P 884 - Bonded steel-steel cast connections using the example of truss nodes of round hollow section constructions

P 868 - Extension of an analytical numerical hybrid model for the warpage simulation of large structures Weld distortion is still one of the main problems in welding technology. It reduces the quality of the welded structure, impedes the smooth execution of the manufacturing process and leads to high post-treatment costs. To find the optimum welding parameters, clamping conditions or pre-deformations for minimising distortion in simple welded constructions, time-consuming and cost-intensive experiments are currently still widely used. Thermomechanical FE simulation is also becoming increasingly popular for this purpose. However, it is reaching its limits in the field of industrially relevant, large structures with multiple weld seams. Presented here is the analytical numerical hybrid model for weld distortion calculation, which was developed at the Chair of Joining and Welding Technology at BTU Cottbus. Taking into account the significant influencing factors on the plastic deformations occurring during welding, mechanical loads equivalent to the thermomechanical load of each weld seam are determined using the analytical shrinkage force model. These are transferred to a finite element model of the structure and the deformation of the entire structure is calculated using an elastic analysis. The mutual influence of the individual weld seams and different manufacturing steps is taken into account by means of feedback. The methodological approach is explained in detail in the report. In addition to the fundamentals of the hybrid model, other important aspects such as the detection of different types of impact, industry-relevant welding processes and materials, as well as the unstable behaviour of thin-walled structures during welding and curved trajectories in space are also discussed. After verifying the analytical numerical hybrid model on elementary I-joints, application examples are used to demonstrate the procedure. The complexity of the welded constructions considered increases successively, starting with simple I- and T-joints. The model is then applied to a welded construction with eight seams and the recording of different welding scenarios is analysed. This is followed by the calculation of a ship panel which is joined with 88 weld seams in three production steps. The calculated welding distortions of each production step are compared with experimentally determined distortions. Authors: V. G. Michailov, C. Stapelfeld, N. Doynov Publication: 2014

P 813 - Development of efficient dimensioning principles for the bearing piles of combined steel sheet pile walls As world trade has been steadily increasing for decades, the number of containers transported and the size of ships has also increased the demands on the size of quay walls in harbour facilities. The most common steel construction solution for this in deep-water harbours is the combined steel sheet pile wall, which consists of up to 45 m long H-shaped H-shaped load-bearing piles and Z-shaped intermediate piles. Proof of stability must be provided for this construction. With the conversion of the standards from the national DIN 18800 (2008) to the European DIN EN 1993-1-1 (2010), the stability verifications in steel construction have changed. Whereas previously separate verifications could be performed for flexural buckling and lateral-torsional buckling, there is now a combined stability verification. Comparative calculations in harbour construction have shown that the new verification leads to more solid structures. What is currently not taken into account in the design is the structure-soil interaction. This project therefore served to estimate the influence of the soil and to develop ways of recognising previously unconsidered bedding. To this end, a parameter field was first defined that takes into account the current situation and developments in Europe in the near future. The depth of the basin and the nature of the soil were taken into account, as were variations in the design of the sheet pile wall and its loading. The deformation behaviour of an embedded single soldier pile and the behaviour and stiffness due to the flushing sand soil were determined experimentally. The values were used to create a framework model, which led to a parameter analysis and the determination of applicable soil parameters. At the same time, the influence of imperfections and soil bedding on the stability behaviour of soldier piles was investigated using framework models. Single and double bearing piles, different bearing conditions (especially bedding of the pile over the full length or over a partial length) and flexural buckling and lateral-torsional buckling behaviour were considered. In addition, the influence of the welding pattern and degree of welding on the torsional stiffness of partially welded double bearing piles was investigated experimentally and numerically. Based on the findings, solutions were developed to take soil bedding into account in the stability analysis. Finally, simplified criteria were derived from the soil properties, the formulae for incorporating the values into the stability analysis and the verification formulae from DIN EN 1993-1-1, Section 6.3.3 (2010), with which buckling around the weak axis and lateral-torsional buckling can be completely excluded. In summary, it can be said that the soil-structure interaction of combined steel sheet pile walls was investigated with the aid of extensive experimental and numerical investigations and approaches and simplified criteria were developed with which the influence of the soil can be taken into account in the stability analysis. The IGF project 16493 N of the Forschungsvereinigung Stahlanwendung e.V., Düsseldorf, was funded via the AiF within the framework of the programme for the promotion of joint industrial research and development (IGF) by the Federal Ministry for Economic Affairs and Energy on the basis of a resolution of the German Bundestag. The project was carried out at the University of Stuttgart by the Institute for Construction and Design and at the Technical University of Hamburg-Harburg by the Institute for Geotechnics and Construction Management. Authors: U. Kuhlmann, B. Leitz, A. Just, J. Grabe, C. Schallück Publication: 2014