WIND PRESSURE COEFFICIENT PROVISIONS FOR LARGE FLAT ROOFS

摘要

The existing literature on wind-induced pressures on roofs of low-rise buildings is generally limited to regular-shaped, mostly rectangular roofs with relatively small dimensions, say less than 60 m. Large roofs for industrial and institutional buildings have not been considered in the formulation of wind code and standard provisions. Therefore, it is important to assess the efficiency of the current national building code/standard provisions as to their applicability for very large roofs. This paper presents experimental results of wind loads on flat roofs of low-rise buildings with large dimensions carried out in an atmospheric boundary-layer wind tunnel for different wind directions. Nine low-rise buildings (5, 7.5 and 10 m high) have been modeled and tested in open-country terrain exposure. The buildings have square plans with full-scale horizontal dimensions ranging from 60 to 180 m. Comparison of the results with respective provisions adopted by ASCE 7-10, NBCC 2015, EN 1991-1-4:2005 and AS/NZS 11702, 2011 indicates that some of the current provisions may lead to considerably conservative designs by increasing the size of the edge and corner zones. A variety of approaches were considered in order to redefine the size of the edge and corner zones with respect to the magnitude of the pressure coefficients provided for all roofs in the different codes/standards when dealing with large roofs of low-rise buildings.