P 884 – Adhesive bonded tubular cast steel – steel joints in framework structures
With the welding of cast steel nodes with steel tubulars sophisticated designs in the field of building construction, bridge construction, crane construction and wind energy plants are currently being realized. A variety of research projects were carried out in the past decades to develop design guidelines for welded hollow section nodes under static and fatigue loads. As fatigue cracks initiate from the weld root, higher safety measures are required during the design process such as a classification in low FAT classes.
In this research project an adhesively bonded joint for tubular steel hollow sections and cast steel components was developed and investigated. In a first step constraints as well as mechanical and thermal stresses in the steel construction were analyzed and requirements for the bonded connection were derived. Production and manufacturing tolerances turned out to be a central issue, as thick film bonding and precise manufacturing processes are required. Surface analytics and adhesion tests showed a sufficient bond strengthklebto corundum blasted cast steel surfaces. On the basis of bulk and lap shear test, two adhesives were identified and characterized that fulfill the previously defined requirements. A semiautomated joining device was developed and tested using the injection method for manufacturing test specimens. This device combines the three processes joining, fixing and injection of adhesive. Filling experiments showed a filling free of air bubbles in the joint gap.
To investigate the durability of the adhesive bonded joint quasi-static load tests were carried out on the bonded hollow section samples under various external influences. Fatigue tests on bonded tube joints showed the load bearing capacity of the adhesively bonded joint for non static loading. Furthermore, the adhesives were tested for their resistance regarding creep loading. The load carrying capacities of bonded tube samples with variation of tube cross section, adhesives layer thickness, overlap length and with defined imperfections were determined in experimental investigations.
To optimize the geometry of the adhesively bonded joint numerical studies were performed to demonstrate the significant reduction of stress peaks resulting from the enlargement of the thickness at the ends of the adhesive layer. Finally, the knowledge gained in this research project was applied for manufacturing and testing full scale components of cast steel tubes with an outer diameter of 298.5 mm. The static load bearing capacity of the adhesively bonded joint accounted for F = 2 MN with low scattering for an overlap of only 110 mm. Adhesively bonded tubular joints represent an innovation that opens new constructive possibilities as well as sophisticated designs for steel hollow section structures in the field of building construction, bridge construction, crane construction and wind energy plants.
The research project (IGF-Nr. 16586 N) was carried out at Karlsruher Institut für Technologie KIT, Versuchsanstalt für Stahl, Holz und Steine, an der HochschuleMünchen, Labor für Stahl – und Leichtmetallbau und an dem Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung IFAM, Bremen. FOSTA has accompanied the research project work and has organized the project funding from the Federal Ministry of Economics and Technology through the AiF as part of the programme for promoting industrial cooperation research (IGF) in accordance with a resolution of the German parliament.
Only available in german language.
T. Ummenhofer, M. Albiez, Ö. Bucak, H. Ehard, B. Mayer, H. Fricke