BOMI Desin & Oper Ch. 4 Flashcards
Chapter 4
Most common causes of building collapse:
Bad design; faulty construction; foundation; extraordinary loads
Dead loads
Permanent loads on the structure. Include the weight of structural members and all attachments that remain throughout the life of the building, pipes, electrical conduits, HVAC, lighting fixtures, flooring, permanent partitions, suspended ceilings, and roofing
Live loads
Move on and off the structure and vary in magnitude and location. Make it difficult to estimate the magnitudes and positions of these loads. (Occupants, furnishings, machinery, movable partitions, rain, snow and ice.)
Loads unique to geographical regions:
Snow loads; Wind loads (3-4 stories high require special wind force consideration); Seismic Loads (earthquakes); Vibration Loads (caused by heavy traffic, trains, subways, heavy trucks); Shock Loads (load suddenly applied to a structure)
Stress
Load per unit of area and is measured in pounds per square inch (psi).
Tensile stress
Tension, magnitude of tension (stretching a material_
Compressive Stress
Stress applied to materials, resulting in a compaction, or decrease of volume. Long structural elements (columns) w/aspect ratios greater than 2:1 will buckle when compressive stress is increased due to elastic instability.
Shear Stress
Is the magnitude of shear in a structural member. Slipping tendency along a plane in a material caused y parallel but opposite forces applied to the two sides of the plane.
Cellular Steel floor system
Used in office buildings, hotels, and apartment buildings. Made of cellular panels consisting of light-gauge galvanized or painted sheet steel.
Composite steel floor
Consist of a steel deck bonded w/a concrete slab, so the two act as a unit in resisting the total loads. (Cracks can form, so place reinforcing bars)
Open Web Joist floor
Well-suited to buildings intended for comparatively light floor loads not subject to vibration or heavy concentrations. (steel bar joists made from bars, small angles, or other steel shapes_
Loadbearing walls
Carry the ceiling (roof or upper floor loads to the foundation oar loadbearing). Most common in single-story, residential, and light commercial construction.
Nonloadbearing walls
Used as partitions or dividers
Curtain wall
Exterior building wall of any material that is hung on the external structure and carries no vertical loads
Interior walls
Loadbearing interior walls are permanent walls built to be strong and are excellent fire walls
Composite columns
Steel column shapes surrounded by and bonded to reinforced concrete
Friction piles
Load transfer to the soil is accomplished by shearing forces, or friction, on the sides of the piles.
End-bearing piles
With deep rock, the pile load can also be transferred directly from the end of the pile to the rock.
Floating foundations
Made of concrete heavily reinforced w/steel, so entire foundation will act as a unit.
Maintaining Steel
Regular inspections and cleaning are more important than repainting.
Spalling
Breaking off of pieces of concrete due to the pressure created by moisture freezing w/in the concrete.
1) The designer had to make special considerations for wind as the building was taller than ______ stores, the minimum height that usually necessitates such consideration. a-1 or 2; b-3 or 4; c-5 or 6; d-7 or 8
b-3 or 4
2) The type of stress an upper floor places on the columns that support it is ______ stress. a-tensile; b-compressive; c-cohesive; d-shear
b-compressive
3) Compared w/steel and concrete decks, all of the following are characteristics of a wood floor system except: a-shorter spans; b-less fire resistance; c-more dimensional stability; d-lower cost
c-more dimensional stability (They offer less dimensional stability.)
4) Most ______ are erected using a combination of reinforced concrete and structural steel to achieve composite columns and avoid constructing extremely large columns on the lower floors, which take up valuable space. a-field houses; b-low rise buildings; c-high rise buildings; d-single story buildings
c-high-rise buildings
5) Bill may select steel for construction of his new building due to its ability to last indefinitely, and under proper conditions, require little painting maintenance. This is an example of the advantage of ______ when using steel for construction. a-high strength; b-uniformity; c-elasticity; d-permanence
d-permanence
6) Bill has decided to choose precast concrete rather than reinforced concrete for construction of his new building. In doing so, he hopes to achieve greater independence of construction from weather conditions. Another advantage of using precast concrete is found in the: a-floor to floor heights; b-quality control and concrete strength; c-continuity between structural members; d-heavier weight that increases the size of the foundation
b-quality control and concrete strength
Precast concrete
Reinforced concrete that is cast and hardened into desired shapes away from the building site.
Reinforced concrete
steel rods or bars supply reinforcement because of their high tensile strength. Poured on-site. Combine many advantages of concrete and steel.
7) Sheila, the building manager, has noticed a large crack between a concrete terrace and its retaining wall after a harsh winter. This most likely is an indication of a problem w/the foundation soil and ______. a-frost; b-nutrients; c-shifting; d-moisture
a-frost
8) A shallow foundation system may use ______ for the building foundation to support load-bearing walls located on average to good loadbearing capacity soil, as well as boundary and retaining walls. a-steel piles; b-spread footing systems; c-mat and raft systems; d-floating sytems
b-spread footing systems
Shallow Systems
Most economical type if the soil near the ground surface has adequate loadbearing capacity (Spread footing systems and mat and raft systems).
Spread footing systems
generally square blocks of concrete. Support load-transmitting elements such as walls, pilasters, columns, or piers.
Mat and Raft systems
used over soils of low loadbearing capacity when other foundations are inadequate or when spread footing sizes become so large that hey impinge on each other.
9) The inspection team noted a general decay of the concrete surface involving loss of the cement paste, resulting in the loosening of the aggregate. This is an example of ______. a-cracking; b-spalling; c-disintegration; d-corrosion
c-disintegration
Disintgegration
General decay of the concrete surface involving loss of the cement paste and loosening of the coarse aggregate.
