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Abstract: Dedicated to Prof. Dr.‐Ing. habil. Joachim Lindner on the occasion of his 80th birthday The aesthetical and structural advantages of tubular structural elements sustained the increase in their use in Brazil in last decades. The joints between tubular members remain a critical issue, with many studies indicating that further research is still needed, particularly for some geometries. In the past, some experiments on the influence of the chord stresses over the brace load capacity were published, but a definitive answer to this design issues was not reached. The first part of this paper presents an experimental evaluation centred on the effect of tension and compression chord stresses over RHS chord to SHS braces T‐joints. The results showed that compressive chord stresses could considerably reduce the joint resistance. In contrast, when tension chord stresses are applied the joint resistance increases but this is still not considered in the design codes. Still considering the tubular joints structural behaviour, there are cases where the ultimate resistance of the tubular joints may be enhanced by using flange plates as reinforcement, instead of replacing the chord or braces with stronger sections. Bearing this scenario in mind, the second part of this paper presents some experimental results of SHS T‐joints reinforced with flange plates to achieve a more economical design. The results showed that the joint resistance could be increased about 88 % using the reinforced plate with the same thickness of the chord profile. [ABSTRACT FROM AUTHOR]

Abstract: Applying the theory of structural state of stress, this paper investigates the behaviour characteristics of concrete‐filled stainless steel tubular (CFSST) short columns during their experimental working process. First, the sum of the generalized strain energy density (GSED) values (Eij) of the short column at every load value (Fj) is normalized as Ej,norm to describe the structural state of stress. Then, the state of stress jump is identified by applying the Mann‐Kendall (M‐K) criterion to the Ej,norm‐Fj curve creatively, following the rule of quantitative change to qualitative change. The investigation reveals the general state of stress mutation characteristics of short columns at specific individual loads, leading to an update of the failure load. Furthermore, it is verified that the simulative working behaviour of short columns can also reflect the state of stress characteristics revealed through the investigation into the experimental data. Hence, we formulate the relationship between the failure loads of CFSST short columns using the simulative data, and then validate it through both experimental and simulative data. In total, this study explores a new way to reveal some unseen working characteristics of structures; hopefully, it will initiate similar research on various structures, and the results achieved will lead to more rational design codes. [ABSTRACT FROM AUTHOR]

Abstract: Introduction of the Direct Strength Method into the design of cold formed steel members according to EN 1993‐1‐3. Cold formed steel members have a varied area of applications in steel lightweight constructions but are subject to local and global instabilities due to compressive and bending stress. The design method of the European Standard EN 1993‐1‐3 is based on the Method of Effective Widths covering local and distortional buckling. Unfortunately, an EN 1993‐1‐3 design is time‐consuming and prone to errors, furthermore the results are often conservative. This paper is going to introduce a new, practical design method for cold‐formed steel sections that combines the established European regulations of global instabilities with the Direct Strength Method (DSM) described in the North American standard AISI Standard 100 regarding local stability analysis. Based on comparative studies of mono‐symmetric cross‐sections it is possible to demonstrate that this new method offers a great potential of improving the design of cold‐formed sections, additionally improves the economic efficiency of lightweight steel sections. More theoretical and experimental investigations are needed, deeper leading questions are to answer, until this method is able to supplement the European standard. [ABSTRACT FROM AUTHOR]

Abstract: Trough girders are widely accepted in engineering on account of lowing construction depth and protection against traffic noise pollution, but most of them are used for simple‐supported girder bridges with a span of generally less than 30 m. On the railway line of Nanjing–Qidong in China a new railway bridge will be built which has a span of over 64 m but a construction depth of less than 2.4 m on which Shanghai–Nantong railway line is also passed, so the type of concrete‐filled steel tube tied‐arch bridge with trough girder was chosen. For such a new structure hardly used in engineering, there are no research results yet available about mechanical properties of the structure. This paper therefore makes for the bridge an experimental model of 1:4 geometric scale in order to test mechanical properties under operation load, cracking load, and ultimate load such as cracking diagram, load‐carrying capacity, stress distribution, and failure mechanism. According to the experimental results, when the model is subjected to longitudinal bending moment, the failure mode is similar to that of pure bending of a girder, and when the model is subjected to transverse bending moment failure mode behaves like the flexural failure mode of the traditional reinforced concrete structure. A non‐linear element analysis is also made on the model with the results in good agreement with that of the experiment. The same modeling method is applied to the finite element analysis of the real bridge, considering various load in design. In the analysis, it is finally verified that this new type of bridge meets specification requirements in strength, rigidity, and resistance to cracking. [ABSTRACT FROM AUTHOR]

Abstract: Failure of a steel pallet rack in Athens. Pallet racking systems have peculiar characteristics which differ from usual steel structures that make them sensitive to stability failure modes. In the present paper a rack failure is presented where the rack has failed due to lateral torsional and distortional buckling of its most stressed uprights. The structural behavior was studied by a combination of experimental and numerical/analytical methods. The investigations included test loading, bending tests on pallet beams, compression tests on stub column and bending tests on beam end connectors. Subsequently, a global geometrical non‐linear analysis is performed on the 3‐D system. Its results indicate by comparison with the pictures of the actual structure that the collapse mode is correctly detected. Conclusions are drawn that recommend the performance of static and dynamic analyses on an obligatory basis. [ABSTRACT FROM AUTHOR]