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Translation abstract A mechanically consistent approach for stability verification of timber beams in compression and bending around the strong axis – part 2: experimental tests and numerical simulationSlender timber beams in bending can be designed using different methods in view of out‐of‐plane stability. Lateral torsional buckling may be verified either using the so called equivalent member method or by means of 2nd order calculations, considering equivalent imperfections. Applying current codes, however, determining the lateral torsional buckling resistance using either of these both methods, leads to different results. In this paper, the background of both verifications is investigated in deep. Moreover, as an alternative approach, a non‐linear calculation with an imperfection shape in affinity to the critical shape was presented in part 1 of this paper. By scaling the curvature, the same results as by the equivalent member method can be achieved. It was shown that plasticity effects can be considered as well. In this part 2, results of lateral torsional buckling tests on glued laminated timber beams are presented, with nearly ideal boundary conditions and load direction remaining vertical through‐out the test. Based on these test first tentative values can be obtained for the imperfection compatible with the alternative lateral torsional buckling approach presented. [ABSTRACT FROM AUTHOR]

Translation abstract Buckling lengths in the digital age – a didactic‐technical toolThe critical load of a member in the case of stability failure is the basis for the design according to the equivalent member method of EN 1993‐1‐1. It has become established that the critical load is determined via the buckling length. In the simplest case, the buckling length corresponds to one of the Euler cases, which rarely occurs in typical steel structures. In more complex systems, the buckling length often depends on adjacent structures and their stiffnesses. Determining the buckling length is so important that it is usually taught in steel construction lessons, although it is a classic structural analysis problem. The same happens at the Innsbruck Chair of Steel Construction. A tool that is didactically and technically state‐of‐the‐art and intended to improve education has been developed as part of educational modernization. This tool can playfully convey access to the determination of buckling lengths on complex structures while modern numerical methods take over the actual calculation work in the background. The developed software buckL.ing (freeware) is available for download on the Unit of Steel Construction and Mixed Building Technology's homepage (www.uibk.ac.at/stahlbau/software). [ABSTRACT FROM AUTHOR]

Better and simpler possibilities of structural optimization due to increasing computational power but also for reasons of environmental sustainability, the use of materials and their reusability lead to greater acceptance towards more advanced numerically intensive, so‐called 'design by analysis' methods like geometrically and materially non‐linear analyses with imperfections (GMNIA). The general choice of imperfections and their combination in such models, especially for slender cross sections of intermediate length prone to an interaction between a global and local plate buckling, is crucial in terms of the reached load‐bearing capacity. Annex C of EN 1993‐1‐5:2010 makes use of the '70 %‐rule' for the combination of imperfection modes and amplitudes. This rule postulates that two GMNIA calculations should be conducted when local and global interactive buckling may be dominant; one with 100 % + 70 % of the maximum specified amplitude in either case. In addition, extended information is provided on the choice and combination of imperfections in the newly introduced and currently available draft of the prEN 1993‐1‐14:2020 (design assisted by finite element analysis). Although information is provided on how the local and global imperfections should be combined, it is not stated when it is relevant to consider those. Based on conducted GMNIA simulations on SHS/RHS (square and rectangular hollow sections) and I‐shaped sections, this article presents general decision support on the choice of equivalent imperfections. On the basis of numerical analysis, the developed flow chart and design routine allow for the decision whether the consideration of the interaction of local and global imperfections is required or not. [ABSTRACT FROM AUTHOR]

Experimental investigations on high‐strength CHS for crane‐ and scaffolding construction So far, only a limited amount of experimental results is available for the derivation and verification of design principles for cold‐formed, high‐strength crane and scaffolding tubes up to S960. In this article, the authors present the conduction and results of buckling tests on centrally loaded scaffolding and crane tubes of steel grades up to S960. Measurements of residual stresses as structural imperfections using the sectioning method are discussed on ungalvanized and galvanized CHS in S960. Additionally, the geometric imperfections of the test specimens, which were captured by 3D scanning, are discussed and compared with the approaches of the European buckling curves. The deformations of the test specimens in the buckling tests were recorded using digital image correlation (DIC). The effects of galvanization and the buckling direction on the load‐bearing capacity are highlighted and elucidated. [ABSTRACT FROM AUTHOR]

