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Machine learning for design and analysis of steel frame halls The use of digital tools in design and construction processes increases efficiency, especially for recurring tasks and processes, such as the dimensioning of components or structures, which follow similar patterns. This paper develops an artificial intelligence (AI)‐based assistant for use in the pre‐design and design of steel frame halls as a prototypical co‐pilot. For this purpose, the necessary database of steel frame halls is first compiled from project archives of TRAGRAUM Partnerschaft Beratender Ingenieure mbB. This will be examined in the context of data analyses according to the decisive description parameters and similarities, so that finally suitable AI surrogate models for the prediction of the hall parameters are trained by means of regression analyses. Furthermore, an interface to the finite element program SOFiSTiK is implemented, which passes the predictions of the AI regarding the parameters of the steel frame halls to a parameterized input file and triggers the calculation and design. In the course of the calibration of the AI substitute models, in addition to the approximation qualities, possible safety margins to be provided are also discussed in the context of this article. This article shows that the prototypical co‐pilot for the preliminary design of steel frame halls could be successfully implemented. Furthermore the AI newly generated hall frames can be classified as stable with respect to the validation considerations. An outlook on future further developments of this approach as well as the transfer to other applications complete this paper. [ABSTRACT FROM AUTHOR]

Investigation of an engineering model for the assessment of the seismic behaviour of large mobile equipment For large mobile equipment in seismically active regions, seismic stability is an essential and often decisive design criterion. The seismic behaviour of such large equipment is usually characterised by complex nonlinear types of behaviour (uplift, tilting and rocking), which are difficult to compute and analyse in practice. In this paper, a highly simplified engineering model is presented or developed step by step, which should be able to represent basic features of the typical behaviour of large mobile equipment transverse to the rail under seismic excitation. The typical rocking motion of the equipment, as determined in previous analyses, is to be reflected in the simplified model. The engineering model will be designed in such a way that it is able to reproduce qualitative statements about uplift and rocking or tilting as a function of incisive model parameters and seismic excitation. The dissipation mechanisms of the model are presented and seismic tilting spectra are generated using different approaches. The suitability and applicability of these approaches for assessing uplift and rocking tendencies for large mobile equipment is reviewed using representative series of bucket wheel machines and stackers as examples. In addition, parameters are determined for quantitative application to further large mobile equipment and the delimitation criteria of qualitative and quantitative applicability are compiled. [ABSTRACT FROM AUTHOR]

Damage equivalence factors for deck slabs of steel railway bridges According to EN 1993‐2, the fatigue verification of railway bridges can be based on internal forces due to the standard load model 71. These internal forces are to be multiplied by a dynamic coefficient Φ2 and a damage equivalence factor λ. In this paper, factors λ1 allowing for the damage effect of traffic on quadrilaterally supported plates with torsionally flexible supports at the longitudinal edges as encountered in single‐track railway‐brides in a span range between 10.0 and 27.5 m are derived for three standard traffic situations. The required damage equivalence factors λ are obtained from the factors λ1, considering the annual traffic volume and the requested service life. [ABSTRACT FROM AUTHOR]

Unexpected fatigue cracks at main girders of a railway bridge – strain measurements under service and analyses based on fracture mechanics At a steel railway bridge, erected and taken into service in 1960, fatigue cracks were detected at some transverse stiffener to web connections at the lower flange of the main girder. These findings were surprising, because this specific connection detail was suggested in previous national design standards for fatigue. The paper presents the comprehensive strain measurements under service to show the local stress field at the critical detail within the web plate of the main girder, indicating the well‐known phenomenon of distortion‐induced fatigue, but with unexpectedly high resonance‐like bending stresses in the web. Based on fracture mechanics analyses, with implementation of the measured strain/stress data due to local and global effects at the transverse stiffener connection, as well as the measured material properties (fracture toughness and crack growth parameters) the remaining fatigue life was analysed. The positive results allow an unrestricted train operation in the future. It also turned out, that the mixed‐mode effects must be taken into account and considering only mode I at the crack tip may lead to unsafe results. [ABSTRACT FROM AUTHOR]

Design model for headed studs as shear connectors under additional tensile loading Headed studs are primarily subjected to shear when used as shear connectors in usual steel‐concrete composite structures. Consequently, initial design rules for shear connectors in composite structures did not address tensile forces directly. In case of horizontally lying headed studs embedded in a thin concrete slab such as in composite bridges, the headed studs may be subjected to tensile forces. For horizontally lying studs, current design rules consider a possible failure caused by a tensile load due to pull‐out by specifying geometric boundary conditions. As a consequence, relatively long shear connectors are required, which lead to uneconomical or impractical embedment lengths of the shear connectors. As meanwhile European code rules for fasteners under shear and tension (EN 1992‐4) have been developed, the upcoming Eurocode 4 refers to them for the design of shear connectors under combined tension and shear in composite structures. The fastening technology allows a direct design for tensile loading for different failure mechanisms, considering the influence of the reinforcement and concrete strength. Following this idea, this paper presents a design model for shear connectors in steel‐concrete composite structures under additional tensile loading based on experimental and numerical investigations considering recent developments in fastening technology. [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]

Penstocks with multiple thrust rings – accurate forces at thrust rings due to constraining effects and comparison with a simple design model Thrust rings are a component of penstocks and have to transfer the longitudinal forces of the steel pipe to the surrounding rock mass. Longitudinal forces occur primarily due the pressure loads at valves or at pipe covers. Within this paper, the realistic load bearing behaviour of different penstocks geometries with multiple thrust rings is presented, including constraining effects due to internal pressure and temperature. Results are shown with and without friction effects between steel pipe and surrounding concrete and are based on numerical FE analyses. In addition, a simple 1D beam model (design model), developed by the authors, is presented. The forces at the thrust rings are compared between both models. It is shown that also for different load combinations the simple 1D beam model gives accurate results for practical application. The FE study also shows, that always the load combinations with the constraining effects due to internal pressure and temperature must be analysed – a superposition of the results of the individual load cases leads to misleading results. [ABSTRACT FROM AUTHOR]