16.10.2009 The front facade proved to be a particularly demanding challenge. It is mounted above the main entrance and has been designed as a double facade. The inner insulation glass façade rests on line-shaped bearings all round and forms the actual space closure. The outer, secondary façade was made as a construction with point-to-point in-place fittings. The space between the facades is accessible for cleaning and service work, with the service personnel moving across mobile ladders and equipped with safety ropes.
The facade is inclined by 16.5° from the vertical to the outside and is about 13 metres in height. Its dimensions at the upper edge are 41 metres and 40 metres at the lower edge. The lower edge of the façade is 14 metres, the upper edge 27 metres above the top edge of the building. As a result of this angle, the façade is actually an overhead glazing, according to building laws. The glass joints between the panels were left open.
For this point-held glazing made of laminated safety glass (VSG), the outside consists of 10 mm heat-strengthened glass (TVG), the inside of 8 mm TVG. The individual panes have a maximum width of 3.454 mm and a height of 1.917 mm, each resting at the upper and lower edge of the glass on six fischer FZP-G-Z undercut glass fixings. The edge spacing to the glass edges is only 85 mm.
The dead weight of the construction is absorbed by two steel angle elements. The undercut glass fixings are mounted on to the substructure with steel lugs with large bores to ensure stress-free support for the glazing. The substructure made of S 235 construction steel consists of triangular hollow profile locking elements, stiffened with vertical flat steel posts.
Successful failure load and residual load-bearing capacity tests
Proof of the load-bearing capacity was determined by means of failure load test. For this purpose, the facade builders Rupert App of Leutkirch carried out tests at their headquarters in the Allgäu under supervision of the State Material Test Institute (MPA Darmstadt) and the Land building authority of Baden Württemberg. The testing regime to establish the maximum load required a horizontal installation position and loading the glass façade with sandbags. These tests resulted in an adequate minimum safety level of g = 4.30.
To evaluate the residual load-bearing capacity, the Darmstadt Material Testing Institute carried out the appropriate tests. For the tests, building components were examined in their original installed position at an inclination of 16.5° from the vertical. In line with the test concept, half the wind load was applied on to the test elements by using sandbags. The laminated safety glass panes were then struck at different points inside and out with a pick hammer and destroyed as scheduled. The panes broke into pieces with a breakage picture typical for heat-strengthened glass. No significant deformation was found even after putting the panes under stress in as many as eight different points.
The condition for a successful test: no failure after 24 hours under simulated reduced wind load and dead weight. The simulated wind load was then removed and the construction assessed. No significant changes from the initial situation were found. The construction was then observed for another period of 24 hours, again without any changes worth mentioning from the initial situation.
Summary
The Porsche-Museum goes to new dimensions of structural engineering. This is also true of the unusual design of the glass panorama façade which is absolutely unique in its present form. The project has been made possible by the close and constructive collaboration between owners, planners, test institutes, experts, building authorities, facade builders and the facade expertise of the fischer group of companies.
More information:
http://www.fischer.de/en/