Research Projects in the Space Structures Research Centre
Surrey Univ.
Propagation of Local Instabilities in Braced Domes
. Researcher K Abedi
Supervisers G A R Parke and H Nooshin
The phenomenon of 'snap-through' in a dome is a 'dynamic event'. The occurrence of snap-through causes the release of kinetic energy. If the dome is capable of absorbing the kinetic energy, the instability will not propagate. However, if the dome is unable to absorb the sudden release of kinetic energy, progressive collapse of the dome will occur. The research has resulted in the development of a procedure for modelling the phenomenon of progressive collapse in domes.
Semi-rigidity of Connections in Space Structures
. Researcher M R Chenaghlou
Supervisers H Nooshin and J E Harding
Experimental and analytical investigations show that connections in space structures normally behave in a semi-rigid manner. In order to take the effects of semi-rigidity of the connections into account, two basic steps are necessary. Firstly, a reliable method must be evolved to predict the behaviour of connections as separate entities. Secondly, a suitable procedure should be evolved for the modelling of the connections as integral parts of the structural system. The research has resulted in the development of a number of conceptual tools that provide a means for the prediction of the effects of the semi-rigidity of connections on the behaviour of space structures.
Polyhedric and Geodesic Configurations
. Researchers O C Champion and J Moon
Superviser H Nooshin
Polyhedra have been the subject of fascination and interest to mathematicians, philosophers and artists since the ancient times. Structural forms based on polyhedra have subsequently become popular with engineers and architects. However, the difficulty of data generation for these polyhedric configurations has been a barrier to advancement in this area. The research has helped to evolve procedures based on the concepts of 'formex algebra' to facilitate the generation of polyhedric forms and to broaden the boundaries of knowledge in this field. As a consequence of this work, polyhedric forms and geodesic domes of all kinds can be generated for practical applications with ease and convenience through a standard function in the programming language Formian.
Force Density Method and Configuration Processing
. Researcher F Dansik
Superviser H Nooshin
The objective of this work has been to carry out an in-depth investigation into the 'force density' method for 'form finding' of space structures such as cable nets, membranes and tensegrity systems. These structures often require a preliminary stage of form finding before they may be subjected to rigorous structural analysis procedures. Also investigated are algorithms for regularisation of the stress distribution and element lengths of the structures.
The Concept of Pelevation for Shaping of Structural Forms
. Researcher I S Hofmann
Superviser H Nooshin
'Pelevation' is a geometric concept for the shaping of structural forms. The concept can be used to generate a wide range of surfaces for grid domes and shell structures. The surfaces are obtained by superposition of a number of simple surfaces such as spheres, cones, paraboloids, ellipsoids, cylinders, saddle shaped surfaces, ... etc. The concept allows creation of surfaces that fit the exact requirements of the designers in a convenient manner. The research has involved a far reaching exploration of different aspects of the concept of pelevation and has provided a comprehensive range of tools for the practical application of the concept. These tools are available for use through a standard function in the programming language Formian.
Regularisation of Structural Forms using Genetic Algorithms
. Researcher Y Kuroiwa
Superviser H Nooshin
In many practical cases, it is desirable to regularise the member lengths in lattice space structures. One method for achieving this purpose is to take the nodal coordinates of a space structure as unknowns and try to determine them such that the member lengths are regularised as far as possible. The problem will then become a constrained nonlinear optimisation problem and the main objective of the research has been to find a solution to this problem. It has been found that a particular genetic approach provides an effective solution for the problem. This genetic method can be applied through a standard function in the programming language Formian.
Nexorades: a Family of Interwoven Space Structures
. Researcher O L S Baverel
Supervisers G A R Parke and H Nooshin
Nexorades are a family of lattice space structures that are ideal for many types of temporary structures. The elements of a nexorade are interwoven and the system can be erected quickly using simple connectors. The problem with the nexorades is that, without suitable conceptual tools, their geometry is rather difficult to work out. Investigations have shown that the geometric detail of a nexorade can be determined by a genetic method similar to that used for regularisation of member lengths of a lattice space structure. This method for the shape finding of nexorades is now available through a standard function in the programming language Formian.
Topology Optimisation of Double Layer Grids
. Researcher H Ebrahimi
Supervisers H Nooshin P L Disney
In general, optimisation of the topology of structural forms has proved to be a rather challenging field of research. It is believed that the evolutionary methods of optimisation provide a suitable medium for topological optimisation and the objective of this project is to employ a genetic approach to evolve a method for the generation of optimum configurations for double layer grids.
Seismic Design of Barrel Vaults
. Researcher A Sadeghi
Supervisers H Nooshin, J E Harding and
G A R Parke
Supervised by The traditional methods for the seismic design of structures are mainly modelled on the seismic behaviour of multi-storey buildings. Therefore, the application of these methods to space structures is not really appropriate. The objective the project is to carry out a detailed study of the seismic behaviour of a family of space structures, namely, barrel vaults, and to put forward recommendations for the seismic design of this family of structures.
Effects of Semi-rigidity of Connections on the Behaviour of Double Layer Grids
. Researchers MR Davoodi and MH Pashaei
Supervisers H Nooshin and P L Disney
The objective of this project is to carry out a large scale experimental investigation of the static and dynamic behaviour of double layer grids with Mero-type semi-rigid connectors. In particular, the effects of different levels of 'tightness' of the bolts in the connectors will be examined in detail. The experimental results will be used to provide information regarding the effects of the semi-rigidity of connections on the behaviour of double layer grids.
Space Structure Bridges
. Researcher K Stech
Supervisers H Nooshin, P L Disney and G A R Parke
Bridges, built from the ancient times to the present era, cover a wide variety of structural forms. The initial objective of this project is to explore different classes of bridge forms and to study their basic characteristics and limitations. The ultimate objective is to evolve new bridge forms that are suitable for very long spans.
Cable Domes
. Researcher S El-Lishani
Supervisers H Nooshin and P L Disney
A particular category of lattice domes consisting of combinations of 'stiff elements' and 'cable elements' have been popular in the recent years. These include such domes as the 'Geiger domes' and 'suspen domes'. The objective of this project is to explore various possibilities for dome configurations in the above mentioned category and to carry out an in-depth study of their behaviour.
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