Recently, the use of spatial structures in various applications such as building, airport and stadium roofs has significantly increased due to their excellent properties. Unfortunately, spatial structures are susceptible to failures that limit their structural performance. This has attracted the attention of researchers who are looking for new techniques for improving the properties of such materials for design optimization and improved efficiency.
Presently, three-dimensional spatial structures are generally grouped into three groups based on how they resist loads. They include tension, compression and reticulated structures. Due to their different mechanical and geometric properties, different structural analyses are used for structural analysis of the three structures. For example, finite element and finite difference methods are used for structural analysis of compression structures including shell structures while tension structures are analyzed using finite element methods. Reticulated structures, on the other hand, are analyzed based on the linear elastic theory. However, it is important to understand the structural behaviors of membrane structures as well as finding the design limitations. This will help in design optimization of anticlastic membranes supported at the beam edges.
In a recent research paper published in Journal of Structural Engineering, Professor Thomas Kang at Seoul National University in collaboration with Ms. Marta Gil Pérez (MSc) and Dr. Seongwon Hong (Post-doctoral researcher) developed design charts with a detailed guideline for the design of irregular anticlastic membranes. The membranes are supported by two asymmetric circular arches and two parallel non-equal beams. The authors further introduced irregularities for wider design possibilities. Eventually, they investigated significant finding during design development stages, therefore, developing case studies of irregular anticlastic membrane structures with asymmetry about the provided axes.
From the case study results, the authors observed the behavior of trapezoid-shaped panels defined by the opening angle, width, midspan and arch curvature. Consequently, regular panels with the same width as the midspan width in trapezoid panels exhibited similar limitations attributed to the fact that the maximum stress is achieved at the midspan. However, under downward loading conditions, the opening angle affects the structural behaviors while for the same arch curvature, stress increase is linearly proportional to the width. This further allowed calculation of the opening angle for any arch curvature and width at the midspan. In addition, the design chart provided the limitations for a different combination of the parameters for both trapezoid-shaped panels and inclined panels. The study successfully developed design aid charts for a variety of irregular anticlastic membranes. It uncovered various parameters that are important for the optimization and design of efficient membrane structures. For instance, it is realized that for all the panels, the maximum stress is reached across the transverse dimension in the midspan region regardless of the arch curvature. This is due to the dependence of the inclination angle to the width only. The limitations associated with the inclination angles could be easily identified from the chart. The study will, therefore, advance the design and use of spatial membrane structures in various fields.
Hong, S., Pérez, M. G., & Kang, T. H.-K. (2018). Case Studies of Irregular Anticlastic Membrane Structures with Asymmetry. Journal of Structural Engineering, 144(8), 05018001.