Pressure coefficient distributions for the design of hypar membrane roof and canopy structures

Membrane structures are used in the built environment as roof or canopy and must therefore be designed to resist the external conditions. Nonetheless, the topologies of membrane structures are not covered by existing wind load standards and relevant wind load distributions for the basic shapes of these structures are almost not available. To have a realistic analysis of the wind loading, wind tunnel tests can be performed for each design. However, due to the lack of resources or time, for many projects the wind analysis will be based on rough approximations by relying on conventional shapes in the Eurocodes, with applying very high safety factors or designing unsafe structures as risk. Therefore, this paper presents a study of the orientation and curvature dependency of the wind load distributions over hypar roof and canopy structures. This study is performed with a numerical wind tunnel, using CFD with Reynolds averaged Navier Stokes equations. The outcomes are summarised in pressure coefficient distribution plots for most important wind orientations for hypar roofs and canopies with different curvature. The presented pressure coefficient distributions can be used in line with the Eurocode to derive more relevant wind load estimations for hypar membrane structures. These wind load estimations will give the engineer information about the average response of these structures under wind loading and will facilitate more reliable wind design of membrane structures

Editorial to the Proceedings of the TensiNet - COST Action TU1303 Symposium 2016

The TensiNet Association, in collaboration with the COST Action TU1303 “Novel structural skins: Improving sustainability and efficiency through new structural textile materials and designs” and the Newcastle University organized the TensiNet - COST Action TU1303 Symposium 2016 held in Newcastle upon Tyne, UK, from Wednesday 26th to Friday 28th October 2016. This paper presents the 3-day event introducing the topics selected for the sessions, the keynote lectures and speakers and the sponsors which supported the organization of the symposium

(Un)folding the membrane in the deployable demonstrator of contex-t

The paper presents a system, made out of foldable ‘kinked’ beams and a membrane skin, based on a concept referring to origami. The anticlastic curvature of the membrane is obtained by transforming flat triangular parts into space. The following research question is considered: can the foldable system be stable in intermediate configurations? To obtain a well-tensioned membrane in the intermediate positions, the belts connecting the membrane to the frame can be released or increased in tension. A full scale ‘demonstrator’ has been built within the frame of IP-project Contex-T8. Although the deployment - rotating the ‘kinked’ beams about the central axis - was feasible, the tensioning and structural behaviour of the membrane, attached in the nodes of the frame, was not yet thoroughly examined. For that reason one single unit has been analysed. Forces and deformations in the membrane are verified for different opening angles using integrated models including the membrane, connecting belts and ‘kinked’ beams (for the frame). The results of the experimental investigations and numerical models are compared and occurring discrepancies are clarified

Preliminary investigation to Tensairity arches

This paper investigates the load bearing behavior of Tensairity arches. The main goal of the research is to get a basic understanding of Tensairity arches and their feasibility. It analyzes the influence of the width/height ratio and the shape of the arch. Four different test models were constructed and experimentally tested. The experiments were conducted on 2m span scale models supported on two hinges and were symmetrically loaded. The arches have a constant cross section throughout their entire length and have a strut attached to the bottom and top of the airbeam. The experiments were performed with an internal pressure in the airbeam of 200 mbar and no cables were used

Numerical investigation of the structural behaviour of a deployable tensairity beam

This paper investigates numerically the load bearing behaviour of a deployable Tensairity beam. More precise, it studies the influence of the cables that connect the upper and lower strut of the deployable Tensairity beam on its load bearing behaviour. Finite element analysis shows that these cables are pretensioned when the airbeam is inflated. When both diagonal and vertical cables are present, only the vertical cables become tensioned. These tensioned cables are able to take compressive forces, by the same amount as their initial pretension. This has as result that these cables avoid the hinges to deflect under compression. Or in other words, the pretensioned cables ‘block’ the hinges. Once the external load has reached the value whereby the value of the pretension becomes zero in at least one cable, the hinge is not blocked or supported anymore by this cable. The hinge will experience larger displacements and the stiffness of the deployable Tensairity beam decreases

Implementation of bending-active elements in kinematic form-active structures - Part I : design of a representative case study

