WIND AND MOTION INDUCED LOADS

Abstract

The buffeting wind load on structures includes the part of the total load that may be ascribed to the velocity fluctuations in the oncoming flow,U(x _f ,y _f ,z _f ,t)=V(x _f ,y _f ,z _f )+u(x _f ,y _f ,z _f ,t),v(x _f ,y _f ,z_f,t) and w(x _f ,z _f ,t),as well as any motion induced contributions. The theory presented below was first developed by A.G. Davenport [13, 14]. In the following it is a line like horizontal bridge type of structure that is considered. It is taken for granted that its z _f –position in the flow prior to any loading is constant along the entire span, that the wind field is stationary and homogeneous and that the main flow direction is perpendicular to the span-wise x -axis of the structure, in which case x _f is constant and y _f may be exchanged by x. It is then only the velocity fluctuations in the along wind and the across wind vertical directions expressed in structural axis that are of interest, i.e. the componentsU(x,t)=V+u(x,t) and w(x,t).