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Till Vallée

Cette personne a quitté l’EPFL

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Publications associées (43)

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Modeling of thermal responses for FRP composites under elevated and high temperatures

Thomas Keller, Till Vallée, Yu Bai

Based on temperature-dependent thermo-physical property models developed previously, a one-dimensional model was proposed to predict the thermal responses of FRP composites in time and space domain, up to high temperatures. An implicit finite differential ...

2008

Modeling of thermo-physical properties for FRP composites under elevated and high temperatures

Thomas Keller, Till Vallée, Yu Bai

A decomposition model for resin in glass fiber-reinforced polymer composites (GFRP) under elevated and high temperature was derived from chemical kinetics. Kinetic parameters were determined by four different methods using thermal gravimetric data at diffe ...

2007

Modeling of stiffness properties of FRP composites under elevated and high temperatures

Thomas Keller, Till Vallée, Yu Bai

When subjected to elevated and high temperatures, the mechanical properties of FRP composites, such as the E- modulus and viscosity, experience significant changes. At a certain temperature, a composite material can be considered a mixture of materials tha ...

2008

Adhesively bonded lap joints from pultruded GFRP profiles. Part I: stress-strain analysis and failure modes

Thomas Keller, Till Vallée

Quasi-static axial tension experiments were performed in a laboratory environment on epoxy bonded, balanced double-lap and single-lap joints from pultruded GFRP flat sections. Full-scale specimens were used to avoid size effects. Parameters investigated we ...

2005

Adhesively bonded joints composed of pultruded adherends: considerations at the upper tail of material strength statistical distribution

Thomas Keller, Till Vallée

The Weibull distribution, used to describe the scaling of strength of materials, has been verified on a wide range of materials and geometries; however, the quality of the fitting tended to be less good towards the upper tail. Based on a previously develop ...

2009

Structural concept, design and experimental verification of a GFRP sandwich roof structure

Thomas Keller, Till Vallée

This paper reports on the design and construction of a lightweight glass fiber-reinforced polymer roof structure in Basel, Switzerland. The sandwich construction allowed for an integration of static, building physical and architectural functions that enabl ...

2008

Adhesively bonded lap joints from pultruded GFRP profiles. Part II: joint strength prediction

Thomas Keller, Till Vallée

A method to predict the strength of adhesively bonded single and double lap joints from pultruded GFRP composite adherends subjected to quasi-static axial tensile loading is presented. The method is based on a quadratic through- thickness shear-tensile int ...

2005

Experimental Investigations and Probabilistic Strength Prediction of welded Double Lap Joints composed of Timber

Yves Weinand, Till Vallée, Bernhard Stamm, Benjamin Hahn

Wood-to-wood bonds obtained by means of friction welding are a relatively new type of connections holding high potential to compete with existing structural adhesives, since a load bearing bond is formed almost instantaneously. This paper addresses the que ...

Elsevier2012

Moment resisting connections composed of friction-welded spruce boards: experimental investigations and numerical strength prediction

Yves Weinand, Till Vallée, Bernhard Stamm, Benjamin Hahn

Research on friction welded wood-to-wood connections has shown high potential for further development regarding the industrial application of timber construction. This paper addresses the question to which extent welding of wood can be applied to fabricati ...

Springer Verlag2014

Experimental investigations on welded double lap joints composed of timber

Yves Weinand, Till Vallée, Bernhard Stamm, Benjamin Hahn

Fabrication of wood-to-wood connections by means of friction welding is an relatively new process holding high potential for development. To connect wooden pieces by means of friction welding, they are initially pressed against each other. The rapid moveme ...

Elsevier Science, Reg Sales Off, Customer Support Dept, 655 Ave Of The Americas, New York, Ny 10010 Usa2011

Probabilistic strength prediction for double lap joints composed of pultruded GFRP profiles, part I: Experimental and numerical investigations

Thomas Keller, Till Vallée

Experimental and numerical investigations were carried out on adhesively bonded full-scale double lap joints composed of pultruded GFRP profiles with relatively thick adhesive layers. Thick adhesive layers are often used in infrastructure applications in o ...

2006

Adhesively bonded lap joints from pultruded GFRP profiles. Part III: Effects of chamfers

Thomas Keller, Till Vallée

Quasi-static axial tension experiments were performed in a laboratory environment on epoxy bonded, balanced double-lap joints composed of pultruded GFRP flat profiles. The parameters investigated were the overlap length (from 50 to 100 mm), the adhesive la ...

2006

Probabilistic strength prediction for double lap joints composed of pultruded GFRP profiles, part II: Strength prediction

Thomas Keller, Till Vallée

A probabilistic method for the strength prediction of adhesively bonded double lap joints composed of pultruded GFRP adherends subjected to quasi-static axial tensile loading is presented. The prediction method is based on the experimentally determined mat ...

2006

Modeling of direct load transmission in sandwich beams with lightweight concrete

Thomas Keller, Till Vallée, Erika Schaumann

The direct load transmission behavior of hybrid sandwich beams consisting of a bottom fiber-reinforced polymer skin and a top concrete skin was investigated experimentally. The sandwich core consisted of lightweight concretes of different brittleness (sand ...

2009

Numerical modelling and strength prediction of welded double lap joints made of timber

Yves Weinand, Till Vallée, Bernhard Stamm, Benjamin Hahn

Welding of wood is a relatively new method of joining load bearing elements, which holds the potential to compete with structural adhesion, since it allows for an almost instantaneous bond. First experimental and numerical investigations showed that failur ...

Elsevier Ltd. Selection2011

Direct load transmission in hybrid FRP and lightweight concrete sandwich bridge deck

Thomas Keller, Till Vallée, Erika Schaumann

Direct load transmission experiments on hybrid short-span beam specimens for a novel bridge deck were performed. The sandwich construction consists of three layers: a fiber- reinforced polymer composite (FRP) sheet with T-upstands for the bottom skin, ligh ...

2008

Shear resistance of lightweight concrete core of FRP-concrete sandwich structure

Thomas Keller, Till Vallée, Erika Schaumann

This paper presents a model to predict the shear resistance of the unreinforced lightweight concrete core of a recently developed hybrid sandwich concept for bridge decks. The sandwich skins consist of a fiber-reinforced polymer (FRP) composite sheet for t ...

2009

Flexural behavior of a hybrid FRP and lightweight concrete sandwich bridge deck

Thomas Keller, Till Vallée, Erika Schaumann

This paper presents a new concept for a lightweight hybrid- FRP bridge deck. The sandwich construction consists of three layers: a fiber-reinforced polymer composite (FRP) sheet with T-upstands for the tensile skin, lightweight concrete (LC) for the core a ...

2007

GFRP posts for railway noise barriers – experimental validation of load-carrying performance and durability

Thomas Keller, Till Vallée, Florian Riebel

As part of a 15-year railway noise remediation plan, 300km of noise barriers will be installed in Switzerland over the next few years. To enable pultruded glass fiber- reinforced polymer (GFRP) materials to be used for the noise barrier posts, a specificat ...

2008

Shear loaded friction-welded crosswise arranged timber boards

Yves Weinand, Till Vallée, Benjamin Hahn

Friction welding of wood is a bonding technology that can be used for joining timber elements, and in which the adhesive is formed from thermally modified cell wall material within the substrate during the welding process. In this paper, this principle is ...

2017