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Flashcards

313 Structures Mid term

Erin Light English 107 cards

313 Structures Mid term

Cards in this deck (107)

  1. 1Simply Supported BeamTwo Supports
  2. 2Continuous BeamThree or more supporte
  3. 3Overhanging BeamTwo supports where one or both are not located at the end
  4. 4Propped BeamTwo Supports where one end is fixed like a cantilever
  5. 5Examples of Fixed SupportEmbedded base, Beam-column moment connections, steel strap welded to a gusset plate, reinforced concrete wall-floor connection
  6. 6Examples of Roller SupportsNeoprene Pad, steel cylinder
  7. 7Examples of-- represented by triangle
    --T-plate, clip angle, truss joint, connected column base plate
  8. 8Simple Beam (no load) Shear Diagram ShapeRectangle
  9. 9Uniform Load Beam Shear Diagram ShapeTriangle
  10. 10Cantilever on right shear + moment diagrams--moment starts at zero --> continues negative
    --Shear starts negative --> continues negative
  11. 11Cantilever on left shear + moment diagrams--moment starts at negative (max value) then moves up toward zero
    -- shear positive as usual then downward forces move shear toward zero
  12. 12Variables that influence materialE (elastic modulus), Fy (yield strength)
  13. 13Stabilityresists collapse
  14. 14Stiffnessprevents deformation
  15. 15Synergythe total is more than the sum of the individual elements
  16. 16Live Loads for commercial, residential, and storage, and DL for offcie○ Residential 40#/sq ft
    ○ Commercial 50#/sqft
    Storage 125 psf (light) 250 psf (heavy)
    --office: 50psf
  17. 17Inertia MassExplains why buildings deform during earthquakes because of the movement of mass
  18. 18Architectural goals at different Richter Scales<5 --> no damage
    5-6 --> architectural/facade damage only
    >6--> no collapse
  19. 19Standard Design Wind Speed Height30' (10m
    110mph (20-25psf) account for in Cali
    -- wind governs lateral design for tall builsigns
  20. 20Leeward building side--opposite of wind contact
    --experiences a vaccum
    --plift pushes the roof up and out
  21. 21Windward sideexperiences wind pressure
    -30-65 psf
  22. 222D object has how many DOF?3
    --includes beams
  23. 23Hysteresis Loop--Area on stress/strain graph outside which permanent damage occurs
    --indicates ductile performance
    --area= amount of energy/work
  24. 24Axial tensionmost efficient use of material
    --use in suspension
    --consistent throughout most forms?
  25. 25Axial Compressionless efficient than tensions because there is instability and potential for failure
    --use thicker material to combat failure
  26. 26Flexural Stress--Most common (ex: beams)
    --creates moment action --> rotation --> deformation
  27. 27Where does max stress occur in a beamtop and bottom (middle axis is neutral)
  28. 28Shear Stressalways in pairs
    -- cracking occurs at 45 degrees
  29. 29Thermal Stress--causes thermal deformation (expansion/contraction)
    (1) Unrestrained
    (2) Restrained --> causes large amounts of force because the object does not have enough space to expand
  30. 30Torquehappens when force does not go through the middle of a member and twists the object (avoid!)
    --occurs in tied situations (ex: hanging signs)
  31. 31Flat Chord Trussaka Warren truss
    -- acts like beam --> solve like beam    Flat Chord Truss
  32. 32Pratt Truss--all members in tension --> preferred in building constructionPratt Truss
  33. 33Howe Trussnot good for load bc all diagonals are in compressionHowe Truss
  34. 34pitched trussGood for drainagepitched truss
  35. 35Bow-String TrussBow-String Truss
  36. 36Vierendael TrussVierendael Truss
  37. 37Vertical Truss (braced frame)--resists tension and compression
    --not good for seismic, good for wind    Vertical Truss (braced frame)
  38. 38Direction Shear walls cannot resist loadperpendicular to long side
  39. 39length limits for beam, cables, slabsbeam: L/d=20
    cable: L/d=10
    slabs: L/d=30
  40. 40factors that affect shear and moment (beam)Load, type of supports, length
    (not affected by height, material, or shape)
  41. 41Factors that affect shear + bending stress (beam)height, material, shape
  42. 42where does maximum bending stress occurMaximum bending stress happens at top and bottom
    Material along neutral axis (middle) is not under stress
