Presentation on theme: "Tuesday, Oct. 6 Test Review Steel 1 Lecture Pin-up laminated beam lab project at end of class in Pit. Thursday, Oct. 8 Mid-term submission of Learning."— Presentation transcript:
Tuesday, Oct. 6 Test Review Steel 1 Lecture Pin-up laminated beam lab project at end of class in Pit. Thursday, Oct. 8 Mid-term submission of Learning by Observation Book due. –Printed in final proposed format – 11x17 paper (may be bound or stapled in order) –Wood section photos, and detail drawings –See examples on web site(Dan Crawford, Jeremy Smith, Rodney Bell [432mb file] )
Steel Lecture No.1
It is common today to talk about 'the iron and steel industry' as if it were a single thing; it is today, but historically they were separate products. Steel is a metal alloy whose major component is iron, with less than 2% carbon content. Carbon is the most cost effective alloying material for iron, but many other alloying elements are also used. Carbon and other elements act as a hardening agents. Ordinary structural steel, called mild steel, contains less than 3/10% carbon Steel with increased carbon content can be made harder and stronger than iron, but is also more brittle. Alloys with carbon content higher than 2% are known as cast iron (typically 3-4% carbon). Varying the amount of alloying elements and their distribution in the steel controls qualities such as the hardness, elasticity, ductility, and tensile strength. Increased tensile strength, hence very economical for tension members, or even columns restricted in dimensions due to architectural considerations. Elastic modulus of these steels is not increased by the added elements, hence their use for beams is justified only when deflection (sag) is not a controlling factor.
Ferrous or Non-Ferrous Metals are classified as either ferrous (iron based) or non-ferrous. Ferrous metals are those containing a substantial proportion of iron, such as stainless steel and galvanized iron. Carbon content is a crucial determinate of the properties Non-ferrous metals are all the others, such as aluminum, copper, and zinc.
Ferrous Metals The principle constituent of all ferrous metals is iron, which is the second most abundant metal and fourth most abundant element of earth. Cast Iron: Brittle Mild Steel Wrought Iron: weak, mallable
Non-ferrous Metals Almost all non-ferrous metals share one desirable characteristic; they resist corrosion and generally have excellent workability. As with iron and steel, almost all non-ferrous metals used in construction are alloys. An alloy is a partial or complete solid solution of one or more elements in a metallic matrix
Steel Alloys Mild Steel ASTM36 A36 steel typically used for wide flange shapes Higher strength, low alloy ASTM A9992 or A572 A572 steel typically used for angles, channel, plates, bars
Cast iron usually refers to grey any of a group of iron-based alloys containing more than 2% carbon.iron It is made by remelting iron, often along with substantial quantities of scrap iron and scrap steel, and taking various steps to remove undesirable contaminants such as phosphorus and sulfur. Carbon and silicon content are reduced to the desired levels, which may be anywhere from 2% to 3.5% for carbon and 1% to 3% for silicon depending on the application. Other elements are then added to the melt before the final form is produced by casting. Iron is most commonly melted in blast furnace. After melting is complete, the molten iron is removed or ladled from the hearth of the blast furnace. This process is thought to have been devised by the late 18th century ironmaster John Wilkinson, whose innovative ideas revolutionized the field of metallurgy.iron Crystal Palace Joseph Praxton London 1851 cast iron and glass
Wrought iron is commercially pure iron, having a very small carbon content (carbon content does not exceed 0.15 percent), but usually contains some slag. It is tough, malleable, ductile and can be easily welded. However, it is too soft to make blades and swords, or at least for their cutting edges, which need to be made of steel with a higher carbon content. Common reference to 'wrought iron' means iron of this composition. However, it should be confined to iron that has been wrought into a finished product. wrought - purified by repeatedly beating with hammer. Wrought iron has been used for thousands of years, and typically represents the "iron" that is referred to throughout history.
