Disposal Decision Analysis Of Existing Reinforced Concrete Bridges In Tibet Based On Condition Assessment

Reinforced concrete bridges are widely used in Tibet because of its characteristics such as durability, easy construction, low cost. The safety and durability reinforced concrete bridges are subject to many factors such as increasing traffic, low construction standard, quality problems, overload vehicle, natural disasters, natural aging of material and structure. Meanwhile, Tibet is located in areas with cold, hypoxia, dry, longer freeze climate and with some rivers containing chloride, sulfate and other harmful substances, which have a strong corrosive effect on concrete and concrete bridges. These harsh environmental conditions caused a very serious impact on carrying capacity, durability of road bridges in Tibet. How to make an accurate, fast and effective disposal to these bridges is a major problem to bridge management departments in Tibet. In this paper, the disposal decision of Tibet existing concrete bridges are researched, which included the following works includes:①Based on field research on existing bridges disease in Tibet, the main factors influence bridges conditions are analyzed. A bridge condition evaluation model is proposed with AHP by considering the influence of the bridge bearing capacity, durability, functionality, strengthening the economy and aesthetics, which can make a fuzzy comprehensive evaluation on bridges conditions.②Considering that the maintain method in "Highway Bridge Maintenance Specifications" is too simple, the factors influence bridge repair and reinforcement levels are analyzed. By considering bridge performance, fitness repair, restoration, environmental attributes and other indicators, a method which can determine the level of bridge repair and reinforcement is proposed with fuzzy comprehensive evaluation method.③Base on Value Engineering theory, functional analysis is made on bridge disposal options and corresponding functional evaluation index system is established. Variable Methods are employed to give a comprehensive evaluation of system function. The whole life cycle costs of different reinforcement bridge maintenance program are analyzed and a disposal model programs is proposed.④Taking a real bridge for example, the whole processes of bridge condition assessment, repair and reinforcement level decision and disposal program optimization are presented. The results are consistent with the engineering practice, which verified the accuracy of proposed disposal decision method of existing bridge in Tibet.This thesis has a positive significance in scientific utilizing potential Capacity of existing reinforced concrete bridge for management, ensuring safety of existing bridges, saving construction funds and improving the management quality of roads and bridges in Tibet.