Research On Wind Load Response Characteristics Of Tower Crane Slewing Mechanism Under Non-Working Conditions

In order to meet the increasing demand for urban housing,China's housing construction operations have increased year by year.Tower cranes play an important role in the construction of high-rise buildings.The demand for lifting weight is also increasing,and their design requirements are gradually increasing.Coastal cities in my country are often affected by bad weather such as typhoons.Tower cranes used in coastal construction sites often collapse under the influence of typhoons.In the non-working state,the tower crane releases the slewing mechanism so that its superstructure can rotate freely,thereby generating a weathercock effect to improve its wind resistance.Whether the weathercock effect is formed and the length of time required directly affects the wind resistance of the tower crane.Therefore,in-depth study of the response characteristics of the slewing mechanism to wind load can provide theoretical guidance for the wind resistance design of the tower crane.The main research content of this paper is to simulate the sequence of wind load,establish a dynamic analysis model of the tower crane system under wind load,and study the dynamic characteristics during the rotation process through dynamic simulation,which provides a theoretical basis for the wind resistance design of the tower crane.In this paper,the wind spectrum is used to simulate the time series of pulsating wind loads in the downwind direction and the crosswind direction based on the harmonic superposition method.The spectral deviation of the simulated spectrum and the target spectrum can be used to determine the accuracy of the time series.Numerical simulation of the field parameters provides a basis for the establishment of the generalized external force matrix of the tower crane system.The modeling process of the tower crane system is based on the flexible multi-body system dynamics theory.The floating frame of reference formulation method is used to model the tower crane.According to the equivalent principle of constant length,the space truss structure is simplified and equivalent,and its motion form is analyzed to decompose the space motion into multiple plane motions.According to the floating frame of reference formulation method,the finite element method is used to discretely describe the generalized coordinates of the deformation description system of the flexible member.The generalized coordinates can be used to describe the large deformation and large rotation of the boom structure with large flexibility,which is convenient for derivation modeling The dynamic equations of the overall system are obtained.From the kinetic energy of each member,the virtual work of elastic force,the loading condition and the composition of the structure,the mass matrix,stiffness matrix,generalized external force matrix,constraint equation and Jacobian matrix of each member are obtained.A class of Lagrange equations can be integrated to obtain the system dynamics equations.The generalized-? method is used to solve the dynamics equations,and the time-response curves of the displacement and velocity of multiple key points of the tower system under different wind loads are obtained.The comparison of simulation solutions verifies the accuracy of the model,and provides a theoretical basis for the stress response and dynamic stability analysis of the system.The ANSYS software is used to verify the stress response of the system,and the results are accurate.Although the modeling and calculation of the truss structure can be achieved through the existing commercial finite element software,its implementation from modeling to displacement response to dynamic stress,stability analysis data and processes need to be transferred from ANSYS to ADAMS and then returned to ANSYS,and The data processing and exchange are complicated.In order to establish a unified modeling process,this process includes the processes of displacement response,dynamic stress response and dynamic stability conversion.MATLAB programming is used to achieve a complete unified calculation process.Through the calculation of displacement,displacement,stress response and dynamic stability during rotation under wind load,it provides guidance for practical engineering design.