What does a bowstring truss look like?
Bowstring trusses typically feature a parabolically shaped top chord constructed of several wood elements (laminations) mechanically connected through the depth of the member. The bottom chord is often constructed of straight timber members with bolted splices.
What is a bowstring truss used for?
A bowstring truss is a structural device commonly used in bridge-building and, less often, in industrial architecture. Used to span wide, column-free spaces, it consists of an arched beam (the bow) joined at each end by a straight beam (the string), with diagonal support beams joining the two.
Why can’t you put out a fire with people inside?
The thick smoke generated by a building fire can quickly overwhelm and asphyxiate anyone trapped inside, so you might believe that breaking an exterior window would help people inside breathe more easily. This is usually a bad idea, particularly in the event of a house fire.
What is the cause of most fire deaths?
Causes of Fires and Fire Deaths Careless smoking is the leading cause of fire deaths. Smoke detectors and smolder-resistant bedding and upholstered furniture are significant fire deterrents. Heating is the 2nd leading cause of residential fires and ties with arson as the 2nd leading cause of fire deaths.
What is another name for a bowstring truss?
The bowstring truss, also known as the arched rib truss, uses similar components to other truss systems such as the use of a top chord, bottom chord, struts, and ties. (Figure 1). Top chords are under compression, bottom chords are under tension, struts resist compressive forces, and ties resist tensile forces.
Why do firefighters break windows after a fire?
The reduced heat and improved visibility allow firefighters to safely and quickly rescue trapped occupants and extinguish the fire. Heat and smoke rise, so cutting a hole in the roof and breaking out windows in strategic locations allows the smoke to vent upwards, allowing cool air to enter the structure from below.
Should you break windows during a fire?
Never break windows in an attempt to give those trapped in a burning building some fresh air. The thick smoke generated by a building fire can quickly overwhelm and asphyxiate anyone trapped inside, so you might believe that breaking an exterior window would help people inside breathe more easily.