collapsed building
TRANSCRIPT
-
8/2/2019 Collapsed Building
1/32
Building Structure
&Types of Collapse
-
8/2/2019 Collapsed Building
2/32
STRUCTURE ELEMENTS
Columns
vertical structural members ofa building
Beams horizontal structural members
of a building
Combination of columns andbeams form the frame of thebuilding
-
8/2/2019 Collapsed Building
3/32
STRUCTURE ELEMENTS
A beam is supported by oneof three methods
cantilever beam - supported
or anchored at one end only
continuous beam - supportedat both ends and at the center
simple beam - supported atboth ends
-
8/2/2019 Collapsed Building
4/32
STRUCTURE ELEMENTS (cont)
Wall (load bearing)
wide column
carry the dead
weight of building
Floor
horizontal elementsfor creatinguseable space
-
8/2/2019 Collapsed Building
5/32
STRUCTURAL BUILDING TYPES
Unframed Building Partially Framed
Fully Framed Monolithic Building
-
8/2/2019 Collapsed Building
6/32
BUILDING MATERIALS
Timber
commonly used in early 19th century
Brick
usually in columns and walls
Stone
older buildings
-
8/2/2019 Collapsed Building
7/32
BUILDING MATERIALS (cont)
Reinforced concrete
structural concrete with steel reinforcement
Structural Steel
facilitate quick erection of frame
-
8/2/2019 Collapsed Building
8/32
LOAD
Loads = forces acting upon astructure
Dead Load
weight of building itself andequipment permanently attached
eg. walls, floors, columns, girdersa. concentrated load
b. distributed load
-
8/2/2019 Collapsed Building
9/32
LOAD (cont)
Live Load any load other than dead load
buildings content
e.g. furniture, humans Axial Load
force that passes thru the center
of a structure
most efficient way by which aload can be transmitted thru a
structural support like a columnor bearing wall
can withstand greatest load
-
8/2/2019 Collapsed Building
10/32
LOAD (cont)
Eccentric Load (off-centered)
off-centre, perpendicular to planeloading
when structural elements shifted slightly
common in partial collapsed ordamaged buildings
Torsional Load (twisting) load that creates a twisting stress on a
structural members
Both can cause a collapse
-
8/2/2019 Collapsed Building
11/32
STRESS
Stress = force exerted upon astructural member that strains ordeforms its shape
Compression
a force pressing or squeezing a
structure together
-
8/2/2019 Collapsed Building
12/32
STRESS (cont)
Tension stress placed on a structural member
by a pull of forces causing extension
Steel is strong in compressive andtensile strength
Concrete is strong in compressivebut weak in tensile strength
Rope is strong in tensile strength
& has no compressive strength
-
8/2/2019 Collapsed Building
13/32
TYPES OF
COLLAPSE PATTERNS
Lean over
a wood-frame building can collapse to one side
Lean to (Supported)
support at one end of structure member gave way,and that end collapse
triangle shape void
-
8/2/2019 Collapsed Building
14/32
Cantilever Collapse (Unsupported Lean to)
unstable
support at one end of horizontal member gaveway, but that end is suspended
secondary collapse likely
TYPES OF
COLLAPSE PATTERNS (cont)
-
8/2/2019 Collapsed Building
15/32
V-shaped Collapse
integrity of horizontal member fails due toexcessive load
collapse of a floor at the center of the floor beam
void at either ends
large scale or localised
TYPES OF
COLLAPSE PATTERNS (cont)
-
8/2/2019 Collapsed Building
16/32
Pancake Collapse
when floor beams pull loose or collapse at both
ends
small voids created by strong supporting objectsbetween floors
extensive searching
use of natural opening e.g. stairwell provide quickaccess
TYPES OF
COLLAPSE PATTERNS (cont)
-
8/2/2019 Collapsed Building
17/32
EXAMPLES OF
PANCAKE COLLAPSE
-
8/2/2019 Collapsed Building
18/32
Curtain Fall Collapse
occurs when a masonry wall (stone wall) dropslike a falling curtain cut loose at the top
Chain Reaction Collapse excessive impact loading caused by collapse of
higher floors resulting in failure of lower floors
Inward/Outward Collapse
wall breaks apart horizontally
rotational collapse
TYPES OF
COLLAPSE PATTERNS (cont)
-
8/2/2019 Collapsed Building
19/32
90 Collapse
failure of bottom of
vertical support,causing the elementto fall straight outand the top strikingthe floor
similar to a fallingtree
TYPES OF
COLLAPSE PATTERNS (cont)
-
8/2/2019 Collapsed Building
20/32
EARTHQUAKE COLLAPSE
PATTERNS
This 2500-car-capacity parking structure, a 1991addition to the Cal State University - Northridge
campus, suffered partial collapse in the intense
shaking of the Northridge earthquake. A close-up of
of this entrance to the parking structure shows the
closely spaced fractures in the reinforced concrete
columns which allowed "bending" of the outer wall
6th floor of a 8-story high office
building collapsed. A high rise
building near the damaged building is
hardly affected.
