Ch. 15 Wood frame building collapse Flashcards
There are three ways that a wood frame bldg. can collapse during a fire.
What are they?
90 DEGREE ANGLE-one wall may fall straight outward.
LEAN OVER-when the entire bldg. may lean over and collapse on its side.
INWARD-OUTWARD- when one or all 4 walls may crack apart and fall in a inward-outward collapse.
What is a warning sign of a 90 degree collapse?
A 90 degree collapse is often signaled by the corners of a wall splitting apart.
What is the warning sign of a lean over collapse?
The lean over collapse is often indicated by the structure starting to tilt or lean to 1 side.
An inward-outward collapse may not exhibit any structural warning at all; sometimes the only indication that a collapse is imminent is what?
A serious fire burning for a long time on the LOWER floor of the bldg.
An inward-outward collapse is the most dangerous of the three collapses because there are usually no signs prior to it happening. It may involve the collapse of 2, 3, or 4 walls simultaneously. FF’s in the flanking zones will survive a collapse. Where are the 4 flanking zones around a burning wood frame bldg.?
The four flanking zones are the corner safe zones at each corner of the bldg. where the wall will not fall into.
What are the FOUR (4) most widely used methods of wood frame construction?
- Braced Frame
- Balloon
- Platform
- Lightweight wood frame NEW
Out of the four types of wood frame construction which type presents the greatest firefighting danger according to DUNN?
Braced frame construction
During the early stages of a fire in a Balloon constructed wood frame bldg., which part of the structure should be quickly examined for fire spread?
The attic
What is the danger to FF’s during the early stages of a fire in a bldg. built using lightweight wood construction?
Early floor and roof collapse of truss floors and roofs.
The entire bldg. may eventually collapse but its the early stage of the fire, when FF’s arrive that a floor or roof fail, especially the floors.
Three factors contribute to an inward-outward collapse of a braced frame wood bldg.;
What are they?
- Fire destruction of bearing walls
- Failure at the mortise and tenon joint
- Exterior wall overload (ex. Fire escapes)
In Braced frame construction; the bearing walls are interconnected with the interior floors if the bearing wall fails during a fire what will happen to the floors?
The interior floors will collapse if a bearing wall fails during a fire.
In a peaked roof bldg. with braced frame construction the bearing walls support the majority of the roof rafters. The bearing walls run which way to the ridgepole?
The bearing walls run parallel to the ridgepole
In flat roof bldg.’s the bearing walls are usually the walls with the _________ dimension, and the non bearing walls have the _________ dimension.
Fill in the blanks
Bearing walls have the GREATEST dimension
Non bearing walls have the SHORTEST dimension
Wooden bldg.’s located on a corner plot or standing alone are more susceptible to collapse during fires than wood bldg.’s in the center of the row. When a serious fire burns out the entire 1st floor of a 3 story wood bldg. there is also a danger of collapse.
What type of collapse can occur in the 2 scenarios above?
A GLOBAL collapseNEW
