2.0 Literature Review
For one to obtain a better understanding with regards to the buckling produced from loading the legs of cold-formed steel top hat sections numerous studies were reviewed and evaluated.
2.1 Stability Issues of Cold-Formed Purlins
Cold formed steel purlins are known to illustrate certain unique properties, in a structural sense, due to their small thicknesses, the fabrication process, the high slenderness of the elements of their cross-sections and their open section nature. Hancock et. al. (5) identifies the three basic modes of buckling modes present in cold-formed steel member in compression as local, distortional, and overall buckling as illustrated in figure 2.1 below. Local buckling is a buckling mode that entails only plate flexure within the line junctions between adjacent plates, which stay straight. The distortional buckling mode involves the rotating of the lip-stiffened elements of the section about the flange-web junction. Finally, overall buckling consists of translation of cross sections of the member without section distortion. This last mode may be of either flexural-torsional or Euler buckling.
(INSERT HANCOCK BUCKLING ILLUSTRATIONS)
J. M. Davies (6) describes in his “Recent Research Advances in Cold-Formed Steel Structures”, the difficulties that face engineers calculating local buckling as a consequence of the increasing complexity of sections shapes that are becoming ever more complicated and of the increasing importance of distortional buckling. He indicates that distortional buckling is at least as likely as local buckling and warrants similar considerations in design but is less well known and documented. Takahashi et al. (7) was the first to publish a paper delving into this mode of...
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...ed attention. Schuste and Acharya (24) demonstrate effectively in their paper, the over conservative nature of design codes when top hats are considered. Pastor and Roure (13) illustrate the effect of bending on open cross-section citing the top hat section as an example and proving the behaviour of the member under pure bending. More recently Honfi (25) attempts to create optimisations to hat sections by means of genetic algorithms.
It is clear that cold formed steel is a field that is developing in terms of growth and understanding though the purlins that are used are often noted to be over conservative in nature, even of those studied thoroughly such as C and Z cross sections. Top Hat cross sections have proven merit for shorter spans but the literature effectively shows it as a subject that requires further study which I aim to contribute through this project.
Compare with other types of bridges, suspension bridge can span the longest distance without using lots of material. However, if the issue of stiffness was not fully cosidered, vibration would be occurred on the bridge deck under high wind. A few week after the Tacoma Narrow Bridge was operated, the bridge start oscillation and its oscillation kept increasing day by day. Therefore engineers tried to build more cable between the bridge, but it is still unsuccessful. After four months the Tacoma Narrows Bridge was build, the bridgre which normally vibrated in a vertiacal motion, began to oscillate with the opposite side out of phase (torsional model), under the wind of 68 km/h. Due to the extremely violent oscillation, the failure bagan at the mid-...
While some people reveal their dark sides the moment two people meet, most attempt to hide their dark side until later. The Adventures of Huckleberry Finn by Mark Twain follows Huckleberry Finn as he travels down the Mississippi River in a raft and how he meets many types of people who use the immediate showing and prolonged showing of the dark side of their human nature. Through the persona of fourteen year old Huck Finn, and his interaction with the minor characters, Twain reveals the hypocrisy, flagitiousness, and the irony of the situations in which Huck encounters, establishing the theme of every human has a darker side due to nature.
-Developed and implemented strip casting overseas to eliminate a step in the steel making process
The extraordinary power of the steel industry to shape the life of its communities and the people in them remain...
US Army Correspondence. (2000). METAL PROPERTIES, CHARACTERISTICS,. US ARMY REPAIR SHOP TECHNICIAN WARRANT. Retrieved from www.hnsa.org/doc/pdf/metal-properties
Laws such as the lever law and Euler’s Buckling Theorem come into play when testing and competition begins. A structure of wood and glue surely has much more to offer than meets the eye.
Next, The Eiffel Tower is a renowned monument for France. Being that it was originally built as an entrance way, some precautions were made. The safety token was moveable staging, guard rails and screens only one man died during construction. (Eiffel Tower). The tower stands 320 meters tall it uses over 18,000 pieces in the steel structure. Each year the high heats cause the structure to grow six inches, but then retracts back after the summer time. So, that is why the idea of thermal rivets were used in assembly, because the rivets allow the structure to keep its shape. Over 2.5 million rivets were used. (Eiffel ...
Mechanical Engineering 130.2 (2008): 6 - 7. Academic Search Complete. Web. The Web. The Web.
Ballet is a popular dance form that originated in the 1500s around the time of the renaissance. It consists of many different forms that have evolved over the years. Some examples of these forms include French Ballet, Vaganova (Russian Ballet), Cecchetti (Italian Ballet), and Balanchine. Ballet forms and variations originated mainly from Italy, Russia, and France. However, today, many different forms of Ballet exist. Despite the many different variations, all Ballet has certain things in common. It is an effective form of exercise, requires special equipment, contains many set principles, and can result in specific injuries.
This paper will first discuss the development of the steel industry. Next, it will examine steel, and in the impact it had on the transportation industry. Finally, it will discuss systematic management practices of this time and how they gave birth to the scientific approach that is still in use today.
Works Cited Journal articles: • Lane, Thomas. “Crazy Angles, Soaring Steel.” Building vol. 274 no. 8588 (28) 2009, July 17, pp. 40-46.
After quenching, the heated steel will cool down. Due to the different rate of cooling, the different types of microstructure will be formed. The formation of pearlite, bainite and martensite determine the physical properties such as hardness, strength and ductility.
The basis for the understanding of the heat treatment of steels is the Fe-C phase diagram. Because it is well explained in earlier volumes of Metals Handbook and in many elementary textbooks, the stable iron-graphite diagram and the metastable Fe-Fe3 C diagram. The stable condition usually takes a very long time to develop, especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The Fe-C diagram shows which phases are to be expected at equilibrium for different combinations of carbon concentration and temperature. We distinguish at the low-carbon and ferrite, which can at most dissolve 0.028 wt% C at 727 oC and austenite which can dissolve 2.11 wt% C at 1148 oC. At the carbon-rich side we find cementite. Of less interest, except for highly alloyed steels, is the d-ferrite existing at the highest temperatures. Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite + cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the two phase fields liquid + austenite, liquid + cementite, and liquid + d-ferrite. In heat treating of steels the liquid phase is always avoided. Some important boundaries at single-phase fields have been given special names. These include: the carbon content at which the minimum austenite temperature is attained is called the eutectoid carbon content. The ferrite-cementite phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite particles dispersed with a ferrite matrix after extended holding close to A1. The Fe-C diagram is of experimental origin. The knowledge of the thermodynamic principles and modern thermodynamic data now permits very accurate calculations of this diagram.
Some steel containers are made through deforming the steel by means of extruding, forging, spin forming, ...