Ch. 16 Collapse of bldg.'s under construction Flashcards
A bldg. being constructed or dismantled with temporary wood ladders, open shafts, open stair, propane…..is more deadly than an occupied or completed bldg. that has many safeguards, like enclosing walls, interior partitions and walls & doors around the stairs. What is the major life hazard during daytime hours at a construction site?
Bonus Who is especially the life hazard?
The workers trapped on the upper floors are the major life hazard.
-ESPECIALLY the worker inside the cab of the crane.
Bldg.’s under construction or demo are unstable structures, collapse happens fast when columns, girders and bearing walls have not been installed, not been fastened together or the supports are not yet protected with fire retarding material. Who is the major life hazard at fires after work hours (night) in these bldg.’s?
After work hours a fire will grow unnoticed into a large fire and the major life hazard will be the FF’s.
The hazard will be fire and collapse of the structure.
When does a crane collapse happen most?
(4 answers)
Hint-MOAD
-Moved
-Overloaded
-Assembled
-disassembled
NOT during fires
The worst type of crane incident is when they fail and collapse on nearby bldg.’s, both the bldg. being worked on and adjacent bldg.’s. Collapsed bldg.’s can go on fire due to broken gas pipes and electric sparks. Conversely if a fire is exposing a crane the IC should set up a collapse zone of?
Set up a collapse zone EQUAL to the height of the crane.
What type of streams should be used to protect the crane operator being exposed to fire?
Master streams
There are 2 different types of frameworks used for high rise structures; Reinforced concrete (cast in place) and structural steel. Which one experiences the most serious fire and collapse hazard of all bldg.’s under construction?
Cast in place (reinforced concrete)
The most serious fires and most serious collapse in cast in place bldg.’s under construction involve what?
Involves the heavy fire load created by the combustible formwork used to support cast in place concrete floors.
Concrete provides what type of strength to the cast in place structure?
Compressive strength
Steel reinforcement provide what type of strength to the concrete at a cast in place structure?
Tensile strength
How many days dose it take concrete to reach its maximum strength after it is poured?
27 Days
After each floor is poured and hardened the combustible formwork and supporting shoring is disassembled and rebuilt for the next higher floor. Concrete floors can have enough strength to enable the formwork to be removed after how many hours after being poured?
48 hours
Construction engineers state that within how many hours of pouring that the entire concrete floor can collapse on FF’s if the wood formwork below is destroyed by fire?
24 hours
Spalling is caused by the rapid heating of moisture inside the concrete. What are the two types of spalling that may be experienced during a fire?
Explosive Spalling-which propels concrete downward with an explosive force, accompanied by a loud noise.
Dropping Spalling-which is similar to a plaster ceiling collapse.
Both types can seriously injure or kill a member.
When using aerial master streams to extinguish fires in formwork supporting floors, all FF’s should be removed to where during the operation?
All FF’s should be removed from the bldg. during this operation.
FF’s responding to fires 10-20 stories high may need to use the hoists designed for the workers. When can members use the material and equipment hoist?
Only to transport firefighting equipment to the upper floors.
Members should not use the material & equipment hoist even if the car is suggested by the workers or watchman.
