Research Of Low-carbon Bridge Evaluation System Based On Total Life Cycle

With the promotion and popularization of low-carbon,environment-friendly green buildings in China,the low-carbon,environmental protection,and sustainability of bridge construction have also become a trend of development.However,the construction of low-carbon bridges in China is uneven and there is no objective and systematic evaluation.It is difficult to properly guide the standardization of low-carbon bridges.Therefore,it is of great practical significance to carry out systematic research on the evaluation system of low-carbon bridges based on the perspective of the total life cycle of the bridge.The main research contents and research results of the thesis are as follows:(1)The entire life-cycle of bridge is divided into four stages: planning and design stage,construction stage,operation and maintenance stage,and demolition stage.Analyzing the carbon emissions inventory at each stage respectively and summarize the carbon emission factors of the four types: energy,building materials,equipment,and transportation,and build a bridge life-cycle carbon emissions calculation model.Based on the calculation results of carbon emissions from 37 bridge project examples,a carbon database of typical bridges was established.The statistical analysis obtained the carbon emission baseline values for concrete bridges and steel bridges,and the concept of emission reduction rate was proposed as the basis for the quantitative evaluation of bridge carbon emissions.(2)To compensate for the lack of quantitative evaluation,a low-carbon bridge evaluation index system was established.Through the collection of low-carbon evaluation indicators combined with expert interviews to determine the preliminary evaluation index,collect opinions of bridge-related experts and scholars on the importance of indicators through questionnaires,use SPSS for factor analysis to obtain the final evaluation index system,and give each indicator detailed assessment points.The indicator system consists of 4 first-level indicators and 17 second-level indicators.(3)Based on the concept of emission reduction rate,a comprehensive evaluation system for low-carbon bridges was established using a combination of quantitative analysis and qualitative analysis,and the classification and evaluation criteria for low-carbon bridges were proposed.Firstly,the low-carbon bridge evaluation model is constructed by the AHP method and the fuzzy comprehensive evaluation method,and then whether the bridge meets the emission reduction requirements can be judged through the emission reduction rate,and whether or not the evaluation level needs to be revised is determined.Finally,the low carbon level of the bridge is determined according to the principle of maximum membership degree.(4)Incorporate two extension plans of a municipal bridge in Nanjing and Southern Taizi Lake Bridge in Wuhan as the engineering cases,the comprehensive evaluation method established in this thesis has been used to calculate and the baseline emission reduction rate and the maximum degree of membership to evaluate the two cases,and the evaluation results were specifically analyzed.Discussed the factors that may affect the carbon emissions and proposed corresponding measures for reducing emissions.