TrusSteel - Cold Formed Steel Trusses

1 2 3 4 5 6 7 8 3.04 Specified Design Loads Trusses are required to transfer various types of loads down to the support structure. Ultimately all loads must be carried down to the foundation of the structure. Truss design (specified) loads include both live and dead loads which may be uniformly distributed or concentrated at various locations. These loads consist of gravity loads, wind loads, earthquake loads, snow loads, rain loads, etc. Referenced within the IBC, the standard that deals with loads is the American Society of Civil Engineers (ASCE) standard, Minimum Design Loads for Buildings and Other Structures. The latest version of this standard is published in cooperation with the Structural Engineering Institute (SEI) and is referenced as SEI/ASCE7, or commonly as "ASCE7" where the last two digits reference the year the standard was published. ASCE7 is the reference standard that a Building Designer will use when determining what loads a building element must resist. It is the responsibility of the Building Designer to specify all the loads that the framing members will encounter and communicate them to the truss designer. The truss designer will use those Special Conditions • Jobsite conditions that may cause rough handling of the trusses. • High moisture or temperature conditions. • Extreme environmental exposures that may cause corrosion to CFS members. • Use of trusses to transfer wind or seismic loads to the supporting structure. • In-plane and out-of-plane loads, such as lateral loads, are examples of loads that are required to be transferred to the supporting structure. • Fire resistance requirements. • Higher adjacent roofs that may discharge snow onto lower roofs. • Location from coastline, building exposure, building category and height above ground for wind. • Parapets, signage or other obstructions that may cause snow drifting or prevent the free run-off of water from the roof. These types of building elements may also induce additional dead loads that must be applied to the trusses. • Any other condition that affects the load carrying ability of the roof or floor framing. • Floor trusses, office loads or ceramic tiles require special considerations during the building and truss design process. loads when designing the truss system, so it is very important that the specification of these loads be both thorough and clear. Live/Environmental Loads: These loads are non-permanent loads. Examples include the weight of temporary construction loads and occupant floor loads. Environmental loads are produced by snow, wind, rain or seismic events, are usually uniform in their application, and are set by the building codes or the building designer. They will vary by location and use, and should be furnished in pounds-per-square-foot or other clearly defined units. Dead Loads: Dead loads include the weight of the materials in the structure and any items permanently placed on the structure. Special Loads: Special loads can be live or dead. Examples of special loads might include mechanical units, poultry cages, cranes, sprinkler systems, moveable partition walls, attic storage, etc. The weight, location and method of attachment must be provided to the truss designer. Multiple load cases may be required in truss design. Rebuilding the Pentagon INFORMATION REQUIRED FOR TRUSS DESIGN ENGINEERED BY ALPINE S P E C I F Y I N G / D E S I G N I N G

• Cover