  43. 43where does max shear stress occur (beam)neutral axis
  44. 44What affects the axial compressive load of capacity of a columnmaterial, section size
    --not affected by height
  45. 45seismic response spectrumshows the maximum building acceleration in an earthquake in accordance with the building’s
    period of vibration.
  46. 46Braced Frame not allowed in Californiak-brace (high seismic risk)
  47. 47Stage of Design when member sizes are decidedDD (Design Development)
    (post schematic design, pre construction documents)
  48. 48Buckling Occursperpendicular to long axis
  49. 49One Way SlabL1/L2 >2
    --All loading is resisted in the short direction
  50. 50Two Way SlabL1/L2<2
    --Stronger + Stiffer
  51. 51How to solve slabDivide short direction into 1' sections along the longer side --> solve as beam
  52. 52How to solve walldivide into 1' long columns
    (force is w x 1')
  53. 53Guyed Cable/Cable Styed--Floor Deck
    --Pylon    Guyed Cable/Cable Styed
  54. 54Saddle--Extremely effective (uniform tension and compression)
    --surface structure system
    --gain strength through shape
    --hyperbolic paraboloid
    --combination of arch and cable that make it the strongest form possible    Saddle
  55. 55Dome--uniform compression in both directions
    --lower 20% of members experience uniform tension in long direction --> cracking    Dome
  56. 56Barrel--all in compression
    --gains strength through surface shape
  57. 57Folded plate-- results in truss action
    - gains strength through surface space
  58. 58Building Code2018 International Building Code (US-wide)
    2019 California Building Code (hospitals, schools)
    2020 LABC (residential projects)
    --all updated every 3 years
  59. 59Design Process1. Material
    2. Mechanics
    3. Elements
    4. Systems
  60. 60Form Structural Systems--gain strength by redirecting forces through form
    --flexible
    --ex: arch, tent, air pressure, cable
  61. 61Vector-Active Structure Systems--made of short, rigid, linear elements in which force direction is controlled by vector orientation and splitting forces among multiple bars
    --Triangulation
    --ex: flat, trusses, curved trusses, space truss
  62. 62(Cross) Section-Active Structure systemsrigid linear elements that gain strength through interior (sectional (bending)) forces
    --beam-based
    -ex: beam, frame, grid, slab, frame
  63. 63Height-Active Structuresgain strength/redirect forces through height extension that stabilize the load through the ground
    --ex: high rises, tube column structure, small column spacing
  64. 64Surface-Active Structure Systems--gain strength though surface form/resistance
    --flexible, but resistant to tension and compression
    --ex: saddle, barrel, shell, plate, folded plate
  65. 65Bearing Wall/Box Systemuses shear walls to resist lateral load
    -- most materials other than steel
    --Gravity load path: 1. slab, 2. joist, 3. bearing walls, 4. wall footing
    --Lateral Load path: 1. slab, 2, shear walls, 3. footing
  66. 66Building Frame System-- Beams + Columns
    -- Frame supports all gravity load and can resist lateral load
  67. 67Moment Frame System--excellent ductility (good for earthquakes) by reducing force through bending
    --gravity force resisted by columns
    --lateral force resisted by moment frame
    --rigid joints    Moment Frame System
  68. 68Dual Systemused for high rises
  69. 69cantilever column systemuseful for small spaces with small gravity and lateral load
  70. 70other systemsrequire peer review (not found in IBC, CBC, or LABC)
  71. 71What to do if piles are uneven heightsput bracing acrosss the top --> shorter pile becomes statically determinate
  72. 72piles act ascantilevers
  73. 73rigid diaphragm--stiffer than support wall
    --concrete slab or concrete-filed metal deck
    --walls pick up for proportional to their stiffness
    --whole system deforms
  74. 74flexible diaphram--softer than support wall
    --all deformation occurs in diaphragm (arc-shaped)
    --analyze as simple beams
  75. 75Truss Determinacy2J = R + M
    Statically determinate
  76. 76Which approach is more conservative: Tributary load or concentrated load?Tributary Approach
  77. 77bd for beams and columnsbeams -> d is the larger dimension (height)
    Columns--> d is the smaller dimension
