Static structures (e.g. – buildings) – With component having discrete prestressing means – Axially loaded vertical structure
Patent
1995-12-14
1998-09-01
Canfield, Robert
Static structures (e.g., buildings)
With component having discrete prestressing means
Axially loaded vertical structure
52514, 527214, 527363, 527374, 527381, 527413, E04C 334
Patent
active
057994510
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
This invention relates to the repair and reinforcement of structural members, and more particularly to the external lateral reinforcement of load bearing structural members.
The repair and strengthening of structures will progressively increase in importance in the construction industry due to the need for upgrading of an ageing building stock, which is chronically exposed to an environmental loading of varying nature. This is particularly true in areas where hazards, like earthquakes and strong winds have not been taken into account during the design stages. However, the need for strengthening of weak structures may also arise as a result of the introduction of new stricter codes of practice, better understanding or redefinition of expected loading and new definitions of risk. Notwithstanding the above, in places where quality control measures are still not strictly implemented during construction, many structures are still built with inherent errors due to bad design, poor construction materials and poor construction workmanship. Hence, a large proportion of buildings are in need of repair or strengthening, before they are even completed.
Many load bearing members, particularly reinforced concrete columns in structures and buildings, fail to perform satisfactorily in service, because they have insufficient strength and/or ductility to withstand the external forces involved. When the elastic limits of a structure subjected to external actions are exceeded, its ductility will be the deciding factor in preventing damage and collapse. Where damage has taken place, an urgent objective is to repair and reinforce any damaged structures.
A variety of repair and reinforcement methods are currently in use. These methods include, gluing of thin steel sheets, plate bonding, jacketing, heat tensioning of thin steel plates or tie plates, tying of steel ties using screws, heated and hammered spirals etc. Most such techniques are extremely costly, time consuming, need skilled personnel for welding and gluing, and require a further concrete jacket to be applied around the damaged member thereby increasing its dimensions. In addition, it is quite difficult to evaluate the effectiveness of any repair or reinforcement.
Other proposals have involved wrapping or winding various materials around the structural member. In GB1446425 a concrete structural member of circular section is surrounded by a tensioned wire of high tensile strength wound helically onto the member. In U.S. Pat. No. 4,786,341 a fibre-reinrorced plastic is applied onto the outer periphery of a concrete structural member. Finally in U.S. Pat. No. 5,044,044 a concrete column is overlapped with high strength stretchable fibres, coated with hardenable material to form an outer shell, and a hardenable liquid injected under the fibres in an amount sufficient to cause the stretching of the fibres. None of these methods have been found to be very efficient or effective.
In British Patent Nos. 1054588, 1156245, and 1157494, there is described a concrete pressure vessel which is circumferentially stressed by means of prestressing wires wound therearound under tension in a plurality of layers, such wires being accommodated in circumferential troughs or channels which are provided in or on the outer surface of the vessel or structure and serve to locate the layers of wires. However, the prestressed wires are merely positioned to assist the walls of the concrete pressure vessel or other circumferentially stressed concrete structure to withstand the internal pressure involved, and there is no suggestion that the pre-stressed wires increase the vessel's strength and ductility, when subjected to axial, bending and shear actions.
SUMMARY
It is an object of the present invention to provide a method of repairing, strengthening or reinforcing a structural member, which comprises laterally confining the member in order to improve its strength and ductility and thereby enhance its ability to withstand external forces, particularly of seismic origin.
In one aspect,
REFERENCES:
patent: 1107255 (1914-08-01), Rae
patent: 2480180 (1949-08-01), Bolton
patent: 3813098 (1974-05-01), Fischer et al.
patent: 3817010 (1974-06-01), Stegmuller
patent: 4323200 (1982-04-01), Denoor
patent: 4432175 (1984-02-01), Smith
patent: 4786341 (1988-11-01), Kobatake
patent: 5043033 (1991-08-01), Fyfe
patent: 5133510 (1992-07-01), Davis
patent: 5218810 (1993-06-01), Isley, Jr.
patent: 5326410 (1994-07-01), Boyles
patent: 5444952 (1995-08-01), Jackson
Canfield Robert
The University of Sheffield
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