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A crash bar (also known as a panic exit device, panic bar, or bump bar) [1] [2] is a type of door opening mechanism which allows users to open a door by pushing a bar. While originally conceived as a way to prevent crowd crushing in an emergency, crash bars are now used as the primary door opening mechanism in many commercial buildings.
A pallet of "8-inch" concrete blocks An interior wall of painted concrete blocks Concrete masonry blocks A building constructed with concrete masonry blocks. A concrete block, also known as a cinder block in North American English, breeze block in British English, or concrete masonry unit (CMU), or by various other terms, is a standard-size rectangular block used in building construction.
The starter bar is constructed in discrete blocks secured to one side of a planar spine provided in segments and arranged end to end. Adjustable spacers in the form of tapered blocks are disposed between the blocks of the bar to allow the starter bar to be self-supporting in a curved configuration corresponding to the casting path.
Plastic spacers and bar supports do not bond well with concrete and are not compatible materials. [1] Plastic has mechanical properties (holds the bar in position) but no structural properties, and is a foreign element within the construction. When the concrete is poured into the form, a small gap is created between the concrete and the plastic.
Reinforced concrete, also called ferroconcrete, is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility.
Patented originally in 1912, the lockrod was first used to secure railroad boxcar doors. Today, sometimes confused with locking bars or bar locks, lockrods have evolved to secure virtually every trailer or container that has a swing door (a door that swings open and closed rather than rolls up).
The disposal of bricks in these often highly irregular raking patterns can be a challenging task for the bricklayer to correctly maintain while constructing a wall whose courses are partially obscured by scaffold, and interrupted by door or window openings, or other bond-disrupting obstacles.
Carl Jacob Prinzler (June 6, 1870 – May 30, 1949) was an American engineer who invented the "panic bar" device for doors that allowed them to be opened from the inside despite being locked on the outside.