Adaptive Concrete Beams Equipped With Integrated Fluidic Actuators

Abstract

The rapidly growing world population is a great challenge for the building industry. Due to the impending scarcity of resources, it is not possible to provide the growing mankind with sufficient living and work places and infrastructure with current construction methods. For wide-spanning beams and slabs, the decisive design criteria are mainly determined by deformations rather than stresses, since deflections must be limited. This leads to structural elements, which are not fully utilized. However, if the deformations can be reduced, significant material savings can be achieved. Sensors, actuators, and a control unit enable components subjected to bending to adapt to high but rare loads. This article presents a solution that allows beams to react actively to loads by use of integrated actuators. The newly developed integrated hydraulic actuators allow the structure to react specifically to a wide range of load cases, by adjusting the internal hydraulic pressure. This is a clear advantage in load-bearing systems because there is often no dominant load case. This internal actuation concept is a new approach, as previous adaptive structures either have externally added actuators or are composed of truss structures in which single bars are actuated. In this paper, the concept is explained analytically, simulated with the finite element method and validated experimentally.

Adaptive Hüllen und Strukturen

“…Die experimentelle Evaluation erfolgte in Vier‐Punkt‐Biegeversuchen. Durch die gezielte Erhöhung des hydraulischen Drucks in den Aktoren wird die Durchbiegung der belasteten Balken stets minimal gehalten [37]. Die Versuche stimmen mit den Ergebnissen von numerischen Simulationen gut überein.…”

An Actuator Concept for Adaptive Concrete Columns

“…These serviceability limits also often govern the design, such that the structural elements are again oversized for the stresses acting in those elements. Through actuation it is possible to induce counter deformations which reduce or even compensate the deformations allowing the structural member to be sized according to the stresses [18][19][20]. Which of these actuation strategies yields the most material and emission savings depends highly on the type of building or structure that is to be actuated.…”

“…Therefore, new actuation and actuator concepts are being developed to address other performance requirements. In [20] actuators were integrated into the component crosssection for the first time using the example of a beam. In this use case only small strokes (<0.5 mm) and moderate forces (<50 kN) are required to compensate deformations caused by external loads.…”

Using Influence Matrices as a Design and Analysis Tool for Adaptive Truss and Beam Structures

“…The cement industry alone causes 5.4% (United Nations Environment Programme, 2019;Kelleter et al, 2020) of the global emissions of greenhouse gases and up to 10% of the total anthropogenic CO 2 emissions (Scrivener et al, 2018). Overall, the building industry accounts for 35% of all global CO 2 emissions, thus being a significant contributor to the ongoing climate change.…”

“…The integration of such active elements allows an adaptive structure to monitor its stress state and to react accordingly. In case of rarely occurring, high external loads, the structure may induce forces counteracting those from the external load, respectively change its stiffness distribution to homogenize stresses and strains (Sobek and Teuffel, 2001;Senatore et al, 2018a), induce counter deformations (Sobek et al, 2002;Senatore et al, 2018b;Kelleter et al, 2020), or generate shape changes to establish a more efficient load transfer (Neuhaeuser et al, 2013;Reksowardojo et al, 2019), thus increasing structural performance. Due to this increase in performance, the passive elements of the adaptive structure can be dimensioned for lower, more frequently occurring loads, which reduces the structures' resource consumption and embodied energy while using comparatively little operational energy (Senatore et al, 2018c;Schlegl et al, 2019).…”