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89 Cards in this Set
- Front
- Back
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Wood is strong in both what?
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compression and tension
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Wood is primarily used in what system?
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one-way system where the load is transmitted thru the structural members in one direction.
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Joists are a common wood use what is the size and spacing?
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2x 6 , x8 x10 x12
Spacings are 12", 16" and 24" OC |
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Joists must be laterally supported by what?
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Sheathing - top edge is held in place by this material however the bottom edge requires bridging Max interval is 8' - and either solid or cross bridging may be used
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Most common use for solid wood beams is?
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Plank and beam framing 4x6 nominal width span between girders and bearing walls is 4,6,8'
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Plank and beam framing normal max spans are what?
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10-20 ft
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Glue lam construction are made of what?
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Individual pieces of 3/4" lumber and come in standard widths of 3 1/8", 5 1/8", 6 3/4" and 8 3/4"
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Typical Glue lam spans are what?
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15 ft to 60 ft
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What are the 3 types of Manufactured wood products used today
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Lightweight I joists
Glue Laminated products Trusses |
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Lightweight I joists allow for what
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long spans and are more problem free do to the manufacturing method free from checks and warping
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Glue laminated beams have what
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Higher Modulus of Elasticity than regular wood products
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Glue laminated products have how much allowable stress in bending?
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2 as much as regular douglas fir
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Truss are held together with what?
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Metal Plates
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Wood Trusses can span how far
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24 to 40 ft and typical depth is 12- 36"
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Common Spacing for wood trusses
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24" O.C.
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Steel is the most commonly used material structural material why?
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High strength, availability, and ability to adapt
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Steel is what kind of Material
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Ductile- meaning it can tolerate some deformation and return to its original shape.Before it breaks
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Steel is used in what type of construction typically?
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multifloor construction because of the strength and Structural continuity.
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Two most common structural systems are what?
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Beam and Girder
Open web steel joist system |
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In a beam and girder system which way to the members span?
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girders span shorter distances
Beams span longer distances |
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Typical spans for Beam and Girder System is what?
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25- 40 ft with the beams being spaced 8'- 10' O.C.
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Open Web Steel joists span between what?
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Beams and bearing walls
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Standard Open web joists can span up to how long?
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60 ft
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Long Span Open web joists can span up to how long?
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96 ft
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Deep Long span joists can span up to how long?
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144 ft
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Depth of standard joists range from what Depth?
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8" to 30" in depth in increments of 2"
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Long Span Joists range from what Depth?
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18" to 72"
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Open Web floor joists are typically spaced how far apart
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2 to 4 ft OC
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Open Web Roof Joists are typically spaced how far apart?
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4 to 6 ft OC
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Two Primary types of Concrete are what?
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Cast in place and Precast
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Cast in place concrete structural systems are classified in two general types, what are they?
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One Way systems and
Two way systems. |
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One Way Systems
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slabs and beams are designed to transfer the loads in one direction.
Example beam and girder system |
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Typical span for a One way system is?
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15 to 30 ft
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What are the 3 principle two-way concrete systems
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flat plate
flat slab waffle slab |
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Which of the 3 systems is the simplest?
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Flat Plate- slab is designed to be reinforced in both directions directly into the columns.- limited to light weight and short spans.
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Flat plate is used for what type of building.
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Building where floor to floor height needs to be kept to a min
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A flat slab is used for what?
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Where the span is large or the live loads are heavier.These plates require drop panels to provide for punching shear
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Flat Slab can accommodate what kind of loads and spans?
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heavier loads and economical spans to 30 ft
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Two Primary types of Concrete are what?
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Cast in place and Precast
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Cast in place concrete structural systems are classified in two general types, what are they?
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One Way systems and
Two way systems. |
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One Way Systems
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slabs and beams are designed to transfer the loads in one direction.
Example beam and girder system |
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Typical span for a One way system is?
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15 to 30 ft
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What are the 3 principle two-way concrete systems
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flat plate
flat slab waffle slab |
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Which of the 3 systems is the simplest?
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Flat Plate- slab is designed to be reinforced in both directions directly into the columns.- limited to light weight and short spans.
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Flat plate is used for what type of building.
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Building where floor to floor height needs to be kept to a min
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A flat slab is used for what?
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Where the span is large or the live loads are heavier.These plates require drop panels to provide for punching shear
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Flat Slab can accommodate what kind of loads and spans?
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heavier loads and economical spans to 30 ft
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Waffle Slab System can support what?
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Heavier loads at a slightly longer spans up to 40 ft economically.
