Steel and Composite Steel-Concrete Structures
Reinforced Concrete Structures
Partially Bonded Non-metallic Prestressing Tendons
Expert Systems for Prestressed Concrete Bridge Design
Parallel-lay Rope Terminations
Very Long Span Bridges
Lateral Stability of Precast Concrete Beams
Polyester and Aramid Fibre Properties
Non-metallic Reinforcement for Concrete
Analysis of Symmetric Structures
Structural Vibration and Control
Dynamics of Nonlinear Elastic Systems
Mechanics of Historical Construction; Curriculum Development
Structural Mechanics in Molecular Biology
Dr R.E. McConnel
A project to investigate the use of asymmetric hot-rolled steel sections ("ASB") and deep-troughed concrete-filled floors ("slimfloor") for large-span buildings is almost complete. A stub-girder arrangement using the ASB beams in order to extend the span range beyond the present practical limitation of 6 m has been tested for a span of 13.2 m. The results obtained are currently being assessed.
A study of light-weight shell-like large-span roof structures has been completed. An appropriate 2-noded beam-column finite-element, that can model member buckling in conjuction with both initial imperfections and a range of lateral loads within the length of the element, has been developed, and it has been calibrated against some small-scale model roof domes. Both point and distributed loads have been applied, and satisfactory agreement between predicted and measured behaviour has been obtained.
An investigation into the use of different constructional materials in large-span shallow domes of reticulated, composite construction has begun. Initially a light-weight triangulated network will be erected; and this will act first as a temporary support for the infilling membrane, and subsequently with the membrane as a composite structure to carry the in-service loads. The use of both concrete and synthetic membranes will be investigated. Both experimental and theoretical studies will be conducted.
Dr C.T. Morley
Research has continued on the application (with appropriate caution and safeguards) of the upper-bound theorem of plasticity theory to predict the collapse loads of reinforced concrete structures _ most recently beam-and-slab bridges in bending and shear(H17,H18,H19). Work has also continued on simplified approaches to the analysis of structures made of materials exhibiting marked strain-softening after little or no plastic flow. Progress is being made using the Galerkin method, and tests are being carried out on heavily-reinforced slabs with a single developing yield-line with limited rotation capacity. Research continues on compressive membrane action in reinforced-concrete slabs.
Dr C.J. Burgoyne
Dr J.M. Lees
The project on beams prestressed with partially bonded non-metallic tendons has now been completed. It showed that it is possible to achieve both high strength (normally associated with fully bonded systems), and high rotation capacity (normally associated with unbonded systems), by judiciously debonding the tendons. This has been achieved in two ways; by alternately bonding and debonding the tendon along its length, or by coating the tendon with a surface layer of known, low, shear strength. The tendons were made from aramid fibres, in the form of resin-bonded pultrusions or braided rods. Associated work has been investigating the bond behaviour between the rods and the concrete, since the mechanism of bond breakdown is critical to the behaviour of the tendons(H23).
Dr C.J. Burgoyne
This project has now been completed by the award of a PhD. The system now takes due account of thermal and creep effects, and also takes into account additional factors caused by the construction sequence. It is now possible to design quite complex structures, with different configurations, in short periods of time; which allows designers to explore alternative designs. Hitherto, the calculations were so complex that the first valid solution would have been accepted. Wherever possible, the system has been configured in such a way that the fundamental behaviour of prestressed concrete structures is built-in. Only when it is not possible for the system to calculate a value of some particular parameter does the designer have to specify a value; and the designer is then given guidance as to the range of allowable values, and why a particular parameter has to be chosen. In this way, the designer is free to choose the optional parameters, leaving the computer to do the drudgery. Values calculated by the system can be overridden by the designer if necessary, provided the structural criteria remain satisfied [Sundaram, J., PhD dissertation, see Section IV].
Dr C.J. Burgoyne
The behaviour of parallel-lay rope terminations has been studied. The transverse properties of the fibres have been measured, as have their friction and abrasion characteristics. These have then been combined with the results of a complex, non-linear finite element analysis, which has taken account of the relative motion of the barrel, fibre and spike in the terminations. Predictions have been made about the amount of abrasion that is likely to take place under different operating conditions; and these have been correlated with fatigue-test data obtained elsewhere. The investigation has shown that the behaviour of the terminations can now be understood, and the methods will allow the effects future changes in termination geometry to be predicted(H3).
