Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

SHORING (from " shore," a prop)

Online Encyclopedia
Originally appearing in Volume V24, Page 1007 of the 1911 Encyclopedia Britannica.
Spread the word: del.icio.us del.icio.us it!

See also:

SHORING (from " See also:shore," a prop)  , an operation connected with See also:building . It is often necessary before actual building is begun to support adjoining premises while the See also:work of excavating for underground apartments is being carried out . The See also:art of See also:shoring comprises the temporary support of buildings, and may become necessary because of the failure or See also:settlement of some portion of the structure or for the purpose of upholding the upper portion while alterations are being made in the See also:lower . There are several different forms of shoring, each adapted to suit See also:peculiar circumstances . Much of the shoring for See also:ordinary cases is done with heavy, roughly sawn timbers strongly braced together, but for especially heavy work See also:steel members may be introduced and prove of See also:great value . There is the trouble in connexion with their use, however, that connexions between steel members are not made with the same facility as between pieces of See also:timber . The See also:form of See also:shore in most See also:general use is that known as the raking shore . It consists of one or more timbers sloping from the See also:face of the structure to be supported and bedded upon the ground . As the ground is usually of a more or less yielding nature, a stout timber See also:plate termed a See also:sole-piece, of sufficient See also:area to withstand being driven into the See also:soil, is placed to receive the See also:base of the raking timber or timbers . A See also:wall-plate, with the See also:object of increasing the area of support, is fixed to the face of the wall by means of hooks driven into the wall . Where space is available an See also:angle of 6o° is the best to adopt for the See also:main shore, the See also:auxiliary members ranging in their slope from 450 to 75° . In many cases, especially in towns, the angle of slope is governed by outside influences such as the width of the footway .

Rakingshores are erected in " systems " of two or more members placed in the same See also:

vertical See also:plane at right angles to the face of the wall . The different members rise fanwise from the sole-plate to support the wall at different points . The distance horizontally between the systems depends on the See also:condition of the building being propped up, and also upon the spacing of its window and other openings . The usual spacing is Io ft. or 15 ft.• apart, but this distance has often to be varied ccording to the positions of the openings in the wall . The application of the shores should be carefully made and support given only where there is a corresponding thrust inside, such as from a See also:floor or roof, as without this the shore is liable to See also:act more as a destructive See also:agent than a supporting one, and cause the wall to See also:cave in at that point, or placed against a See also:parapet wall it might have the effect of pushing it over . The members, therefore, should be so placed as to meet the wall at a point somewhat below the floor or roof, so that if their length were continue 1 they would meet and support the end of the floor or roof inside . Perhaps the best See also:idea of the positions and functions of the various component parts of a See also:system of raking shores can be obtained from a description of the various members, coupled with some little study of the illustrations (fig . I) . The names of the different timbers are therefore set out here, and against each See also:part is given a See also:short description of its use and position . Raking Shore, or Raker.—This is a piece of timber sloping up from the sole-plate to the wall-piece . For a detail See also:drawing of the connexion between the raker and wall-plate see fig . 2 .

The See also:

top and longest shore is often formed in two pieces, in which form it can be more conveniently handled . The upper piece is termed the See also:riding shore or rider, and the lower member which supports it is known as the back shore . At the junction of the rider and back shore a pair of folding wedges is introduced and driven in to give the See also:head of the rider a See also:firm bearing against the See also:needle and wall-plate above . The sole-piece has already been mentioned as the timber base upon which the shores take their See also:bed or bearing . It usually consists of a piece of 11 by 3 See also:plank, but when the ground is soft or the load supported very great it should be bedded on a See also:platform of timber to spread the See also:weight over a large area . The sole should be placed sloping down towards the building at something less than a right angle (say 8o°) with the inside of the shore to enable the latter to be gradually wall ukz levered to a firm bearing with the aid of a pr•"iilj~l,\\~ 9,er crowbar . Wedging should not be resorted to or the already shaky building may sustain further injury through the vibration . When in position the See also:foot of the shore is fixed by See also:dog-irons to the sole- =pia piece, and for additional See also:security a See also:cleat 1s spiked on the sole tight up to the shore to prevent any slipping . Braces.—W See also:hen more than one shore takes a bearing upon the sole-piece the feet of the several members are stiffened and braced. either by having rough boarding nailed right across them or by being See also:bound together with a number of rounds of hoop-See also:iron . For further strength also braces of 1-in. boards, 6 to 9 in. wide, are taken across from the wall-plate to the topmost shore and spiked to each intervening member, binding the whole together . These braces should be fixed a little below the junctions of the heads of the shores with the wall-plate . The wall-plate has already been referred to .