-
8/2/2019 Collapsed Building
21/32
MORE PICTURES
Buckling of freeway support columns under the
Simi Valley Freeway at the north end of the San
Fernando Valley. This buckling shows thestructural failure produced by high vertical
acceleration.
Examples of ground floor collapse due to
inadequate design in vertical support
-
8/2/2019 Collapsed Building
22/32
POOR BUILDING RENOVATION
& URBAN DECAY
Gravity loading cause collapse of verticalsupport due to:
inadequate design
overloading
reduction in capacity due to age, corrosion or non-engineering alteration
May occur after a building that suffered aninitial collapse left standing
-
8/2/2019 Collapsed Building
23/32
WARNING SIGNS OF
STRUCTURAL COLLAPSE
Movement in floor or roof
Sponginess
Sagging or bulging walls
Columns and walls out of plumb
Beams twisted out of alignment
Cracks appearing
Creaking and groaning noises
Unable to close doors and windows
-
8/2/2019 Collapsed Building
24/32
VOIDS
Spaces created when building or structurecollapses
May contain trapped victims
Depend on:
type of collapse
presence of large or heavy objects
-
8/2/2019 Collapsed Building
25/32
STRUCTURAL COLLAPSE
HAZARDS
Ask these questions before proceeding withrescue:
structure?
occupancy?
HAZMAT?
storage area?
Adjacent structures affected?
Utilities affected and isolated?
5 types of structural collapse hazards
-
8/2/2019 Collapsed Building
26/32
HAZARDOUS MATERIALS
Examples:
chemicals
dust
radioactive materials
biological hazards
pressure cylinders
asbestos
Seek information
-
8/2/2019 Collapsed Building
27/32
SURFACE HAZARDS
Examples:
rough terrain
moving and falling debris
sharp objects
flooding
holes in floor
hanging objects
Personal protection
Movement with care
-
8/2/2019 Collapsed Building
28/32
BELOW DEBRIS HAZARDS
Examples:
flooded basement
oxygen deficient atmospheres
toxic environment
Clear egress
Ventilation
-
8/2/2019 Collapsed Building
29/32
DAMAGED UTILITIES
Examples:
live electrical wires
ruptured gas lines
broken water mains
broken sewer systems
Isolate as early as possible
Dont assume, always check
-
8/2/2019 Collapsed Building
30/32
STRUCTURAL STABILITY
Constantly monitored and reviewed
Shore damaged structures before enteringand commencing S&R
Eyes and ears open
-
8/2/2019 Collapsed Building
31/32
CONCLUSION
Understanding stability of collapsed/partiallycollapsed structure is an ART and SCIENCE:
intuition
logical assessments
NEVER be hasty when operating in collapsedbuildings
Make safe before proceeding
-
8/2/2019 Collapsed Building
32/32