LINER TRAYS
AUTHOR
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Prof. Dr. Markus Kuhnhenne RWTH AACHEN Web: http://www.stb.rwth-aachen.de/
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ABSTRACT
Liner trays are thin-walled components of lightweight metal and used as the inner cladding of a double shell wall system. Trapezoidal profiles or corrugated sheets are used as the outer cladding. They are connected directly or via a distance construction to the narrow flanges of the liner trays. When using distance constructions, the distance of the fixing can be chosen larger, because of the independency of profile geometry. While the outer cladding serves as weather protection, the liner tray has a supporting function. In addition, the narrow flanges are stabilized by the shear stiffness of the outer cladding. In the European standard EN 1993-1-3 the design method is given for liner trays in clause 10.2. The design procedure distinguishes between pressure and tension in the wide flange. When tension is applied to the wide flange, the ultimate bending moment is reduced by a reduction coefficient that takes into account the effect of a fixing distance s1 over 300 mm. If the fixing distance is less than 300mm, the bending moment does not have to be reduced. The current design rule of the fixing distance is rather conservative, and furthermore limited to a maximum fixing distance s1 = 1000 mm, which is no longer sufficient due to the increasing architectural requirements. The problem with an increased fixing distance s1 is the reduction of the shear stiffening via the outer shell. Investigating the effect of reduced shear stiffness in more detail is part of this research work. This module gives a new design method for fixing distances until 2000 mm.
LEARNING GOALS
After the module, you will be able to …
- … remember why new solutions were created.
- … comprehend why the new solutions do not comply the application range of the current design method.
- … apply the design method for liner trays according to EN 1991-3-1
- … analyze the effect of the influence of the fixing distance from the narrow flange under pressure on the overall load-bearing capacity.
- … synthesize the influence of the fixing distance from the narrow flange under pressure on the overall load-bearing capacity.
- … evaluate the ultimate bending moment of a liner tray until a fixing distance of 2000 mm.