Study On Assessment Theory Method For Structural System Serviceability Safety Of Cable-stayed Bridges

Now in China there are approximately 100 cable-stayed bridges which have been in service for many years. A wide variety of structural damage and deficiency appear inevitably in considerable parts of cable-stayed bridges after the bridges have been completed and are used in certain period due to aging structural materials, increasing vehicle load, increasingly worse environment influence, so that their structural safety, durability and service life are affected. Therefore, the safety of cable-stayed bridges presents increasingly concerns. It is quite indispensable to giving the serviceability safety evaluation method of cable-stayed bridge system. Considering the structural characters of long span cable-stayed bridges, on the basis of the probabilistic model of structure member resistance and the probabilistic analysis method of load for exiting structure of cable-stayed bridges, this dissertation studies the serviceability safety assessment theory method of cable-stayed bridge system on the basis of reliability of structures. The main work is as follows.Through a literature review process and a comprehensive nationwide survey, this paper includes a thorough investigation to identify the probable causes of diseases in structure, and a systematic analysis is made on those reliability assessment methods having been used internationally. The characters of assessment theory method for structural system serviceability safety of cable-stayed bridges are discussed. Based on the time-dependent reliability and the system reliability of structures, the ideas and theory of safety assessment for cable-stayed bridge in service is presented.Considering the particularity and complexity of location and service condition for existing bridge in contrast with the proposed bridge, after the characteristics of load for existing bridge are analyzed, the analysis foundation, the reference period and the magnitude. prediction of evaluation load and evaluation method of load effect random process for existing bridge are studied. The probabilistic analysis method of load model for exiting structure of cable-stayed bridges is established.On the basis of in-site experimental results for the existing structure of cable-stayed bridges, time-varying model of cable strength is put forward. The important effects of degradation of cable strengthen due to corrosion with time are discussed. Based on the experimental results, the element of degradation of resistance...