Dr C.J. Burgoyne
Mr F.A McRobie
A PhD has been awarded on the dynamic stability of very-long span bridges (with spans over 2km) under wind loading. An improved model has been developed to examine the wind-induced oscillatory behaviour of such highly flexible bridges in both twisting and vertical motions: it uses four coupled oscillators. Two of these relate to the structural displacements in plunge and twist, while the other two relate to the behaviour of the leading-edge and trailing-edge fluid wakes. Active control measures such as moving winglets, and passive damping systems such as tuned mass dampers, have been included in the model to investigate their effectiveness in mitigating dangerous oscillations of the structure [Srinivasan, G., PhD dissertation, see Section IV].
Work is also in progress assessing the applicability of computational fluid dynamics (CFD) to the design of long-span bridges. Using a fully-coupled fluid-structure finite-element code, the various aeroelastic instabilities such as flutter and vortex-induced oscillations can be modelled in the time domain, providing detailed insights to supplement wind-tunnel tests and simpler mathematical descriptions(H8,H24).
Dr C.J. Burgoyne
A study of the lateral stability of precast concrete beams has been undertaken. These beams can become unstable under their own self-weight, especially when lifted, since in this configuration the restraint to lateral deflection is removed, and a toppling behaviour can result. Also of interest is a problem that arises during transportation, when the beam is supported on turntables at both ends. In this configuration, the primary problem arises from lateral loads caused by uneven ground or by centrifugal forces during cornering. The study has included the effects of initial imperfections, and has investigated the minor axis bending stresses that are induced. Design recommendations for these cases and for beams on rotationally flexible bearings are shortly to be published. Studies have also been undertaken on the effectiveness of temporary stiffening frames.
Dr C.J. Burgoyne
The long-term mechanical properties of polyester and aramid fibres are being studied, with a view to drawing up safe levels of tension load for long-term structural applications. In the case of polyester, the uses are normally as soil-reinforcement, while for aramids, the normal uses would be as prestressing tendons. In both cases, a proper understanding of the stress-rupture, creep and relaxation properties c an have a significant impact on the economics of using such materials(H9).
Dr C.J. Burgoyne
Although the normal use of non-metallic systems in concrete will be as prestressing tendons, such systems can also be used to reinforce against shear, and to provide restraint against compressive failure. Both end-uses require modifications to the conventional wisdom about structural behaviour(H16).
In the case of shear reinforcement, yielding of the reinforcing links can no longer be relied on, which means that plasticity theorems no longer hold. This, in turn, means that an explicit relationship is required between the shear deformation and the forces in the links. As with the partially-bonded longitudinal tendons discussed above, the bond behaviour is critical, since this controls the way in which the elements move relative to one another. A model of the equilibrium of the "tooth" of concrete between shear cracks is being developed.
The ability of systems based on fibres to provide restraint against compressive failure is well-known; but it has been ignored in the current design philosophy that "under-reinforced" failure is desirable, so that the tendon fails before the concrete. If beams are to be built with non-metallic tendons, and those tendons are brittle, that would imply that "over-reinforced" failure, where the concrete crushes before the tendon snaps, is desirable. Thus, a significant increase in structural ductility can be achieved by providing hoop reinforcement in the compression zone. The consequence is not to increase the overall strength significantly, but rather to enhance the strain capacity, so that substantial amounts of energy are dissipated within the concrete when it crushes.
A review of the most logical applications for composites in concrete has been undertaken. It has been concluded that resin-free rope systems are the most suitable material for use as external, unbonded, post-tensioning tendons; while partially-bonded pultrusions would be sensibly applied as internal pretensioning strands. It has also been concluded that these materials are not suitable for the reinforcement of concrete. It will be important for there to be a sensible appreciation of the costs of the various materials, including whole-life costs, before these materials can be satisfactorily applied. Novel forms of bridge construction should also be considered(H1,H2).
Dr C.R. Middleton
Dr C.T. Morley
Research on bridge assessment is continuing, with emphasis on the development and evaluation of collapse-analysis methods for assessing the strength and safety of various types of concrete bridges under different load configurations. The COBRAS generalised yield-line collapse-analysis program, developed within the group, has now been successfully released through the University's technology transfer company, C.U.T.S. This program is believed to be the world's most advanced commercially available yield-line program. It has now been successfully used both by the group and also by sixteen bridge authorities and consultants to assess the strength of a large number of concrete bridges as part of the national bridge assessment programme. Very substantial savings have resulted from the more realistic predictions of strength that have been obtained using this approach(H26,H27,H28).
