Wind effects on monosloped and sawtooth roofs

Wind is one of the significant forces of nature that must be considered in the design of buildings. The actual behavior of wind is influenced not only by the surface (or boundary-layer) conditions, but also by the geometry of the building. All sorts of turbulent effects occur, especially at building corners, edges, roof eaves. Some of these effects are accounted for by the wind pressure coefficients. Wind pressure coefficients are determined experimentally by testing scale model buildings in atmospheric boundary layer wind tunnels.;In this study, a series of wind tunnel tests with scaled building models were conducted to determine the wind pressure coefficients that are applicable to monosloped and sawtooth roofs. In the estimation of wind pressure coefficients, the effects of building height, number of spans and terrain exposure are considered and analyzed in detail. Both local and area-averaged wind pressure coefficients are calculated and compared with values in ASCE 7 design load guidelines.;Wind pressure coefficients on "special" sawtooth roof buildings (sawtooth roof monitors separated by horizontal roof areas) are also investigated. It is found that increased separation distances result in increased peak negative wind pressures on the sawtooth roof monitors that exceed the wind pressures determined on a classic sawtooth roof building.;Analysis of the test results show no significant difference between the extreme wind loads on monosloped roofs and sawtooth roof buildings and by implication, current design provisions in ASCE 7 for monosloped roofs may be inadequate. The author-defined pressure zones for the windward span, middle spans and leeward span of sawtooth roofs based on wind tunnel tests allow more accurate determination of different levels of suction on the roofs.;Finally, the author proposes the design wind pressure coefficients and wind pressure zones for these two types of roofs and suggests future enhancement to existing ASCE 7 design load provisions for sawtooth roof systems.