Abstract. This paper focuses on energy harvesting of traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case study, in situ vibration measurements are presented and analyzed. From those results, a prototype of cantilever piezoelectric harvester was designed, tested, and modeled. Even though the considered bridge vibrations are characterized by small amplitude and a low frequency (i.e. below 15 Hz), it is shown that mean power of the order of 0.03 mW can be produced, with a controlled voltage between 1.8 and 3.6 V. A simple model is proposed for the theoretical prediction of the delivered power in terms of traffic intensity. That model shows good agreement with the experimental results and leads to a simple but effective design rule for piezoelectric harvesters to be used on bridges.Piezoelectric energy harvesting from traffic-induced bridge vibrations 2

We investigate the physics behind the complex thermo-mechanical behavior of clays. Depending on their loading history, clays exhibit thermal expansion or contraction, reversible or irreversible, and of much larger magnitude than for usual solids. This anomalous behavior is often attributed to water adsorption, but a proper link between adsorption and thermo-mechanics is still needed, which is the object of this paper. We propose a conceptual model starting from the scale of the adsorption up to the scale of the geomaterial, which successfully explains the thermo-mechanical behavior of clays. Adsorption takes place between clay layers at the nanometer scale. The mechanics of the clay layers is known to be strongly affected by adsorption, e.g., swelling with humidity increase. Here we investigate the effect of drained heating and show that an increase of temperature decreases the amplitude of the confining pressure oscillations with the basal spac

For elastic-perfectly plastic materials with constant properties, the well-known Melan's theorem gives a sufficient condition for shakedown to occur, independently on the initial state. It has been conjectured that Melan's theorem could be extended to temperature-dependent (or time-dependent) elastic moduli, but no theoretical result is available. This paper aims at providing results in that direction, with a special emphasis on time-periodic variations. If Melan's condition is satisfied, we show that shakedown indeed occurs provided the time fluctuations of the elastic moduli satisfy a certain condition (which in particular is fulfilled if the time fluctuations are not too large). We provide a counterexample which shows that setting such a constraint on the elastic moduli is necessary to reach path-independent theorems as proposed. A simple mechanical system is studied as an illustrative example.