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Masonry
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Masonry Section
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Masonry is generally limited to what type of wall?
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Bearing
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Masonry is good in what?
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Masonry has a high compressive strength but is weak in tension and bending.
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Three types of masonry bearing walls construction are/
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Single wythe
Double wythe Cavity |
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Masonry walls have what advantages to them
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strength
design flexiablity attractive appearance resistance to weathering fire resistance. |
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Structural System Selection
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Critera
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What is the primary concern for an architect of a structural system?
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the primary consideration is the ability of the structural system to resist the anticipated and unanticipated load that are placed on the building.
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Dead Loads
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Vertical loads due to the weight of the building and premanent equipment
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Live Loads
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Are loads due to the particular use and occupancy and are considered moveable or temporary, people furniture, wind, earthquake and snow loads are not considered live loads
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Live Load Reduction
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IBC allows live load reduction in most cases except for public assembly occupancy
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Live Load in a public Assembly is what?
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A live load my no be reduced for a public assembly occupancy with the live load less than or equal to 100 psf or for any member supporting on floor of a parking garage or with a live load exceeding 100 psf
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Live Load Reduction Formula
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L = Lo ( 0.25 + 15 / √ kLL At
Lo = uniform live load KLL = Live load element factor At = tributary area supported by a structural member |
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Live Load Factor
L |
L must not be less than 0.5 Lo for members supporting 1 floor or 0.4 Lo for members supporting more than one floor
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Allowable percentage of Reduction formula
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R = 23.1 ( 1 + D / Lo )
D = Dead load Lo = Live Load |
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Minimum Roof Live Load
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Lr = 20 R1(R2)
R1 is based on the tributary area At if the area is between 200 and 600 sq/ft use this formula R1 = 1.2 - 0.001 At R2 is based on roof slope if the roof does not exceed 4 in/ft or exceeds 12 in/ft use this formula R2 = 1.2 -0.05 F |
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For purposes of calculation wind is considered a what?
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Static Force
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Velocity of Wind
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First Variable - the pressure on building varies as the square of the velocity
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Velocity of Wind Formula
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Ppsf = 0.00256v2 mph
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Wind Velocity is higher or lower at the ground level of a building?
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Since wind acts as any fluid where a surface causes friction and slows the fluid, wind velocity is lower near the ground and increases with height
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Wind speed values are taken at what standard height
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33 ft above ground
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What are the three factors that effect wind loading on a building
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Wind velocity
Height Buildings Surroundings |
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What is the pressure on the windward side of the building?
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positive pressure
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What is the pressure on the leeward side of the building?
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negative pressure or suction
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Other local areas of wind pressure occur where thru out a building
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Corners, overhangs, parapets and other projections
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Openings at the ground floor of a building might cause what to happen?
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Normal wind speeds to increase to unacceptable levels
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Building drift is what?
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Distance a building moves from side to side in the wind
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Building Drifts maximum should be what?
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Should not exceed 1/500 of the height of the building.
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Calculation for the pressure at the bottom of a retaining wall?
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P= p ( h / 2 )
Example Retain wall is 8 ft in height, the soil is free draining silt sand and is 45 psf. therefore 8(45) = 360psf the horizontal load (360psf /2) * 8 = 1440 psf |
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What is the weight of water and what is force on structures called
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62 lbf/ft 3 and hydrostatic pressure.
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fa = P /A
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To solve for unit stress
P = external force ie (24,000 lbs) A = area of Cross section 1.5 in/sq fa = 24000/1.5= 16000 psi |
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P= fa /A
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To solve for external Force
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A= P / fa
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To solve area - Stress
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Tensile and Compressive stress that accompany beam action cannot be calculated using what formula.
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fa = P/A
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Horizontal Shear
fv = V / Aw |
To solve for shear stress
fv = unit stress V= Max. Vertical shear Aw = the area of the web ( depth of the section x web thickness) |
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Modulus of elasticity of a material.
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Indicates its degree of stiffness.
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E= f /s
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To solve for Modulus of Elasticity
E = psi or ksi f = unit stress = (psi) s = unit deformation (in per in) |
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P/A
E = _____ e / l |
P = Force , A = cross section area , e = total Defromation
l = length |
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Pl
E = _____ Ae |
P = Force , l = length , A = cross section area , e = total Defromation
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Pl
e= _____ AE |
P = Force , l = length , A = cross section area , E = Modulus of Elasticity
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E for steel is equal to what?
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E= 29,000,000 psi
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E for wood is equal to what?
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E= 1,000,000 to 1,760,000 psi
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