Thomas Keller
École Polytechnique Fédérale de Lausanne
Composite numberUltimate tensile strengthGlass transitionEngineeringFinite element methodComposite materialEpoxyGlass fiberMaterials scienceGirderJoint (geology)DeckStiffnessFracture (geology)PolymerPultrusionFracture mechanicsStructural engineeringAdhesiveFibre-reinforced plasticForensic engineeringStress (mechanics)
332Publications
45H-index
4,885Citations
Publications 330
Newest
#1Sonia Yanes-Armas (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
#2Julia de Castro (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 15
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract The rotational behavior of the web-flange junctions (WFJs) of a pultruded glass fiber-reinforced polymer (GFRP) bridge deck system with trapezoidal cell cross-sectional geometry was investigated. The rotational response of three WFJ types, in two bending moment directions each, was characterized. An experimental procedure based on three-point bending and cantilever experiments conducted on the web elements and simple analytical models was used. The WFJs generally exhibited non-rigid and...
14 CitationsSource
#1Maria Savvilotidou (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract The effect of physical aging and continuation of curing on the physical and mechanical properties of a commercial cold-curing structural epoxy adhesive used in bridge construction has been investigated during the first year. Since adhesive bridge joints are sealed, only dry conditions were taken into account. Predominant physical aging in the earlier age and predominant curing in the later age affected the physical and mechanical properties. The E-modulus exhibited a maximum in the earl...
24 CitationsSource
#1Myrsini Angelidi (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract The ductility and time-dependent recovery of a ductile acrylic adhesive were investigated in this work. The quasi-static true tensile and compressive strain behaviors were examined at different strain rates, taking large deformations into account. Yield stress, elastic modulus, and failure strain exhibited a logarithmic dependency on increasing strain rate, while yield strain and stiffness after yielding were insensitive to strain rate. High energy-based ductility indices were obtained ...
11 CitationsSource
#1Carlos Pascual (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
#2Julia de Castro (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 15
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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The encapsulation of dye solar cells in translucent, structural and lightweight glass fiber-reinforced polymer laminates was investigated with a view to designing multifunctional envelopes for daylit buildings. Small and large integrating sphere experiments and solar radiation experiments were performed to determine the light transmittance of the laminates and the electrical efficiency of the encapsulated cells. An overall cell efficiency of 3.9% (before encapsulation) only decreased to 3.4% aft...
5 CitationsSource
#1Mario Garrido (IST: Instituto Superior Técnico)H-Index: 23
#2João R. Correia (IST: Instituto Superior Técnico)H-Index: 34
Last. S. Cabral-FonsecaH-Index: 11
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AbstractComposite sandwich panels with reinforcement ribs or webs are being increasingly considered for structural applications in civil engineering. Such panels are prone to creep when subjected to significant permanent loads and therefore the effects of this phenomenon must be duly accounted for in their design. Data regarding the viscoelasticity of sandwich panels and their constituent materials is still scarce and often cannot be directly used for creep predictions in design practice. To add...
14 CitationsSource
#1Haifeng Fan (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
#2Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract Pull-out experiments were performed on three carbon fiber-reinforced polymer (CFRP) ground anchors simulating their applications in different rock types which provided different confinement levels. The CFRP tendons comprised, on the ground side, a prefabricated conical anchor body of high-strength grout in which two CFRP straps were embedded. The anchors reached an average load-bearing capacity of 1384 kN with final failure occurring in the CFRP straps. Grout failure was successfully pr...
13 CitationsSource
#1Thomas KellerH-Index: 45
Two applications of post-tensioned CFRP strap elements recently developed at the Composite Construction Laboratory (CCLab) of the Swiss Federal Institute of Technology Lausanne (EPFL) are presented. The first application concerns post-tensioned non-laminated CFRP straps used for the strengthening of existing concrete flat slabs against punching shear. Four strap elements are installed crosswise around the column in predrilled openings and are anchored and post-tensioned from the bottom side of t...
#1Kyriaki Goulouti (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Julia de Castro (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 15
Last. Thomas Keller (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 45
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Abstract Energetically critical points in thermally insulating building envelopes are caused by penetrations of building interior concrete slabs through the envelope insulation layers to create external balconies. A new highly insulating balcony thermal break element has been developed which enables both structural continuity and thermal insulation in the envelope’s insulation layer. The element is composed of combined structural and thermally insulating AFRP/GFRP loop and sandwich components. T...
4 CitationsSource
#1Alireza Farajzadeh Moshtaghin (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
#2Steffen Franke (Bern University of Applied Sciences)H-Index: 7
Last. Anastasios P. Vassilopoulos (EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 28
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In this study, an experimental campaign was conducted to characterize the length effect on the elasticity and tensile strength of clear spruce wood parallel to the grain direction. Four groups of specimens of different lengths, cut from the same log, were tested under the same conditions under longitudinal tensile loading. The cross-sectional area of the specimens was selected as being constant and sufficiently small to exclude the effect of variations of the properties in the transverse directi...
10 CitationsSource