14,981 research outputs found
Turbulence, Inequality, and Cheap Steel
No full textIron and steel production grew dramatically in the U.S. when mass production technologies for steel were adopted in the 1860s. According to new measures presented in this study, earnings inequality rose within the iron and steel industries about 1870, perhaps because technological uncertainty led to gambles and turbulence. Firms made a variety of technological choices and began formal research and development. Professional associations and journals for mechanical engineers and chemists appeared. A national market replaced local markets for iron and steel. An industrial union replaced craft unions. As new ore sources and cheap water transportation were introduced, new plants along the Great Lakes outcompeted existing plants elsewhere. Because new iron and steel plants in the 1870s were larger than any U.S. plants had ever been, cost accounting appeared in the industry and grew in importance. Uncertainty explains the rise in inequality better than a skill bias account, according to which differences among individuals generate greater differences in wages. Analogous issues of inequality come up with respect to recent information technology.technological change, Bessemer steel, technological uncertainty, turbulence, inequality, innovation
Analysis of an alternative topology for steel-concrete-steel sandwich beams incorporating inclined shear connectors
No full textThis thesis presents a new concept in steel-concrete-steel sandwich construction in which a bi-directional corrugated-strip core is proposed as an alternative inclined shear connector. The focus is on the feasibility study of fabrication techniques and the theoretical study of the structural responses of both unfilled and concrete-filled steel-concrete-steel sandwich beams under static flexural loading using numerical and analytical methods. Two possible fabrication techniques to create the proposed bi-directional corrugated strip core are presented. The unfilled sandwich beam is studied using a finite element method and three analytical methods referred to as the modified stiffness matrix, the braced frame analogy, and the discrete beam methods The finite element method is used to investigate the stiffness and strength behaviour of the unfilled sandwich beam.The modified stiffness matrix method provides good correlation with the finite element method. The other two analytical methods are less accurate. The assessment of the effect of geometrical parameters defining the bi-directional corrugated-strip core is carried out. The responses of the strength and stiffness, especially the transverse shear stiffness, are examined and discussed. The optimum configuration of the core is found at the angle of the inclined part of the corrugation is about 45°. The concrete-filled sandwich beam is studied using the finite element method. The finite element method is used to investigate the transverse shear strength and the crack development of a four-point loaded concrete-filled sandwich beam. The assessment of the effect of geometrical parameters defining the inclined shear connectors is carried out. The responses of the concrete-filled sandwich beam are examined and discussed. The optimum advantage of the transverse shear strength of the concrete-filled sandwich beam is also found when the inclined shear connectors align at an angle 45º. It is found that creating the proposed core with a 45° pattern provides a great advantage in transverse shear stiffness and strength in both the unfilled and concrete-filled sandwich beams
Behaviour of semi-rigid composite connections for steel framed buildings
No full textDuring propped construction the steel-concrete composite action resists dead as well as
imposed loads. Conversely, the steel section alone resists the floor self-weight in unpropped
beams. The major difference between propped and unpropped composite beams lies in the
ductility requirements rather than in the strength requirements. Relatively few studies have
been carried out to assess the rotation requirements for unpropped semi-continuous
composite beams. The outstanding critical factor in the case of unpropped construction is the
dead load stress that must be carried by the steel beam alone prior to hardening of the
concrete.
This research overcomes the difficulties involved in modelling the composite and noncomposite
stages by using a numerical integration technique developed from the basic
principles of structural mechanics. The method incorporates the fully non-linear material
properties and requires very little assumption. The technique was initially validated using the
experimental results from plain steel beam bending tests. The subsequent comparison
between the model predictions and the results from the large-scale frame test carried out for
this research purpose, showed that the method is capable of predicting non-elastic load vs.
end rotation behaviour within a high degree of accuracy. Thus the model can be used with
confidence in order to predict the connection rotation requirements for a wider range of
loading configurations than is practically possible from experimental testing alone.
A parametric study is carried out using the numerical integration technique developed for the
semi-continuous composite beam on a total of 2160 different beam configurations, utilising
different steel grades and loading conditions. In this study the influence of dead load stress on
the connection rotation requirement has been thoroughly evaluated along with several other
factors including span to depth ratio, location within the building frame, ratio between the support (connection) moment capacity and span (beam) moment capacity, loading type, steel
grade and percentage of the beam strength utilised during design. The connection rotation
capacity requirements resulting from this study are assessed to establish the scope for
extending the use of composite connections to unpropped beams.
The large-scale experiment that has been carried out provided an opportunity to investigate
the behaviour of a modified form of composite connection detail for use at perimeter
columns (single-sided composite connections) with improved rebar anchorage.
Additionally, another extensive parametric study is carried out using the numerical
integration technique developed for the steel beam to establish the influence of strainhardening
on elastic-plastic frame instability design
Tariffs and Steel: The US Safeguard Actions
No full textThis paper presents a multi-product price linked spatial equilibrium model of world steel trade. The model is used to analyse the impacts of the safeguard trade barriers brought about by the United States in order to protect their domestic industry from so called unfair competition. Emphasis is placed on the likely effect to the Australian industry and possible policy responses available to the industry. A case study is made on Australia's three largest export products, namely slab, hot-rolled and cold-rolled steel, which share some substitutability in supply and demand due to the nature of the industry.trade, spatial equilibrium model, steel, International Relations/Trade,
Tariffs and steel: US safeguard actions
No full textA multiproduct spatial equilibrium model of world steel trade is presented in this paper. The model is used to analyse the impacts of the safeguard trade barriers brought about by the USA in order to protect their domestic industry from the so-called unfair competition. Emphasis is placed on the likely effect on the Australian industry and possible policy responses available to the industry. A case study is made of Australia’s three largest export products; namely, slab, hot-rolled and cold-rolled steel, which share some substitutability in supply and demand because of the nature of the industry. As a result of the safeguard barriers to steel trade, world steel prices fell and trade shifted away from the USA to other importing regions.spatial equilibrium model, steel, trade, International Relations/Trade,
Stal nierdzewna w budownictwie - zalety i przykłady zastosowań
No full textThe paper discusses the problem of using stainless steels in construction. Characteristics of steel marking systems in the
European standards have been characterized. Basic types of steel are presented together with their short characteristics.