Due to their low self-weight and their inherently high flexibility, technical textiles offer great possibilities for the integration in kinematic structures. Furthermore, the implementation of active bending in a transformable design creates new challenging perspectives. The paper describes an integrated approach for transformable textile hybrids where an improved design is obtained through a parameter study, performing a structural analysis in the different phases of the deployment. The studied parameters include (i) the form-finding position, (ii) the prestress (ratio), (iii) the used materials and sections (including the fibre directions) and (iv) the number of bending-active elements. This research confirms the feasibility of realizing kinematic form-active structures with integrated bending active elements, where both the membrane and the supporting structure are stable in the different configurations. Due to the high interaction between the bending-active supporting system and the pretensioned membrane, the different parameters influence each other significantly. In a next step, an experimental verification of the designed pringle-shaped textile hybrid is carried out in order to both confirm the possibilities and reveal the remaining challenges

A Deployable Mast for Adaptable Textile Architecture

p. 252-263Proposed here is a concept for a deployable mast with angulated scissor units, for use in adaptable temporary architectural constructions. The adaptable structure serves as a tower or truss-like mast for a temporary tensile surface structure and doubles up as an active element during the erection process. The mast consists of scissor-like elements (SLE¿s) which are an effective way of introducing a single D.O.F.(degree of freedom) mechanism into a structure, providing it with the necessary kinematic properties for transforming from a compact state to a larger, expanded state. The scissor units used here are not comprised of straight bars, but rather consist of angulated elements, i.e. bars having a kink angle. Although primarily intended for radially deployable closed loop structures, it is shown in this paper that angulated elements can also prove valuable for use in a linear threedimensional scissor geometry.De Temmerman, N.; Mollaert, M.; De Laet, L.; Van Mele, T.; Guldentops, L.; Henrotay, C.; Debacker, W.... (2009). A Deployable Mast for Adaptable Textile Architecture. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/650

Assessing 19th century fireproof buildings

Construction details of 19th century fireproof buildings are discussed. The paper deals more specifically with Brussels industrial iron framed buildings. The innovations and developments of construction techniques are illustrated by going deeper into three representative Brussels case-studies. The changes in construction techniques and the applications of new materials are explained by the evolving insight in 'fire safety'. Some attention will be paid to international developments, more specifically the introduction of the Eurocodes. Directions are given on how to apply this knowledge when dealing with 19th century 'fireproof' buildings.SCOPUS: cp.kinfo:eu-repo/semantics/publishe

A quest for early tensile structures at Expo 58

Expo 58, the first post-war world’s fair (Brussels) was appreciated for its unprecedented col-lection of lightweight structures. Recent study has revealed how hanging roof structures have pushed contemporary building practice to its limits. These pavilions demonstrated an early mas-tering of tensioning calculation and specific building techniques, but both design and construc-tion phases met with unexpected problems. In particular the choice of the materials to cover the curved surfaces presented a challenge difficult to meet with contemporary means. New archival research revealed three textile structures at Expo 58, which help to further probe the state of knowledge and practice in lightweight building in Belgium from 1955 on-wards. The bandstand cable net by architect O. Schomblood and engineer A. Paduart; the roof of the snackbar by architect R. Bastin and engineer R. Greisch and the ceiling of the International Science Exhibition by architect A. Jacqmain and engineer L. Culer are textile structures using cotton fabric as cover. These structures were erected as part of the fair’s functional equipment supervised by Expo 58’s Technical Service and have remained unpublished. Archival material documents the planning and construction processes through letters, plans, photographs, building specifications, bills, construction site accounts and calculation reports.This paper highlights the methods and tools used, and the issues at stake during the design and construction of these early textile structures. Cotton canvas was chosen in all three cases in spite of several experiments with Cocoon, a sprayable plastic. Different structural concepts were developed, blurring the difference between cable reinforced tensile structures and tensioned ca-ble nets. The work of engineers, architects and controlling agency reveals the state of knowledge on, and ambition in, building with innovative, precisely calculated and detailed tensile structures in textile. The contractors’ experience on the other hand, when available, appeared to be mainly in the field of classical tent building and interior furnishing: practices with long-standing, hands-on knowledge in handling textile covers. By focusing on the documents produced to communi-cate the design and to steer and monitor the construction process, this paper investigates how both fields of construction knowledge were confronted. What is revealed is neither a situation of structural or material innovation, nor of a perfect mastering of concepts and processes, but an amalgam of approaches, materials, techniques and actors at a crossover point between estab-lished, general construction practices and ambitious lightweight building calling for increased control and mastering of calculation and execution.info:eu-repo/semantics/publishe