Experimental study on wind load in roof and overhang of a gable building

Abstract

The present paper discusses on effect of boundary-wall on wind load in the roof and overhang of gable building. Pressures on roof and overhang are measured at varying distances of boundary-wall away from the building. Data were obtained in simulated conditions for open country and suburban terrain, at a scale of 1:25, in a Boundary Layer Wind Tunnel at Indian Institute of Technology Roorkee. Plan dimensions of gabled roof building model are 300mm×150mm and wall height 130mm with roof slope10 o. An overhang eaves length of 60mm and boundary-wall of height 66mm have been chosen for the experiment. Significant changes have been observed in magnitude of pressure coefficients on the roof and overhang with varying distances of boundary-wall from the building. In addition, the wind loads on roof and overhang have been compared with different codal values. A gable roof building model representing a building of plan dimensions 7.5m × 3.75m × 3.25m (wall height, H) was fabricated as shown in Figure 1. Roof overhang extended upto 1.5m from building wall. These buildings are regarded as simplified model of typical low rise building in India for warehouses and residential houses. Experiment for the stand-alone condition was performed for different angles of wind incidence ranging from 0 o to 90 o at an interval of 15 o. In the case of interference, the experiment was performed for 0 o, 30 o, 60 o and 90 o angles of wind incidence by shifting the boundary wall position at 1H, 1.5H, 2H, 3H, 4H, 5H, 6H and 7H from the wall of building. Detailed study of interference of boundary wall has been carried out where D/H=0 implies no boundary wall for the subsequent discussion. The different zones for roof & overhang and lay out of pressure taps are shown in Figure 2. Particular attention has been paid to position of pressure taps near the edge and corner of the eaves where airflow may become separated to form a region of high velocity gradient with high local turbulence and vortices. © Museo Ideale L. Da Vinci.