Examples of use of stainless steels in construction are discussed, both in terms of construction elements and equipment.W pracy poruszono problematykę zastosowania stali nierdzewnych w budownictwie. Scharakteryzowano systemy
oznaczeń stali trudnordzewiejących w normach europejskich. Przedstawiono podstawowe rodzaje stali wraz z ich krótką
charakterystyką. Omówiono przykłady zastosowania stali nierdzewnych w budownictwie, zarówno w odniesieniu do elementów konstrukcyjnych, jak i wyposażenia obiektów
The steel industry in the European Union: Composition and drivers of energy prices and costs. CEPS Special Report No. 80, 17 December 2013
No full textThis report assesses the energy costs borne by the steel industry in the EU between 2010 and 2012, and compares the energy costs, including both the energy components and other regulatory costs, to production costs, turnover and margins of steel-makers. The estimates of energy costs are based on primary sources, i.e. is on information provided by steel-makers through a written questionnaire. This information was validated by the research team by checking annual energy bills, when available, and other public sources. In this respect, this exercise represents a unique fact-based investigation into the costs of energy for steel-makers in Europe, whereas most of the information currently available in the public domain is based on secondary or statistical information.
In 2012, the median EU steel plant pays about €33/MWh for gas, up from €26/MWh in 2010. As for electricity, in 2012 the EU median plant pays €62/MWh, up from €59/MWh in 2010. The report also includes a comparison with the prices of energy carriers paid by producers based in the US
Effect of interlamellar spacing on the elastoplastic behavior of C70 pearlitic steel: Experimental results and self-consistent modeling
No full textThe effect of pearlite microstructure characteristics on strength and deformation of C70 pearlitic steel was investigated. Tensile tests under X-ray diffraction coupled with self-consistent model have been used to identify the role of interlamellar spacing on the ferrite plasticity parameters and residual stress induced by plasticity. Tests have been carried out on two pearlitic microstructures with interlamellar spacing Sp = 170 and 230 nm respectively. Ferrite critical shear stresses ðs0c ðaÞÞ are equal to 75–86 MPa for interlamellar spacing Sp = 230 nm and 105–120 MPa for interlamellar spacing Sp = 170 nm. Moreover, the compressive residual stress measured in ferrite phase is higher in elasto-plastically deformed sample (total strain of E11 = 1.2%) having larger interlamellar spacing (rR Fea ¼ 161 MPa for Sp = 230 nm and rR Fea ¼ 77 MPa for Sp = 170 nm)
Microstructure investigation and flow behavior during thixoextrusion of M2 steel grade
No full textThe microstructure investigation and flow behavior during thixoforging of M2 steel parts were investigated. Partial remelting was performed at processing temperatures ranging from 1290 ◦C to 1340 ◦C corresponding to a liquid fraction range between 10% and 30% (according to differential scanning calorimetry measurements and quantitative image analyses). A conventional microstructure for thixoforming process was obtained: spherical solid grains surrounded by liquid phase. The microstructure across the heated billets was relatively homogeneous with bigger grain size near the surface. Successful thixoextrusion for producing parts was finally achieved at processing temperatures. By investigating the microstructure and load-displacement curves, different mechanisms in various forming stages were proposed
Quenching and partitioning - a new steel heat treatment concept
No full textSteel continues to be one of the primary materials in use today, however, even after 200 years of published research, innovative methods are being discovered and exploited to produce steel with enhanced properties. One such recent discovery has been termed Quenching and Partitioning (Q&P). The Q&P heat treatment process is reported to produce a multiphase microstructure consisting of retained austenite
stabilised to room temperature, and a harder martensitic phase. This combination is prospected to form a new generation of high strength, formable sheet steel well
suited to the demands of the automotive industry. Previous research has reported on the application of Q&P to commercial grades of steel, however, the temperatures
required have hampered study of the process. In this investigation a model alloy has enabled separation of Q&P into its individual stages for closer inspection. Standard
metallographic techniques were used to examine the microstructure of the material, followed by X-ray diffraction measurements to determine the stability of the
austenite phase fraction before and after partitioning, confirming the effectiveness of the partitioning process in stabilising retained austenite. Estimations of carbon
concentration via lattice parameter measurements have provided evidence of austenite carbon enrichment, but also suggest that some carbon remains unaccounted for, possibly as an equilibrium distribution between epsilon carbides and strained interstitial sites. In-situ partititioning in a neutron diffractometer has been utilised to obtain real-time measurements of the partitioning process. These measurements suggest that redistribution of carbon within martensite occurs before partitioning to austenite becomes kinetically significant. The trapping of carbon within
energetically favourable locations is postulated to be a major factor in retarding carbon migration from martensite to austenite when compared to mathematical models of the partitioning process. Neutron diffraction measurements of carbon interstitial occupancy in austenite have also provided further evidence of austenite carbon enrichment during the partitioning process
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