COSC 254 Final
Fireproofing
"fire protection"; originally steel encased by brick or concrete, but the load was so dang heavy! First alternative was metal lath and plaster around steel members. kinds pg. 460
Fully Restrained Moment Connection
'rigid' ; Sufficient rigid that the geometric angles between members will remain virtually unchanged under normal conditions
Simple connections
'shear connections';
Partially Restrained moment connection
'simi rigid connections' same purpose as fully restrained; both can be used to construct moment-resisting building frames
fabricator
**creates shop drawings; deliver to the site steel components that are ready to be assembled without further processing
CH 15
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CH. 12
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METALS IN ARCHITECTURE
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space truss/frame
3D truss!!
Bronze
90% copper, 10% tin; used for form of statuary, bells, ornamental metalwork, door and cabinet hardware, ect.
AISC
AMERICAN INSTITUTE OF STEEL CONSTRUCTION
First all-metal structure
Cast iron bridge; built in late 18th century in England carries traffic even today over the Severn River
ASTM A992
High strength, low alloy steel which is the preferred type for standard wide-flange structural shapes
Bolts
High-strength (ASTM A325 and A490), which are heat treated during manufacturing to develop their greater strength; Carbon Steel Bolts(also called unfinished or common bolts ASTM A307) find limited use such as in fastening in minor framing elements. Inserted into holes 1/16 inch larger than the diameter of the bolt.
nonstructural metal framing
LGS members used for framing interior partitions and other nonloadbearing applications
ASTM A36
Mild structural steel, predominant steel type in buildings for decades; higher strength: ASTM A572
Tempering
Partial reheating; a 'thermo-mechanical process'
Wrought Iron
Purified by beating it repeatedly with a hammer; relatively high cost; contains even less carbon that most steel alloys
Quenching
Rapid cooling; a 'Thermo-mechanical process' used immediately after rolling
Rigid Perimeter
Same as Rigid core except the stabilized part of building is perimeter. Again using shear connections and diaphragm action to support rest of building
Rivet
Steel fastener consisting of a cylindrical body and a formed head; a pneumatic hammer produces head on opposite side
Carbon content
Too much makes a hard but brittle metal(Cast iron), while too little produces a malleable, relatively weak material(wrought iron)
Composite columns
Type I: steel wide-flange column surrounded by sitecast reinforced concrete Type II: Steel pipe filled with concrete Type III: Wide-flange in pipe, then concrete added Advantage is that it reduces steel usage, greater rigidity against wind forces, and simplified beam-column connections
anodize
adding thin oxide layer of controlled color and consistency to the surface of the metal
Stainless steel (ASTM A240 and A276)
addition of chromium and nickel; has even greater corrosion resistance but costs alot more than conventional structural steel
Turn-of-nut method
after bolt is tightened to snug, it is then turned a certain amount whether that be one third of a turn or one full turn
topping
after elements erected, topping is poured over them for smooth finish about 2 inches thick; it is a working part of structural action and helps to make the slab one structural unit, sometimes even putting reinforcing in it
Shop drawing
after finished by the fabricator, they go to the engineer and architect to be reviewed and approved; show the GC exactly where and how to install stuff, but are first reviewed by the architect and engineer
Calibrated Wrench Method
again to determine tensile strength; a special torque control wrench is used to tighten the bolts
Bessemer Process
air was blown into a vessel of molten iron to burn out the impurities; another economical steel-making process was the open-hearth method; produced inexpensive steel in 1850's
Ferrous metal
aka Iron Based metal;
Structural mill
aka breakdown mill; where beam blanks are reheated as necessary and passed through succession of rollers that squeeze metal into desired shape and size, then go on to be cut into shorter segments by hot saw
nonferrous
all other metals; more expensive, less corrosive, used for finishes and is pleasing to the eye
Hollow structural sections (HHS)
also called 'structural tubing', makes them suitable for structures that are subject to torsional (twisting) stresses and/or buckling
Steel
any range of alloys of iron that contain less than 2 percent carbon; contains high tensile strength(which concrete and masonry do not have any of),
metal decking
at its simplest is a thin sheet of steel that has been corrugated to increase its stiffness; usually puddle welded
Gusset plates
at the joint of a truss
Lockpin and collar fastener or swedge bolt
boltlike steel pin with annular rings that relies on a steel collar in lieu of a conventional nut to hold the pin; installed by single worker; again once certain tension is reached, the tail of the lockpin breaks off
Wet-cast process
bottom layer of wet concrete is deposited in the casting bed; then a second layer of concrete, with collapsible tubes, dry crushed stone, or light weight aggregate carefully positioned to form the voids, is placed.
