Research On Mechanical Characteristics Of Support Frame Of External Tower Crane

With the development of economy,more and more super high-rise buildings have been built.With unique advantages,the external tower crane has become an essential engineering equipment in the construction of super high-rise buildings.The external tower crane is attached to the outer wall of the building through the supporting frame,and all loads are supported by the supporting frame.The frequent changes of working conditions of the tower crane will affect the stability of the supporting system to varying degrees.Therefore,it is of great significance to research the mechanical characteristics of the external tower crane support system for the installation,design and later optimization of the tower crane.Based on an engineering project,this paper introduces the ZSL750 tower crane in detail,including the size parameters and load-bearing conditions of the tower crane.After the tower crane structure was reasonably simplified,ANSYS finite element model was established,which mainly completes the following work:The structure of the supporting frame and the change of the force were analyzed.The supporting frame is mainly composed of supporting main beam,secondary beam,diagonal tie rod and lower strut.The upper supporting frame only supports the horizontal reaction of tower crane,the diagonal strut of the lower supporting frame supports the horizontal reaction,and the main beam supports the vertical reaction of tower crane.The stress of supporting frame girder was checking,at the same time,according to the actual size parameters,the finite element model of the lower support frame was established,and the maximum deformation of the main beam under different working conditions was obtained by simulation.Compared with the maximum deflection of the theoretical calculation,the reliability of the theoretical calculation was verified.The working conditions of tower crane were divided into eight kinds,and two special working conditions of the first and final external hanging of tower crane were selected.According to the load distribution under different working conditions,the deformation of the supporting frame and the stress of the supporting frame on the wall joint were analyzed by using the finite element software.And the maximum deformation of the braced frame under different working conditions and the changing trend of the forces in X,Y and Z directions are obtained.This paper analyzed the relationship between the support distance of the supporting frame and the verticality of the tower crane,and a mechanical model was establishedto solve the problem,the approximate expression relationship was obtained between the supporting distance of supporting frame and the verticality of tower crane,which has reference value for the study of the verticality of the tower crane and related contentsThe tower crane was simplified as a three mass three degrees of freedom model,and the simplified model was used to analyze the modal and harmonic response of the external towercrane and the independent tower crane.The influence of the support frame on the dynamic characteristics of the external tower crane and the independent tower crane was analyzed according to the numerical value and curve.At the same time,according to the existing analysis results,we can determine the natural frequency that may cause the tower crane to resonate.We can take the natural frequency as the objective function to optimize the tower crane in the later stage,and provide reference for the optimal design of the tower crane.