Experimental Study On Wind Load Of Rectangular High Buildings

Wind load is an important design load of structures. It plays a crucial role on the design of tall structures(such as chimney,tower,backstay),high-rise buildings,long-span bridges,roof structures and so on. Gust wind loads on buildings include static wind loads and fluctuating wind loads,and the latter is a random process of time and space,therefore, random vibration theory is used to study the wind-induced response. So the study on the Stat. characteristics of wind forces becomes an important topic of wind engineering. Recently,numerical simulation method is applied to forecast the wind-induced response on high-rise buildings,it can save research cost and make re. for preliminary design. Wind forces are made up of along-wind,across-wind force and torque,they interfere with each other and were usually studied in wind-tunnel . The Building Load Code we use now is based on the base moment at the bottom of buildings,If we know wind force characteristics along the height of buildings, such as wind force coefficients,wind force spectrum and spatial correlations,We can simulate wind loads in time domain through numerical simulation method to analyze wind-induced response of buildings. Wind-tunnel tests with simultaneous point pressure measurements and HFBB on nine rectangular cross-section models of various side ratios and aspect ratios are presented. Through analyzing the test data,wind force characteristics were studied from the aspects of local wind force,total wind force and generalized wind force. The experiential formulae of local wind force coefficients ,Strouhal numbers of rectangular tall buildings are proposed,their reliability and versatility is verified through comparison with results of the wind tunnel tests. The cross-correlation in time domain,coherence and phase in frequency domain are also studied to simulate wind loads better. The overall base forces and moments are obtained by synthesis of local wind forces,comparisons are made with the results obtained from two measurement techniques in two wind tunnels. Then,generalized wind force coefficients of bend-mode,shear-mode and linear mode are presented,effects of mode,side ratio and aspect ratio on generalized wind force spectrum are also studied to prepare for wind-induced response analysis and structure preliminary design. At last,simplified empirical formula to evaluate across-wind dynamic response of rectangular tall buildings under wind load are proposed in this paper,By using these formulae, aross-wind dynamic responses can be conveniently evaluated by algebra operation instead of by complex integral calculus.