Research to develop a method for interactively drawing failure mechanisms and automatically deriving compatible failure-mode geometries has been initiated. Model tests examining ductility requirements in concrete bridge slabs and the effects of reinforcement corrosion on bond and strength have also been conducted.
A major research contract funded by the Highways Agency, investigating shear in beam-and-slab concrete bridges, has been completed. Five half-scale bridge models have been tested in the laboratory to verify newly developed plasticity solutions for the collapse behaviour of this form of bridge(H17,H18,H19). As a result of this research, guidelines on the use of plastic analysis for determining the shear capacity of concrete beam-and-slab bridges have been submitted to the Highways Agency. This work forms the basis of a new advice note for the profession on the general application of plastic analysis methods for shear strength in bridge assessment.
A research project funded by the Highways Agency, which developed methodologies for assessing the whole-life performance of concrete bridges and in particular making allowance for the effects of material deterioration and actual vehicle loads on structural strength and safety, has now been completed(H31).
Following on from this work, a new research contract has been awarded by the Highways Agency to further research into the whole-life performance of concrete bridges and, in particular, to develop practical deterioration models for use in the assessment of concrete bridge performance. This project is part of an ongoing research effort aimed at investigating the suitability and limits of application of reliability-analysis methods in bridge engineering and bridge management(H15,H29,H30).
A novel software package combining yield-line methods of structural assessment with reliability analysis has been developed: it allows variability in the key parameters of strength and loading to be taken into account in a structural assessment. This provides a quantitative measure of the relative failure probabilities of structures, and it can be used for ranking existing bridges in order to identify those most in need of strengthening or replacement.
An investigation into the use of non-destructive testing techniques for determining the location and degree of corrosion in the reinforcing bars of concrete structures is continuing.
Dr S. Pellegrino
Dr S.D. Guest
A significant effort is under way, on behalf of the European Space Agency, to develop design and simulation techniques for the latest generation of deployable membrane reflectors. These reflectors consist of an expandable hub connected to a series of thin-walled foldable ribs, supporting a precision-cut membrane. This technology is being developed as a successor to space-rigidised inflatable reflectors. A computational scheme for determining the shape and pre-stress distribution in this kind of reflector has been developed for axi-symmetric configurations and has been validated experimentally(H20,H21,H22). Work on offset configurations is under way. The foldable ribs that will be used in these reflectors are similar to longitudinally curved tape measures. A study of their folding and deployment behaviour has shown that these ribs can be folded by forming localised elastic folds, like straight tape measures. However, for some particular patterns of folding the ribs may not be able to deploy fully, due to the existence of two different equilibrium configurations(H35).
Work has continued on new concepts for deployable reflector antennas. A new way of packaging thin-shell reflectors that was first developed during the course of a final-year undergraduate project has been presented at an international conference(H37) and has been selected for further development by Composite Optics Inc., San Diego.
Work is under way on gravity compensation systems for deployable structures. The purpose of such systems is to reduce, or eliminate, gravity loading on large spacecraft structures during ground testing. However, they interact with the supported structure in ways which are not fully understood. A methodology has been established for modelling this interaction in the case of rigid-panel solar arrays(H6), and experimental work is under way to validate the proposed approach.
The unexpected "multi-path" motion of a particular reflector that deploys automatically without difficulty, but does not properly retract when the direction of rotation of the deployment motors is reversed, is being investigated. Preliminary results have been presented at the Fourth World Congress of Computational Mechanics(H34).
Models of foldable membranes based on earlier work by Drs Guest and Pellegrino have been exhibited at the Science Museum in London, in the new Biomimetics display in the Challenge of Materials gallery. A model structure on loan from the Deployable Structures Laboratory attracted much attention during the official opening of the new display.
In September 1998 the Deployable Structures Group hosted the first ever symposium on Deployable Structures. The meeting, which was co-sponsored by the International Union of Theoretical and Applied Mechanics (IUTAM) and the International Association for Shell and Spatial Structures (IASS), attracted more than 80 participants from 18 countries. The proceedings of the Symposium will be published by Kluwer International Publishers.
An invited paper on deployable structures, reviewing work at Cambridge during the last ten years, has been presented at the "state of the association" meeting of IASS, in Madrid(H32).
