Assessment of intermediate support of multi-span sandwichpanels

• Applicant: Professor Dr.-Ing. Jörg Lange
• Subject Area: Structural Engineering, Building Informatics and Construction Operation
• Term: from 2018 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 401248346

Sandwich panels in construction are made of two thin steel faces which are connected by a heat-insulating core material, usually polyurethane-foam (PUR) or mineral wool. In Germany approximately 20 million m² are installed for walls and roof covering annually. They are characterized by a very good combination of waterproofing, thermal insulation, and load-bearing. The complete wall or Roof structure is combined in one single element, which also carries live loads such as wind and snow. Due to the prefabrication and the low self-weight large panels can be mounted in a single lift. This leads to continuous beams. In this application a combination of large bending moments and bearing forces result at the internal bearing points. The bearing force reduces the ultimate moment capacity (Moment-bearing force-interaction). This reduction can only be assessed experimentally. A generally approved design provision which takes the local loading situation into account is not available. Goal of this research project is the identification of the decisive mechanical relationships that affect the interaction. Furthermore a design model shall be developed in order to avoid further experimental analyses. Most available design models are based on a theoretical approach in which the ultimate moment (e.g. the wrinkling stress) is calculated assuming no interaction. This has to be seen skeptical, since the exact calculation of the wrinkling stress is still an unsolved problem. However the theoretical wrinkling stress in undisturbed regions might be helpful for the assessment of the interaction-problem. Up to now most theoretical approaches for the calculation of wrinkling stresses depending on bearing loads are based on a global analysis of the bending moment which is superimposed on the local bearing loads. A look into the hitherto existing publications shows a large difference in the models and the results combined with a small accordance with experimental results. This proofs the need for further research.

• DFG Programme: Research Grants