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Structural analysis of steel frames is typically performed using beam elements. Since these elements are unable to explicitly capture the local buckling behavior of steel cross-sections, traditional steel design specifications use the concept of cross-section classification to determine the extent to which the strength and deformation capacity of a cross-section are affected by local buckling. The use of plastic design methods are restricted to Class 1 cross-sections, which possess sufficient rotation capacity for plastic hinges to develop and a collapse mechanism to form. Local buckling prevents the development of plastic hinges with such rotation capacity for cross-sections of higher classes and, unless computationally demanding shell elements are used, elastic analysis is required. However, this article demonstrates that local buckling can be mimicked effectively in beam elements by incorporating the continuous strength method (CSM) strain limits into the analysis. Furthermore, by performing an advanced analysis that accounts for both geometric and material nonlinearities, no additional design checks are required. The positive influence of the strain hardening observed in stocky cross-sections can also be harnessed, provided a suitably accurate stress–strain relationship is adopted; a quad-linear material model for hot-rolled steels is described for this purpose. The CSM strain limits allow cross-sections of all slenderness to be analyzed in a consistent advanced analysis framework and to benefit from the appropriate level of load redistribution. The proposed approach is applied herein to individual members, continuous beams, and frames, and is shown to bring significant benefits in terms of accuracy and consistency over current steel design specifications.

The Wagner coefficient is a key parameter used to describe the inelastic lateral-torsional buckling (LTB) behaviour of the I-beam, since even for a doubly-symmetric I-section with residual stress, it becomes a monosymmetric I-section due to the characteristics of the non-symmetrical distribution of plastic regions. However, so far no theoretical derivation on the energy equation and Wagner’s coefficient have been presented due to the limitation of Vlasov’s buckling theory. In order to simplify the nonlinear analysis and calculation, this paper presents a simplified mechanical model and an analytical solution for doubly-symmetric I-beams under pure bending, in which residual stresses and yielding are taken into account. According to the plate-beam theory proposed by the lead author, the energy equation for the inelastic LTB of an I-beam is derived in detail, using only the Euler–Bernoulli beam model and the Kirchhoff-plate model. In this derivation, the concept of the instantaneous shear centre is used and its position can be determined naturally by the condition that the coefficient of the cross-term in the strain energy should be zero; formulae for both the critical moment and the corresponding critical beam length are proposed based upon the analytical buckling equation. An analytical formula of the Wagner coefficient is obtained and the validity of Wagner hypothesis is reconfirmed. Finally, the accuracy of the analytical solution is verified by a FEM solution based upon a bi-modulus model of I-beams. It is found that the critical moments given by the analytical solution almost is identical to those given by Trahair’s formulae, and hence the analytical solution can be used as a benchmark to verify the results obtained by other numerical algorithms for inelastic LTB behaviour.

Wire-arc directed energy deposition (DED), also known as wire-arc additive manufacturing (WAAM), is a metal 3D printing technique that is recognised for its high efficiency, cost-effectiveness, flexibility in build scales and suitability for the construction sector. However, there remains a lack of fundamental data on the structural performance of WAAM elements, especially regarding their fatigue behaviour. A comprehensive experimental study into the fatigue behaviour of WAAM steel plates has therefore been undertaken and is reported herein. Following geometric, mechanical and microstructural characterisation, a series of WAAM coupons was tested under uniaxial high-cycle fatigue loading. A total of 75 fatigue tests on both as-built and machined coupons, covering various stress ranges and stress ratios (R= 0.1, 0.2, 0.3 and 0.4), have been conducted. The local stress concentrations in the as-built coupons induced by their surface undulations have also been studied by numerical simulations. The fatigue test results were analysed using constant life diagrams (CLDs) and S-N(stress-life) diagrams, based on both nominal and local stresses. The CLDs revealed that the fatigue strength of the as-built WAAM steel was relatively insensitive to the different stress ratios. The S-Ndiagrams showed that the surface undulations resulted in a reduction of about 35% in the fatigue endurance limit for the as-built WAAM material relative to the machined material, and a reduction of about 60% in fatigue life under the same load level. The as-built and machined WAAM coupons were shown to exhibit similar fatigue behaviour to conventional steel butt welds and S355 structural steel plates, respectively. Preliminary nominal stress-based and local stress-based S-Ncurves were also proposed for the WAAM steel.

