Mg. Villagran-Valenzuela, Mauricio

Recurrent impact protection devices usually need to dissipate large amounts of energy to prevent damage to the infrastructure they protect and to make efficient use of them. This requires that protection devices consider some type of damping and have some mechanism to recover their original form. In this study a novel device is proposed, capable of absorbing a large part of the energy imposed by impact loads and recovering its original form autonomously. The device proposed in this article is composed of rigid parts with articulated joints, an elastic element that allows the recovery of its shape and an element that dissipates energy by friction. The necessary equations were developed to describe the non-linear behavior of the device and parametric simulations of the proposed model were performed to describe the dynamic interaction between the device and a mass that impacts. Additionally, a scale model of the device was constructed to be experimentally tested, which allowed to verify the effectiveness in the dissipation of energy, the reduction in the force transmitted to the support structures and the decrease in the rebound speed of the impacting mass. An error parameter was defined for a load-unload cycle between experimental results and analytical calculations. The error considers both the impact force and the dissipated energy, obtaining values of up to 6%. The energy absorption capacity of the device –between 83% and 93% of the impact energy– was verified experimentally, as well as the reduction of the impact speed –between 91% and 96%.

Coastal evolution is an important research topic worldwide and has become increasingly relevant due to growing anthropogenic pressure on the coast and a climate change scenario (Masselink et al., 2016). The Gulf of Arauco covers an area of roughly 40,000 km2 and has a sandy-rocky coastline located in a very seismic environment. The area has suffered several major earthquakes during the last century (Valdivia 1960, Maule 2010) and seismic displacement has widely affected the coastline (Béjar-Pizarro et al., 2010). Despite these findings, the morphological evolution of sandy coastlines is mainly caused by wave-driven littoral processes. In this paper, using numerical modeling (Delft3D), we aim to characterize the longshore sediment transport (LST) direction at several spots (7 beaches) spread along the coastline of the Gulf of Arauco. Wave patterns were identified at each study site, revealing the importance of Santa Maria Island, located at the entrance to the gulf, despite the approach direction of deep water waves. The island acts as a moderator of wave patterns, softening the highly energetic swell that comes from the Antarctic Ocean and sorting the wave propagation inside the gulf. Moreover, LST patterns were characterized at each site for dominant wave conditions (SW swell and NW winter storms) and it was possible to explain how each condition has a different response at each spot, even under similar co-seismic displacements. Adaptation capabilities differ from site to site, suggesting a dynamic equilibrium of beaches in the area.