02 Fakultät Bau- und Umweltingenieurwissenschaften
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/3
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Item Open Access Guidelines for a finite element based design of timber structures and their exemplary application on modelling of beech LVL(2023) Töpler, Janusch; Buchholz, Lea; Lukas, Julian; Kuhlmann, UlrikeDesign verifications of buildings are usually carried out supported by a finite element analysis (FEA), for which, however, there are only a few and almost exclusively non-binding application rules. Within the Cluster of Excellence Integrative Computational Design and Construction for Architecture (IntCDC) at the University of Stuttgart, Guidelines for a Finite Element-Based Design of Timber Structures have been developed. The scope of the guidelines is daily engineering practice, expert engineering applications and product development and certification. Essential parts of the guidelines are design procedures, modelling (including geometrical, material and imperfection modelling), analysis, model verification and validation and design. The content and application of the guidelines are described and illustrated in this paper using two benchmarks. These two benchmarks, which are based on experimental investigations, deal with the elastic material modelling of glulam made of beech laminated veneer lumber (beech LVL) and dowel-type connections for beech LVL members. The experimental basis of the benchmarks is described. With the experiments for the benchmarks, all Poisson’s ratios and the complete elastic material stiffness matrix of beech LVL are determined by means of an optical measuring system. The experimentally determined stiffnesses of the investigated dowel-type connections in beech LVL are compared with normative values. Based on the experiments, a numerical model is developed in RFEM (Dlubal).Item Open Access Update on the revision of Eurocode 3 : evolution by improvement and harmonization(2021) Kuhlmann, Ulrike; Schmidt‐Rasche, Christina; Jörg, Fabian; Pourostad, Vahid; Spiegler, Jennifer; Euler, MathiasThis paper provides an overview of recent work regarding the revision of Eurocode 3 on the European level. Selected scientific and technical issues are described and there is a summary of the activities executed within European Standardization Committee CEN/TC250/SC3 ”Design of Steel Structures“ chaired by Prof. Dr.‐Ing. Ulrike Kuhlmann. This includes the description of current normative developments for the 2nd Generation of Eurocodes, which aim at evolution through improvements and harmonization of the existing codes. In addition, a technical review of selected rules is given for several issues, which support the code revision and reflect well the recent tendencies in steel structures.Item Open Access Finite element based design of timber structures(2023) Töpler, Janusch; Schweigler, Michael; Lemaître, Romain; Palma, Pedro; Schenk, Martin; Grönquist, Philippe; Tapia Camú, Cristóbal; Hochreiner, Georg; Kuhlmann, UlrikeItem Open Access Lateral torsional buckling of glulam beam-columns : axial compression and bending verification(2024) Töpler, Janusch; Kuhlmann, Ulrike; Schänzlin, JörgItem Open Access Structural member stability verification in the new part 1‐1 of the second generation of Eurocode 3 : part 1: evolution of Eurocodes, background to partial factors, cross‐section classification and structural analysis(2020) Knobloch, Markus; Bureau, Alain; Kuhlmann, Ulrike; da Silva, Luís Simões; Snijder, Hubertus. H.; Taras, Andreas; Bours, Anna‐Lena; Jörg, FabianThis two‐part article gives an overview of the developments of the structural member verification in prEN 1993‐1‐1:2020 “Eurocode 3: Design of steel structures - part 1‐1: General rules and rules for buildings”, one of the second generation of Eurocodes. These developments were undertaken by Working Group 1 (WG1) of Subcommittee CEN/TC250/SC3 and by Project Team 1 (SC3.PT1) responsible for drafting the new version of EN 1993‐1‐1. In the past, WG1 collected many topics needing improvement, and the systematic review conducted every five years also yielded topics needing further development. Based on this, the current version of EN 1993‐1‐1 has been developed into a new draft version prEN 1993‐1‐1:2020 enhancing “ease of use”. The technical content of this new draft was laid down at the end of 2019. Many improvements to design rules have been established with respect to structural analysis, resistance of cross‐sections and stability of members. This two‐part article focuses on member stability design rules and deals with the basis for the calibration of partial factors, the introduction of more economic design rules for semi‐compact sections, methods for structural analysis in relation to the appropriate member stability design rules, new design rules for lateral torsional buckling plus other developments and innovations. This first part of the article primarily serves to explain the general background to the