Risk Assessment System And Key Issues For Bridge Engineering

Bridge risk situations, which can be called bridge risk briefly, is the situations that some targets of certain group are influenced because of some uncertain factors during planning, designing, construction, service, maintenance, repairing and removing stages of bridge. The process, which identifies the bridge risk situations, quantifies their probability and influences degree, and gives some appropriate countermeasures based on relative analysis, comparison and evaluation studies, is bridge risk assessment. The targets of this thesis are to establish a systematic frame of bridge risk assessment, including its basic theory frame, some key fundamental models and some basic assessment method.The definition of bridge risks in broad sense and in narrow sense is made clear firstly in the thesis, and a bridge risk research frame is proposed, which is composed of basic theory research and practicality method research. Furthermore, scopes and contents of them are also made clear.Bridge accident statistical analysis, risk loss analysis, risk probability analysis, risk appraisal and decision making, engineering insurance strategy are further studied as key models. Based on statistic and analysis of 500 bridge accidents, a systematic bridge accident statistics research is given. Some statistical rules and primary conclusions of accident causes, accident time, accident loss, accident hurt and death are obtained. A uniform risk loss model are defined, and a basic loss estimate method is also proposed, which is composed of loss extent model, loss value conversion model, loss time value model. Basic loss estimate methods and their key parameters of structural loss, human hurt and death, construction delay, traffic delay are given in detail, including some case studies. Basic mathematic format of bridge risk probability are defined, and a uniform risk probability estimate model are proposed, which is composed of risk situation appearance probability and loss occur limit situation probability. According to this approach, research results of accident statistical research, natural disaster research, structure reliability research are combined with risk probability evaluation organically. Risk probability estimation will be more accurate and practicable. Decision theory is firstly introduced into bridge risk assessment systematically in the thesis. Based on the conclusion and summary of current risk assessment methods, a new bridge risk decision theory frame is proposed, which is based on utility function and As Low As Reasonable Possible criterion, what more, a new decision process, which is composed of satisfied decision criterion and optimization decision criterion, is also given. Finally, from the view point of bridge risk assessment, some issues about bridge engineering insurance is...