Analysis Of Structural Seismic Responses Of Certain Urea Prilling Tower

The urea prilling tower, such tall building, is comparatively sensitive to the response of earthquake. At present, there is no other domestic guiding data to guide urea prilling tower designs yet, except the"Specification for design of urea prilling tower". Therefore, adopting the finite element method to study the seismic response of the urea prilling tower to guide and perfect the urea prilling tower designs, appears very necessary.In this paper, considering the changes of the tower thickness and seismic intensity, the multi-dimensional seismic behavior of the Urea Prilling Tower was analyzed by using finite element software, SAP2000. Firstly, modal analysis of the urea prilling tower was used to study the dynamic characteristics of the structure; Secondly, mode-superposition response spectrum method was introduced to study the deformation conditions, the changes of the internal force at the bottom of the tower and the stress trend of level and vertical key sections; Thirdly, time-history analysis method was employed to study the changes of deformation and internal force under frequent earthquake, get the envelope curves of displacement and internal force along its height, identify the weak parts and local abnormal reaction positions of the structure; Finally, structural deformation was taken as index to study gravitational P ?Δeffect impacting on the structural deformation under earthquake.As is analyzed above, it can reach main conclusions as follows: concluded from the dynamic characteristics of the structure, the fundamental frequency of the structure is comparatively high, which shows the characteristic that the overall stiffness is high. The main vibration mode of the structure is horizontal, and the vertical is not obvious. When adopting mode-superposition response spectrum method to calculate urea prilling tower which is a high-rise structure, it should consider the impact of high-order mode and choose the right amount of vibration. Through time history analysis, which is an effective complement to the response spectrum analysis, it can observe the whole process of earthquake response. The calculation shows that the position of abrupt change in stiffness is the weak department of the structure, which needed to pay special attention to. The structure's response under earthquake has a linear relationship with the seismic intensity. Multi-dimensional seismic effect on the base shearing force and the level displacement of the structure is great, therefore, in order to fully grasp the seismic resistance of the urea prilling tower, taking the multi-dimensional seismic effect into consideration is very necessary. Second-order effects on the structure of the natural vibration period and the top horizontal displacement have some influences, and as the thickness of the tower decreasing, gravitational P ?Δeffect on the structural deformation increases. Therefore, the second-order effect should not be neglected to such a high-rise construction as the thickness of the tower decreasing.