a b s t r a c tIn this paper, a new adaptive deployable spatial scissor-hinge structural mechanism (SSM) is introduced, which can be converted by means of actuators between a multitude of arch-like, dome-like and double curved shapes, where it can be stabilized and carry loads. This novel SSM is a spatial extension of a planar SSM introduced recently that can achieve a wide range of planar geometries. Main differences of the proposed structural mechanism from current deployable structures are the new connection type of the primary units and the proposed modified spatial scissor-like element (MS-SLE). With the development of this new connection detail and the modified element, it becomes possible to change the geometry of the whole system without changing the dimensions of the struts or the span. After presenting some disadvantages of current deployable structures and outlining the main differences of the proposed spatial SSM with existing examples, the dimensional properties of the primary elements are introduced. Then, geometric principles and shape limitations of the whole structure are explained. Finally, structural analyses of a typical structure in two different geometric configurations are performed, in order to discuss stiffness limitations associated with the advantage of increased mobility.

This paper presents the research which is carried out in the field of adaptive structures at the Institute for Lightweight Structures at the University of Stuttgart. The application of adaptive systems in the field of architecture and structural engineering creates new chances to design lightweight structures. Different concepts of active control can be used to manipulate the forces, the deflections and the vibration of structures. These concepts are categorised into two groups: control of external loads and control of internal forces. Active shape control can be used to reduce the external wind load by changing the shape of the cross-section of wide-span bridges or high-rise towers. Alternatively active force and/ or stiffness control can be used to manipulate the internal flow of forces and stresses in structures. Systems with active force control superimpose the actively generated forces with the already existing forces, while systems with active stiffness control redistribute the forces according to their varying stiffness distribution. The authors use active elements with variable length and/ or stiffness in static indeterminate structures to control the deflections and redistribute the forces. A bridge with actively controlled elements is presented, where the stress peaks can be reduced and a homogenisation of the force distribution can be obtained.

Preface 'Lightweight construction-a demand of our time' was the title of an article written by Fritz Leonhardt 1 in 1940. Against the background of Germany's economic situation at that time-strongly affected by a lack of resources resulting from the recently erupted war-Fritz Leonhardt considered topics such as the availability of raw materials and the importance of mass flows. From these considerations, he derived instructions for the building industry. The instructions could be summed up as an overarching demand for 'lightweight'. In the decades after the war, Frei Otto then laid the foundations for a fulminant development of lightweight construction, which led to spectacular buildings such as the Munich Olympic roofs. Today, the developments initiated by Fritz Leonhardt and Frei Otto are more relevant than ever: The ever more noticeable consequences of global demographic growth as well as large migration movements and the imminent exhaustion of various resources are distinctive challenges that lie in front of us all. Again, it comes to the careful use of limited resources, but now on a much larger scale. Today, more than ever, we need a 'lightweight for all', with a scope that is much larger (both thematically and geographically speaking) than before. Lightweight construction of the future will not only strive to minimize the volume and weight of materials used. It will also have to pay close attention to a minimization of embodied energy and to the development of recycling-friendly construction methods. Another important feature will be that lightweight construction will have to provide solutions for many different countries and cultures because the problems confronting us are global and can only be tackled with a global approach.

Functional gradation of concrete elements makes it possible to align the internal composition of structural components with specific structural and thermal performance requirements. This alignment is made possible by continuously altering the characteristics of the material, including its porosity, strength, or rigidity, in up to 3 spatial dimensions. This principle can be applied to minimize the mass of the element and to create multifunctional properties. Numerical design methods are used to develop the gradation layout that serves as a digital blueprint for such components. This paper describes tests performed on functionally graded beams. These tests have made it possible to derive conclusions with respect to the elements' structural behavior. These tests also allow for a precise assessment of the weight savings that can potentially be achieved compared with structural components made from normal concrete. Test results were subsequently replicated by numerical simulations. The models calibrated in this step have established the basis to develop numerical design methods that rely on the principle of topology optimization.

Glass offers a wide variety of possible applications for the realization of even the most ambitious designs in architecture, and in the past two decades it has experienced an unparalleled burst of innovation. For planners, this means working constantly with this high-performance material.

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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.