Inpesting Appraising And Reliability Assessment Of Existing Concret Simple Supported Beam-bridge

With the rapid development of economic construction and transportation our considerable bridges have cracking, damage, steel rusting and concrete carbonation which has seriously affected the normal use. Some old bridges are in danger.Therefore inspecting, appraising and service life for existing bridges have aroused the interest of the engineers and technicians. The main researches are as follows:1. It has summarized the contents of bridge structure inspecting, including concrete strength, defect dection, as well as the depth of carbonation, the detection of steel corrosion, structural deformation and crack detection and so on.2. It summarizes some basic concepts and theories, and puts forward some calculation methods of reliable index, such as First-order Second-moment Method, JC Method and Monte Carlo Method.3. It establishes the resistance attenuation model of bridge structure considering structural component materials performance, geometric parameters, models of calculation and time parameter.4. Concrete bridge loads are mainly composed of permanent and variable loads. Basic variable loads are vehicle loads and their influent force. When bridge is in the course of service the parameters influencing variable loads are random variables changed by time. According to Traffic Department data it establishes the service bridge load model.5. The goal reliable index is the fundamental basis for reliable assessment, but the variability is not considered. The dynamic method of reliable assessment is discussed, and it presents a quantitative calculation method about structural reliability rating. So it improves the objectivity of the assessment.6. Previous structural reliability analysis methods are based on static reliability. This has a certain gap with the actual existence. Based on the results of previous studies time-varying reliability theory is introduced and the limit equation of time-varing reliability is established.7. It abtains time-varying reliable indexβ(t) this moment about bridge structure according to the limit equation which has been set up in this paper. Then we will know the the status of bridge structure comparing to the goal reliable index [β].8. The ANSYS software is used to simulate static load tests and modal analysis, and the results are similar to the field tests. So the remaining useful life to a certain level of reliability is forcasted based on time-varing reliable analysis method.