Chapter 6 Wood Floor Collapse Flashcards
Destructiveness of collapse depends upon (structural hierarchy effect)…?
the FIRST structure to fail and where this structure is POSITIONED within the building
Floor collapse depends on first structure to fail…
column will be worse than girder
girder worse than beams
LIght Weight truss floors?
wood truss
wood laminated I-beam
lightweight cold formed steel c beams
open web bar joists
Fire resistance of a floor is related to?
its MASS (bulk)
and
SPACING in the floor system
-lightweight floors have less mass and greater spacing
Traditional wood floors are ____ inches on center-lightweight floors can be ___apart?
16-18 inches
2-4 FEET
This reduction of mass and increased spacing will ?
reduce fire resistance and allow floors to burn through and fail faster
3 ways floors will Fail during fire?
Floor Deck collapse- only wood deck is burned through and collapses, leaving joists intact
Floor Beam collapse- several joists may fail, causing a localized failure of a section of floor- more DEADLY collapse
Multilevel Floor collapse-describes progressive floor failure. here a floor collapse triggers the subsequent collapse of floors below and of one or more enclosing walls. MODST DEADLY
Multilevel collapse often happens in ?
burning buildings that have columns and girders supporting floors…a building with a frontage of 25 feet or more usually has columns or girders
The chances of multilevel floor or “progressive” collapse occurring are great when the first structure to fail is..?
COLUMN/GIRDER OR BEARING WALL
V-SHAPED floor collapse?
floor collapses at the center, cause by CENTER FLOOR OVERLOAD
Pancake collapse?
floor collapsing onto the floor below-causing the lower floors to collapse, can be caused by the shock or impact of a heavy falling object,
When there is a danger of a multilevel floor collapse?
withdrawn FF’s from inside building and setup defensive operation
-master streams outside collapse zone
Most DANGEROUS time for floor collapse is ?
during the end of the fire- DECAY STAGE-after fire has been extinguished
Salvage and Overhaul time is when collapse danger is highest because at this time?
a. building structure is destroyed by fire
b. impact of powerful hose streams has weakened structural supports
c. building content and structure may have absorbed tons of water
In building appears in danger of collapse..?
overhauling should not be done
-IC should use hydraulic overhauling
