Post-occupancy Evaluation Of Urban Underground Complex And Design Optimization Strategies

The problems of traffic congestion,resource shortage,and deterioration of the environment caused by rapid urbanization in China have become increasingly prominent.Urban underground complexes(UUCs)are important approaches to alleviate traffic congestion,expand urban space capacity and improve the quality of urban environment.However,there is still a lack of post-occupancy evaluation(POE)research on the development and utilization of UUCs.It is still unclear whether they have played valuable roles in social and economic aspects and whether they match the needs of users.The existing status and problems of UUCs cannot be fed forward to architectural planning and design in time,which may cause irreversible losses and huge waste of resources.Therefore,this study takes typical UUCs that have been built in China as research objects to carry out a comprehensive and systematic POE.A total of 2,742 questionnaires were distributed through multiple rounds of field research.The current problems and causes of UUCs was systematically discussed from macro to micro level.The two key issues which were space accessibility and legibility,physical environment and users’ comfort were extracted and in-depth researches were carried out.The subjective and objective methods which are physical environment and spatial elements measurement,questionnaire surveys,free interviews,behavior maps,space syntax,and cognitive maps were comprehensively used.The key factors in each problem were identified and the quantitative relationship was discussed.Thus,the corresponding design optimization strategies to improve the quality of UUCs were put forward.In the part of basic theoretical research and pilot POE studies(Chapters 1,2,and 3),through in-depth analysis of the particularity,development,evolution and driving factors of UUCs,the three-dimensional city theory was used as the starting point to analyze the design connotation of UUCs.Combined with the particularity of POE research on UUCs,a systematic analysis framework was built.Through the analysis of the spatial characteristics of UUCs and the needs of users,the key factors of POE research on UUCs were extracted,and an evaluation system of UUC was established,taking Chengdu Tianfu Square UUC as an example to conduct an experimental evaluation to verify the rationality of the evaluation system.In the main part of POE(Chapter 4),a comprehensive and systematic POE study was carried out with typical UUCs that have been built in China as the research objects.Data were collected through on-site distribution of questionnaires,online questionnaires,in-depth interviews,field research,and behavior maps.Based on one-way ANOVA analysis of variance,correlation analysis,factor analysis,analysis hierarchy process(AHP),fuzzy comprehensive evaluation and other mathematical statistics methods,a comprehensive satisfaction evaluation system was established.Combined with the opinions of experts,as well as different groups of people such as staff,merchants and visitors,the weight of each indicator was clarified.From macro to micro level,the current problems and causes of UUCs were systematically discussed,and the two key issues which were space accessibility and legibility,physical environment and users’ perception of comfort were extracted.In the key issue research part(Chapters 5 and 6),space accessibility and legibility,physical environment and users’ perception of comfort found in POE studies were deeply studied.Combined with space legibility and subjective comfort evaluation,using quantitative methods such as space syntax,physical environment and spatial elements onsite measurement with subjective questionnaires distributed at the same time,regression models were established to extract key influencing factors.The correlation between each factor and the subjective evaluation results were revealed,and the direction of design optimization and improvement was clarified.The research on space accessibility and legibility found that:(1)The space accessibility of UUC is affected by the overall space structure,space visibility,vertical transportation facilities,and entrances and exits connected to urban space.The indicator "entrance and exit connected to urban space" proves that UUCs are important components of multi-level pedestrian system in the three-dimensional city.If an open network can be formed through multi-level urban interface,the arrival efficiency of people and space utilization efficiency can be improved.(2)In terms of space legibility,“environmental familiarity” and “frequency of use” in individual characteristic factors have significant positive impacts on users’ perception of space legibility.However,the positive effects of the spatial characteristic factors such as "traffic system","clear functional divisions" and "identity and openness of entrances and exits" are relatively more significant.The results provide an objective basis for corresponding design optimization strategies.The physical environment and users’ perception of comfort research used a diachronic investigation in two typical seasons of winter and summer.By discussing the correlation between physical environment elements and users’ perception of comfort,and based on the particularity of UUCs,space elements were incorporated to discuss the joint influence on user’s perception of comfort.A multiple linear regression model was established.The variables that finally entered the model were "temperature","skylight area","decorative materials" and "spatial scale" in winter,and "spatial aspect ratio","visual transparency","crowdedness","outside view" and "carbon dioxide concentration" in summer.It shows that no matter in winter or summer,physical environment and architectural space factors will jointly affect users’ subjective comfort perception.Although their effects have seasonal differences,in general,space factors have the greatest impact on comfort perception,followed by physical environment factors.In the part of design optimization strategies(Chapter 7),based on conclusions of POEs and the research of key issues,the objectives and principles of design optimization on UUCs were firstly proposed.Based on POE research findings,from the perspective of users’ needs,the design optimization strategies of UUCs were proposed from the aspects of urban level,traffic,function,space and use.Meanwhile,according to the key influencing factors and their quantitative relationships found in the research on space accessibility and legibility,the physical environment and users’ perception of comfort,specific suggestions for improvement were put forward respectively.At the same time,POE results,typical examples,result visualization,mathematical statistics analysis and other methods were used for intuitive explanation.And The feasibility of the design optimization strategies were verified by simulation.This dissertation fills the research gap of POE on UUCs through comprehensive and systematic progressive POEs,enriches and improves the relevant database and theories.Through in-depth research on key issues,the key factors and quantitative relationships that affect space accessibility and legibility,users’ perception of comfort were discussed,and systematic optimization strategies were proposed accordingly.This research may improve the planning and design of UUCs to better match the needs of users,and help UUCs to play a better role in both social and economic aspects.It is also helpful to discover the current situation of UUCs in time and feed back to architectural planning and design,meanwhile,providing a reference for the design and practice of UUCs in the future.