Crane Structure Limit State Design Method

With modern port technology development, port handling machinery play increasingly important role, functions gradually increase. As the conditions of use of certain environmental restrictions, the failure chances increase, and the consequences become increasingly serious. Therefore reliability increasingly acute, as the market focus of the international competitiveness of its products. Product design decisions of the inherent reliability of products, if the design was not reliable hidden danger, products manufactured in failure to fill even after the damages have to spend double the price. Reliability designs from both security and economic considerations, as load factors etc. can not be accurately determined, the design risk (or failure probability) should limit to an acceptable level. This need probability theory, mathematical statistics, reliability theory subjects introduced to the port handling machinery design, research port handling machinery limit state design in the basis of probability statistics. Put load, material properties, component actual size as a probability distribution based on the statistics, through lots of investigation, get the probability distribution and parameters of the basic variables, then with the probability reliability knowledge, calculating the probability of failure, to estimate the security of port machinery metal structure. As considering various circumstances the limit design method can make the structure whose reliability and economic rationality (used less materials, light weight, easy to manufacture, transport and installation, short construction period, low cost and ease of future service and maintenance, etc.) are harmonized.This thesis, based on the principles and methodologies of limit state design in China steel structure and relevant domestic and international standards, norms, to study the limit state law theories of the crane metal structure, have built a completed calculating method including the reliability, the statistical analysis methods of load cases, material properties and structural resistances, and the identification methods of objectives reliable indicator.In the one hand, exploring the practical limit state design method of port crane metal structure, including the method of determining partial load factors, structural resistance coefficient and the importance of structural factors .As an example, a real product manufactured whose metal structure is designed by the allowable stress rules, and the different domestic and international norms limit state law, then check the strength, static stiffness ,dynamic stiffness, buckling, plates stability and fatigue one by one. As the strength, stability, fatigue indicators reach over 90% of the allowed index, lists results to analyze. On the other hand, based on the FOSM method, experiences of manufactures and users and actual examples, deriving from the Principle, in accordance with the checking point method, matlab program get recommended values of the coefficients in the most dangerous working conditions of a certain objective reliable indicators and a new set of structural parameters through design. With ANSYS analysis of the probability design PDS, check strength, the static and dynamic stiffness, fatigue and stability respectively for the above group structure parameters overall, the safety level of the standard recommended and the problems revealed are captured after data analysis ,as well as make some recommendations for Chinese port crane design and manufacture , at last provide a new probabilistic method to some larger port machinery enterprises for reference.In addition, the ultimate aim of this paper is in service of the practical application of constructions, I sincerely hope that my research could help and for reference on the extension, application and future revisions of our country's crane design norms and the design of other mechanical structure , promote the quality and reliability of mechanical structure design, and realize actually the reality of its engineering significance.