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This article explores the possibility of optimizing geometry and mass of a beam based on the conditions for ensuring local buckling. The subject of the study is a box-shaped beam with non-linear walls. This type of beam is unpopular because it has not been studied properly. This fact only indicates its novelty. However, researches and experiments prove that this type of beam is superior to current types of beams in terms of local buckling. This indicates relevance of further research and use of beams with non-linear walls in structures, where local stability is the main aspect in choosing the geometric dimensions of the beam. To optimize this type of beam, a numerical experiment was performed by using the finite element method in ANSYS. The experiment confirmed the possibility of geometric optimization with maintaining similar performance of local stability. The results of this study are obtained formulas. The first formula is required to find the local buckling stresses of box-shaped beams with optimized non-linear walls. This formula was found by approximating the results of a numerical experiment using the least squares method in a MathCAD. The second formula is required to find benefit in mass when using optimized geometry.

Background and Objectives: Scleral buckling and pars-plana vitrectomy are therapeutic options for the treatment of rhegmatogenous retinal detachment. Comparative studies still support the value of scleral buckling in phakic eyes. Nevertheless, the number of sceral buckling procedures may be continuously decreasing over time. The study aims to analyse the incidence of scleral buckling procedures for the treatment of patients with retinal detachment in Germany over time., Material and Methods: The numbers of scleral buckling procedures (OPS 5-152) and rhegmatogenous retinal detachment (ICD H33.0) in Germany are analysed on the basis of data from the quality reports published by the Federal Joint Committee and secondary analyses of the DRG-based billing system (DRG-Statistik) of the Federal Statistical Office between 2006 and 2017., Results: Based on the quality reports, numbers of scleral buckling procedures performed between 2006 and 2017 dropped by 49% from 8841 to 4510. During this period of time, the number of rhegmatogenous retinal detachments, identified by the ICD code H33.0, rose by 102% from 11 507 to 23 314. A decrease in scleral buckling procedures of 42% between 2006 and 2017 was also observed in the DRG Statistics. Regional and age-dependent subgroup analyses suggests that there are both regional and age-dependent differences in the practice of scleral buckling., Conclusions: Our analysis clearly illustrates that scleral buckling procedures are now less commonly performed in Germany than in 2006. However, the total of ~ 4500 billed procedures in 2017 in Germany shows that scleral buckling is still an important and current therapeutic option in the treatment of retinal detachment., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Buckling techniques are used for rhegmatogenous (break-induced) retinal detachment. The aim is to achieve a functional closure of the retinal breakwith permanent retinal attachment by scleral indentation and coagulation of retinal holes. The surgery is primarily extraocular. The use of different buckling methods depends on various factors. The success rates are high at 54 - 97% after the initial procedure, but decrease as the macula is detached. When the possibilities of the scleral buckling procedures are exhausted, pars plana vitrectomy is the next therapeutical option. In recent years, however, there is a trend to primarily address even a simple rhegmatogenic retinal detachment with vitreous surgical methods., Competing Interests: Honorierte Referententätigkeit für die Firmen Bayer, Novartis, Alimera., (Georg Thieme Verlag KG Stuttgart · New York.)

For many decades, scleral buckling surgery was the only reasonable surgical procedure in eyes with primary rhegmatogenous retinal detachment. In recent years, primary vitrectomy has apparently become the treatment of choice, although evidence from comparative clinical trials is missing. In this article, data from clinical trials and indications for buckling surgery are presented., Competing Interests: Nein., (Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: Enhanced depth imaging (EDI) optical coherence tomography (OCT) provides high-definition cross-sectional images of the choroid. Information on alterations in choroidal thickness (CT) after scleral buckling surgery (SBS) and pars plana vitretomy (PPV) are rare., Methods: The medical charts of 44 patients (44 eyes) who underwent SBS versus PPV for macula-off rhegmatogenous retinal detachment (RRD) were retrospectively analysed. Patients with a follow-up ≥ 6 months were included. Postoperative EDI-OCT images concerning CT were evaluated 1 week, 1 month and 6 months postoperatively in 2 groups: group 1: cerclage + cryopexy + subretinal fluid drainage (SRD) + SF6 or air (n = 28 eyes), group 2: PPV + laser photocoagulation + C3F8. Subfoveal CT was compared between the groups and with the non-operated fellow eye., Results: Subfoveal CT in groups 1 and 2 was thicker 1 week postoperatively. There were no significant differences between the groups 2 or when comparing the operated eye with the fellow eye 1 and 6 months postoperatively., Conclusion: There were no differences in subfoveal CT 1 and 6 months after SBS between the eye with macula-off RRD and the fellow eye. Thicker CT 1 week postoperatively after SBS may most likely be induced by scleral buckle reduced blood flow and increased haemostasis in the choroidal circulation and by scleral and choroidal inflammation after cryopexy versus laser photocoagulation after SBS versus PPV., (Georg Thieme Verlag KG Stuttgart · New York.)

