Study On The Performance-Life-Cost Based Design Method And System Development For RC Girder Bridges

At present, a large number of in-service bridges are shown many problems such as poor durability, short service life and excessively high maintenance cost and management etc during the development of the bridge engineering. According to these problems, the bridge design concept based on life-cycle analysis was proposed. However, there are no clear standards or criterions which are formulated by the bridge design concept based on life-cycle analysis to be followed in China. The existing theoretical results are not operable for actual design. On the other hand, most of the researches only focus on the theory but not the practicality. Wherefore, it is necessary to bring the life-cycle design concept throughout the whole design process to enhance its operability. On the basis of existing international research results, a performance-life-cost based optimization design method of concrete girder bridges was proposed, calculation models of all the life-cycle cost aspects of conctete girder bridges were established, common diseases and methods of maintenance of concrete girder bridges were analyzed systematically, maintenance plan during the life-cycle of concrete girder bridges was optimized by the optimization model delveloped in this thesis. Finally, life-cycle cost analysis based design system for RC girder bridges (BLCAS) was developed. Main work of this thesis has been done is as follows:1. The exiting theory of bridge design based on life-cycle was summaried and analyzed, the performance-life-cost based optimization design method of concrete girder bridges was proposed, then the main steps and main content of t method was analyzed, and the proposed design process of the performance-life-cost based optimization design method of concrete girder bridges was given in the form of a flowchart.2. Calculation models of all the life-cycle cost aspects of conctete girder bridges were established, while the individual cost of existing user costs and social costs were improved from the perspective of maintenance methods.3. The common diseases and methods of maintenance of concrete girder bridge were analyzed systematically, then an optimization model for maintenance strategy considering the request of multiple objectives and constraints was formulated, the non-dominated sorting genetic algorithmII (NSGA-II) was used to solve the optimization model. At last, an engineering example was analyzed to verify the effectiveness and applicability of the method proposed in this thesis.4. A user-oriented conceptual design life-cycle cost analysis based design system for RC girder bridges (BLCAS) was developed by the development environment of VB. Up to five alternatives for the same project can be compared and analyzed at the same time by the system. Finally, the thesis demonstrated how to use the system through an engineering example, and the accuracy and stability of system are verified at the same time.