European Commission Mandate M/515 that led to the further evolution of the Eurocodes and to illustrate the developments in prEN1993‐1‐1:2020 that pertain to new material grades, partial factors, cross‐sectional classification and structural analysis. These form the necessary background to the changes to member buckling design rules, which are treated more specifically in the second part.Item Open Access Analytical and numerical investigations on imperfection-sensitive timber members subjected to combined bending and axial compression(2021) Töpler, Janusch; Kuhlmann, UlrikeThe verification of slender timber members at risk of lateral torsional buckling is one of the basic verifications in timber design. However, latest investigations have shown that the design formulas provided in Eurocode 5 for imperfection-sensitive members subjected to combined bending and compression tend to be conservative and more advanced verification methods are needed. Analytical and numerical models are presented that allow for the consideration of the geometrically and materially nonlinear behaviour as well as of the size effect of tensile strength ft,0 for Nx-My-Mz interaction. These models and calculation results increase the understanding of the main influencing parameters of the load-bearing capacity of imperfection-sensitive timber beams and columns and may be the basis of a revision of the current design formulas provided in EN 1995-1-1.Item Open Access Buckling resistance of longitudinally stiffened panels with closed stiffeners under direct longitudinal stresses(2022) Pourostad, Vahid; Kuhlmann, UlrikeThe buckling behaviour of panels may be determined according to EN 1993‐1‐5 [1]. Most of the design rules relating to stiffened panels in EN 1993‐1‐5 were derived on the basis of open‐section stiffeners. Several recent investigations have shown that the application of the design rules according to EN 1993‐1‐5 considering the torsional stiffness of the stiffeners may overestimate the resistance of the panels. Therefore, the recent Amendment A2 to EN 1993‐1‐5 states that the torsional stiffness of stiffeners should generally be neglected in determining critical plate buckling stresses. In addition, prEN 1993‐1‐5 [2] provides rules for considering the torsional stiffness of stiffeners. However, in this article it is shown that even the rules of prEN 1993‐1‐5 are not sufficient to overcome the safety deficiencies. The article focuses on the investigation of the buckling behaviour of stiffened panels with closed‐section stiffeners subjected to constant longitudinal compression stresses. Improved rules have been developed that allow to consider the torsional stiffness of the stiffeners. Based on an extensive numerical parametric study, a new interpolation equation between column‐ and plate‐like behaviour is proposed. In comparison to [3], the investigations have been extended to the effective width method. They show that the proposal provides a safe and economic solution for the reduced stress method and the effective width method when considering the torsional stiffness of stiffeners by calculating the critical plate buckling stresses.Item Open Access In-plane buckling of beech LVL columns(2022) Töpler, Janusch; Kuhlmann, UlrikeItem Open Access FE-gestützte Bemessung im Holzbau(2020) Töpler, Janusch; Kuhlmann, UlrikeIm Rahmen des Forschungsprojekts RP7 im Exzellenzcluster Integrative Computational Design in Architecture and Construction (IntCDC) an der Universität Stuttgart werden zurzeit Regelungen für die FE-gestützte Bemessung von Holzbauteilen entwickelt. In diesem Beitrag werden der aktuelle Stand des Forschungsvorhabens und die noch geplanten Untersuchungen vorgestellt. Schwerpunkte des Vorhabens sind die Verifizierung und Validierung von FE-Modellen, die bautechnische Nachweisführung anhand solcher Modelle und die Materialmodellierung im Holzbau.Item Open Access A statistical assessment of the fatigue strength improvement of butt-welded joints by flush grinding(2023) Braun, Moritz; Baumgartner, Jörg; Hofmann, Gloria; Drebenstedt, Karl; Bauer, Niklas Michael; Bakhschi, Hadi; Kuhlmann, UlrikeAll major rules and guidelines include fatigue design (FAT) classes for flush ground butt-welded joints. These FAT classes vary between FAT110 and FAT155; however, in the majority of cases, the underlying database and specimen-related details are unclear or unknown. This study evaluates 1003 fatigue test results gathered from various literature sources and tries to relate the fatigue strength improvement to typical specimen types and test conditions. To this goal, statistical methods based on correlation analysis are employed. Next, proposals for updates of rules and guidelines for flush ground butt-welded joints made of steel are established by determining new FAT classes and a suitable slope exponent. In addition, an overview of design standards and recommendations is given and main influencing factors are discussed.
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