Work has continued on the use of symmetry in structural analysis, and R.D. Kangwai has completed his PhD on this topic. A new advance has been the development of a symmetry extension of Maxwell's rule for the rigidity of pin-jointed structures. [Kangwai, R.D., PhD dissertation, see Section IV]
Dr S. Pellegrino
A study of rotary actuators driven by heat-induced phase transformations in shape-memory wires has been completed. Several working actuators have been designed, made, and tested. Analytical models for predicting the response of a complete actuator, including the temperature distribution in the wires, friction between their components, etc., have been found to work well.
Work on stick-slip piezoelectric actuators has continued. These actuators use an inertial mass to cause stick-slip motion of a tube whose movement is resisted by friction; they can achieve sub-micron accuracy. This principle has been extended to rotary actuators(H10) and also to two-degree-of-freedom actuators, which combine linear and rotary motion. Earlier work on actuators of this type has been published(H4).
Dr S. Pellegrino
Work on the non-linear vibration of thin-walled open-section cantilever beams has been completed. Due to the low torsional rigidity of these structures, at certain frequencies of excitation coupling between flexural and torsional modes of vibration leads to large amounts of energy being transferred from the directly excited mode to other modes. Regions of non-linear resonance with single and multi-mode periodic and aperiodic responses have been studied, both experimentally and by developing two-degree of freedom analytical models that incorporate modal interactions.
A new, robust implementation of the restoring-force method has been applied to the identification of pre-stressed cable structures(H36).
Mr F.A. McRobie
Research is being conducted into the dynamical behaviour of nonlinear elastic systems, focusing on the application of dynamical systems theory(H33, H25). In collaboration with Dr J Lasenby, the use of Clifford Algebra has been developed as the appropriate mathematical framework in which to construct a large-rotation rod theory suitable for finite-element implementation. Work has also been undertaken on the development of dimension-reduction algorithms for extracting low-dimensional dynamic models from massive numerical simulations, by the application of techniques of inertial manifold approximation(H7).
Professor C.R. Calladine
Work continues on the buckling of thin shell structures under compressive load. The main effort is being directed to understanding why the buckling strength of thin cylindrical shells is found in experiments to be proportional to thickness raised to the power of 1.5 rather than 1.0 in classical and in most current "imperfection sensitivity" analyses. Careful analysis of the self-weight buckling of open-topped cylindrical shells, by both experiment and computation, is providing suggestive clues pointing to a new way of thinking about the buckling of thin shells.
Professor C.R. Calladine
Professor A.C. Palmer
A laboratory-scale study of lateral thermal buckling of pipelines on the sea-bed has been completed. [Miles, D.J., PhD dissertation, see Section IV]. The mechanics involves a long, flexible elastic rod supported on a frictional foundation. It turns out that well-known results for the behaviour of such a beam on an elastic foundation give very little help in understanding the phenomena. The buckles that develop first, as temperature increases, eventually stop growing; growth always occurs in newly-formed lobes. This unexpected behaviour leads to some very simple design rules. Quite why the behaviour has such a simple pattern is at present not understood. [See also Petroleum Engineering.]
Work continues on the application of mechanics to masonry and geotechnical construction(H11,H12,H13,H14). It may seem strange that there is anything new to say about the methods of construction that were used two or three centuries ago. But the conventional structural wisdom of today is firmly rooted in nineteenth-century elasticity; and it is largely inappropriate to masonry and geotechnical construction, just as it was inappropriate to the understanding of the actual behaviour of real steel structures, as pointed out by Lord Baker in the 1950s. Our undergraduate and post-graduate courses on the theory of structures and solid mechanics continue to place a proper emphasis on the development of appropriate theory and the importance of experimental investigation.
Professor C.R. Calladine
Dr M.A. El Hassan
Work continues on the mechanics of double-helical DNA, making use of the results of single-crystal assays of atomic-level structure of both naked DNA and DNA bound to protein moieties. It has been known for some time that the flexibility of DNA involves a direct coupling between roll, slide and twist _ three of the six Eulerian degrees of freedom of an idealised dinucleotide step _ thereby proving a well-observed preferred mode of deformation of the molecule for mild distortion. A different and new mode of deformation has been discovered for stronger bending of DNA about proteins, which involves a simple physical pivoting of base-pairs about each other at the major-groove side. The same mode occurs whether the protein approaches from the major-groove side (CAP) or from the minor-groove side (TBP); and it appears to be an intrinsic feature of the double-helical structure(H5).