Eiffel Tower Paris Gustaf Eiffel Wrought iron
Galleria Umberto is a public gallery in Naples, southern Italy. It is located directly across from the San Carlo opera house. It was inaugurated in 1890 and was the cornerstone in the decades-long rebuilding of Naples--called the risanamento (lit. "making healthy again)--that lasted until WW1. It was named for Umberto I, king of Italy at the time. It was meant to combine businesses, shops, cafes and social life -- what today might be called a "mall". The design was by Emanuele Rocco and employed modern architectural elements reminiscent of a similar and earlier building in Milan. The "Galleria" is a high and spacious cross-shaped affair surmounted by a glass dome braced by 16 metal ribs. Of the four glass-vaulted wings, one fronts on via Toledo (via Roma), still the main downtown thoroughfare, and another opens onto the San Carlo Theater. It has returned to being an active center of Neapolitan civic life after some years of decay. Retrieved from "http://en.wikipedia.org/wiki/Galleria_Umberto"http://en.wikipedia.org/wiki/Galleria_Umberto
The Home Insurance Company Building William LeBaron Jenney, 1893 Chicago Steel One of the early true skyscrapers. Steel framing was fireproofed with masonry
Allied Bank Building - Houston, Texas SOM / Lloyd Jones Fillpot
The Primary Metals of Construction Steel structural Aluminum weather resistance Copper electrical, plumbing, roofing
Steel Forming methods Hot rolling method used to shape heavy steel beams and columns by heating steel and passing back and forth through a set of rollers Cold forming method used to form thin steel components such as door frames and studs
Steel Hot rolling: Eliminates flaws and is used to make structural shapes such as wide-flange beams and channels.
Steel Cold formed Increases strength, but decreases ductility
Steel Strength 50,000 psi Steel is the strongest of the three main structural system materials: steel concrete wood Steel is equally strong in both tension and compression. High strength results in visually light weight structure
Steel Rust requires protective coating paint galvanizing Fire protection spray on cementuous coating insulates steel from heat which causes steel to weaken -Spray -Cladding -Encasement (composite steel & concrete)
Steel Recyclable steel is one of the most recyclable building materials. Recycled steel requires much less energy to produce a ton of steel than starting from raw ingredients. Insensitive -The value of recyclable materials offsets the cost of demolition. *Fun Fact: The automobile is the most recycled product in the U.S.
Recycling Steel How exactly is steel made? The Steel Manufacturers Association (SMA) video, The Refrigerator Door shows how old, discarded scrap becomes brand new steel, through the energy efficient electric arc furnace process -- providing thousands of jobs and cleaning up the environment!
Steel A Kit of Shapes.
Examples of Standard Shapes of Structural Steel
Steel Organizing the Structural System Grid Systems orthogonal radial
Organizing the Structural System
Steel Grid Hierarchy Advantages of a grid The grid establishes repetitiveness Repetitiveness simplifies fabrication and assembly processes
Open Web Joists Sometimes called bar joists are shop fabricated, standardized lightweight trusses made from hot-rolled or cold-formed steel sections. Used in a similar fashion to wood joist construction, and they are available in a variety of spans, depths, and load-carrying capacities.
The open web has the advantage of permitting pipes, ducts, and conduits to pass through the joists within the floor construction depth.
Open-Web Steel Joists Produced in 3 series K-series span up to 60 – depth ranges from 8 to 30 LH-series (longspan) span up to 96 – depth ranges from 18 to 48 DLH-series (deep longspan) span up to 144 – depth ranges from 52 to 72 Spacing between OWJ-s ranges from 2 to 10.
Metal decking is manufactured from sheet steel in a corrugated, ribbed, or cellular form. The edges overlap or interlock to form a working platform during construction and permanent formwork for a concrete floor slab. Most floor decking is now composite metal decking, which has deformed or patterned ribs that bond to the concrete so the deck and concrete act together as a unit to support the loads.
Light Gauge Steel Framing Lightweight, or light gauge, metal framing is analogous to wood framing. Instead of wood studs, joists, and rafters, light-gauge steel members, made of cold-formed sheet steel, are used. Instead of using nails, connections are made with screws, bolts, or welds.
Preliminary Design of a Steel Structure Dimensioning Corrugated steel roof decking depth of = 1/40 of the span (standard depth = 1, 1 ½, 2 and 4) Open-web steel joists depth of = 1/20 of span for heavily loaded floors or widely spaced joists. Depth = 1/24 span for lightly loaded floors, closely spaced joists and roofs. Typical joist spacing range Steel beam depth = 1/20 of span (width usually 1/3 to 1/2 of depth) Steel girder depth = 1/15 of span (width usually 1/3 to 1/2 of depth) Triangular steel roof trusses depth = 1/4 to 1/5 of span. Rectangular trusses depth = 1/8 to 1/12 of span. Steel column size. Add up the total roof and floor area supported by the column. A W8 supports up to 3000 sq ft. W sq ft.