The MX3D Bridge is the world’s first additively manufactured metal bridge. It is a 10.5 m-span footbridge, and its dynamic response is a key serviceability consideration. The bridge has a flowing, sculptural form and its response to footfall was initially studied using a 3D finite element (FE) model featuring the designed geometry and material properties obtained from coupon tests. The bridge was tested using experimental modal analysis (EMA) and operational modal analysis (OMA) during commissioning prior to installation. The results have shown that the measured vibration response of the bridge under footfall excitation is 200% greater than predictions based on the FE model and contemporary design guidance. The difference between predicted and measured behaviour is attributed to the complexity of the structure, underestimation of the modal mass in the FE model, and the time-variant modal behaviour of the structure under pedestrian footfall. Both OMA and EMA give a dominant natural frequency for the bridge of between 5.19 Hz and 5.32 Hz, higher than the FE model prediction of 4.31 Hz, and average damping estimates across all modes of vibration below 15 Hz of 0.61% and 0.74% respectively, higher than the 0.5% assumed within the design guidance, slightly reducing the peak response factor predicted for the bridge.

Structural analysis of steel frames is typically performed using beam elements. Since these elements are unable to explicitly capture the local buckling behavior of steel cross-sections, traditional steel design specifications use the concept of cross-section classification to determine the extent to which the strength and deformation capacity of a cross-section are affected by local buckling. The use of plastic design methods are restricted to Class 1 cross-sections, which possess sufficient rotation capacity for plastic hinges to develop and a collapse mechanism to form. Local buckling prevents the development of plastic hinges with such rotation capacity for cross-sections of higher classes and, unless computationally demanding shell elements are used, elastic analysis is required. However, this article demonstrates that local buckling can be mimicked effectively in beam elements by incorporating the continuous strength method (CSM) strain limits into the analysis. Furthermore, by performing an advanced analysis that accounts for both geometric and material nonlinearities, no additional design checks are required. The positive influence of the strain hardening observed in stocky cross-sections can also be harnessed, provided a suitably accurate stress-strain relationship is adopted; a quad-linear material model for hot-rolled steels is described for this purpose. The CSM strain limits allow cross-sections of all slenderness to be analyzed in a consistent advanced analysis framework and to benefit from the appropriate level of load redistribution. The proposed approach is applied herein to individual members, continuous beams, and frames, and is shown to bring significant benefits in terms of accuracy and consistency over current steel design specifications. [ABSTRACT FROM AUTHOR]

Aluminium alloys are nonlinear metallic materials with continuous stress-strain curves that are not well represented by the simplified elastic, perfectly plastic material model used in many current design specifications. Departing from current practice, the continuous strength method (CSM) is a recently proposed design approach for non-slender aluminium alloy structures with consideration of strain hardening. The CSM is deformation based and employs a base curve to define a continuous relationship between cross-section slenderness and deformation capacity. This paper explains the background and the two key components - (1) the base curve and (2) the strain hardening material model of the continuous strength method. More than 500 test results are used to verify the continuous strength methodas an accurate and consistent design method for aluminium alloy structures.

The mechanical behaviors of intersecting joints considering damage accumulation in steel tube structures is analyzed through the FE-program ABAQUS. The stress characteristic and failure modes of these joints are concluded. Especially, it has been analyzed influence of the change of geometric parameters to mechanical behavior of joints. Finally, the results indicate the joints have a good mechanical performance and good plastic deformation as to excessive local buckling of chord under the loads.

