Sandwich structures

Fiber-reinforced polymer (FRP) sandwich structures offer high structural efficiency and are lightweight – two reasons why successful applications in the aerospace, naval and automotive industries are widespread. Thanks to their advantageous properties, they are also arousing increasing interest in civil infrastructure.In building construction, the integration of functions into FRP sandwiches can lead to efficient and sustainable solutions. The free formability and potential transparency of glass-fiber laminates can contribute to architecturally attractive freeform structures with integrated energy production.In bridge construction, the use of FRP sandwich decks with complex core assemblies can result in durable and economic solutions that, in the case of concrete deck replacement for example, can increase load-bearing capacity or allow the widening of existing bridges without overloading the substructure.

Function integration

– Integration of structural, building physics and architectural functions
– Structural: in-/out-of-plane and short-/long-term loading, joints
– Building physics: thermal insulation, tightness, energy supply (solar cells)
– Architectural: complex shapes, transparency, color, daylighting, LED

Hybrid and complex assemblies

– Skin materials: FRP, ultra-high performance fiber-reinforced concrete
– Core materials: foams, balsa, timber, lightweight concrete
– Core assemblies: web-core, integrated arch, material combinations
– Core inserts: load introduction locations, water-cooling/heating circuits

Design aspects

– Material safety factors for ultimate and serviceability limit state verification
– Shear wrinkling and shear buckling in web-core sandwiches
– Long-term effects of high permanent loads
– Durability, construction detailing

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Ongoing PhD thesis

Composite sandwich bridge decks on fire
N. Vahedi, T. Keller and A. Vasilopoulos (Dirs.)

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Completed PhD theses

Local structural effects in fiber-reinforced polymer web-core sandwich structures
S. Yanes Armas, T. Keller and J. de Castro San Roman (Dirs.). EPFL, Lausanne, 2017.
Abstract – Full Text

Translucent load-bearing GFRP envelopes for daylighting and solar cell integration in building construction
C. Pascual Agullo, T. Keller and J. de Castro San Roman (Dirs.). EPFL, Lausanne, 2014.
Abstract – Full Text

Structural performance of complex core systems for FRP-balsa composite sandwich bridge decks
M. Osei-Antwi, T. Keller and J. de Castro San Roman (Dirs.). EPFL, Lausanne, 2014.
Abstract – Full Text

Biaxial wrinkling of thin-walled GFRP webs in cell-core sandwiches
B. Dehghan Manshadi, T. Keller and A. Vasilopoulos (Dirs.).EPFL, Lausanne, 2011.
Abstract – Full Text

Hybrid FRP-lightweight concrete sandwich system for engineering structures
E. Schaumann, T. Keller (Dir.). EPFL, Lausanne, 2008.
Abstract – Full Text

The development of material-adapted structural form
S. Dooley, T. Keller (Dir.). EPFL, Lausanne, 2004.
Abstract – Full Text

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