An Experimental Investigation of Wind Load on Tall Buildings with Octagonal Cross-Section

Abstract

In this research work, an experimental investigation of wind load on octagonal cylinder was carried out. The study was performed on both the single cylinder and the group consisting of two cylinders, arranged in staggered form one in the upstream and another in the downstream side. The test was conducted in an open circuit wind tunnel at a Reynolds number of 4.13 x 10⁴ based on the face width of the cylinder across the flow direction in a uniform flow of velocity 13.2 m/s. At first experiment the test was carried out on a single cylinder at various angles of attack from 0° to 50° at a step of 10°. Then the group of two cylinders were taken into consideration for the study and the surface static pressures were measured for various inter–spacing of 1D, 2D, 3D, 4D, 5D, 6D, 7D and 8D, where D is  the width of the cylinder across the flow direction. In each case, the wind velocity was kept constant at 13.2 m/s. The pressure coefficients were calculated from the measured values of the surface static pressure distribution on the cylinder. Then the drag and lift coefficients were obtained from the pressure coefficients by the numerical integration method. It was observed that the drag coefficients become remarkably smaller compared to those for a sharp-edged square cylinder. It was also observed that at various angles of attack, the values of the lift coefficients were insignificant compared to those for a sharp-edged square cylinder. The results will enable the engineers and architects to design buildings more efficiently. Since the results will be expressed in the non-dimensional form they may be applied for the prototype building.