The past 15 years have seen the introduction or major revision of structural stainless steel design codes throughout the world, and at the same time, interest in the use of stainless steel in construction has been accelerating. Historically the high initial material cost of stainless steel has limited its use primarily to specialist and prestige applications. However, the emergence of design codes, a better awareness of the additional benefits of stainless steel and a transition towards sustainability are bringing more widespread use into conventional structures. Although a number of similarities between stainless steel and ordinary carbon steel exist, there is sufficient diversity in their physical properties to require separate treatment in structural design. In addition to the straightforward differences in basic material properties (such as Young's modulus and yield strength), further fundamental differences exist, such as the nature of the stress–strain curve and the material's response to cold‐work and elevated temperatures; these have implications at ultimate, serviceability and fire limit states. This paper describes the use of stainless steel as a structural material, discusses current structural design provisions, reviews recent research activities and highlights the important findings and developments.

It is no longer reasonable to maintain that all kinds of dust are equally dangerous to the lungs. A very convincing array of clinical, statistical and experimental observations has demonstrated that dusts composed, in whole or in part, of silica are capable of exciting a characteristic, progressive, nodular fibrosis of the lungs and that at the same time these organs become abnormally. susceptible to the tubercle bacillus. All the other types of dust that have thus far been investigated can apparently be inhaled almost with impunity for long periods of time.It was originally claimed that only uncombined or "free" silica in the form of quartz was capable of producing this effect, but in recent years there has been a growing tendency to look with suspicion on some of the silicates (combinations of silica with bases). One of them, asbestos, a silicate of magnesium, is now a well recognized cause

To the pathologists who coined it, the term pneumoconiosis was useful to describe all pulmonary reactions due to the inhalation of dust. Under the impetus of compensation laws this group of conditions has received so much attention that today pneumoconiosis is almost a household word. But too few are aware of its original significance and even some medical writers use it interchangeably with the specific term silicosis. As a pathologist I prefer to retain the original meaning and use pneumoconiosis as a generic term to describe all forms of pulmonary reactions to inhaled dust, with no implication as to character, severity or effect on function. The two clinically important forms of pneumoconiosis that are known as silicosis and asbestosis are respectively due to inhaled free silica and asbestos dusts. Other forms have been given special names to indicate the kind of mineral that produces them, but such terms have little

Although the term pneumoconiosis was not introduced until the nineteenth century, clinical symptoms were naturally enough associated with the inhalation of dust in occupation by the earliest medical writers. In the Renaissance both physicians and mining engineers were well aware of the fact that the metal miner suffered from shortness of breath and died prematurely, and anatomists had described "heaps of sand" in the lungs of stone cutters which grated on their knives. They called the condition phthisis, their term for any chronic disease of the lungs which was associated with emaciation and expectoration. While most of the various conditions originally known by this name were differentiated and fully described in the eighteenth and nineteenth centuries, it was not until 1902 that the role of inhaled dust began to be understood. In that year an English departmental committee, of which Dr. J. S. Haldane was the outstanding member, pointed out

Possibly no other television broadcasting system has so developed along lines familiar to American broadcasters than the Japanese. Both the general outlines of Japanese television and specific programs would fit readily into familiar patterns, as visitors to Japan have remarked. This article is intended to present quantitative information on the similarities and differences between the two systems, based upon analysis of the published program schedules in Tokyo and Minneapolis-St. Paul.

Anatomic and roentgenologic studies of the lungs of persons exposed to various types of industrial dusts have demonstrated that inhaled foreign substances do not all produce the same kind of pathologic reaction. Present knowledge is limited by the lack of a sufficient amount of autopsy material to illustrate the evolution of all types of pneumonoconiosis, but the forms produced by pure chemical substances tend to fall into one of three categories. Such disease is predominantly either linear, nodular or diffuse in character. A linear pattern characterizes the general type of response to most inhaled inert foreign materials; nodular lesions are apparently confined to silicosis, while diffuse reaction is exemplified in asbestosis. Mixed patterns are produced by dusts such as granite, which is composed of several different elements. The stages in the reaction to these well known dusts will be analyzed in an attempt to explain the variations in the resultant

Demand for the construction of new structures is increasing all over the world. Since the construction sector dominates the global carbon footprint, new construction methods are needed with reduced embodied carbon and high resource efficiency to realize a sustainable future. In this direction, Metal Additive Manufacturing, also known as 3D printing, can be an opportunity. Many studies are underway to answer open questions about printed metal products and processes for high-tech industries. The construction sector must join the metal 3D printing research more actively to enrich the knowledge and experience on this technology and correctly adapt the process parameters suitable to the construction sector requirements. This paper states the opinion of a research group composed of academics and practitioners from Europe, the US, Japan, and South Africa on how metal 3D printing can be a complementary tool/technology to conventional manufacturing to increase productivity rates and reduce the costs and CO2emissions in the construction industry.

