Structural Systems Flashcards
What are 3 grades of wood?
Stud grades - for studs, including load bearing
#1 structural framing - for headers and long spans
Utility grade - for blocking, etc
What is glue laminated wood?
layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives so that all of the grain runs parallel to the longitudinal axis
What is cross-laminated timber?
several layers of kiln-dried lumber boards stacked in alternating directions, bonded with structural adhesives, and pressed to form a solid, straight, rectangular panel
Lightweight yet very strong, with superior acoustic, fire, seismic and thermal performance, CLT is also fast and easy to install, generating almost no waste onsite.
What is laminated strand lumber?
dried and graded wood veneers, strands or flakes that are layered upon one another and bonded together with a moisture-resistant adhesive into large blocks known as billets
(longer strands) not super strong, inexpensive
What is oriented strand lumber?
OSL is made from flaked wood strands that have a length-to-thickness ratio of approximately 75. The wood strands used in OSL are shorter than those in LSL. Unlike OSB, the strands in OSL are arranged parallel to the longitudinal axis of the member
What is parallel strand lumber?
Dried and graded wood strands are layered upon one another and bonded together with a moisture-resistant adhesive into large blocks known as billets
In the case of PSL, long strands (longer than those used in LSL) are laid lengthwise in parallel.
strong, heavy, relatively expensive
What are wood i-joists?
dimensional lumber with an OSL board in between, used in floors, roofs, etc
What is laminated veneer lumber?
an engineered wood product that uses multiple layers of thin wood assembled with adhesives
like plywood but thicker
What are wood plastic composites?
weather resistant, less likely to shrink and warp more flexible
What is oriented strand board? What is it used for?
strongest & stiffest of nonveneered panels
most common in subfloors and exterior sheathing
What is fiberboard?
made from the smallest grain of wood (compared to OSB and particleboard)
best for interior uses
smoothest surface
What are the plywood bond classifications?
Exterior - for exterior use
Exposure 1 - can handle some water, etc, but not meant to be exposed to weather long term (95% of plywood)
What is a rim board or band joist
Sits on top of the header or floor below or foundation
Seals the open ends o the joists
provides surface for attachment of exterior insulation, cladding, and finish elements
Transfers some of the loads to the floor below
After the attic, this is the most likely place for insulation gaps & air infiltration
Which is stronger, cold rolled or hot rolled steel?
Cold rolled steel is stronger than mild steel
depth to span ratio: beam
Beam depth is generally 1/20 the span, width is ⅓ the depth
depth to span ratio: girder
Girder depth is 1/15 the span, width is ⅓ the depth
depth to span ratio: open web
Open web is 1/20 the span
Roofs, lightly loaded floors, or closely spaced can be 1/24 the span
depth to span ratio: steel decking
Steel decking depth is 1/40 the span
depth to span ratio: triangular steel truss
Triangular steel truss depth is ¼ the span
depth to span ratio: rectangular steel truss
Rectangular truss depth is ⅛ the span
What is the rebar naming convention?
Rebar # refers to the 1/8ths of an inch in diameter
Ex. #8 rebar is 8/8” or 1” diameter
What are the rebar grades?
Grade 60 = 60k PSI, most common
Also comes in 40 & 75, use 75 for columns
What is the correct amount for rebar overlap?
Overlap rebar at the ends by 30x the diameter or use reinforcing bar couplers
What is prestressed concrete?
is substantially “prestressed” (compressed) during production, in a manner that strengthens it against tensile forces which will exist when in service. This compression is produced by the tensioning of high-strength “tendons” located within or adjacent to the concrete
Pre-tensioned - mostly precast concrete
Post-tensioned - mostly cast in place
What are the steps to pouring a slab on grade concrete pad?
- Scrape topsoil off to reveal a more stable subsoil. if the subsoil is not stable you need to truck some in
- At least 4” inches of 1.5” crushed stone to make a capillary break. roll out plastic sheet for moisture barrier
- Formwork. Edge of metal or wood supported by in-ground stakes
- Welded wire reinforcing on chairs or bolsters, or concrete brick to prevent rust moving through
- Pour the slab
- Scree the slab to make level
- Keep damp for atleast a week
8.Control joints every 15’
concrete beam depth & width ratio
Width = 3 x height
one way slab depth
4” - 20” deep, 1/22 the span, post tensioned 1/40 the span
two way slab depth
5” - 12” deep, 1/30 the span, 1/45 if post tensioned
drop panels depth
⅓ the span, ½ slab depth
waffle slab depth
3” - 4.5” (plus depth of dome/pan), 1/24 the span, 1/35 if post tension
concrete beams depth
1/16 the span, 1/24 if posttension
concrete girders depth
1/12 the span, 1/20 if posttension
What is pre-tensioned pre-cast concrete?
compressive stresses induced by high-strength steel tendons in a concrete member before loads are applied will balance the tensile stresses imposed in the member during service
What is the modulus of rupture?
most important for determining a stones ability to accept metal anchor that hold them to buildings
What is flexural strength?
most important for stone’s resistance to wind
What are the most common CMU dimensions?
8 x 8 x 16 or 7 ⅝” x 7 ⅝” x 15 ⅝”
How do you avoid water penetration in masonry?
Double wythe concrete block with capillary break
Finished with stucco, special paints, or special coatings that provide water resistance
Made with water repellent concrete and water repellent mortar
Use in arid climates
what will determine the diameter of a long skinny column?
For long and skinny columns that are not placed far apart, the diameter of the column will likely be controlled by buckling rather than the load from above
What is a theoretical k value?
higher k, more likely to buckle
Multiply by column length
Works for steel or concrete, recommended design k value is for wood
What is shear a function of?
length squared
what is deflection a function of?
length cubed
what typically controls beam size?
bending moment
between shear walls, braced frame, and moment resisting frame - what is most and least expensive?
shear wall - least expensive
moment resisting frame - most expensive (because you have to put extra bolts on each connection)
what is the bending moment formula?
M(max bending moment) = (w (load per ft) x L^2)/8
what is the max bending stress formula?
Fb = M (max bending moment in-lbs)/S (section modulus in^3)
What is a LH type steel joist?
long span (longer than 96’, depth 18” - 48”)
What is a DLH type steel joist?
deep long span (150’, depth 52” - 72”)
What is a SMRF?
special moment resisting frame (SMRF)
Expected to withstand significant inelastic deformations
Typically used in mid/high-seismic regions
What is a IMRF?
Intermediate Moment Resisting Frame (IMRF)
Expected to withstand moderate inelastic deformations
Typically used in low/mid-seismic regions
What is a OMRF?
Ordinary Moment Resisting Frame (OMRF)
Expected to withstand limited inelastic deformations
Typically used in non/low-seismic regions
What is a K series steel joist?
most common, spans up to 60 ft
What is a LH series steel joist?
longer span
What is a DLH series steel joist?
“deep longspan” spans the longest
What are shear studs?
small vertical steel elements that help attach the steel pan to the concrete floor poured above it
How are long slender columns most likely to fail?
buckling