A mechanically consistent approach for stability verification of timber beams in compression and bending around the strong axis, part 1 – derivations Slender timber beams in bending can be designed using different methods in view of out‐of‐plane stability. Lateral torsional buckling may be verified either using the so called equivalent member method or by means of 2nd order calculations, considering equivalent imperfections. However, at present determining the lateral torsional buckling resistance using either of these both methods, leads to different results. In this paper, the background of both verifications is investigated in deep. Moreover, as an alternative approach, a non‐linear calculation with an imperfection shape in affinity to the critical shape is presented in part 1 of this paper. If the curvature amplitude is scaled, the same results as by the equivalent member method are achieved. It is shown that plasticity effects can be considered with high precision as well. In part 2, results of experimental tests on lateral torsional buckling of glued laminated timber and laminated veneer lumber beams are presented, with nearly ideal boundary conditions and load remaining vertical through‐out the test. Based on these test first tentative values can be obtained for the imperfection compatible with the alternative lateral torsional buckling approach presented. [ABSTRACT FROM AUTHOR]

There is currently no reliable and simple design method available in international literature for the determination of the patch loading resistance of slender plate girders having multiple longitudinal stiffeners. The current research focuses on the patch loading resistance of girders having multiple longitudinal stiffeners. An advanced numerical model is developed and verified by own laboratory test results. A numerical parametric study is executed to investigate the load‐carrying capacity of girders having typical bridge geometries. Analysing the numerical simulation results, the structural behaviour obtained is classified based on the stiffener stiffness. Effect of the different geometrical parameters on the patch loading resistance is evaluated with special focus on the stiffener stiffness and distance between the longitudinal stiffeners. The failure modes depending on stiffener stiffness are investigated and the local buckling type failure is characterised by minimum stiffness. For this specific failure mode, an improved design method is developed, giving reliable resistance within the analysed parameter range. The presented resistance model is consistent with the design philosophy of EN 1993‐1‐5. The applicability of the improved design equation has been investigated for multiple stiffener places in unequal distances, which is the common case in praxis, and for bending and transverse force (M–F) interaction. [ABSTRACT FROM AUTHOR]

Introduction: The aim of the study was to investigate the changes in the treatment of patients with retinal detachment over the past 15 years., Method: Files of all 5101 patients hospitalized for retinal detachment surgery between January 2005 and March 2020 were retrospectively analyzed., Results: The number of retinal detachment surgeries over the past 15 years increased continually from 150 to 600 per annum. During the summer months an increased incidence of retinal detachment of approximately 20% could be observed compared to the winter months. Anatomical success rates of emergency surgery carried out at weekends were not lower than those of scheduled routine procedures performed during the week. The relative proportion of buckle surgery decreased significantly from more than 60% down to 5% between 2005 and 2019. While initially an additional encircling buckle was employed in most cases of primary vitrectomy, this technique has almost completely disappeared in recent years without a deterioration of success rates. Liquid silicone tamponade was applied less frequently over the years. The overall anatomical success rates showed a slight trend towards improved results over the past 15 years., Conclusion: The strategies for surgical repair of retinal detachment have changed considerably in recent years: less buckle surgery, more vitrectomy, less add-on encircling buckles and less silicone tamponade. A slight trend towards better anatomical success rates could be observed., (© 2021. Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Translation abstract Investigations on bonded stiffeners in steel and composite bridgesNumerous bridges are in poor condition. In particular, resistance to plate buckling is a problem. Strengthening of buckling‐prone sections in steel bridges is often difficult due to non‐weldable steels and the additional notch effect from conventional joining techniques. The use of adhesives for fixing stiffeners allows material‐friendly reinforcement of buckling‐prone steel sections. Prior to practical application, numerous questions must be answered with regard to the detailing of the stiffeners, the stress on the adhesive layer due to inhibiting buckling, the load‐bearing capacity of the adhesive layer, the resistance to aging and fatigue. On the basis of numerical and experimental investigations, a simple fracture condition could be developed which allows a design of the adhesive layer‘s load‐bearing capacity. A sufficient stiffening effect of the bonded stiffener is given as long as the adhesive layer‘s load‐bearing capacity is sufficient. The aging and fatigue behaviour was investigated in basic tests. It was possible to define boundary conditions that enable resistance for a limited time, but there is still need for further research in this field. [ABSTRACT FROM AUTHOR]