In carrying out studies on the cellular reactions provoked in the guinea pigs’ peritoneal cavity by the injection of tubercle bacilli, differential cell counts were made upon a series of peritoneal fluids previous to the inoculations. This has furnished such a large number of counts upon the normal peritoneal fluid that it has seemed worth while to collect and report the figures, particularly since there is no general uniformity in the results published by other writers,1, 2, 3, 4, 5, 6Peritoneal fluids from 237 apparently healthy guinea pigs have been examined, and as no effort was made to select a particular type of animal, this group probably represents a fair average of any laboratory stock. The observations have been carried on over a period of several years during both winter and summer months. Therefore any effects attributable to seasonal or dietary conditions may be assumed to have been comprehended. The majority of the animals were purchased from 4 different sources; a few were raised in the laboratory. They were of both sexes, of many colors, and they varied in age from a few days to several years.Without previous injection of salt solution or other liquid, samples of peritoneal fluid were withdrawn through sterile capillary pipettes and supravital preparations with neutral red or neutral red-Janus green were made. Differential cell counts were done on 200 living cells after 5 or 10 minutes’ incubation in the warm box. At first as many as 1,000 cells were counted, but this was found to be unnecessary as the distribution of cells in the fluid from the normal peritoneum is very uniform if the preparations are properly made. The serosal cells were not tabulated as their occurrence is probably more or less accidental.

The method to be described is a modification of that used by McJunkin1which proved to be inapplicable for use on lung tissue. After our technique had been perfected Cash2reported a similar method, but ours, we believe, offers certain advantages. Two pathways are employed for injection of the vital stain, either the intratracheal, the intravenous or a combination of the two. In using the former the animal is first killed by air embolism. For the latter method the dye is injected into a vein 10 minutes before its death. In rabbits intravenous injections are made into the ear vein; in guinea pigs, the jugular veins are exposed under local anesthesia with 3 per cent cocaine. Ether cannot be used, as it destroys the capacity of the pulmonary cells to react specifically to the dye.Supravital Staining—(a) Intratracheal injection: 30 to 40 cc. of a warm 1:1500 solution of neutral red made up in physiological salt solution is injected into the guinea pig's trachea, which is then tied off. The whole animal is incubated at 37° C. for 5 to 30 minutes. After this interval the dye ceases to react specifically and stains the nuclei. (b) Intravenous injection: 60 to 80 cc. of the same solution are slowly injected into the jugular vein or carotid artery of a guinea pig. If the animal survives it is allowed to live 10 minutes before being killed by air embolism. Occasionally it dies and the whole body is incubated as just described.Fixation—This is accomplished by dropping the lungs and heart into alkaline Zenker-iormol solution. After intravenous staining the lungs are distended with air. To prepare this fixative add sufficient solid NaOH to U. S. P. formaldehyde solution to give a pH value of 7.6.

Several letters to the editor are presented in response to articles that appeared in the Spring 2016 issue including "Minnesotans at the Top of the World" and "The Modern Dancer's Skin."

TO THE EDITOR:— An editorial in The Journal, September 23, entitled "Exit Talcum from the Surgical Scene" has provoked considerable comment among industrial hygienists. There you make the statement that "These lesions [the talc granulomas] are permanent because the body does not have adequate reparative power against talcum, which is essentially a silicate and which therefore induces a silicosis."I would question the validity of the assumption that a silicate can cause silicosis, and several people have already written me to protest against your generalization. All experimental evidence derived from study of pure silicates indicates that as a class these minerals do not dissolve within the body to liberate their component silica with resultant fibrosis. In fact, most of the silicates are inert materials and only a few of them, like asbestos and possibly mica, may be irritating because of peculiar physical properties. These experimental results, based on the study