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Shoring and Types of ShoringShoring is the means of providing temporary support to attain stability of the structure

under the following circumstances.

(i) To unsafe structures, the stability of which has been endangered due to the unequal

settlement of the foundation, or due to the removal of adjacent buildings, or due to the

defective or bad workmanship, or due to any other reason.

(ii) To structures which might become unstable, when certain alterations are required to be

done in the structure itself (such as re-modelling of walls, etc.) or, during the alterations of

adjacent buildings such as underpinning of (the adjacent building) foundations, dismantling

of adjacent building, etc.

The following points in connection with the installation of shores should be noted.

(i) Temporary support by means of shores to unsafe structures may be given eternally or

intern ally and in certain cases they may be provided from both sides of the wall to produce

additional stability. !ut, before the installation of shores, the necessary permission from thelocal authority should be obtained.

(ii) "horing is used to maintain equilibriums the over-turning forces must be resisted by the

supporting shores. To achieve this, it is essential that the lines of action of the overturning

forces in floors and roofs, the forces in walls and the reaction of the shores must meet at a

single point.

(iii) "horing may be made of timber but for resisting heavy loads, it may be built of steel

tubes, suitably braced steel sections or a combination of timber and steel tubes. #hatever

material is used, shoring should be strong enough to resist the acting forces, consistent with

economy.(iv) This temporary shoring should be provided to unsafe structures till such times as they

have been made stable.

Types of Shoring:

"horing are classified into the following three classes either on the basis of their supporting

characteristics or their position in the space$

%. &aking or 'nclined "hores

.lying or *ori+ontal "hores

. ead or vertical shores.

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&aking "hores

Raking shoresis a system of giving temporary support to an unsafe wall. The

construction of raking shores, also known asinclined shore, varies with the conditions

of site. 'n all cases wall-plate cm. cm. to cm. /0 cm. it si+e is fied against the

unsafe wall with hooks. The wall-plate is further secured to the wall by means of needles.

The needles which are %1 cm. x /0 cm. in section penetrate inside the wall for a distance of

about %1 cm 'n turn, the needles are strengthened by providing wooden cleats. The top end

of the inclined rakers rest against the needles. 2t their base the rakers are supported by a

sole piece bedded in an inclined position in the ground. The rakers are secured to the sole

piece by cleats and dogs. 'n soft ground the area of the sole piece is increased so as to

distribute the pressure over large area. 'n places where more rakers are provided, they are

bound together by means of hoop iron or braces 25 cm. thick and % cm.wide. The

inclination of the outer raker to the ground should vary between 01 to 75. The sets of

shores should be usually placed at to 3.0 m. centre to centre along the wall length.

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lying "hores

Flying shores are hori+ontal supports that are provided for supporting temporarily the

parallel walls of the two adjacent buildings, which may tend to collapse or damage when one

of the intermediate buildings has to be pulled down and rebuilt . "uch conditions

occasionally arise when one of the intermediate buildings from a series of buildings

standing side by side is either required to be reconstructed or has collapsed due to some

reason.

2 single flying shoresconsists of wall plates, struts, straining pieces, hori+ontal shore (or,

hori+ontal strut), needles, cleats and wedges, as shown in the above image. 4ike raking

shores, in this system also, the wall plates are secured against the walls by means of

needles and cleats. Theflying shoresis held in position by wedges, needles and cleats to the

wall plate as shown at section 5 in the image. The inclined struts are supported by the

needles at their one end and straining sill at the other end. "training sill, in turn, is spiked to

the hori+ontal shore.

(i) uring reconstruction of the intermediate building, the flying shorestemporarily take

up the position of the dismantled building.

(ii) The centre-lines offlying shores and struts6 and flying shores and walls, should meet atthe floor levels. 'f the floor levels of two buildings are different or their strengths are

different, then shore positions should be provided as shown in the below image .

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(iii) The maimum distance of about %1 metre between the parallel walls can be supported

by single flying shores. or a distance more than %1 m, a double flying shore, having a

trussed form work as shown in the below image, is employed.

(iv) The flying shores are kept in position so long as the adjacent buildings are made stable

by constructing the building to a sufficient height.

(v) 7nlike the inclined shoring in this type, only one set of shoring is employed to

strengthen the two adjacentwalls.

(vi)2 larger factor of safety should be adopted in design analysis of flying shores because of

uncertainty of actual loads. or shores to be more effective, the struts should be inclined at

38, if possible.

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ead or 9ertical "hores

'n this system of shoring, the vertical members known as dead shores are used to support

temporarily the walls, roofs, floors, etc., by providing horizontal membersknown

as needles, to meet one or more of the following objectives$

(i) To rebuild the lower part of a defective load bearing wall6 or

(ii) To rebuild (or replace) or deepen the eisting foundations, which have either become

unsafe or require strengthening for carrying heavier loads6 or

(iii) To provide large openings in the eisting walls such as doors, windows, shop fronts or

garages at a lower level.

'n the above image, the arrangement is shown to meet first two objectives. 'n this system,wooden needles consisting of thick sections are used to transfer the overhead loads to the

properly braced vertical shores. These vertical or dead shores, in turn, transfer those loads

to the ground on firm foundations below. The other details regarding introducing of rolled

steel joists for supporting, strutting of floors by props, use of wedges, sole pieces, are self-

eplanatory.

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'n the below image, the arrangement is shown to meet the third objective, i.e., providing a

large opening in an eisting wall. To meet this objective following procedure is adopted,

(i) !efore providing dead shores to a building, all door and window openings are properly

strutted to resist any possible deformation, and then inside floors of the building are also

strutted by props or vertical posts. 2t the top and bottom of these vertical struts or posts,

timber heads and sole pieces are provided to distribute the load more effectively, wedges are

also used at the bottom or foot of prop for tightening purpose.

(ii) *oles are than cut in the wall by crow bar at points above the required opening, at a

distance of % to . m depending upon the weight of structure above.

(iii) Through these holes, timber or steel hori+ontal beams, called needles, are inserted and

projected at right angles on each side of the wall. ("ee in above image). The projected endsof needle beams are supported on heavy transfer the loads to the ground and hence are

made to rest on a sole plate, firmly bedded on the ground.

(iv) The shores are removed only after the new constructionwork has attained sufficient

strength and this period of removal usually is not less than / days.

(v) The sequence of removal of shoring system should be needles first and then strutting

from openings and floor strutting inside the building.

"ometimes, raking shores are provided to support the wall from above the proposed

opening to safeguard against shocks and vibrations during wall cutting. 'f raking shores are

used, they should be removed after the whole dead shores system is removed.

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