Res 4A Structural Collapse Flashcards
Tension Forces
Stretch members. Concrete and masonry have no tension strength
Compression Forces
Push on members. Crushed members tend to give warning such a splitting or bowing
Bending Forces
result of vertical loads caused by gravity pushing on slabs and beams. Roof rafters are subject to these forces
Tension and Compression of a beam
Tension bottom, compression top
Shear Forces
Occur in all beams and greatest at adjacent supports. Concrete, diagonal tension cracks.
Where are wood beams subject to shearing
Along a horizontal plane
Light Frame Construction
Skeletal structural framing system of wood or light gauge steel components.
Light Frame Construction degree of flexibility
High up to 300F, Low over 300F which produces a better image
Light Frame Construction is found
wood frame residential, multi-family low rise, light commercial up to 4 stories
Heavy Wall Construction
Independent structural or monolithic system making a grid.
Heavy Wall - Tilt Up Wall Construction
1-3 stories in height, multiple, monolithic, concrete wall panels with independent girder, column, and beams to provide lateral support for floors and roof.
URM Building
Unreinforced masonry building
Heavy Floor Construction
Typical cast in place concrete buildings
Pre Cast Construction
Modular concrete sections constructed on site with hazards at the connection points.
Cantilever Collapse
One end of floor hanging free, other end still attached, one wall has failed
Lean To Collapse
Wall fail or floor break/separation that causes one end to rest on a lower floor
Pancake Collapse
Upper floor fails and falls on lower causing lower floor to fail
V Type Collapse
Heavy loads cause floor to collapse near the center. Two voids created along outer walls
Tent Collapse
One end of floor collapses. Creating a void one EITHER side of the support member.
Secondary Collapse
Often more severe than the initial collapse
Safety Considerations Collapse
“Look outs” monitor structure for movement. Use of transit, plumb bob, level.
Briefing Collapse
Must be conducted, ensure understandings of
1) Rescue plan
2) Specific roles
3) Safety and hazard issues
4) Method of alerting and egress if unexpected failure
List of supporting tasks
Level 3 Account, mark collapse zone, control access, remove civilians, assign Safety officer, lookout crew, securing utilities, victim staging area
Collapse zone
At least 1 1/2 times the total height of structure