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]

Background: Enhanced depth imaging (EDI) optical coherence tomography (OCT) provides high-definition cross-sectional images of the choroid. Information on alterations in choroidal thickness (CT) after scleral buckling surgery (SBS) is rare., Patients and Methods: The medical charts of 122 patients (122 eyes) who underwent SBS for macula-off rhegmatogenous retinal detachment (RRD) were retrospectively analyzed. Patients with a follow-up ≥ 6 months were included. Postoperative EDI-OCT images concerning CT were evaluated 1 week, 1 month and 6 months postoperatively in 4 groups: group 1 cerclage + cryopexy (n = 39 eyes), group 2 cerclage + cryopexy + sponge (n = 28 eyes), group 3 SBS + subretinal fluid drainage (SRD) (n = 25 eyes) and group 4 SBS + sponge + SRD (n = 30 eyes). Subfoveal CT was compared between the groups and with the non-operated fellow eye., Results: Subfoveal CT in groups 1, 2, 3 and 4 was thicker 1 week postoperatively. There were no significant differences between the groups or when comparing the operated eye with the fellow eye 1 and 6 months postoperatively., Conclusion: There were no differences in subfoveal CT 1 and 6 months after SBS between the eye with macula-off RRD and the fellow eye. The use of a sponge or SRD induced no differences concerning subfoveal CT.

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]

Abstract: General design concept for buckling structures – Suggestion for a new part F of EN 1993‐1‐5. A revised version of EN 1993‐1‐5 should soon be published. The reduced stress method will be reworked in section 10. The complementary regulations published recently in this journal, in particular to the biaxial pressed stiffened steel plate, are partly time‐consuming. In addition to these announced rules a concept with „gradual exactness” with which a low limit value of buckling resistance can be fast determined is applied in the code proposal. A new reduction factor is defined for stiffeners, based on an already published proposal for the geometrical imperfection amplitude. Because of the compatibility to the MNA/LBA concept in EN 1993‐1‐6, the suggestion for a new part F of EN 1993‐1‐5 can be used generally for compound steel structures in future. Examples are given for application of the code proposal. [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]

This review article summarizes the relevant surgical strategies for retinal detachment repair and discusses common postoperative complications, as well as factors influencing the functional and anatomical results. Treatment of retinal detachment requires surgery. In most cases, pars plana vitrectomy is performed. In phakic patients with a clear lens scleral buckling can be considered as an alternative. Laser and cryotherapy are still the standard for treatment in symptomatic retinal tears or degenerations without retinal detachment. Postoperatively, the occurrence of a re-detachment as well as the development of proliferative vitreoretinopathy can have a negative influence on postoperative results. Furthermore, typical complications include the occurrence of a cystoid macular edema, epiretinal membrane or even persistent neurosensory detachment. Functional results are significantly influenced by macular involvement and the primary anatomical success rate., Competing Interests: Erklärung zu finanziellen Interessen Forschungsförderung erhalten: nein; Honorar/geldwerten Vorteil für Referententätigkeit erhalten: nein; Bezahlter Berater/interner Schulungsreferent/Gehaltsempfänger: nein; Patent/Geschäftsanteile/Aktien (Autor/Partner, Ehepartner, Kinder) an im Bereich der Medizin aktiven Firma: nein; Patent/Geschäftsanteile/Aktien (Autor/Partner, Ehepartner, Kinder) an zu Sponsoren dieser Fortbildung bzw. durch die Fortbildung in ihren Geschäftsinteressen berührten Firma: nein. Erklärung zu nichtfinanziellen Interessen Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

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]

Competing Interests: Die Autoren geben an, dass kein Interessenkonflikt vorliegt.

The suprachoroidal hydrogel buckle is a new, simple and safe procedure for the treatment of rhegmatogenous retinal detachment. This technique combines the advantages of modern vitrectomy and classic buckling surgery. Placing the suprachoroidal buckle is possible as a stand-alone procedure or in addition to vitrectomy. The cross-linked hyaluronic acid seems to be the ideal agent for the suprachoroidal buckle with a buckling effect over 8 weeks. We need further investigations with long-term results., Competing Interests: Nein., (Georg Thieme Verlag KG Stuttgart · New York.)

The number of retinal detachments in children is rarely compared to the number of retinal detachments in adults; only 3 - 7% occur in children. The main predisposing factors are trauma, myopia, hereditary vitreoretinopathies, retinopathy of prematurity, malformations and Coats' disease. The most frequent paediatric retinal detachments are trauma-associated and vitreoretinopathies are the most common cause of inherited retinal detachment. Disease-specific surgical treatments are discussed. Episcleral buckling surgery should be the preferred method in any case of clear lens, especially for treatment of oradialysis and well-defined localization of peripherally retinal tears. In those suffering from vitreoretinopathy, primary vitrectomy is necessary. The intravitreal use of VEGF-inhibitors to treat vasoproliferative retinopathy in children is a new and effective tool, but we need further results about safety and side-effects in young patients. The functional and anatomical outcomes of retinal detachment in children are less successful than in adults. Further surgical innovations and etiology-specific treatment strategies are required to improve the outcome in this group., Competing Interests: Der Autor gibt an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

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]