基于反演理论的预应力混凝土桥梁损伤分析研究

发布时间：2018-03-27 08:39

本文选题：反演理论　切入点：预应力　出处：《长安大学》2015年博士论文

【摘要】：随着我国交通事业的快速发展,大跨径预应力混凝土箱梁桥被广泛应用于铁路、公路桥上。此类桥型在运营过程中,有相当数量的出现了不同程度的开裂、下挠等损伤问题,且日益突出,已直接影响到结构的安全性、使用性及耐久性。本文主要针对大跨径预应力混凝土梁桥服役期间梁体抗弯刚度退化程度、有效预应力的真实状态进行了研究,提出了以反演理论为基础,通过建立参数反演分析程序,根据预应力混凝土梁桥运营期间不同时间点控制截面实测挠度值,对梁体抗弯刚度损伤及顶板、边跨底板及中跨底板有效预应力进行了反演识别的分析方法。通过分析发现,随着服役时间的不断延长,梁体损伤日益严重,抗弯刚度不断退化。同时,梁体有效预应力也随时间不断减小,其中,顶板纵向有效预应力最大,边跨底板纵向有效预应力次之,中跨底板纵向有效预应力降低程度最小。以在役预应力混凝土梁桥裂缝调查数据为基础,根据统计学原理,建立了正裂缝、斜裂缝特征统计参数。分别分析了正裂缝、考斜裂缝及正、斜裂缝共同作用三种情况对梁体挠度的影响规律。由分析可知,正裂缝、斜裂缝均会对梁体下挠产生影响,其中,正裂缝对其梁体挠度影响较大,斜裂缝对其影响很小。分别分析了正裂缝、斜裂缝及正、斜裂缝共同作用三种情况对梁体截面上缘应力、下缘应力及腹板主应力的影响规律。由分析可知,正裂缝对墩顶截面上缘应力影响较小,对边跨跨中截面、中跨跨中截面上缘应力影响较大;斜裂缝对边跨跨中、中跨跨中截面上缘应力影响较小,对墩顶截面上缘应力影响较大。正裂缝对边跨跨中截面、中跨跨中截面下缘应力影响较大,对墩顶截面下缘应力影响较小;斜裂缝对边跨跨中截面、墩顶截面及中跨跨中截面下缘应力影响均较小。正裂缝对梁体各截面腹板主拉应力影响较小,斜裂缝对梁体各截面腹板主拉应力影响较大。根据钢筋与混凝土相对应变关系,推导了梁体平均裂缝宽度计算公式,通过逐级加载,分析了梁体控制截面区域正截面平均裂缝宽度的变化规律。
[Abstract]:With the rapid development of transportation in China, long-span prestressed concrete box girder bridges are widely used in railway and highway bridges. And it is becoming more and more prominent, which has directly affected the safety, serviceability and durability of the structure. In this paper, the true state of the effective prestress and the degradation degree of the flexural stiffness of the beam during the service period of the long-span prestressed concrete beam bridge are studied in this paper. Based on the inversion theory, a program for parameter inversion analysis is established. According to the measured deflection values of the section at different time points during the operation of prestressed concrete beam bridge, the flexural stiffness damage and roof damage of prestressed concrete beam bridge are proposed. The effective prestressing force of side span floor slab and middle span floor slab are analyzed by inverse identification. It is found that with the continuous extension of service time, the damage of beam body becomes more and more serious, and the bending stiffness is continuously degraded. The effective prestress of beam body also decreases with time. Among them, the longitudinal effective prestress of roof slab is the largest, and the longitudinal effective prestressing force of side span slab is the second. Based on the investigation data of cracks of existing prestressed concrete beam bridge, the statistical parameters of normal cracks and oblique cracks are established based on the investigation data of in-service prestressed concrete beam bridges. The influence of oblique crack, positive crack and oblique crack on the deflection of beam body is studied. From the analysis, it can be seen that the positive crack and oblique crack have an effect on the deflection of beam body, among which, the positive crack has a great effect on the deflection of beam body. The influence of oblique crack on the upper edge stress, lower edge stress and principal stress of web plate of beam is analyzed respectively in three situations: normal crack, oblique crack and positive crack, oblique crack and oblique crack. The influence of normal crack on the upper edge stress of pier top section is small, and on the middle cross section of side span and middle span section is greater, while the effect of oblique crack on the upper edge stress of middle span and middle span is smaller than that of oblique crack. The effect on the upper edge stress of the pier top section is greater. The middle edge stress of the middle span section and the middle span section have a greater effect on the middle edge stress of the pier top section, and the oblique crack has a little effect on the lower edge stress of the pier top cross section, while the oblique crack has a great effect on the middle section of the side span. The influence of normal crack on main tensile stress of web plate of beam body is small, and oblique crack on main tensile stress of web plate of beam body. According to the relative strain relationship between steel bar and concrete, the influence of pier top section and middle span middle span on the lower edge stress of web section of beam body is small, and the influence of oblique crack on the main tensile stress of each section web plate of beam body is greater. The formula for calculating the average crack width of beam body is derived, and the variation law of average crack width of normal section in the region controlled by beam body is analyzed by step by step loading.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U441.4

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