Consideration of an eccentric load introduction in the buckling check acc. to the reduced stress method in EN 1993‐1‐5:2019 – part 1: experimental studies During incremental launching, the cross‐section of a bridge is stressed by biaxial stresses due to the load introduction from the launching bearing on the last pier and the bending moment occurring there. In addition, unavoidable eccentricities from the load introduction occur, which could result in an additional out‐of‐plane bending at the web. While manufacturing‐related tolerances in form of imperfection coefficients or geometric equivalent imperfections are already taken into account in the current regulations for the buckling verification acc. to DIN EN 1993‐1‐5:2019, they do not include eccentricities of the load introduction from the launching bearings. In practice, therefore additional verifications are often required which are not regulated by standards and consequently cause significant additional work for the design and execution. In order to solve this problem, large‐scale buckling tests and numerical calculations were carried out as part of the buckling investigation for the Thulba viaduct and the research project on the buckling verification of longitudinally stiffened plates under multiaxial loading. Based on these, a proposal for the consideration of an eccentric load introduction in the buckling verification was developed by the main author. The present part 1 of this publication describes the experimental and numerical investigations on the effect of an eccentric load introduction considering different types of launching bearings. The results are then compared with the current regulations of the standard in a part 2. Furthermore, in part 2 a proposal for the consideration of an eccentric load introduction by implementing an eccentricity coefficient in the buckling verification using the method of reduced stresses is presented. [ABSTRACT FROM AUTHOR]

Universal high‐performance columns made of high‐strength steels without welding In recent years, steel‐concrete composite columns made of normal‐strength steels are seldom used owing to the economic and technological advantages of precast reinforced concrete columns. Though, the use of high‐strength structural steels bears high potential for the efficient production of composite columns with excellent structural performance that are economically competitive to precast concrete columns, there are currently major obstacles to use of the ultra‐high‐strength steels (UHSS) in Germany. Hollow section composite columns with embedded high strength steel core without welded connections provide an opportunity to regain lost market share. A research project, funded by the AiF (Arbeitsgemeinschaft industrieller Forschungsvereinigungen), is intended to explore the potential of UHSS composite columns by experimental and theoretical investigations. The present paper demonstrates the concept of such composite columns with UHSS and gives first exciting insights into the research results. In addition to column tests under ambient and fire conditions, small scale tests are necessary to investigate various influencing factors and to create the basis for new and easy to use design and construction principles that allow efficient application. [ABSTRACT FROM AUTHOR]

Translation abstract Investigations into the shear load‐bearing capacity of stainless steel sheetsThe design rules for the shear load‐bearing capacity of stainless steel sheets in accordance with DIN EN 1993‐1‐4 are more conservative than for structural steel sheets in accordance with DIN EN 1993‐1‐5. This leads to increased material consumption in stainless steel structures. For this reason, experimental and numerical investigations on the shear buckling resistance of stainless steel plates on torsionally loaded box girder cross‐sections were carried out, which led to a revision of the design specification for the shear buckling resistance of stainless steels for non‐rigid as well as rigid end posts. [ABSTRACT FROM AUTHOR]

Experimental investigations on novel composite columns with a concrete filled hollow section and high‐strength steel plates as core in ambient and fire conditions High‐performance composite columns are commonly carried out with solid steel sections as core profiles. These profiles imply limitations due to reductions of the yield strength depending on the thickness and high residual stresses. In this publication, the authors present a novel section consisting of a concrete filled circular hollow section with locally connected steel plates as core. To increase the load bearing capacity, steels with yields strengths up to 960 N/mm2 are used. Experimental investigations for ambient conditions and in case of fire are presented. The columns showed a promising load bearing behaviour. These investigations will serve as basis for a systematic development of this innovative, high‐performance composite column with a corresponding design concept. [ABSTRACT FROM AUTHOR]