Cast Steel
by pouring molten steel directly into molds and allowing the steel to cool; its more expensive than rolled steel, but it can be more efficient and their shapes and options are much more vast
Cee sections
c-shaped with an extra turn to the inside; used for studs, joists and rafters
Heat treatment
can also affect the properties of a metal
Cold-working
can also affect the properties of a metal; can greatly increase the strength of a metal
Rigid Core
center of building with elevators, stairs, ect. that acts as a core of the building and has diagonal bracing, shear walls, moment connections. Rest of building constructed with shear connections and stabilized by diaphragm action(rigidity possessed by a thin plate of material such as welded steel deck with a concrete topping)
electroplating
coat metals such as chromium and cadmium onto steel to improve its appearance and protect from oxidation
galvanized
coating with zinc to protect against corrosion
Electric arc welding
conceptually simple. in practice, its complex. fig. 11.21; study weld symbols and types on pgs. 429 and 430
Shear connection
connects only the web of the beam, but not the flanges to the column; transmits vertical forces(shear) from a beam to a column
Ferrous
consist primarily of iron; less expensive due to the abundance of iron ore, but have tendency to rust
Mild Steel
contains less than three tenths of 1% carbon, plus traces of beneficial elements such as manganese an silicon
Brass
copper and zinc mainly; resistant to corrosion, like bronze; Copper, bronze and brass are economical materials but expensive, they are used for functional and visual components
mobile crane
crane used for the first couple teirs, usually does the job if building is smaller/shorter
Braced frame
creates stable triangular configurations when stabilizing a building frame fig. 11.30; uses diagonal bracing; uses shear connections
cambered
curved slightly in an upward direction so that they will deflect into a straight line under load; done by using a hydraulic ram that bends the beam, or by a large machine that passes the shape through three rollers and flex's the shape to impart permanent curvature; the old way of doing it would be to heat certain areas and it would swell (much longer and harder process)
hot saw
cuts shape of steel pieces in mill
Galling(tearing)
damage to surface of member if bolt is not accompanied with washers
Pneumatic structures
depend on air pressure for their stability and their capacity to carry snow and wind loads; most common type is air-supported structure in which an airtight fabric usually reinforced with steel cables is held up by pressurizing the air in the inhabited space below it
girders
designed originally as efficient shapes for bridge structures, but are sometimes used in buildings as well; AASHTO(American association of state highway and transportation officials).
composite metal decking
designed to work together with the concrete floor topping to make a stiff, lightweight, economical deck. Use of shear studs welded into the columns every couple inches to form the columns with the concrete.
fastening devices
devices that are inserted in holes drilled into the cured concrete. Examples are nails, drills, ect.
carbon fiber reinforcing
does not require protection from corrosion, and therefore less concrete cover is required compared to steel reinforcing
self drilling; self tapping screws
drill their own holes and form helical threads in the holes as they are driven; used to join light gauge steel members. THey are driven rapidly and they are plated with cadmium or zinc to resist corrosion
Angels
extremely versatile, they can be used for very short beams supporting small loads and are frequently found playing this role as lintels spanning door and window openings in masonry construction
extruded process
extrusion devices squeeze and extremely dry and stiff concrete mix through a moving extrusion die to produce the voided shape directly
eccentrically braced frame
fig. 11.30; ends of the diagonal braces are offset and is used to absorb seismic loads; uses shear loads
Moment-resisting frames
fig. 11.30; have neither shear walls or bracing, but merely rely on moment connections; moment connections more expensive than shear.
Shear Walls
fig. 11/30; stiff walls made of steel, concrete, or reinforced concrete masonry; moment connections NOT required
brakes
folds are made in these large machines
solid slab
for short spans and minimum slab depths
Load-indicator washer/direct tension indicator (DTI)
for slip critical connection; a washer is placed under a bolt and when certain flatness of washer is hit, thus the right amount of tension is in the bolt
welding
gas flame or electric arc used melts both sides of joint and allows it to flow together with additional molten metal from welding rod
weathered steel(ASTM A588)
has oxide coating when exposed and protects from further corrosion; used when exposed to exterior conditions(used for highway bridges, ect.)