H1. Burgoyne, C.J. Advanced composites - the challenge to bridge designers. Proceedings, 5th Small and Medium Span Bridge Conference, Calgary, Canada (July 1998).
H2. Burgoyne, C.J. Rational use of advanced composites in concrete. Keynote Lecture, Proceedings, FRPRC-3, 3rd International Symposium on Non-Metallic (FRP) Reinforcement for Concrete Structures, Sapporo, Japan, 1, 75-88 (October 1997).
H3. Burgoyne, C.J., Brown, I.F. Transverse properties of bulk aramid fibres. Proceedings, FRPRCS-3, 3rd International Symposium on Non-Metallic (FRP) Reinforcement for Concrete Structures, Sapporo, Japan, 2, 35-42 (October 1997).
H4. Darby, A.P., Pellegrino, S. Inertial stick-slip actuator for active control of shape and vibration. Journal of Intelligent Materials Systems and Structures, 8, (12), 1001-1011 (December 1997).
H5. El Hassan, M.A., Calladine, C.R. Two distinct modes of protein-induced bending in DNA. Journal of Molecular Biology, 282, (2), 331-343 (1998).
H6. Fischer, A., Pellegrino, S. Interaction between gravity compensation suspension system and deployable structure. Proceedings, 39th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference and Exhibit, and AIAA/ASME/AHS Adaptive Structures Forum, Long Beach, CA, USA, 2, 1183-1192, Paper AIAA-98-1835 (April 1998).
H7. Foale, S., Thompson, J.M.T., McRobie, F.A. Numerical dimension-reduction methods for nonlinear shell vibrations. Journal of Sound and Vibration, 215, (3), 527-545 (1998).
H8. Frandsen, J.B., McRobie, F.A. Comparison of numerical and physical models for bridge deck aeroelasticity. Proceedings, International Association of Bridge and Structural Engineering Symposium on Long-Span and High Rise Structures, Kobe, Japan, 453-458. IABSE Reports 79 (September 1998).
H9. Guimaraes, G.B., Burgoyne, C.J. Thermal expansion of Kevlar 49 yarns. Proceedings, FRPRCS-3, 3rd International Symposium on Non-Metallic (FRP) Reinforcement for Concrete Structures, Sapporo, Japan, 2, 171178 (October 1997).
H10. Hack, T. Experiments with a new piezoelectric rotary actuator. Proceedings, IEEE International Frequency Control Symposium, Pasadena, CA, USA, 724-732 (May 1998).
H11. Heyman, J. Coulomb's analysis of soil thrust. Proceedings of the Institution of Civil Engineers, Geotechnical Engineering, 131, (2), 83-88 (April 1998).
H12. Heyman, J. Coulomb's memoir on statics: an essay in the history of civil engineering. (Imperial College Press, London, 1997 (reprint)). (First published by Cambridge University Press, 1972). ISBN 1-86094-057-9
H13. Heyman, J. Hooke's cubico-parabolical conoid. Notes and Records of the Royal Society of London, 52, (1), 39-50 (1998).
H14. Heyman, J. Structural Analysis: a Historical Approach. (Cambridge University Press, 1998). ISBN 0-521-62249-2
H15. Hogg, V., Middleton, C.R. Whole life performance profiles for highway structures. Proceedings, Institution of Civil Engineers/Highways Agency Symposium on the Management of Highway Structures, London (June 1998).
H16. Ibell, T.J., Burgoyne, C.J. The shear strength of concrete containing fibre reinforced plastic reinforcement. Proceedings, 23rd Conference on Our World in Concrete and Structures, Singapore (August 1998).
H17. Ibell, T.J., Morley, C.T., Middleton, C.R. A plasticity approach to the assessment of shear in concrete beam-and-slab bridges. Structural Engineer, 75, (19), 331-338 (October 1997).
H18. Ibell, T.J., Morley, C.T., Middleton, C.R. Shear assessment of concrete beam-and-slab bridges. Proceedings of the Institution of Civil Engineers, Structures and Buildings, 128, (3), 264-273 (August 1998).
H19. Ibell, T.J., Morley, C.T., Middleton, C.R. An upper-bound plastic analysis for shear. Magazine of Concrete Research, 50, (1), 67-73 (March 1998).
