PROFILE 3 (SLW & ULTIMATE).pdf - Emenite Limited

advisable to avoid backflow through the joints, and advice of the Technical Services Department shouldbe sought.4.34.3 LOADS• Dead loadsAre loads that do not change over the course of normal operations of the building.They are composed by the self weight of the materials and structural elements.Dead loads include the weights of the roof structure itself and only permanent fixture.• Live loadThe live loads on roofs are additional to all roof covering materials and include snow and other incidental loads but exclude wind pressure.• Wind loadit is a dynamic load generated by the wind. Can be suction or compression depending on diverseaspects: Geometry of the construction, direction of the wind, slope, etc.Because of the complexity of analysis, dynamic loads are normally treated using statically equivalentloads for routine design of common structures.4.3.14.3.1 Wind loads• Suction loads and pressure loadsWind can affect a building and its roof in a pattern determined not only by climate and topography, butalso by wind direction, the shape of the building and the pitch of the roof.Wind blowing at 90° to a building is slowed down when it hits the surface of the building, with a consequentbuild up of pressure. At the same time, it is deflected around the end walls and over the roof,creating areas of negative pressure or suction. The stronger the wind the greater the suction.The force of the wind acting on the windward slope is determined by roof pitch. Research has shownthat where the pitch is less than 30°, the windward slope can be subjected to severe suction or negativepressure. A roof with a pitch greater than 35° generally presents suffcient obstruction to the wind to create a positive pressure on the windward face, although, even here, there is an area close to the ridge wheresuction develops. Leeward slopes are always subject to suction.During strong wind, the uplift pressure on the PROFILE 3® caused by the suction load may be in excess22®PROFILE 3 MANUAL