Research On The Dynamic Evolution Of Safety Risk In The Whole Process Of Tower Crane Construction

Tower crane is one of the most widely used vertical transportation equipments in construction.Due to their own structural defects and safety management defects,the accidents occur frequently which have serious consequences.The traditional risk control tools do not fully consider the characteristics of tower crane operations and management,it is impossible to guide relevant personnel to effectively prevent tower crane accidents.Based on the related risk control theory and the characteristics of the tower crane itself,the dynamic evolution model of the tower crane safety risk in the whole process was constructed to discuss the evolution mechanism of the tower crane safety risk,and provide reference for controlling the tower crane safety risk.First,based on the essential feature of the system for the dynamic evolution system of tower crane safety risk in the whole process as a complex socio-techincal system,it was divided into technical environment sub-system and organizational management subsystem,which represented the installation,use and disassembly process of tower cranes,and explained the modeling principles of complex socio-techincal system in detail.On the basis of modeling theory and model boundaries,the typical safety accidents of tower cranes were analyzed,then summarized the man-machine-environment-management factors that affecting the safety of the whole process of tower cranes,and used expert interviews and questionnaires to screen factors for determing the model variables of two sub-systems.Second,according to analyzing the feasibility of Bayesian network to construct the technical environment sub-system model,it was proposed that the probabilistic risk assessment method combining Fault Tree Theory,Fuzzy Set Theory and Bayesian Network.Then established the Bayesian network model for the installation,use and disassembly of tower cranes.Moreover,the Bayesian network models were revised using the expert survey method,and the parameters of the Bayesian network models were obtained in combination with the fuzzy set theory.Based on this,the accident consequences and probability in the three phases of tower crane were obtained.For the organization management sub-system,by analyzing the feasibility of system dynamic,they were established that the system dynamic feedback loops of safety input of construction units,safe production input of rental units,and safety and production.Then above three feedback loops were integrated to establish the system dynamic flow diagram for the installation,use,and disassembly phases of tower cranes,to describe the interaction and mutual influence mechanisms within the organization safety decision-making and safety management practices.Finally,based on the analysis of the interface and the interface mechanism between the technical environment sub-system and the organizational management sub-system model,the dynamic evolution model of the whole process of tower crane safety risk was established by integrating two sub-systems.Through simulation,the trend of safety risks and accident level in the installation,use and disassembly phases of tower cranes were quantitatively analyzed,which helps relevant units prevent tower crane safety accidents and control safety risks.