It is usually a See also:

deal 9 in. wide by 3 in. thick, secured tightly against the face of the wall with wrought-iron wall hooks, forming a See also:good See also:abutment for the shores and serving to spread the support FIo . I . afforded by them . Holes are cut through this plate to receive the needles (or joggles as they are sometimes termed to distinguish them from the needles used in dead shoring, which are large See also:horizontal members usually of balk timber), which are pieces of See also:wood about t ft. See also:long and 4 in. square in See also:section, cut with a See also:shoulder to See also:butt against the wall-plate . A portion of a See also:brick or See also:stone is removed from the wall and the end of the needle is passed through the rectangular hole in the wall-plate and fitted into the See also:recess in the wall . Fm . 4 . The head of the needle projects about 41 in. beyond the face of the wall-plate and forms an abutment for the head of the shore . The head of the shore is notched to See also:fit the underside of the needle to prevent any See also:movement sideways . If this is not done the shore is liable to be acted upon by the See also:wind and be blown down . A small See also:block of wood, cut somewhat after the See also:fashion of a See also:wedge and termed a cleat, is fixed above the needle to keep the latter quite firm . Cleats are used also in other positions to keep timbers in position .

Wedges are used to obtain a tight bearing for the rider shores and are used at their base . As little force as possible must be em- ployed in See also:

driving them as a.a vibration is liable to injure the already weakened wall . Horizontal shores, or flying shores as they are more often termed by the workman, may be employed for spans up to about 35 ft . They are used to support the party walls of the houses adjoining the premises being rebuilt . They are erected during the pulling down operations and removed as the new building is raised and there is no further need for them . A system of flying shores consists of one or more horizontal timbers, sometimes known as dog shores, cut in tightly between the wall-plates fixed with hooks to the faces of the walls of the ad-joining buildings (fig . 3) . These horizontal members are supported at each end by cleats and needles fixed in the wall-plate as described for raking shoring . The shores are supported in their length by inclined braces springing from needles fixed near the lower ends of the wall-plates and serving to strut the shore at a point about a third of its length from the wall . Corresponding braces are carried from the upper See also:surface of the shore and abut against needles at the upper ends of the plates . Straining pieces are secured to the upper and lower faces of the shore to serve as abutments for the ends of the braces . The best angle for these braces is one of 45 °, but a smaller inclination than this is frequently adopted .

Wedges are inserted, usually at the end of the flyer so as to tighten this up between the wall-plates, and sometimes between the braces and the straining piece, and carefully driven to tighten up the whole and cause each timber to find a See also:

close bearing . If the adjoining premises are of considerable height and especially if it is proposed to undertake extensive excavations, the systems of flying shores may need to be somewhat complicated, each consisting of several horizontal members spaced from to to 13 ft. apart and well strutted one to another and to the wall-plate (fig . 4) . In the application of this form of shoring, as in raking shores, the same rules apply as regards placing the shores on the face of the wall in a proper position to obtain a solid abutment on a floor or roof on the other See also:side . The members should be securely dogged and spiked together to form a homogeneous See also:frame-work capable of resisting the attacks of a strong wind, which in an exposed position will sometimes destroy a poorly constructed framework . Horizontal shores should be adopted wherever possible in preference to raking shores . Besides being more economical, they are more convenient and more effectual than rakers springing from the ground, especially if the height of the building is considerable and the span at the most not much over 30 ft . Apart from the See also:economy effected, they See also:present a See also:direct resistance to the thrust and are well out of the way of any building operations that may be carried on below them, so that there is no See also:risk of their being accidentally disturbed, whereas the feet of raking shores are generally in the way of the workmen, and if not disturbed by accidental blows from materials or carts will very likely be loosened and rendered useless by the digging and pumping which is going on around them . Needle shoring is the next method of temporary support to come under See also:consideration . It is known also as vertical shoring and dead shoring, and is the means usually adopted to support temporarily Fm . 5 . Y[RTICAL IIORING See also:ELEVATION the upper portion of the walls of a building when it is found necessary to reconstruct the See also:foundations or to make large openings in the lower parts of the wall, as, for example, when putting a See also:shop front in an existing building .

Phoenix-squares

- This form of shoring consists of horizontal members of balk timber termed needles (very different from the needles used in raking and flying shoring), which are passed through holes in the wall to be supported, at a sufficient height to allow of the insertion of any See also:

arch or lintels that may be necessary above the opening it is proposed to cut (See also:figs . 5 and 6) . The needles are sup-ported at each end by an upright timber or dead shore, one on each side of the wall to each needle . These should not be allowed to See also:rest upon any floor or vault but be carried down to a solid See also:foundation and set upon and securely dogged to ;a timber See also:sleeper See also:running parallel to the wall . If it is not practicable to take the inner dead shore through intervening floors down to the solid ground in one piece, and it is necessary for its base to be set upon the floor or upon sleepers placed on the floor, the strutting must be continued in a direct See also:line below it until a firm foundation is obtained . Between the needle and the head of the dead shores folding wedges are inserted to force the horizontal supporting balk firmly up to the underside of the See also:masonry . Connexions between the dead shores and t he needles and sleepers are made with wrought iron See also:dogs . The spacing of the systems of dead shoring depends to a large extent upon the material with which the wall is constructed; for See also:brickwork they should be placed at intervals not greater than 6 ft . With this form of shoring especially it is often found necessary to adopt other methods auxiliary to the main shoring . These take the form of raking or flying shores from the face of the building . All the openings in the wall above should be well strutted between their reveals to prevent any alteration of shape taking See also:place . Inside the building vertical shores or strutting must be carried up independently in a direct line between the floors with head and sole plates at floor level and See also:ceiling .

This strutting must start from a firm foundation at the bottom of the building and be tightly wedged up so as to relieve the wall of any weight from the floors and roof . To obviate settlement as much as possible, work done in underpinning should be built slowly with See also:

Portland See also:cement See also:mortar mixed in strong proportions . Before the shoring is removed at least a See also:week should elapse to allow the work to set hard and firm . Then the needles should be carefully loosened and :removed and the holes from which they were withdrawn made good . The See also:remainder of the props can then be " struck," leaving the raking or flying shores until the last . If possible this work should be spread over several days, an See also:interval of a See also:day or two being See also:left between the removal of each portion of timbering to allow the work gradually to set on its new See also:bearings . Shoring should be the subject of careful calculations to ascertain the most suitable sizes of timbers and to determine the most appropriate points of support . This is not always done, however, and much work of this See also:character is carried out by See also:rule of thumb methods . The usual result is that the timber used is of a much greater See also:size than is really necessary, although as the material is not much injured and is available on removal for re-use this fact is not ofgreat consequence . Such methods perhaps work very well for ordinary buildings, but in See also:special cases they may very well See also:lead to shoring being constructed in too fragile a manner, with serious results . Some rules which experience has shown to work satisfactorily for ordinary work are given below, together with the approximate scantlings of the timber required . Rules and Sizes for Raking Shores.—Walls 15 ft. to 30 ft. high should have 2 shores to each system; if 30 ft. to 40 ft. in height, 3 shores each system; if 40 ft. or more in height, 4 shores, with an additional shore for each io ft. in-crease .

