Shoring is the temporary construction of a structure to support new or unsafe structure at the time of constructing or repairing. Before different types of shoring let’s know why it is used.
Necessity of Shoring
- When the structure shows signs of bulging out due to bad human skills.
- When the wall needs to repair due to cracks because of the unequal settlement of masonry or foundation.
- When a structure has to dismantle of very less distance or near other structure.
- When openings are to be made for windows and doors.
Types of shoring
- Raking shores
- Flying shores
- Dead shores
- In this method, inclined members called raker arc used to give lateral support to the wall.
- A raking shore consists of the following components:- rakers or inclined member, wall plates, needles, cleats, bracing, and sole plate.
- The wall plate, about 20 to 25 cm wide and 5 to 7.5 cm thick is placed vertically along the face of the wall and is secured by means of needles of 10 cm by 7.5 cm section.
- These needles penetrate the wall by about 10 cm.
- In order that the needles do not get sheared off due to the thrust of the raker, the needles are further strengthened by means of cleats which are nailed directly to the wall plate.
- Rakers against the needles in such a way that the center line of the raker and the wall meet at the floor level. Thus, there will be one raker corresponding to each floor.
- These rakers are inter-connected by struts, to prevent their buckling. The feet of rakers are stiffened to an inclined sole plate, by the mean of iron dog embedded into the ground. The feet of rakers are stiffened by the help of hoop iron near the sole plate.
- The wall plate distributes the pressure to the wall uniformly.
Points to remember while using Raking shoring in construction
- Rakers should be inclined to the ground by 45, to make them more effective. However, in practice, the angle may vary from 45 to 75. The top raker should be inclined less than 75 degrees.
- For buildings having more story, the length of raker can be reduced by introducing rider raker.
- The rider should be properly braced at intervals.
- The size of the rakers should be chosen according to the maximum force exerted by the wall or structure on which working has to do.
- The centerline of a raker and the wall should not coincide anywhere than the floor level.
- If a longer length of the wall needs support, shoring may be spaced at 3 to 4.5 m spacing, depending upon the requirements.
- The sole plate should be properly embedded into the ground, at an inclination, and should of the proper section. The size of the sole plate should be such that it accommodates all the rakers, and a cleat provided along the outer edge.
- Wedges should not be used on sole plates.
Flying or Horizontal Shores
Flying or Horizontal Shores
- Such shores are used to give horizontal support to two adjacent, parallel party walls which have become unsafe due to the removal or collapse of the intermediate building.
- All types of arrangements supporting the unsafe structure in which the shores do not reach the ground fall under this category.
- If the walls are very close to each other i.e up to 9m, the single flying shore can be constructed. It consists of struts, needles, cleats, horizontal shore, folding wedges, straining, wall plates, etc.
- When the distance between the walls is more, a compound or double flying shore may be provided.
- Flying shores have the advantage that building operations of the ground are not obstructed.
Points to remember while using Flying shoring in construction
- The center lines of flying shore and struts and those of the walls should meet at floor levels of the two buildings. If the floor-levels are different, horizontal shore
- should be placed either midway between the levels of the two-floor of equal strength, or it should be placed at the level of the weaker floor.
- The struts should preferably be inclined at 45′. In no case should this inclination exceed 60 degrees.
- The flying shores should be spaced at 3 to 4.5 m centers, along with the two walls, and horizontal braces should be introduced between adjacent shores.
- A large factor of safety should be used for determining sections of various members of the shoring since it is very difficult to assess the actual loads.
- Flying shores are inserted when the old building is being removed and should be kept in position till the new unit is constructed.
Dead or vertical shores
- Such types of shoring consist of vertical members known as dead shores supporting horizontal member known as needles.
- The needles transfer the weight of the wall to the dead shores. This types of shoring are provided to serve the following purposes:
- To repair the broken and bulging lower part of the wall.
- To rebuild or deepen the existing foundation.
- To make the large opening at a lower part of the existing wall.
- Holes are made in the wall at the required and appropriate height. Needles, which are made of the thick wooden section or of steel, are inserted in the holes.
- Each needle is supported at its two way ends by vertical posts or dead shores.
- The dead shores are made stand far from the walls so that repair work is not blocked at any time.
- The Sole plates and folding wedges support the shores from slipping.
Points to remember while using Dead or vertical shoring in construction
- The section of needles and dead shores should be adequate to transfer the load, which can be estimated with a fair degree of accuracy.
- The needles are spaced at 1 to 2 m. more than or equals to three needles should be used for an opening of the wall.
- If the opening is made in an external wall, the length of outer dead shores will be greater than the inner ones.
- The dead shores are supported on sole plates. Folding wedges should be inserted between the two. It is appropriate to use one single soleplate between two dead shores in a row.
- The floors should be suitably supported from inside.
- If the strength of the external wall is low or weak, raking shores may be provided, in addition to the dead shores.
- Shores should not be removed before the structure has gained their sufficient strength. The shores must remain at least 7 days on the structure from the time of starting. The new work should have proper strutting.
- Removal operation is done in 2 days intervals.
Hence, These are the different types of Shoring. and you should remember the following points while using shoring in construction
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