New perspectives in architecture through transformable structures: A simulation study

Structures enabling transformability of buildings, components and materials at different levels gain significance in view of a sustainable built environment. Such structures are capable of obtaining different shapes in response to varying functional, environmental or loading conditions. Certain limitations of classic tensegrity and scissor-like structures, applied so far in an architectural and engineering context, are attributed to a limited number of possible configurations and a big number of actuators required. In this context, rigid-bar linkages offer a promising alternative with regard to constructability, modularity, transformability and control components integration. In achieving improved flexibility and controllability with a reduced number of actuation devices, a kinematics principle has been previously proposed by the authors that involves the reduction of the system to an externally controlled one degree-of-freedom mechanism in a multistep transformation process. The paper presents application of the kinematics principle in two classes of a transformable spatial rigid-bar linkage structure. Investigation of the system kinematics was conducted using parametric associative design. The kinematics principle is applied on a torus-shaped spatial structural system composed of planar interconnected linkages. Alternative motion sequences of multiple transformation steps by the planar linkages can be implemented for the stepwise adjustment of the joints to their desired values. The actuators employed are positioned at the ground supports and are detached from the main structural body. Thus, minimum structural self-weight, simplicity and reduced energy consumption become possible. The transformation approaches using parametric associative design are exemplified based on a selected motion sequence pattern. The case study demonstrates the high degree of control flexibility and transformability of the system

Adaptive Textile Facade Systems-The Experimental Works at D1244

Adaptive facade systems are a promising approach to achieve a dynamic response to varying weather conditions and to individual user demands. Within the framework of the Collaborative Research Center (CRC) 1244 at the University of Stuttgart the use of adaptive systems and the related architectural potential is explored with the aim of reducing the consumption of natural resources as well as waste generation and hazardous emissions. The targeted parameters for the facade design include solar radiation, temperature, wind speed, relative humidity, daylighting, and user interaction. To generate an experimental platform for the research work, a 36.5 m high adaptive experimental tower, D1244, has been designed and built on the University campus. The temporary facade of the tower is currently being replaced floor by floor, in order to validate different research approaches. The first implemented facades focus on textile systems, because of their lightweight and the different functions that can be easily integrated. Further material systems will be investigated in the next future

Intercomparison of Large-Eddy Simulations of the Antarctic Boundary Layer for Very Stable Stratification

In polar regions, where the boundary layer is often stably stratified, atmospheric models produce large biases depending on the boundary-layer parametrizations and the parametrization of the exchange of energy at the surface. This model intercomparison focuses on the very stable stratification encountered over the Antarctic Plateau in 2009. Here, we analyze results from 10 large-eddy-simulation (LES) codes for different spatial resolutions over 24 consecutive hours, and compare them with observations acquired at the Concordia Research Station during summer. This is a challenging exercise for such simulations since they need to reproduce both the 300-m-deep convective boundary layer and the very thin stable boundary layer characterized by a strong vertical temperature gradient (10 K difference over the lowest 20 m) when the sun is low over the horizon. A large variability in surface fluxes among the different models is highlighted. The LES models correctly reproduce the convective boundary layer in terms of mean profiles and turbulent characteristics but display more spread during stable conditions, which is largely reduced by increasing the horizontal and vertical resolutions in additional simulations focusing only on the stable period. This highlights the fact that very fine resolution is needed to represent such conditions. Complementary sensitivity studies are conducted regarding the roughness length, the subgrid-scale turbulence closure as well as the resolution and domain size. While we find little dependence on the surface-flux parametrization, the results indicate a pronounced sensitivity to both the roughness length and the turbulence closure.Accepted Author ManuscriptAtmospheric Remote Sensin