Shoring is rarely seen more than 5 shores high . The angle of the main shores is usually about 60°, and none of the timbers should exceed an angle of 75°• Some of the lower shores will slope much less than this, at angles between 40°and 6o° . The systems should not be placed at a greater distance apart than 15 ft . It is often found convenient to place them at the piers between window openings . As regards the sizes of the timbers used for walls 15 ft. to 20 ft. high, the shores may be 4 in. or 5 in. square in section; for walls 20 ft. to 30 ft. high, 6 in. by 6 in., or 9 in. by 44 in.; for walls 30 ft. to 35 ft. high, 12 in. by 6 in., or 8 in. by 8 in.; for walls 40 ft. to 50 ft. high, 9 in. by 9 in.; for walls above this height 12 in. by 9 in . For Horizontal or Flying Shores.—For spans not exceeding 15 ft. the See also:

principal strut may be 6 in. by 4 in., with raking struts 4 in. by 4 in.; for spans exceeding 15 ft. but not exceeding 35 ft. the size of the principal strut should be from 6 in. to 9 in. square, and the raking struts from 6 in. by 4 in. to 9 in. by 6 in . Interesting examples of shoring on a large See also:scale may frequently From a photograph by 'W . T . See also:Green . be seen applied to large buildings in the course of repair or restoration . The rebuilding of the foundations of the retro-See also:choir and See also:lady See also:chapel of See also:Winchester See also:cathedral which was carried out in the autumn From a photograph by W . T .

Green . of 1906 necessitated the erection of a very elaborate and complicated " Gathering the See also:

Flock on See also:Maxwell See also:Bank," a soft-ground See also:etching; " The See also:Ferry over the See also:Blyth," " Walberswick See also:Pier," soft-ground; " Dutch Greengrocery," " See also:Noon on the Zuider Zee," " De-venter," " Strolling Players at Lydd," " An See also:April Day in See also:Kent," and " Staithes," all etchings; " A Wintry Blast on the See also:Stour-See also:bridge See also:Canal," " Peveril's See also:Castle," and " See also:Niagara Falls," dry points; " The See also:Curfew," " A Span of old See also:Battersea Bridge," and " Sunrise on See also:Whitby Scaur," aquatints; " Ebbtide, Putney Bridge," The Weary See also:Moon was in the Wane," " Solway Fishers," " The Lifting See also:Cloud," and " A Slant of See also:Light in Poiperro See also:Harbour," mezzotints . Short was elected A.R.A. in 1906 when the See also:rank of See also:associate-engraver was revived . As head of the See also:Engraving School at the Royal See also:College of Art, See also:South See also:Kensington, he had great See also:influence on younger engravers . Short was elected to the Royal Society of Painter-Etchers and Engravers in 1885, and took a prominent part in conducting its affairs . In 1910 he succeeded See also:Sir See also:Seymour See also:Haden as See also:president . He received, amongst other distinctions, the See also:gold See also:medal for engraving at the See also:Paris See also:International See also:Exhibition, 1889, and another gold medal (Rappel) 1900 . The Etched and Engraved Work of See also:Frank Short, by See also:Edward F . See also:Strange (1908), describes 285 plates, by the artist . (C . H.*) SHORTHAND, a See also:term applied to all 'systems of brief See also:hand-See also:writing which are intended to enable a See also:person to write legibly at the See also:rate of speech . Synonyms in See also:common use are See also:stenography (from vTEVOS, narrow or close), and tachygraphy (from Taxbs, See also:swift), or occasionally brachygraphy (from (3paxus, short) .