Tension controlled bolts
have protruding splined ends that extend beyond the threaded portion of the body of the bolt; installed by single worker; tightened by a shear wrench that grips both the protruding ends and the nut and turns them against each other; when tightened to a certain tension the end pops off
quenched
heated hot and then plunged in cold water, becomes much harder but very brittle
annealing
heated to high temp. then cooled very slowly
Forging
heating metal until soft, then beating it into shape
tempered
heating to moderate degree and cooling it more slowly, making it both hard and strong
tap
helical cutting tool
laser cutting
high quality results in thin metal plates
girts
horizontal z-shapes of channels that span from column to column on the roof
Stiffener plates
installed in the flanges of the column to better distribute the forces into the body of the column
machining
is a process of cutting unwanted material from a piece of metal to produce the desired shape
Light Gauge steel
is the noncombustible equivalent of wood light frame construction; and is metallic-coated with zinc or aluminum-zinc alloy to provide long-term protection against corrosion; ASTM A1003
tagline
line that the ironworker uses to help guide the steel hanging from the crane
subpurlins
little truss things that are used for roofing that support different kinds of roofing; small roof framing member that spans between joists or purlins
Double/single tees
longest spans, eliminate still more nonworking concrete
Titanium
low in density, about half the weight of steel, very strong, and one of the most corrosion resistant of all metals; very expensive and just recently begun to appear on the construction site in form of roofing sheet metal
Brazing and Soldering
lower temp. welding that use a welding rod with lower melting point that joint metals and the rod connects the two pieces. not as strong but easy to make.
Stainless steel
made by alloying steel with other metals such as chromium and nickel, it is harder to form, more expensive, but more pleasing to the eye; most common type is '304 stainless steel
cellular decking
manufactured by welding together two sheets, one corrugated and one flat
thermal breaks
materials with high resistance to the flow of heat
Tensile fabric structure
membrane supported by masts or other rigid structural elements such as frames or arches; consists of a woven textile fabric and is generally reinforced with steel cables along the main lines of stress; stabilized with prestress
Wide Flange shapes
more efficient that American standard, and are used for most beams and columns. Two basic proportions: Tall and narrow for beams, and squarish for columns and piles. Nomenclature starts with letter W followed by nominal depth in inches and then the weight of the shape in pds. per foot. EX: W21X23. range from 4 to 44 inches, and 9 to 730 pds per LF
Open-Web steel Joist (OWSJ)
most common shape; closely spaced to support floor and roof decks; produced in 3 series...K, LH(Longspan), and DLH(Deep longspan)
precast concrete
most elements are used for making floor and roof slabs; constr. process is parallel to that of steel framing;
Zinc
most important use is for galvanizing (coating to prevent from rusting),
Spray-applied fire-resistive materials (SFRM)
most prevalent type today; consist of either a fiber and a binder or a cementitious mixture, and are sprayed over the steel to a certain thickness
Slip form process
moving hoper deposits a zero slump concrete mix in the casting bed
plasma/laser cutting
newer method more common when cutting steel; uses a digitally prepared model
Aluminum
nonferrous metal most often used in construction; self-protecting from corrosion; reflects more heat and light than any other architectural material and is used for roofing, duct work, window or door frames, siding, hardware, wiring...ect.
bearing pad
pad that is placed between concrete that is resting upon other concrete precast elements so that the concrete does not rub against each other and cause damage
leveling plates
placed below the baseplates
raising gang
ppl working with cranes
casting beds
precast concrete elements produced in permanent forms called casting beds; length 400-800 ft.
hollow-core slabs
precast elements suitable for intermediate spans, internal longitudinal voids replace much of the nonworking concrete
Joist Girders
prefabricated steel trusses designed to carry heavy loads, particularly bays of steel joists
Basic-oxygen process
process of converting iron to steel, in which a hollow, water cooled lance is lowered into a container of molten iron and oxygen is blasted into the molten to rid it of carbon.
casting
process of pouring molten metal into a shaped mold
Stamping
process of squeezing sheet metal between two matching dies to give it a desired shape or texture
castellated beam
produced by flame cutting the web of a wide-flange section along a zigzag path, then reassembling the beam by welding its two halves point to point, thus increasing depth without increasing its weight.
Cast Iron
produced from iron ore in a blast furnace; unpredictable brittleness; contains 3 to 4 percent carbon and large quantities of impurities than steel;
Drawing
produces wires by pulling a metal rod through a series of progressively smaller orifices in hardened steel plates until the desired diameter is reached
Manual of Steel Construction
published by AISC (American Institute of Steel Construction)****
corbels
reinforcing within pretensioned columns for a multistory section; corbels are the things that stick out in a column to support beams and/or girders
filigree precast concrete system
relatively thin precast elements that are either conventionally reinforced or prestressed are used as the form work for site casting of beams and slabs
filigree precast concrete system
relatively thin precast elements that are either conventionally reinforced or prestressed are used as the formwork for site casting of beams and slabs; because the forms end up being in the final structural unit, the cost is much less than conventional forms.
