SS 2

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  1. P-delta effect
    • refers to abrupt changes in ground shear, overturning moment and/or the axial force distribution at the base of a sufficiently tall structure
    • secondary effect on frame members produced by vertical loads acting on a building frame that is laterally displaced by earthquake loads
  2. ductility from highest to lowest
    • 1) steel
    • 2) reinforced concrete
    • 3) reinforced masonry
    • 4) wood
  3. three-hinged gables frame
    • -its supports permit rotation
    • -moment at the center is zero
    • -max moment occurs at the intersection of the column and sloping beam
    • -statiscally determinate
    • -moment is generally less than in a rectangular rigid frame
    • -horizontal thrust at three-hing base: arch rotates when temp changes, directly proportional to the load, directly proportional to span, inversely proportional to the rise
  4. reinforced concrete columns
    the area of longitudal reinforcement must be at least 1% of the column cross-sectional area of the column
  5. if wind speed double, the wind pressure...
    increases fourfold
  6. wood members
    • -glue laminated members generally shrink less than sawn timber
    • -shrinkage in wood is generally greater in heavier pieces than in lighter pieces of the same species
    • -shrinkage is usually greater in hardwoods than in softwoods
    • -where wood joists are supported from a steel beam by joist hangers, the tops of the joists when installed should be above the top of the beam to provide for shrinkae of joist
    • -greatest shrinkage occurs across grain
  7. proctor test
    • -test used to determine soil's optimum moisture content and density
    • -properly compacted fill is sometimes used for the support of buildings where this is anticipated, typical soil samples are subjected to a laboratory compaction test called "proctor test"
  8. glue laminated members
    • -with proper quality control, the adhesive is at least as strong as the wood
    • -the individual laminations are thin enough to be readily seasoned before fabrication
    • -members may be varied in cross-section along their length in accordance with strength requirements
    • -lower grade material is often used for the less highly stressed inner laminations, which the outer laminations are comprised of higher grade
  9. section modulus
    a measure of a beam's bending strength

    • S=M/F
    • M=bending moment
  10. basement walls
    • -basement walls are usually designed to resist earth pressure by spanning between the basement floor and the first floor
    • -if the first floor is not in place when the backfill is placed, temporary bracing is required
    • -in most cases, the bending moment in the wall requires the use of reinforcing steel
  11. earthquake design
    • -torsion occurs when center of resistance of the primary lateral load resisting system is not coincident with the center of mass of the building
    • -torsional forces result when lateral forces act on a building that has a rigid diaphragm, usually of concrete or steel
    • -torsion can occur in any shape building and with any type of lateral load resisting system
  12. Partheon
    • -greek arch
    • -was adapted from wood construction of early Greek temples to marble
  13. Pantheon
    • masterpiece of ancient arch
    • inside span of 142ft
    • largest dome of ancient world
  14. lamella
    series of parallel arches that are skewed with respect to the axes of a building and intersect another series of skewed arches
  15. rigid frame
    • -consists of beams and columns rigidly connected together so that the joints are capable of resisting bending moment
    • -rigid frames can efficiently resist both vertical and horizontal forces
    • -greatest use is in multistory construction and may be constructed of either steel or reinforced concrete
  16. spans and loads
    1)waffle slab
    2)flat slab
    3)flat plate
    4)one-way slab and beam
    • 1)heavy loads and square bays up to 40ft
    • 2)economical for heavy loads, but not for spans ovre 25-30ft
    • 3)not economical for heavy loads or spans over 20-25ft
    • 4)might be economical, but as economical for square bays and heavy loads
  17. load acting on a cable
    • when the only load is its own weight - it takes shape of catenary
    • when a uniformly distributed horizontally spans, the cable would assume the shape of a parabola
  18. what historic structure contains a dome built without any temporary centering?
    Santa Maria del Fiore in Florence
  19. internal forces in the web members of a parallel chord truss:
    A) decrease toward the center span
    B)remain relatively constant across the span
    C) increase toward the center span
    A) just as in beam flange forces increases toward the center - the truss chords increase towards the center
    (this multiple choice question has been scrambled)
  20. three-hinged gabled frame properties
    • -has a hinge at the center and each support and is statiscally determinate
    • -hinges at the supports permit rotation
    • -hinges at the center also permits rotation, which prevents any moment from being developed at the center
  21. machine bolts and wood screws
    may be used for either wood-to-wood or wood-to-steel
  22. split rings
    • -used only for wood-to-wood connections
    • -circular grooves are pre-cut into the contacting faces of the wood members to be joined so that half the ring fits into each member, while a bolt is used to hold the two members together
  23. shear plates
    made of pressed steel or malleable iron and are used for wood-to-steel connections using one shear plate or for wood-to-wood connections using two shear plates
  24. UBC deflection limits
    • wood members:
    • L/360 - live load
    • L/240 - dead load + live load

    • steel members:
    • L/360 - live loads
  25. prestressed concrete
    -prestressing of concrete is done by either pretensioning or posttensioning
  26. E values
    • E=29,000,000 psi for steel
    • E=10,000,000 psi for aluminum
  27. what determines the load-carrying capacity of a wood column?
    • 1)modulus of E, which depends on species and grade
    • 2)allowable compressive stress Fc
    • 3)ratio l/d (l=unbraced length and d=least lateral dimension of column)
    • 4)cross-sectional area of the column
  28. posttensioning
    steel tendons are stressed after the concrete is cast on site, by jacking against anchorage at the ends of the members
  29. pretensioning
    high strength steel is tensioned before concrete is cast. after concrete hardens, prestress wires are cut and prestress force is applied to the concrete through bond therefore no end anchorages are required
  30. kl/r
    • -k is a constant determined by the degree of fixity at the ends of the column
    • -k is a constant that depends on the buckled shape of a column at failure
    • -an increase in the value k results in a decrease in the column load capacity
    • -k factor is used to convert the actual length of the column to the effective length
Card Set:
SS 2
2013-07-25 19:24:53

Structures Exam
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