Stydy On Evaluation Methods About The Bearing Capacity Of Existing Masonry Arch Bridges

Masonry arch bridges, especially stone arch bridges, are widely used at home and abroad. These bridges were generally constructed long time ago, and they are now bearing much more working load than their initial design load. As the surrounding environment changes, the material capability deteriorates as well as the bridge diseases and damage develop, many existed masonry bridges have to face the lack of bearing capability. The precise and rapid evaluation method of the bearing capacity of masonry bridges is the research direction of the thesis.1、The research developments on bearing capacity of masonry bridges at home and abroad are introduced in this thesis. Besides, the characteristics of the working internal forces and the destruction state of masonry bridges are analyzed. The evaluation methods of existed bridges are summarized and the merits and drawbacks of each method are discussed. The comprehensive evaluation method is finally proposed, which could increase the evaluation reliability.2、The research on key factors which decide the bearing capacity of masonry bridges is carried out. With the help of finite element model, the internal forces of controlling sections are obtained and analyzed so as to find the influence of each factor to the internal forces of the main arch. Taking the filler on the arch and the flank into account, a body element model is created, and according to the finite calculation, a reduction coefficient to the living load effect is decided. As for the beam element evaluation, an adapted calculation method is proposed.3、Wencheng Bridge is employed as the engineering background in this thesis. The technical state of the bridge is evaluated by both the old and the new code, and the merits and drawbacks of the two evaluation methods are analyzed. Some reasonable propositions are put forward to the evaluation of the technical state of masonry bridges.4、The calculation formulae of the bearing capacity of bridges are corrected and according to the loading test results of a number of masonry bridges, the reasonable calibration coefficient is discussed.5、On the basis of Wencheng Bridge, the reasonable check coefficient is discussed. The comprehensive evaluation method with the correction coefficient based on detection and loading test is proposed, which could increase the evaluation reliability.