Erector
responsible for assembling into a frame on the site the steel components furnished by the fabricator; the erectors workers are called 'ironworkers'
Cold-worked/Cold-formed
rolled or bent in room temperature; allows it to gain considerable strength
Milling
rotating cutting wheel is used to cut metal from a workpiece
Bearing type connections
sides of the bolts in the connected members bear against the bodies of the bolts; used for shear
gypsum sheathing panels
similar to gypsum wallboard but with glass mat faces and a water resistant core formulation
flame cutting torch
slender, high temp. gas flame with a jet of pure oxygen to burn away the metal
Tin
soft, ductile silvery metal that forms a self protecting oxide layer
extrusion
squeezing heated but not molten metal through a shaped die to produce a long metal piece with a shaped profile matching the cutout in the die
lathe
stationary cutting tool used to make cylindrical shapes
baseplates
steel components that distribute the concentrated loads of the columns across a larger area of a concrete foundation, usually shop welded to the column except for largest columns.
Hot-dipped galvanizing
steel dipped in liquid zinc and it forms a thick layer or coating which is most durable form of galvanizing
plumbed up
straightened and square; checking alignment with plumb bobs, transits, or laser levels.
Roller straightener
straightens the steel if there are any bends while they are cooling
Magnesium
strong, remarkably lightweight metal that is much used in aircraft but remains too costly for general use in buildings
fastening systems
systems cast into the concrete to help with connections. Examples are anchor bolts, weld plates, dovetail slot, ect.
drift pin
temporary pin that ironworkers carry in their toolbelts to put into the bolt holes until the bolts are provided by the raising gang
Slip critical connection
they are preloaded to such an extent that friction between adjoining faces of the steel members resists moving between members; used for tension; must be tightened to at least 70% of tensile strength; stressed in tension; uses the turn of nut method to get right amount of tensile strength
ductile
they can be hammered tin or drawn into wires; liquefied by heating and will re-solidify as they cool
gauge
thickness of steel
intumescent mastics/paints
thin coatings that allow steel structural elements to remain exposed to view in situations of low to moderate fire risk. They expand when exposed to fire to form a thick and stable char that insulates the steel from the heat of the fire for varying lengths of time
Plasma cutting
tiny supersonic jet of superheated gas that blows away the metal
Moment connection
transmits bending forces between a beam and column; connects the beam flanges strongly across the joint; more expensive than shear, therefore used only to the extent required.
steel truss
triangulated arrangements of steel members that are generally deeper and lighter than improved beams and can span correspondingly longer distances.
Tier
two stories of a building frame comprised of structural steel
Channels
used as truss members and bracing, for short beams, lintels and stringers in steel stairs
channel sections
used for top and bottom wall plates and for joist headers
Drill press of lathe
used to drill
tower crane
used to hoist steel on upper tiers for taller buildings
'mini mills'
utilize electric arc furnaces; only mini in comparison with other mills, but use scraps from cars to make top quality steel
Advantages of LGS
versatile, flexible, simple and inexpensive tools, large range of int. and ext. finish materials, very noncombustible, lighter than wood, span longer distances, straighter and more uniform, cannot fall victim to termite or decay. Can be carried out under any weather, not as resistant to sound compared to masonry. thermal conductivity higher than wood
Chromium
very hard metal that can be polished to a brilliant mirror finish. It does not corrode in air; it is used for ornamental metalwork, it is used in stainless steel and other metals to provide hardness, strength and corrosion resistance
Beam Blanks or Booms
very thick approximations of the desired final shape, which are then rolled into final form
Demand-critical welds
welds subject to high stresses during seismic activity
Impact Wrench
what is used to tighten bolts
alloy
when metals are mixed with other elements to modify its properties for a particular purpose
Copper
when oxidized, it forms a self-protecting coating that ranges in color; has highest thermal and electrical conductivity of any metal in construction and mainly used for roofing, flashing sheet, piping and tubing and wiring
architecturally exposed structural steel(AESS)
when steel is exposed and there is a high quality for appearance and quality
dry-packed
where grout is stiff but not actually dry at the time that it is installed; exposed metal connectors not covered by topping are usually dry-packed
Cooling bed
where pieces sit to cool off
rolling
which may be done either hot or cold, forms the metal by squeezing it between a series of shaped rollers