【作者】 艾辉；

【导师】 杨庆国；

【作者基本信息】 重庆交通大学 ， 结构工程， 2012， 硕士

【摘要】 本文首先通过查阅文献资料,了解目前预应力混凝土的发展现状和预应力损失的研究动态。目前,一部分使用中的预应力混凝土连续刚构桥出现了箱梁开裂、跨中挠度过大等问题。这些问题很大程度上是因为有效预应力不足。设计时对预应力损失的预估不足,施工时操作不规范都是造成预应力损失过大的原因。对于预应力混凝土连续刚构桥来说,影响预应力损失的因素众多。预估有效预应力和实际有效预应力很难完全吻合。理论计算下的成桥状态与实际状态往往不符。这就留下了安全隐患,缩短桥梁使用寿命。预应力损失的研究已经摆在了一个很重要的位置。本文从理论上参考《公路钢筋混凝土及预应力混凝土桥涵设计规范》等各种规范,采用Midas/Civil软件对依托工程胡家沟1号大桥建模分析,以此得到理论数据。然后通过在胡家沟1号大桥8号墩上预埋锚索测力计,得到预应力损失的实时实测值。分析对比预应力损失实测值与理论值。再将预应力损失实测值以一定的组合代回模型中,这样就可得到更接近于实际情况的成桥状态。最后再分析对比实际预应力损失情况下的成桥状态和原先计算的理论状态。通过本文的研究,验证了预应力损失预估是否与实际相符,并研究了有效预应力不足对桥梁成桥状态的影响。这对预应力混凝土桥梁预应力损失研究有这积极的意义,并对预应力混凝土桥梁的设计和施工具有一定的指导意义。结论如下：①预应力实测值和理论计算值的衰减规律走势上大体相近,但实测值平均低于计算值74.14MPa。②由于预应力损失实测值大于原计算值,桥梁结构合拢段控制节点弯矩值大幅度上升4000kN·m以上,这对桥梁结构受力非常的不利。③由于预应力损失实测值大于原计算值,桥梁结构合拢段控制节点的竖向位移均增大2mm左右,这对桥梁结构的成桥线形造成明显影响。④在预应力损失过大的情况下(预应力损失50%),中跨合拢段节点和边中跨合拢段节点弯矩值均大幅度上升28.27%,这对桥梁结构受力非常的不利。合拢段控制节点的竖向位移均增大7mm左右,这对桥梁结构的成桥线形造成明显影响。更多还原

【Abstract】 First of all, by searching the literatures and informations, knows the current development status condition of reinforced concrete and the research progress condition of prestress loss. However, some serious problems emerging in prestressed concrete continuous girder bridge, such as box girder fracture, excessive midspan deflection and so on. These problems is, to large extent, on the account of insufficiency of effective prestress. The estimation shortage of loss of prestress in design and non-standard construction are the main course for excessive loss of prestress. For prestressed concrete continuous girder bridge, the influence factors on prestress are numerous and the estimation of effective prestress can hardly match the actual effective prestress. The completed status of bridge can hardly agree with the actual status theoretically. Thus, safety loophole emerges, the service life becomes shorter. So the research on loss of prestress is a matter of great account.We refer to "Reinforced Concrete and Prestressed Concrete Bridge Design Specifications" and other various specification and we also use Midas/Civil for modeling analysis on the project on the Hu Jiagou1st bridge, in order to get the theoretical data. Then we obtain the real-time measured value of the loss of prestress from the pre-embedded anchor load on the8th pier of this bridge and analyse the actual and theoretical value of the loss of prestress. Put the actual loss of prestress combination back to the model to access the actual status of the completed bridge. Finally, we compare the completed status of bridge in actual prestress loss with the theoretical one. From this research, we verify whether the estimation of loss of prestress corresponds with the actual status and also we study the influence of loss of effective prestress on completed status of bridge. This research has significant meaning on the loss of prestress of prestressed concrete bridge and shows guidance for the design and construct of prestressed concrete bridge. Results are as follows:①The measured values and theoretical calculated values of prestress is similar in the trend of the attenuation law, but the former is lower than the theoretical calculated value by74.14MPa.②Due to the loss of prestress measured value is greater than the calculated value, the bending moment of the control point of closure section of the bridge increased significantly, up to more than4000kN·m, it will do a great harm to the bridge structure. ③Due to the loss of prestress measured value is greater than the calculated value, the vertical displacement of the control point of closure section of the bridge increase about2mm, which cause significant impact on the bridge line shape of the bridge structure.④In the case of large loss of prestress (prestress loss is50%), the value of the bending moment of the point of midspan closure section and the side span closure section increased significantly to28.27%, it is bad for the bridge structure, the vertical displacement of the control point of closure section increase about7mm, which cause significant impact on the bridge line shape of the bridge structure.更多还原