Analysis Of Natural Vibration Frequency And The Stablity Of Ally Arm Of Steel Arch-gate

The west spillway is an important part of hydraulic structures in Huairou reservoir. The type-selection of gate in the west spillway in Huairou reservoir is steel arch-gate. The west spillway gate is 12 meters wide and 6.3 meters high, and it uses fixed winch hoist to fulfill opening and closing. Its main function is flood water storage, and it often operates under two conditions which contains completely opening and completely closing.This paper briefly expounds the principle of the finite element method and the analysis process, introduces the basic situation of finite element software ANSYS, and introduces the theory of structure natural frequency and structure stability analysis based on ANYS platform. With the help of the finite element analysis software ANSYS, this paper creates the steel arch-gate model, and calculates its natural vibration frequency under the completely closing and just-hoisting conditions, analyzes and compares its natural vibration frequency variation under the two conditions. It also analyzes the stability of ally arm with the method of eigenvalue buckling analysis, calculates the first ten order critical buckling load and buckling mode of the ally arm, and summarizes the ally arm-related variation of parameters influence on its stability. The analytical results of the natural vibration frequency of the gate and the stability of ally arm can provide technical support for the safe and efficient operation of the gate management. The variation of the stability of ally arm can provide references for the steel arch-gate design. The main conclusions of this paper are as follows:1. There was almost no resonance possibility for the gate when the gate was under completely closing condition, but when the gates was just opened, the resonance possibility for the gate increased greatly.2. The other frequencies are basically the same under the two conditions except for the first-order natural frequency, vibration mode is basically the same. And with the increase in orders, frequency increases.3. If the resonance of gate occurs, the vibration situation will be quite serious under the two conditions, so we should give full attention to the possibility of resonance of gate, and take appropriate measures to prevent the occurrence of resonance.4. When the structural instability of the main beam of ally arm in the gate occurs, ally arm around its plane of the flange of main beam deformed is shown as its main form. The performance for the first ten buckling mode is mainly for main beam buckling deformation on the upper ally arm, and the critical buckling load of the first ten are basically the same. And the value of deformation decreases with the increasing order.5. The beam height has the greatest influence on its stability among the parameters of ally arm, followed by the flange width. Other factors, such as the angle of ally arm, column webs in the section height and width, diagonal strut flange diameter and wall thickness that change in size almost have no effect on stability of ally arm.