See also:

Greek and See also:Roman Tachygraphy.—The question of the existence among the See also:ancient Greeks of a system of true tachygraphy, that is, of a shorthand capable of keeping See also:pace with human speech, has not yet been solved . From surviving records we know that there were, both in the 4th See also:century B.C. and in the See also:early centuries of the See also:Christian era, as well as in the See also:middle ages, systems in practice whereby words could be expressed in shortened form by signs or See also:groups of signs occupying less space than the ordinary method of longhand writing . But such systems appear to have been systems of brachygraphy or stenography, that is, of shortened writing, which were not necessarily also systems of tachygraphy properly so called . If, however, as there is some See also:reason to believe, the Roman system of tachygraphy, as exhibited in the Tironian notes (see below) was derived from a Greek system, it may fairly be inferred that the latter system was also a See also:developed system of tachygraphy . But, be that as it may, no very early specimens of Greek shorthand have hitherto come to light; and the See also:key to the decipherment of the See also:steno-graphic See also:inscriptions in the waxen See also:book of the 3rd century in the See also:British Museum (see below) still remains to be discovered . We are therefore in the dark whether we have in this MS. an example of true tachygraphic writing . Here it may be noticed that 'certain words of See also:Diogenes Laertius have been taken to imply that See also:Xenophon wrote shorthand notes (ulrovrtµetwa6yevos) of the lectures of See also:Socrates; yet a similar expression in another passage, which will not See also:bear this meaning, renders it hardly possible that tachygraphy is referred to . The surviving records of Greek shorthand are not very numerous, although they are scattered through a long See also:period of See also:time, beginning with the 4th century B.C. and extending to the 14th century . They have been arranged in three groups . At the head of the first See also:group, which embraces all that has been found dating down to the 3rd century, is a remarkable inscription, unfortunately fragmentary, on a See also:marble slab discovered'on the See also:Acropolis of See also:Athens in 1884, which is attributed to the 4th century n.c.; and it is on this See also:discovery that the actual claim of tachygraphy to have been practised among the ancient Greeks chiefly rests . The inscription describes a system, or rather part of a system, whereby certain vowels and consonants can be expressed by strokes placed in various positions . But here, too, it has been urged that we have the explanation of a system of brachygraphy only, and not one of tachygraphy .

To the first group also belong a few specimens of shorthand writing on papyri of the and and 3rd centuries, and, above all, the most important MS. of Greek stenographic symbols hitherto discovered . This is the waxen book already referred to (Brit . See also:

Mus., Add . MS . 33,270), consisting of seven wooden tablets coated with See also:wax on both sides, and two covers thus coated on the inner sides, which seems to have been the exercise-book of a shorthand See also:scholar who has covered its pages with symbols, which in places are repeated again and again as if for practice . arrangement of shoring to uphold the masonry while the work of underpinning the walls was being carried on . The foundations of the eastern portion of the cathedral were found to be dangerously insecure, being in fact laid upon a bed of soft See also:marl only io ft. below the surface of the ground, in spite of the fact that at a See also:depth of 16 ft. a hard solid stratum of See also:gravel, at least 6 ft. thick, is arrived at . The See also:medieval builders without doubt entertained suspicions as to the sustaining See also:power of their proposed foundation, and so to ensure stability, as they thought, strengthened it by placing below the masonry horizontal layers of See also:beech trees, filling up the interstices with hard See also:chalk and flints . These contrivances were not sufficient to prevent the See also:gradual sinking, through succeeding centuries, of the heavy See also:mass of masonry . This not only affected the footings of the building, but caused fissures of an alarming nature in the vaulting and walls . Under the direction of Mr T . G .

See also:

Jackson a carefully designed arrangement of shoring was applied, consisting of raking shores, flying shores and needling, for the purpose of the under-pinning, with specially designed timbering to support the See also:arches and vaulting while they were undergoing repair . The foundations were found to be much undermined by See also:water, which filled the excavations made for the underpinning in such quantities that it was necessary to employ a See also:diver to See also:deposit cement See also:concrete in bagfuls upon the gravel bed to which the new foundations are taken down . The See also:illustration (fig . 7) will readily explain the See also:external shoring above described, while fig . 8 shows the interior shoring of the See also:presbytery .

End of Article: SHORING (from " shore," a prop)
[back]
SHOREHAM
[next]
SHORNCLIFFE

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click and select "copy." Paste it into a website, email, or other HTML document.