| With the rapid in crease of traffic volume and the accumulation of natural damage of structure materials, many RC bridges in existence can not meet modern traffic development so that they need proper repair and rehabilitation. However, it is the groundwork of optimal choice for rebuilding schemes of the existing RC bridges that their residual service life is forecast and their safety in the fudicial period for service target are evaluated properly. The safety evaluation, the residual service life forecasting and optimal choice decision-making for rebuilding schemes of the existing RC bridges are studied aiming at the limited fund for repair and rehabilitation, aging and deterioration of reinforced concrete structures, and various rebuilding schemes. The details are as follows:1. Dynamic reliability model for existing RC bridges is brought forward. Based on studying the most correlated factors with the resistance deterioration, a deterioration model of resistance in the lifecycle for the structure is established. Because of the difference between the fudicial period for service target and the fudicial period of designing, the model of load effect is modified considering the safety of the bridge. It will make the transformation trend of factors consistent with the fact in the following dynamic reliability calculation2. Based on the above dynamic reliability model for existing RC bridges, a dynamic reliability calculation method is put forward. And the reliability index is controlled taking time into account according to the same reliability level in the fudicial period for service target with it in the fudicial period of designing. Based on the above theory, the calculation flow of the residual service life prediction for existing RC bridges is advanced for project workers to use expediently.3. Considering the long-term effect after repair and reinforcement including the benefits and the failure loss because of environment pollution and so on, the object function using the radio of the effect and repair cost is put forward for the optimal choice decision-making for rebuilding schemes of the existing RC bridges.4. Considering the influence on the bridge carrying capacity because of the steel corrosion, the deterioration model of resistance after repairing for the existing RC bridges is put forward. Base on the dynamic reliability and economy optimization theory, economical residual service life is predicted.5. Based on the above research, the calculation flow for life-cycle design of repairing and reinforcing bridges is put forward. And in the end an existing simply supported RC bridge is analyzed based on the above methods to validate its feasibility. The method and results have certain referenced value for designer, bridge construction manager, and researcher. |
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