Search

The response of structures bonded to the surface of a transversely isotropic half-space (TIHS) under the effect of time-harmonic forces is investigated using a coupled FE-BE scheme. To achieve this end, a Finite Element program has been developed for frequency domain analysis of 3D structures, as the first step. The half-space underlying the structure is taken into consideration using a Boundary Element technique that incorporates half-space surface load Green’s functions for a transversely isotropic medium. Next, the two programs are combined using a direct coupling algorithm and the final program is obtained. To validate the results, some benchmark problems are solved with the FE and the BE programs, separately and then the coupled technique is checked with the results of some special cases for which the solutions are available in the literature. At the end, a parametric study is carried out on several common types of structures to study the effects of the degree of anisotropy of transversely isotropic soil medium on the dynamic behavior of the structure. Moreover, the effect of soil-structure interaction (SSI) on the natural vibration frequency of the structures is also studied.

Whether it is glass, ceramics, cement, or concrete, minimizing thermal conduction through disordered materials is a determining factor when it comes to reducing the energy consumption of cities. In this work, we explore underlying physical processes involved in thermal conduction through the disordered glue of cement, calcium-silicate-hydrates (CSH). We find that at 300 K, phonon-like propagating modes in accordance with the Boltzmann transport theory, propagons, account for more than 30% of the total thermal conductivity, while diffusons, described via the Allen-Feldman theory, contribute to the remainder. The cumulative thermal conductivity proves to be close to both equilibrium molecular dynamics calculations and experimental values. These findings help us establish different strategies, such as localization schemes (to weaken diffusons) and scattering mechanisms (to constrain propagons), for reduction of thermal conductivity of CSH without sacrificing its mechanical properties. [ABSTRACT FROM AUTHOR]