Research On The Tower Crane Metal Structure Damage Mode And The Method Of Risk Assessment

With the popularization and application of large-scale lifting machinery in the industrynowadays, the whole machine safety performance research has a development of structuremaximization and parameters complicated. As a common lifting tool in many kinds ofimportant workplaces, the safe form of the whole tower crane structure performance is reallyserious. Based on the theory of the accident causation, analyzed the common damage mode ofthe tower crane accident, built the complete risk assessment index system, then put forwardthe quantitative risk assessment method based on combination of empowerment. Meanwhile,through the result of field tests and finite element analysis to illustrate the correctness whetherthe risk assessment result can be the basis of screening of applying the further tradictionalsafety assessment or not.In this article, the specific research content can be included to the following five parts:（1）Through statistical analysis of domestic and abroad accident cases, classifedaccidents from the accident causation. Summarized the causes and preventioncountermeasures of all kinds of accidents, then obtained the main damage patterns whichaffect the accident categories.（2）Built the complete risk assessment index system from the four aspects: human,machine,environment and management,then finished assessment index combinationempowerment by combined with the subjective analytic hierarchy empowerment andobjective entropy weigh. To build factor sets and assessment sets for all levels of indicatorsand make sure the risk of each assessment set membership, so that making up a set ofquantitative risk assessment method of the tower crane.（3）Selected a tower crane which used for nearly30years as an assessment prototype,and arranged the example analysis on the risk assessment. Through investigating the actualworking conditions of tower crane and the relevant index information available to the expertscoring, obtained the data of membership by combined with a number of expert survey, andregarded the whole integrated quantitative risk values to determine the level of risk.（4）The field test is mainly to obtain the static or quasi-static maximum stress andmaximum displacement of the tower crane through selected typical test points in the typicaloperating conditions. Through proposing the function relations between the extent and themaximum stress value in the case of load determined, finally, provided a theoreticalmaximum stress prediction support for other testing condition under different extent. （5）The whole machine finite element statics analysed and completed the defects of thefewer number of the measured points, achieved the stress value under typical workingconditions. However, the modal analysis in dynamics extracted and analysed the first fivefigure mode, calculated the natural frequencies of the actual use of tower crane, obtained thepossible strength failure status in the process of loading or unloading through the stressresponse analysis. Comprehensive analysis result showed that the machine used in the droplevel is safe under various operating conditions, and verified the basis of screening whichconclude by the risk assessment results is correct.