A Study On Some Topics Of Reliability Assessment For Existing Reinforced Concrete Bridges

The existing bridges are precious property of the society. And they are the keys to transportation safety. However, there are a large number of bridges which have been deteriorated, damaged and have insufficient load-bearing capacity. It has become a worldwide problem. How to assess these bridges scientifically and reasonably also become a subject that is followed with great interest at home and abroad. Therefore, a research on reliability assessment theory for existing bridges not only has important theoretical significance, but also has wide application prospects and great economic benefit and social benefit. In this paper, to aim at the characteristics of existing highway reinforced concrete bridges, some topics of reliability assessment are studied. The major contents are summarized as follows:1. Based on available research results, a comprehensive study on the assessment methods for the reliability of load-bearing capacity of existing reinforced concrete bridges is performed. Considering the loading features of existing reinforced concrete bridges, modification methods of characteristics for dead load and vehicle load are discussed. Also, considering the time-dependent feature of the structural resistance for existing reinforced concrete bridges, probability models for assessment of the present resistance and time-dependent resistance are illustrated. Based on Bayes theory, a method for deducing and modifying structural material strength by actual survey data is discussed. A time-dependent resistance model is given. According to regression analysis method and minimum square method, a method for determining or modifying the model parameters by available resistance information is presented. Based on the above load and structural resistance models, models of reliability analysis of load-bearing capacity considering load history are discussed, and their solutions are given. Taking the present time and the initial time as the analysis starting point respectively, models of reliability analysis of load-bearing capacity in further service time with time-dependent resistances are established, and their solutions are discussed. Failure rate is used to analyze the failure risk of existing reinforced concrete bridges. Taking the present time as the analysis starting point, the formula of failure rate within further service time for existing structures is derived. Models of system reliability analysis of reinforced concrete bridges are discussed preliminarily. The above methods are applied to reliability assessment of The Shang Heng Bridge in Zhuhai City. The bridge is a 13...