Overview on purlins

In first instance, you choose the number of supports: purlin on two supports, continuous along two or three bays. Please note that a purlin can have one or two overhang at its extremities. Then, depending on the position of the purlin (wall, intermediary or ridge), you chose its assembling: inclined, inclined with stiffeners at mid-span, vertical with canted angle, double and inclined, etc…

Eventually, the definition of the purlin is completed with the following data:

• Environmental parameters (moister content, …)
• wood category
• Cross-sectional dimension
• Initial cambers of principal rafters and tie-beam
• Supports (resting, with shoe or imbedded in masonry)

Overview on rafters

In first instance, you choose the number of supports: rafter on two, three or four supports. Please note that a rafter can have one or two overhangs the edge of the roof. Then, the definition of the rafters is completed by the following data: Environmental parameters (moister content…) Wood category Cross-sectional dimension

Overview on loads

Dead loads of the roof: you have the choice between two input modes. In the first mode, you choose in predefined lists the various components attached to the roof or the floor. The total load is then automatically computed. In this case, you can select the nature of the roof covering, the fastening system, the plates and insulation components, etc… In the second mode, you input directly the desired total load.

Snow load: You have the choice between three distinct methods to specify the snow loads, either using the map from the standards, or you select the standard zone, or you input directly the desired values. To complete the snow load definition, you specify the altitude of the construction, then still using predefined lists, you select the various parameters to be considered such as the presence of snow retaining structures, the exposition coefficients, etc… Furthermore, to allow considering snow accumulation schemes, it is possible to identify up to three loading zones and to attach a different multiplying factor to each of these. It should be noted that, for a rafter, you have in addition the possibility to specify vertical point loads at the extremity of the overhang to model snow accumulation.

Wind load (optional): You have two definition modes to determine the base pressures, either using the map from the standards to select the construction region, or you select a zone. Please note that in the case that the purlin transfers the wind bracing loads, you can input the compression load they are subjected to.

Roof maintenance load: Using lists, you select the usage category of the roof and the positioning of the load. The load value is then automatically determined. Please note that you are always free to specify specific load values. Load combinations: the load combination and the various factors included in these combinations are automatically determined without further user input.