Numerical analysis and cable activation in hybrid bending-active structures with multiple cables

Abstract

Recent applications of bending-active structural principles have facilitated the development of unique, material and energy efficient, free-form lightweight systems. The systems are realized through the application of an interdisciplinary design, computational fabrication, exclusive assembly techniques and construction. These aspects are directly linked to the form-finding process through the bending-active members’ activation. A number of design and construction parameters necessary for the morphological objectives succession, as well as the consideration of the deformation behavior of the systems, have raised the challenge of associating generative configuration parameters with their respective post-formed load-deformation behavior. Along these lines, the present paper examines the design of a planar hybrid bending-active system that consists of a single elastic member interconnected with cable elements at equal length intervals of 1 m. The three-stage development of the system consists of its assembly in planar arrangement (i) and erection (ii) following an initial uniform cables’ length reduction, in connection with the appropriate kinematic constraints of the ground supports. In a consecutive post-tensioning stage (iii), the supports are fixed and the cables’ length is further reduced to provide higher system prestress conditions and a differentiated span to height ratio. In a preliminary stage, the system load-deformation behavior under uniformly distributed vertical load is investigated at the end of its erection (ii&Q) and post-tensioning stage (iii&Q). The analysis examines seven system configurations with increasing number of cable segments, from two to eight. For the eight cable segments system, fourteen alternative post-tensioned configurations, emerging from individual, or group, cable activation, are investigated in their load-deformation behavior. The analysis provides insights into the configurability of the hybrid systems and their load-deformation behavior. In conclusion, the paper discusses design aspects that contribute towards structurally efficient configurations of the hybrid system series.