Application Research On The Externally Prestressed Strengthening Technique In The Uniform Beam

In recent years, with the rapid development of China's economy, transportation growing prosperity, it raised higher requirements for the development of the bridge. However, many of the existing old bridges have been unable to meet the needs of existing traffic, bridge diseases have become increasingly prominent, seriously affecting transport. Reinforcement and repair of the old bridge has become one of the main methods to solve such problems. It is simple and convenient for external prestressing reinforcement method in many reinforcement methods, which reinforcement does not affect traffic, effectively improve structural rigidity, and it is widely used in bridge reinforcement in recent years. This article relies on practical projects to uniform continuous externally prestressed concrete beam bridge reinforcement techniques for the study. By analyzing the causes of disease, finite element software simulation, construction monitoring data comparison, it analysis and evaluation for external prestressing reinforcement technology can be done.In this article, we use a method of numerical simulation and theoretical analysis for detailed analysis and research of the external prestressing reinforcement mechanism, reinforced design, reinforcement effect evaluation and other aspects of uniform continuous girder bridge. This not only has important theoretical significance, but also to provide a reference for future external prestressing reinforcement design. The main contents of this article are as follows:1) By introducing the status of bridge worldwide, it can discuss the importance and urgency of reinforcement. Meanwhile it can simply introduce the research status of external prestressing reinforcement method and its advantages and disadvantages.2) Comparative analysis of various characteristics and applications suitable for bridge reinforcement methods, through comparative analysis, it can highlights the advantages and disadvantages of the external prestressing reinforcement methods and reinforcement mechanism. For external prestressing reinforcement techniques, it can respectively do theoretical explanations of the external prestressing reinforcement method, the basic composition of the system, and the similarities and differences of the theoretical calculation.3) From two aspects to optimize the arrangement of the external tendons. One is calculating the reasonable length of external prestressing cable range freely to avoid the effect of sympathetic vibration; the other is optimizing the structure of the linear arrangement of external tendons according to the principle of external prestressing arrangement.4) Do simulation analysis by using finite element software Midas/civil for a domestic Bridge prestressing reinforcement, and do comparative analysis, respectively, from the change of stress and displacement before and after. The results show that:after using external prestressing reinforcement for uniform continuous girder bridge, the main girder stress reserves obviously, bridge linear gets a favorable recovery, crack shrink or even disappear. It proves that this method is feasibility for uniform continuous girder.5) Through simulation analysis, we can do external prestressing reinforcement design of this bridge, comparative analysis of monitoring data before and after reinforcement. By comparing analysis of the theory and measured values of the girder deformation monitoring point in various conditions, concluded:It is normal for deflection increments of external prestressing stretching in various stages. The measured stress and deflection changes of the main girder are similar of Midas analysis results in stages of stretching, their trends are consistent. It explains that construction effect achieve the desired design effect. It also verified that using Midas/civil for the construction simulation of external prestressing reinforcement is reasonable.