A: Design and planning methodology

A06 – Integration of active elements within a building’s structure

Current design methods for dimensioning building structures are based on expected maximum loads within the lifetime of a building.

Consequently, structures are oversized for most of their service life, which leads to an unnecessary mass. Adaptive structures avoid this by replacing the mass with energy supplied to the system as needed.

The aim of subproject A06 is the activation of structures by actuators and sensors leading to adaptivity with respect to vibration mitigation and load transfer. Eventually, active and passive elements make up the building’s structure and work together realizing an optimal load transfer for any given external load, resulting in large savings in construction material, especially steel and concrete.

Actuation principle of deformation minimization and resulting qualitative force states in the truss
Actuation principle of deformation minimization and resulting qualitative force states in the truss

To reach this goal, the project’s research focuses on the following challenges:

  • Integration of adaptive elements into arbitrary truss structures
  • Enhancement of passive structures, especially sophisticated high-rise structures, by the use of adaptive elements
  • Find design engineering methods to integrate actuators into structural elements for creating adaptive elements
  • Definition of feasible cost functions for finding an optimal distribution of active elements within a given structure

To save construction materials, A06 develops concepts for manipulating a building’s structure based on governing load cases together with their probability of occurrence. Starting from the actuation principle and the respective forces and expected oscillation amplitudes, the placement of actuators and sensors can be determined based on simulation models of the examined structures. To quantify the quality of the placements, approaches such as observability and controllability from control engineering were pursued and a steady-state compensability gramian was derived. Additionally, approaches for the extension of the classical FE-method were developed, so that the active elements can be considered in the structural analysis.

First investigations were carried out on conventional high-rise building typologies. Due to the prevailing stiffness-governed design problem, mass reductions of up to 50 % of the primary load-bearing structure can be achieved by a subsequent deformation adaptation. However, it was also shown that a further reduction and thus optimization requires specifically designed adaptive typologies. For the actuation of the load-bearing structure a serial and a parallel linear actuator were developed in cooperation with the subprojects A01 and C02.

The actuation concepts as well as the results of the structural design serve to create a requirement profile for the utilized sensors and linear actuators, so that these can be selected optimally afterwards.

Based on this work, the modular support structure of the demonstrator tower was designed in close interdisciplinary cooperation with Z01. A prototype frame was planned and built to revise the design details as well as the functionality of the serial and parallel linear actuation.

 

Experimental validation of the actuation concept of the prototype-frame
Experimental validation of the actuation concept of the prototype-frame

The expertise gained from the developments of the actuation concepts in this project serves as a basis for new and integrated design concept of adaptive structures.

Principal Investigators

  • Prof. Dr.-Ing. Dr.-Ing. E. h. Dr. h.c. Werner Sobek, Institute for Lightweight Structures and Conceptual Design
     
  • Prof. Dr.-Ing. habil. Dr. h.c. Oliver Sawodny, Institute for System Dynamics
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