Prefabricated Wood Truss Roof Failure under Wind Induced Loads

This paper presents a study to evaluate the performance of single-story multifamily buildings’ truss roof structures subjected to tornadic wind loads. This study was conducted to determine whether the roof structures of a condominium complex located in Florida were damaged by the storm event that occurred at the site. The investigation consisted of an assessment of the storm wind speeds and a detailed structural engineering analysis. The roof framing consisted of prefabricated long span wood trusses with metal gusset plate connections, supported on exterior masonry block walls and anchored to tie beams with hurricane straps. A challenge for this investigation was to determine wind loads generated by tornadic winds which are different in magnitude compared to wind loads produced by straight line winds for the same wind speed. This paper describes in detail the analysis performed which revealed that the primary mode of failure was at the truss connector plates caused by wind uplift forces. The failure pattern obtained from the analysis was consistent with the damage assessment noted from on-site observations which indicated that the majority of failures occurred at truss plates along the truss top chords.