Long-term load-bearing capacity of glass/PTFE fabrics under consideration of manufacturing and assembly influences when used in civil engineering

• Applicant: Professorin Dr.-Ing. Natalie Stranghöner
• Subject Area: Structural Engineering, Building Informatics and Construction Operation
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 557719891

In textile architecture, membrane structures made of coated fabric membranes are often made of polytetrafluoroethylene (PTFE)-coated glass fiber fabrics (glass/PTFE fabrics for short), as the PTFE coating applied to both sides has an anti-adhesive effect and thus prevents deposits. Furthermore, these fabrics have a favorable fire behavior. However, the sensitivity of the glass fabric to buckling and the sensitivity of the glass filaments to moisture have a disadvantageous effect on long-term wear behavior. If the coating breaks, moisture can penetrate the glass fabric, to which the glass filaments react with a reduction in strength. Another risk is posed by processing at low temperatures, as the stiffness of the glass/PTFE fabric increases at low temperatures, making it difficult to tension the glass/PTFE fabric correctly during installation, which can lead to creases and/or initially unrecognized cracks at the beginning of the service life, which might lead to larger cracks and premature replacement of the fabric during operation. The aim of this project is to analyze and characterize the monoaxial long-term load-bearing behavior of typical glass/PTFE fabrics used in the construction industry (full-surface glass/PTFE fabric as well as open and laminated glass/PTFE mesh fabric), taking into account production- and installation-related pre-damage in the form of creases/folding under the influence of moisture and alternating stresses due to wind. Analytical concepts for describing and recording the long-term load-bearing behavior are to be developed for this purpose. In addition, the residual load-bearing capacity under high (approx. 70°C) and low temperatures (approx. -25°C) is to be analyzed after pre-damage and long-term loading. Furthermore, as part of the project, modification factors are to be developed for the computational recording of strength reductions as a result of long-term stress, taking into account pre-damages in the form of creases/folding, and tolerance specifications are to be defined, which will be linked to fabrication tolerance quality classes to be developed for design and acceptance as part of construction supervision during fabrication/manufacturing and assembly. In Phase I of this project, glass/PTFE fabrics will be investigated as a base material under artificial weathering; in Phase II, the influence of welding on the long-term load-bearing capacity of the glass/PTFE fabrics will be investigated and a correlation between artificial weathering and outdoor weathering for use in Germany will be derived.

• DFG Programme: Research Grants