Thin‐walled cold‐formed steel elements represent an attractive structural solution due to the fast manufacturing and erection time on‐site. Their small thickness leads to imperfection and sensitivities to eccentricities. An experimental programme was performed on short members with lipped channel cross section, subjected to eccentric compression about the minor and major axes, in a large range of eccentricities. The specimens were manufactured on a folding machine. Before testing, the dimensions of all specimens were measured. Shortening of all specimens was measured in two ways, i.e., 1) using the displacement gauge integrated with the machine crosshead beam and 2) from deformation fields obtained using digital image correlation (DIC) system. The quantitative results, presented as the ultimate loads versus the eccentricity curve, emphasise the influence of the eccentric load on the capacity of the element. Finite element (FE) analyses were performed to simulate the behaviour of short members in eccentric compression using the commercial FE software ABAQUS/CAE and ANSYS. Static non‐linear analyses were conducted in displacement control. Both geometrical and material nonlinearities were included. An isotropic linearly elastic‐perfectly plastic constitutive model was considered, with von Mises yielding the criterion and associated flow rule. Failure modes were identified due to numerical and experimental tests. Plastic mechanism models were derived, resulting in the derivation of post‐ultimate, rigid‐plastic curves, characterising a post‐ultimate structural behaviour. [ABSTRACT FROM AUTHOR]

Steel tube struts in braced excavations – Simplified design for cross section class 4 Steel tubes are often used as excavation struts. When designing long struts without intermediate supports, tubes with large diameter and small wall thickness are particularly economical. This may lead to reaching the limit of cross section class 4 requiring a shell buckling analysis according to EN 1993‐1‐6. In this article a simplified design method using section‐related buckling stresses based on EN 1993‐1‐6 Annex D is described. Ready‐to‐use section‐related buckling stresses are given for commonly used steel tubes of cross section class 4. [ABSTRACT FROM AUTHOR]

Copyright of German Journal of Exercise & Sport Research is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Allowable compressive rail force due to track‐bridge‐interaction for ballastless track On modern continuously welded railway tracks on bridges the rails are exposed to additional axial stresses due the interactions between the track and the bridge. On ballasted track the total compressive force within the rail must be limited to prevent rail buckling. In the 1980s extensive theoretical and experimental research was conducted and a limit value for the additional compressive rail stress of 72 MPa was introduced. For the more ridged ballastless track systems this limit value was raised to 92 MPa. However, this was done without any transparent scientific basis. For the case of the Itz Valley Bridge on the new highspeed line between Ebensfeld and Erfurt the calculated additional stresses due to the track‐bridge‐interaction could not be verified with these limit values. To determine a new case specific limit value for the additional compressive rail stresses extensive investigations were conducted and are presented within this article. The behaviour of the ballastless track system under high compressive rail forces was analysed numerically and experimentally. As a result, failure mechanisms and limit states were defined and verified for secure combinations of input parameters. This example shows the potential of the system to withstand high compressive rail forces and presents a possible method to define new limit values for the additional compressive rail stresses for ballastless track systems on bridges. [ABSTRACT FROM AUTHOR]

Structural stability tests on two‐span channel members in bending, axial compression and torsion The use of slender steel members promotes the competitiveness of steel structures in structural engineering. However, these members often necessitate stability verifications. Global research activities in this field have so far mainly focussed on single‐span members with doubly symmetric cross‐sections. For mono‐symmetric sections such as channels, only a few design models exist based on experimental evidence. Moreover, the potential of structural systems such as multi‐span members is yet not entirely exploited in the normative verification models. Therefore, this paper presents a comprehensive experimental study on the stability behaviour of two‐span members with steel channels under combined loading. Five‐point bending tests were conducted to determine the load‐bearing capacities and to experimentally analyse the influence of the constructional detail of the central support, the axial load, the slenderness ratio and other parameters on the load‐bearing behaviour. The article provides the scientific basis for extending the scope of the stability verification for members subjected to bending, axial compression and torsion in Annex C.2 of the novel EN 1993‐1‐1:2022 to two‐span channel members. [ABSTRACT FROM AUTHOR]

