预应力连续刚构桥损伤对其承载力的影响研究
发布时间：2019-01-03 20:59
【摘要】：大跨径预应力混凝土连续刚构桥凭借其跨越沟壑能力强,能适应独特地形、伸缩缝少,行车舒适性好、上部结构刚度大等优点,已经在工程界得到了广泛的应用。但随着服役时间的增长,许多连续刚构桥已经出现了非常严重的下挠和开裂问题。为了解决上述问题,我们必须对损伤后预应力混凝土连续刚构桥的承载力进行研究和探讨,并提出有效可行的加固方案。关于桥梁损伤评估的研究文章较多,但就桥梁整体开裂后对桥梁结构承载力影响程度的研究却较少,另外就桥梁加固方法而言,最为常用也最为有效的是预应力加固,但预应力需要施加多大最为理想,是桥梁加固设计的重要内容,也是其理论研究的关键。本文以陕西洛河大桥为工程背景,针对上述所提出的问题,做了下面三个方面的研究:1)计算预应力损失多少时桥梁底板下缘出现拉裂应力,即采用预应力法加固桥梁时需要施加的预应力控制值。2)分析计算中间跨开裂后对桥梁承载力的影响及全桥开裂后对桥梁承载力的影响程度。3)对比分析中间跨开裂与全桥整体开裂对桥梁结构承载力的影响。研究分析结果表明:(1)当预应力损失达到23.8%时桥梁已经开裂,为了确保结构安全,考虑计算的误差、并结合以往加固的一些经验,大跨径预应力混凝土连续刚构桥预应力损失接近20%时就需加固,加固时所需施加的预应力以原设计值的20%进行控制。(2)就桥梁整体承载能力而言,中间跨开裂后与全桥开裂后,桥梁承载力分别降低了12%和15%。(3)全桥开裂与仅中间跨开裂对桥梁承载能力影响相接近,即对于大跨径预应力混凝土连续刚构桥来说只要一跨破坏,就标志着桥梁已经基本破坏。
[Abstract]:The long-span prestressed concrete continuous rigid frame bridge has been widely used in engineering field because of its strong ability to cross the gully, the ability to adapt to the unique terrain, the few expansion joints, the good driving comfort and the large stiffness of the superstructure. However, with the increase of service time, many continuous rigid frame bridges have appeared very serious problems of deflection and cracking. In order to solve the above problems, we must study and discuss the bearing capacity of prestressed concrete continuous rigid frame bridge after damage, and put forward effective and feasible reinforcement scheme. There are many research papers on bridge damage assessment, but there are few studies on the influence of bridge cracking on the bearing capacity of bridge structure. In addition, in terms of bridge strengthening methods, the most commonly used and most effective method is prestressed reinforcement. However, how much prestress needs to be applied is an important content of bridge reinforcement design and the key of its theoretical research. Based on the engineering background of Luohe Bridge in Shaanxi Province, the following three aspects have been studied in this paper: 1) when calculating the loss of prestressing force, there is tensile crack stress at the bottom of the bridge. That is, the pre-stress control value needed to be applied in the reinforcement of bridge by prestressed method. 2) the influence of cracking of intermediate span on the bearing capacity of bridge and the degree of influence on bearing capacity of bridge after cracking of whole bridge are analyzed and calculated. 3) in the comparative analysis, The influence of interspan cracking and whole bridge cracking on the bearing capacity of bridge structure. The results show that: (1) the bridge has cracked when the prestress loss reaches 23.8. in order to ensure the safety of the structure, the calculation error is considered. The prestressed loss of long-span prestressed concrete continuous rigid frame bridge needs to be strengthened when the loss is close to 20. The prestressing force needed to be applied in the reinforcement is controlled by 20% of the original design value. (2) as far as the overall bearing capacity of the bridge is concerned, After the middle span cracking and the whole bridge cracking, the bearing capacity of the bridge is reduced by 12% and 15% respectively. (3) the effect of the whole bridge cracking and the only middle span cracking on the bearing capacity of the bridge is similar. That is, for long span prestressed concrete continuous rigid frame bridge, as long as one span damage, the bridge has been basically destroyed.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.23;U441
本文编号：2399864
[Abstract]:The long-span prestressed concrete continuous rigid frame bridge has been widely used in engineering field because of its strong ability to cross the gully, the ability to adapt to the unique terrain, the few expansion joints, the good driving comfort and the large stiffness of the superstructure. However, with the increase of service time, many continuous rigid frame bridges have appeared very serious problems of deflection and cracking. In order to solve the above problems, we must study and discuss the bearing capacity of prestressed concrete continuous rigid frame bridge after damage, and put forward effective and feasible reinforcement scheme. There are many research papers on bridge damage assessment, but there are few studies on the influence of bridge cracking on the bearing capacity of bridge structure. In addition, in terms of bridge strengthening methods, the most commonly used and most effective method is prestressed reinforcement. However, how much prestress needs to be applied is an important content of bridge reinforcement design and the key of its theoretical research. Based on the engineering background of Luohe Bridge in Shaanxi Province, the following three aspects have been studied in this paper: 1) when calculating the loss of prestressing force, there is tensile crack stress at the bottom of the bridge. That is, the pre-stress control value needed to be applied in the reinforcement of bridge by prestressed method. 2) the influence of cracking of intermediate span on the bearing capacity of bridge and the degree of influence on bearing capacity of bridge after cracking of whole bridge are analyzed and calculated. 3) in the comparative analysis, The influence of interspan cracking and whole bridge cracking on the bearing capacity of bridge structure. The results show that: (1) the bridge has cracked when the prestress loss reaches 23.8. in order to ensure the safety of the structure, the calculation error is considered. The prestressed loss of long-span prestressed concrete continuous rigid frame bridge needs to be strengthened when the loss is close to 20. The prestressing force needed to be applied in the reinforcement is controlled by 20% of the original design value. (2) as far as the overall bearing capacity of the bridge is concerned, After the middle span cracking and the whole bridge cracking, the bearing capacity of the bridge is reduced by 12% and 15% respectively. (3) the effect of the whole bridge cracking and the only middle span cracking on the bearing capacity of the bridge is similar. That is, for long span prestressed concrete continuous rigid frame bridge, as long as one span damage, the bridge has been basically destroyed.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.23;U441
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