Research On Vibration Characteristics Of Tower Crane Boom Under Slewing Conditio

Tower cranes have become one of the indispensable and important equipment in modern building construction because of their high efficiency and flexibility.Due to the lightweight truss structure and low damping of tower cranes,the sudden change in the state of the jib during rapid start-stop and rotation is likely to cause vibration and cargo swing of the jib,which may cause fatigue damage and deformation of the jib,thereby reducing the strength and stiffness of its structure and eventually leading to structural damage and collapse.Therefore,it is important to study the structural vibration characteristics of the jib of the tower crane for its life safety.In this thesis,based on the principle of structural dynamics,vibration differential equations of the jib of the tower crane are established,and simulations and tests are carried out.The main contents of this thesis are as follows:(1)Based on the structural characteristics and slewing motion behavior of the tower crane,the structure of the tower crane is simplified and the coordinate system of the tower crane under slewing condition is established,the energy equation of rotating flexible beam is derived,and the equivalent moment of inertia for the jib is calculated.Based on Euler-Bernoulli beam theory and rotary flexible beam theory,the vibration of the jib in the slewing plane and the vibration in the lead hammer plane are considered,and the differential equations of tower crane vibration and cargo swing are derived under the slewing motion and luffing-slewing condition using Lagrange’s equation.Finally,differential equations are linearized.(2)Based on the established differential equations for the tangential vibration of the jib and cargo swing of the tower crane under the slewing condition and the combined luffing-slewing condition,the differential equations are resolved and simulated by Runge-Kutta methods in MATLAB,and the response and change law of the jib vibration and cargo swing are compared and analyzed under different angular acceleration of the slewing,cargo mass,slewing radius and luffing trolley speed.(3)Based on the linearized differential equations for the vibration of the jib under the slewing condition and the luffing-slewing complex condition,the effects of the angular acceleration of the slewing,the cargo mass and the slewing radius on the vibration of the jib and the cargo swing are simulated and analyzed after eliminating the cargo swing,and the effect of the cargo swing on the jib vibration of tower crane is also studied.(4)Based on QTZ5513 tower crane,the measurement scheme of jib vibration and cargo swing during the tower crane motion is designed to verify the reliability of the model and simulation results by performing tests on slewing condition and luffing-slewing condition complex conditions.