Next generation structural silicone glazing
This paper presents an advanced engineering evaluation, using nonlinear analysis of hyper elastic material that provides significant improvement to structural silicone glazing (SSG) design in high performance curtain wall systems. Very high cladding wind pressures required in hurricane zones often result in bulky SSG profile dimensions. Architectural desire for aesthetically slender curtain wall framing sight-lines in combination with a desire to reduce aluminium usage led to optimization of silicone material geometry for better stress distribution. To accomplish accurate simulation of predicted behaviour under structural load, robust stress-strain curves of the silicone material are essential. The silicone manufacturer provided physical property testing via a specialized laboratory protocol. A series of rigorous curve fit techniques were then made to closely model test data in the finite element computer analysis that accounts for nonlinear strain of hyper elastic silicone. Comparison of this advanced design technique to traditional SSG design highlights differences in stress distribution contours in the silicone material. Simplified structural engineering per the traditional SSG design method does not provide accurate forecasting of material and stress optimization as shown in the advanced design. Full-scale specimens subject to structural load testing were performed to verify the design capacity, not only for high wind pressure values, but also for debris impact per ASTM E1886 and ASTM E1996. Also, construction of the test specimens allowed development of SSG installation techniques necessitated by the unique geometry of the silicone profile. Finally, correlation of physical test results with theoretical simulations is made, so evaluation of design confidence is possible. This design technique will introduce significant engineering advancement to the curtain wall industry.
Durability by Design: New Results on Load-Carrying Silicone Bonding
In the year 2000, the Herz-Jesu church in Munich, Germany was finalized featuring a glass facade with advanced bonded load-carrying structures. The facade was stiffened in such a way that wind- and dead-loaded glass elements were joined to stainless steel channels by a two-component silicone adhesive for load transfer. Durability aspects related to this type of bonding were already presented by the author at the previous symposium in 2003. The technical questions raised by the design of the Herz-Jesu church initiated detailed research investigations within Germany concerning the application of complex bonding geometries for structural engineering purposes. These studies comprised experimental and theoretical activities which were focused on the mechanical properties of two-component silicone adhesives as well as on the behavior of various bonding geometries resulting from the use of L- and T-type steel elements. In the context of these research activities, attention was also paid to different aspects directly or indirectly related to durability issues. Regarding adhesive material behavior, tensile, compression, and shear tests were performed on aged and unaged specimens in order to analyze the impact of an aggressive environment. Several degradation modes were induced into the specimens in a systematic manner in order to evaluate the load-bearing capacities and failure mechanisms of the different bonding geometries and in order to assess the behavior in the view of partial failure. This paper presents an overview of the obtained experimental results complemented by detailed finite element analysis results. Former results obtained for the U-type bonding geometry are reviewed in the light of new experimental findings. Furthermore, bonding geometries like the T-type bonding are assessed in a similar way as previously done for the U-type bonding geometry. Finally, the paper concludes by directly comparing all investigated bonding geometries with respect to durability aspects.
The Pleistocene Epoch in East Anglia
Abstract The sequence of Pleistocene deposits in East Anglia is tabulated. The following aspects of the Pleistocene are discussed and summarized: boundaries of the Pleistocene, glacial and preglacial, ice advances, interglacials, glaciations, marine horizons, climate and periglacial features. Correlations are given between the Pleistocene deposits of East Anglia and the continent.