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