Analysis On The Maximum Acceleration Of Vertex Of High Rise Buildings Subjected To Wind Loads

The wind.induced load effects are important even decisive for high.rise structures, so wind loads, static and dynamic responses of tall buildings are usually the main content of studying. The high.rise structure will vibrate under the action of lateral force. People begin to feel uncomfortable even insupportable when the vibration reaches a certain limit value. This directly affects work and life of residents. This analysis of vibration effect for comfortable feeling of occupant is usually called comfort analysis. The maximal acceleration response is generally acknowledged used to judge comfort analysis mainly aiming at wind load though there are many standards measuring human comfort degree.The new subject appearing with super high.rise structure is still not deep enough. Though many methods of human comfort have been suggested by various countries, its rationality is worthy of studying. At represent,"Technical specification for concrete structures of tall building"(JGJ3～2002)[1] and"Technical specification for steel structure of tall buildings"(JGJ99-98)[2]in our country stipulate that the checking calculation on comfort is determined by calculation of value of vertex acceleration of structure. Considering the convenience in use, current standard is greatly simplified in theoretical deducing by a large of calculating, analyzing and arranging in selecting parameters and consider cohesion with former code.The main work and innovative achievement in this paper centering on along.wind acceleration of main structure are as follow:①Along.wind acceleration calculation formula of vertex of structure is obtained by theoretical deducing of RMS of acceleration response in frequency domain basing on relative regular structure and with random vibration theory and mode.superposition method of random vibration of wind vibration by reading plenty of related literature.②Along.wind acceleration calculation formula of vertex of structure is simplified and analysis and selection are performed on its parameters which include wind spectrum, spatial correlation function, terrain rough factor, vibration coordinate, and so on. Theoretical deducing is performed on simplification of imaginary part of the frequency response function.③This paper analyzes orthogonal problem of spatial modes in three.dimensional coordinates and checks the orthogonality by choosing a complex structure as example. The method of selecting vibration coordinate in the practical calculation is obtained by calculating the simple mode.④Matlab language is used to program the acceleration formula of vertex, and many examples are used for calculation. Different results are obtained and analysis is performed on structure according the choice of different value of k and the number of modes. Resulting achievements are as follow: The result shows comparatively great differences in acceleration of vertex with different value of k because value of k is more dispersed. Acceleration will increase at different degree with increasing of mode number. The maximum that high order mode of relative regular structure has influence on acceleration may reach more than twenty percent and may reach about ten percent when the value is small. Influence of high order mode can not be neglected some time because value of irregular structure can reach thirty percent. Often first five to eight orders of vibration model are taken to regular structure, and eight to ten orders are taken to relative regular structure, but more than ten orders need to be taken to relative complex structure when calculating along.wind acceleration of vertex.⑤Because when calculating of vertex acceleration the standard does not clear the specific factor k value of davenport spectrum, but consider to introduce of pulsation coefficient based on the dynamic reliability, avoiding the concrete value issues of k, it can not be concretely compared in practice, only as a reference. The k value that literature [3] gets has carried out comparison, and the result is smaller than the standard method computation result.