuous rigid frame bridges considering creep. The limitations of current research are pointed out. A method of envelope design is proposed by using creep as a random variable. 2. The reasonable target state of internal force of continuous rigid frame bridge is put forward, and the objective of reasonable ratio of side to middle span is discussed emphatically, which makes continuous rigid frame bridge have reasonable internal force, simple construction and reasonable economy. The reasonable mid-span ratio of cast-in-place three-span and four-span continuous beams with equal cross-section is studied by means of bending energy minimization method. 3. The mechanism, calculation theory and prediction model of concrete creep are introduced, the difference of prediction model is discussed, and its influence on continuous rigid frame bridge is expounded. 4 taking Haixinsha Bridge as the engineering background, the reasonable mid-span ratio of three span concrete continuous rigid frame bridge considering creep is studied. 5 taking the Fuzhou Bridge as the engineering background, the reasonable mid-span ratio of four span concrete continuous rigid frame bridge considering creep is studied. The main conclusions obtained in this paper are as follows: 1 the distribution of dead load of the structure is reasonable only under the reasonable ratio of side to middle span, and the placement of prestressing tendons is relatively easy, and at the same time, the influence of creep on the structure is minimized. 2 the reasonable ratio of middle to middle span of three-span continuous beam with equal cross-section is 0.79, and that of four-span continuous beam of cast-in-place is 0.81. (3) taking the Haixin Saudi Bridge as the engineering background and the research object, the reasonable mid-span ratio of the three-span concrete continuous rigid frame bridge considering creep is obtained, which is 0.552n0.576. 4 taking the Fuzhou Bridge as the engineering background and the research object, the reasonable mid-span ratio of side to middle span of the concrete continuous rigid frame bridge with four spans considering creep is obtained, which is 0.5770.6.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U448.23;U442.5
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