Flashcards in 8 Masonry And Ordinary Construction Deck (64)
Exterior brick wall is usually constructed with a vertical cavity between the exterior and interior wythes. Known as a
Cavity walls are intended to
Prevent water seepage through mortar joints to interior and increase insulation. Requires metal ties
Masonry walls can be reinforced by
Placing vertical steel rods in a cavity between two wythes. Either brick or brick and block.
Reinforcement of masonry walls can also be accomplished with what
Buttresses, flying buttresses, and pilasters
Because mortar provides little tensile strength the individual openings in masonry walls must be supported by
Beam over an opening in masonry wall, made of steel, concrete or reinforced masonry
Lintels and to a lesser extend, arches, are most common means to supporting loads over masonry openings. Corbelling isn't used only when
Where the Architectural styling makes it attractive
Portion of the exterior wall that extends above roof line. Low wall at edge of roof. Found on exterior masonry walls and fire walls of buildings with combustible roofs
Parapet walls project how high
1-3 ft or more
Parapets, especially in front pose what risk to firefighters.
Most basic and traditional type of masonry building
Where extrior load bearing walls support interior wood floors and roof rafters and joists
Ordinary construction is aka
Type III, masonry wood joisted
In many residential and commercial buildings wood joists are rest on a beam pocket which is
A pocket several inches into wall that is deep enough to suitable support the beam
When pocketed into a masonry wall a joist will be cut at a slight angle known as
Angled cut made in end of wood joist resting in masonry wall allowing beam to freely fall away from wall in case of failure of beam. Prevents beam from acting as lever pushing wall out.
Where a beam transmits a large vertical load to a wall,nether wall may be built out and increased in thickness to support it , known as
Fire resistance of masonry walls depends on
Type of masonry unit used and thickness of wall
Hollow block can crack and spall. Wall of fire rated cmu or brick a an have fire resistance time of
2-4 hrs or more
An officer must monitor changes or growth in masonry wall cracks because
Changes or growth can indicate impending collapse
Mortar can erode form elements such as rain by
Rain seeping in, freezing and causing expansion which causes mortar to crack or flake
Cracks in masonry can be caused by
Foundation settling or saggin interior beams from rot or damage
Structural deterioration of masonry walls prior to fire will contribute to
Structural failure under fire conditions
If masonry walls begin to bulge or lean out, a way of stabilizing it is with
Steel Tie rods, parallel to joists though the wall with bearing plates outside like washers, sometimes in shape of stars.
Tie rods in masonry wall may indicate repair however it may
Be a part of original design
Potential problems for steel tie rods
Heated under fire, expand, reducing strength and weakening walls.
Tie rods used for repair are generally
Less compatible with design of building, may just be form of steel channels
Not uniformly positioned or spaced on walls
Other indications of repair like mortar repair near tie rod bearing plates
Masonry walls usually collapse because of
Failure of interior beams by collapse, pushing against walls forcing them out.
Collapse zone of masonry wall is
At least the height of the building. Corners are safest.
Flat horizontal or vertical board at outer face of cornice, broad flat surface over storefront or below cornice. False front or mansard roof face