H20. Lai, C.Y., You, Z., Pellegrino, S. High precision shaping of deployable membrane reflectors. SPACE98: Proceedings, 6th International Conference and Exhibition on Engineering, Construction and Operations in Space, Albuquerque, NM, USA (April 1998); Edited by R.G. Galloway, S. Lokaj, 46-52 (American Society of Civil Engineers, Reston, VA, USA, 1998).
H21. Lai, C.Y., You, Z., Pellegrino, S. Shape and stress analysis of symmetric CRTS reflectors. Cambridge University Engineering Department Technical Report CUED/D-STRUCT/TR.170 (1997).
H22. Lai, C.Y., You, Z., Pellegrino, S. Shape of deployable membrane reflectors. Journal of Aerospace Engineering (ASCE), 11, (3), 73-80 (July 1998).
H23. Lees, J.M., Burgoyne, C.J., Rigid body analysis of concrete beams pre-tensioned with partially-bonded AFRP tendons. Proceedings, FRPRCS-3, 3rd International Symposium on Non-Metallic (FRP) Reinforcement for Concrete Structures, Sapporo, Japan, 2, 759-766 (October 1997).
H24. McRobie, F.A., Frandsen, J.B. Coupled fluid-structure modelling for long-span bridge design. Proceedings, 4th UK Conference on Wind Engineering, Institution of Civil Engineers Wind Engineering Society, Bristol, 57-62 (September 1998).
H25. McRobie, F.A., Popov, A.A., Thompson, J.M.T. Auto-parametric resonance in cylindrical shells using geometric averaging. Cambridge University Engineering Department Technical Report CUED/D-STRUCT/TR.175 (1998).
H26. Middleton, C.R. Case studies from the U.K. using yield-line analysis for concrete bridge assessment. Proceedings, Bridging the Millennia, Austroads Bridge Conference, Sydney, Australia; Edited by G.J. Chirgwin, 1, 83-97 (December 1997).
H27. Middleton, C.R. Concrete bridge assessment. Proceedings, Bridges 98, 6th Annual Surveyor Bridges Conference and Exhibition, London (March 1998).
H28. Middleton, C.R. Concrete bridge assessment, an alternative approach. Structural Engineer, 75, (23/24), 403-409 (December 1997).
H29. Middleton, C.R., Hogg, V. Review of basic variables for us in the reliability analysis of concrete highway bridges. Cambridge University Engineering Department Technical Report CUED/D-STRUCT/TR.172 (June 1998).
H30. Middleton, C.R., Hogg, V. Review of deterioration models used to predict corrosion in reinforced concrete structures. Cambridge University Engineering Department Technical Report CUED/D-STRUCT/TR.173 (June 1998).
H31. Middleton, C.R., Thoft-Christensen, P. Assessment of the reliability of concrete bridges. Proceedings, 13th ESREDA Seminar, International Seminar on Industrial Application of Structural Reliability Theory, Paris, France (October 1997).
H32. Pellegrino, S. Deployable structures. Current and Emerging Technologies of Shell and Spatial Structures, Proceedings, IASS Colloquium, Madrid, Spain (April 1997); Edited by J. Abel, R. Astudillo, N.K. Srivastava, 175188. Special publication of the Journal of the IASS. (International Association for Shell and Spatial Structures, 1998).
H33. Popov, A.A., Thompson, J.M.T., McRobie, F.A. Low-dimensional models of shell vibrations. Parametrically-excited vibration of cylindrical shells. Journal of Sound and Vibration, 209, (1), 163-186 (1998).
H34. Schulz, M., Pellegrino, S. `Multi-path' motion of deployable structures. In: Computational Mechanics: New Trends and Applications; Edited by E. Onate, S.R. Idelsohn (CIMNE, Barcelona, Spain, 1998).
H35. Seffen, K.A., You, Z., Pellegrino, S. Folding and deployment of curved springs. Cambridge University Engineering Department Technical Report CUED/D-STRUCT/TR.171 (1997).
H36. Tan, G.E.B., Pellegrino, S. Non-linear dynamic identification: an application to prestressed cable structures. Journal of Sound and Vibration, 208, (1), 33-45 (1997).
H37. Tibbalds, B., Guest, S.D., Pellegrino, S. Folding concept for flexible surface reflectors. Proceedings, 39th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference and Exhibit, and AIAA/ASME/AHS Adaptive Structures Forum, Long Beach, CA, USA, 2, 1193-1201, Paper AIAA-98-1836 (April 1998).
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Last modified: October 1999