Setting Out

 

Setting out is done to locate the position of the structural parts as in the detailed drawing with geometrical construction. The setting out is done to locate pile position, pile cap, column position, beam bottoms and slab boundary in the site.

Setting out is done with the reference to grid lines. When the grid lines are given in the drawing, setting out are done with reference to these grid lines using any type of technique means Suring angles or distances. In the absence of any kind of grid lines detail first the location is at the site. Considering other requirements of usage and setting out is done with reference to any base line or permanent structure. In site the base line has marked in the side of the Moors road and all grid lines are marked on around of the boundary wall.

The accuracy of setting out is depending on the usage and for which the structure is used. The method of setting out is depend considering the accuracy required and the measuring instruments availability, there are two types of measuring instruments one is measuring angles and other is by length the whole setting out work is done either by measuring angles or by measuring lengths or by measuring both. Setting out of a pile position and foundation is very important and the accuracy of the whole structure is depending on it.

Setting out was started from ground floor and continued to the other floors. If error is not allowable setting out has to be done again.

 

IMPORTANCE OF SETTING OUT

Setting out is providing pegs, levels, profiles and other information necessary for carrying out construction works. The results of setting out should be the true interpretation of the information given in the drawings.

Setting out should always have independent checks for readily detecting any errors and well recorded methodical approach for future reference. The basic requirements for setting out are the measurement of distance, the measurement of angles and the establishment of levels.

LEVELING

A temporary bench mark is established at the site for the datum of all the leveling work of the building. But in site for the easiness the 1000 mm off line of ground floor finishing level is marked on all around the land boundary wall. It can be get anywhere in site as close reference level. The ground floor finishing level is ± 0.00 in all drawings levels are given from the ground floor finishing level.

All the excavation work had to be done according to the levels given in the drawing. This was essential since all the payments for excavation and back filing were done only after taking site measurement of the excavated area and the levels happened to be more or less the same as those in the drawings.

All the slab and beam work had to be done according to the levels given in the drawings. By tightening and loosing the support jacks the correct levels can be achieved since middle part of the slab can be sag due to the weight of the concrete, levels of the middle part of the slab were established 5 mm higher.

SETTING OUT OF A COLUMN

In column setting out first the corner columns are aligned using plum bob and according to the dimension of the column sections and the centerlines are marked. Then according to the detailed drawing other position of the column centerlines are marked. After locating the centers the centerlines are marked on a cement grout base to avoid disappearance of the marks. Then kickering is done at column section dimension to locate formwork of the column.

But if there are any reinforcement bars straight to the centerlines of a column, then it is difficult to mark centerlines of that column. Then at this situation edge lines are marked instead of centerlines. It must be carefully noted that, the dimension is half of the linear face dimension lesser than the centre to centre dimension.

 

MARKING COLUMN CENTRES

• Setting out of columns is a main task.
• First the theodolite is stout over a base point and bisect a target set or another base point and clamped.
• Then nails are driven at different locations along the line which is described by the vertical cross hair of the telescope, to obtain the grid line on the floor.
• Then the line is marked using an inked thread holding between nails the lines perpendicular to the base line is also marked as required.
• The distances to the centre of each column from two perpendicular grid lines are calculated and noted down.
• Finally, by direct measurements from grid lines are marked to give the column centre.