Transversal load introduction into unstiffened girder webs – interaction with shear force and bending moment and implementation in new Eurocode version Transversal load introductions into unstiffened girder webs are often used economic solutions in building structures, not directly covered in the current Eurocode. Within this paper an engineering design model, developed at TU Graz, is evaluated for cases with additional high shear forces and bending moments acting at the girder. The resulting load carrying behaviour, in cases of interaction between Fz & Vz & My, is presented, based on comprehensive numerical studies, also for girders which are susceptible to web buckling. Finally, the modified design model is presented, which will be part of the new Eurocode version prEN 1993‐1‐1. In addition, a more general solution is shown, which could also be implemented in the Eurocode in form of a national Annex. [ABSTRACT FROM AUTHOR]

An editorial is presented on International Colloquium on Stability and Ductility of Steel Structures (SDSS 2022) being held in the beautiful Portuguese city of Aveiro from September 14 – 16, 2022. Topics include leading European technical committee in the broad field of stability of steel structures; and contributions on imperfection assumptions used for GNIA, residual stresses, and buckling resistances of HSS welded sections.

Bar bundle columns with high‐strength reinforcing steel As part of the AiF project "Bar bundle columns with high‐strength reinforcement steel" the load‐bearing behavior of bar bundle columns in cold and fire conditions was investigated. Bar bundle columns are a new type of composite columns. To this purpose, a bundle of high‐strength reinforcing bars with a yield strength of 670 MPa is placed in a steel tube and then grouted with mortar. The bundle can consist of 1, 3, 7 or 19 bars. To analyze the load‐bearing behavior, relevant material parameters were determined in cold and in fire conditions. Subsequently, large‐scale buckling tests were carried out under room temperature and in fire case. Considering the obtained results, an FE model was created and calibrated. On this basis, a design concept was developed. [ABSTRACT FROM AUTHOR]

Current steel construction research for offshore wind energy This report begins with an overview of current and future developments in offshore wind energy. The focus is on steel support structures. The so‐called monopiles dominate here. Jacket constructions made of tubular sections are used to a much lesser extent. Due to the high dynamic demands and the simultaneously adverse environmental conditions at sea, steel construction‐specific questions arise for research. The Institute of Steel Construction of Leibniz University Hannover has been focussing on these topics for 25 years now. This article addresses three topics typical of steel construction: Connection technology, stability and fatigue. First, it deals with yield point‐controlled tightening of prestressed bolted joints with high‐strength bolts. Then the non‐linear numerical determination the load bearing capacity of shell structures under axial and circumferential pressure, as required for the design of so‐called suction buckets, will be reported on. Finally, research is presented considering the quantification of corrosion on fatigue strength. [ABSTRACT FROM AUTHOR]

The visual system is highly complex. Monocular or binocular disorders can develop, for example during tractive alterations of the macula, such as in epimacular membranes, and result in symptoms, such as double vision, aniseikonia or metamorphopsia. These symptoms are also observed following vitreomacular or vitreoretinal surgery, especially after treatment of large retinal detachment involving the macular area using pars plana vitrectomy or scleral buckle surgery but also as a result of vitreomacular interventions, such as membrane peeling in epimacular gliosis. Some patients have preoperatively existing latent conditions, which are not explicitly addressed during routine preoperative diagnostics. For patients and surgeons it is worth noting that these troublesome symptoms are often manifested in patients with good restoration of best corrected visual acuity following vitreomacular surgery. In such cases, patients tend to be dissatisfied with the surgical result despite good visual acuity. Treatment of postoperative metamorphopsia, aniseikonia and double vision is often difficult. In clinical studies, the maximum depth of tractive retinal folds has been described as a reliable morphological biomarker for the occurrence of metamorphopsia in epimacular gliosis. As metamorphopsia tends to postoperatively resolve slowly and even persist in ca. 30% of cases, this biomarker can have an impact on preoperative consulting and postoperative monitoring. Persistent binocular discomfort is often treatable by exact refraction correction and by applying a vertical and, if necessary, a horizontal prism. This often requires patience on the part of both the patient and the physician but is mostly successful due to fusion and adaptability., (© 2022. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Copyright of Beton- Und Stahlbetonbau is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bautechnik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)