A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Hanging Load Failures in Wood Beams
In the 1971 San Fernando Earthquake, partial roof collapses occurred in concrete tilt-up buildings when wood ledgers bolted to the tops of the tilt-up walls (supporting the edges of the plywood roof diaphragm and tying the roof to the wall) failed as they were subjected to perpendicular-to-grain (cross-grain) bending. Beginning with the 1973 Uniform Building Code, the use of cross-grain bending was prohibited for connecting roof diaphragms to walls. This loading condition is also disallowed through the absence of published design strengths for cross-grain bending and tension in the National Design Specification for Wood Construction. Despite these lessons learned, significantly less attention has been given to avoiding cross-grain tension in everyday loading conditions, such as hanging loads from wood beams. It is common in new and existing construction for the design team to specify HVAC equipment, insulated ceiling systems, fire suppression piping, and other equipment to be hung from wood beams in commercial and industrial buildings. In this paper, recommendations and guidelines for hanging loads from wood beams are summarized from the technical literature used in the US. Case examples of cross-grain tension failures are presented so that explicit building code and design standard provisions can be improved and similar failures can be avoided.
Hanging Load Failures in Wood Beams
In the 1971 San Fernando Earthquake, partial roof collapses occurred in concrete tilt-up buildings when wood ledgers bolted to the tops of the tilt-up walls (supporting the edges of the plywood roof diaphragm and tying the roof to the wall) failed as they were subjected to perpendicular-to-grain (cross-grain) bending. Beginning with the 1973 Uniform Building Code, the use of cross-grain bending was prohibited for connecting roof diaphragms to walls. This loading condition is also disallowed through the absence of published design strengths for cross-grain bending and tension in the National Design Specification for Wood Construction. Despite these lessons learned, significantly less attention has been given to avoiding cross-grain tension in everyday loading conditions, such as hanging loads from wood beams. It is common in new and existing construction for the design team to specify HVAC equipment, insulated ceiling systems, fire suppression piping, and other equipment to be hung from wood beams in commercial and industrial buildings. In this paper, recommendations and guidelines for hanging loads from wood beams are summarized from the technical literature used in the US. Case examples of cross-grain tension failures are presented so that explicit building code and design standard provisions can be improved and similar failures can be avoided.
Hanging Load Failures in Wood Beams
Hunt, Jeffrey (author) / Freidenberg, Aaron (author)
Ninth Congress on Forensic Engineering ; 2022 ; Denver, Colorado
Forensic Engineering 2022 ; 1072-1080
2022-11-02
Conference paper
Electronic Resource
English