  78. 78Synonymy for lumbersolid sawn lumber
  79. 79density of lumber35 pcf
  80. 80Cellular structure of woodhollow, long tubular cells
  81. 81walls of wood cells consist primarily ofcellulose
  82. 82sapwood and heartwood aretwo different parts of the same tree
  83. 83list of softwoods(defined by botanical characteristsics), used for structural framing
    -- pine
    -cedar (naturally decay rsistant)
    -redwood
    -fir
    -spruce
  84. 84list of hardwoods--teak
    -rosewood
    Oak
    Balsa Wood
  85. 85structural lumber is typicallyflat-sawn
  86. 86fungal content in wood occurs whenthe moisture content is > 20%
    (if moisutre is <20%, it is considered "dry")
  87. 87Wood graderange 1-5 (1 is best)
    --min 3 for structure, 2 most common
    -construction?
    Utility?
  88. 88durability/size categories of wood1. Board (1x)
    2. Dimmension (2x or 4x)
    3. Timber (5x +)
  89. 89pressure-treated lumberused to protect against fungi and termites
  90. 90Wood Truss spacing (typical)24" O.C.
  91. 91Nails most common in wood construction6d, 8d, 10d, 16d
    (diffferentiated by nail head and nail shank)
  92. 92nails resist ______ bestshear
  93. 93strongest nail connectionface nailing
  94. 94joist hangerssteel connectors that connect floor joists with supporting beamv b
  95. 95Braced frame systemvery efficent structure b/c resists both tension and compression
    -- wood and steel mostly (concrete not good)
    -- not good for resisting gravity load
    -- compression members rsik buckling in high-magnitude earthquake
  96. 96Concentric-Braced Frame (CBF)-- typical braced frame with one or two diagonals from corner to corner
    -- reist of compression members buckling under high-magnitude earthquakes
  97. 97eccentric braced frame (EBF)-- link beam "e"
    solves buckling problem by limiting the amount of force that enters the system
  98. 98Buckling Restrained Brace (BRB)Solves buckling problem by resisting compression with concrete-cased steel brace
    -- Bond breaker-- separates steel from concrete (prevents concrete from resisting tension)
  99. 99Moment Frame--steel
    -acts like fixed beam
    -- double- curved deformation with fixed supports
    -- single-curve deformation with triangle supprots
    -- diagonal deformation + slide with rollers
  100. 100Reduced beam sectionused in steel moment frames to concentrate stress at the cutout, instead of at the joint, to prevent joint failure
  101. 101Dual Frame systemrequired for high-rise structures (H > 160')
    -- BF + MF or Sheet Wall + MF
    --"inter-reactivity"
  102. 102Base Isolationalternate system for resting earthquake force
    --detatched building from ground to reduce movement of the building and internal equipment vis Rubber Isolator
    -- decreases acceloration
  103. 103stiffness and period of different high buildings-- short builidngs have the highest stiffness, tall buislings lowest stiffness
    --short buidlings = short period, tall building= long period
    -- medium buildings have highest acceloration (same period as earthquake)
  104. 104Types of base isolators--lead core rubber isolator
    -- high damping rubber isolator (synthetic rubber is rigin under gravity load, but softens under lateral load)
    --Inverted pendulum isolator (roller ball supports roll back to equillibrium after lateral force (new upside down version reduced dust build-up)
    -- tuned mass damper ( heavy weight in buidlign pulls the mass back toward center)
  105. 105Our project code classificationR2 type V B constrcution
    == Type V refers to material
  106. 106Current code2020 LABC, 2019 CBC, 2018 IBC
  107. 107Design Calculation Process1. Dead load and live load per floor
    2. Seizmic + Wind load based on Above
    3. Gravity Load per floor and Headers --> determine wood type + size to use
    4. Walls (studs) compression + Buckling--> stud size and spacing
    5. Foundation loading --> size of slab
    6. Lateral (shear) design for whole building (total weight x tributary area per floor)
    7. Most critical horizontal diaphragm
    8. Most critical shear wall
    9. Overturn moment

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Flashcards on 313 Structures Mid term, created by Erin Light on 19/10/2021.
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Erin Light
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