Bore excavation for 300mm diameter piers

This assessment involves calculation of quantities of materials of different elements of the building in project 1. There are nine tasks to be solved.

The summary of take-off quantities of materials s provided in Table 1

Diameter of piers = 300 mm

Depth of piers = 2.5 m

The piers are located at every corner/beam intersection and spaced at a maximum of 1800mm.

From the structural detail of the ground floor, the number of piers is 53.

The volume of one pier is calculated as follows: πr²h (where r = radius of the pier and h = depth of the pier).

Volume = π x (0.15m)² x 2.5m = 0.1767 m³

Total volume of bored excavation for 53 piers = 0.1767 m³ x 53 = 9.366 m³

This is done by removing vegetation and top soil not exceeding 300mm deep starting from the existing ground level so as to prepare the site generally for laying the foundation and ground floor slab. However, it does not include detailed excavation of the slab and beams. The bulk excavation is done 1m beyond the house walls to create adequate working space. It is assumed that the depth of bulk excavation is 300mm. The bulk excavation is measured from the structural details.

The bulk excavation volume is determined by multiplying the length, width and depth of the ground area to be excavated.

Some excavated material will be needed to be used as fill because of the ground is uneven as shown by the contours in the building site plan. About half of the excavated material will be used as fill to level the ground for the slab construction. Therefore the amount of fill material needed is about 37m³. 

The concrete for each of the elements on the ground is determined by multiplying the length with the width and depth of that particular element as follows

Ground floor slab

6.3m x 5.17m x 0.1m = 3.26m³

5.18m x 5.17m x 0.1m = 2.68m³

6.3m x 5.16m x 0.1m = 3.25m³

5.18m x 5.16m x 0.1m = 2.67m³

3.63m x 4.61m x 0.1m = 1.67m³

Beams

Edge beams (EB):

2 x 12.83m x 0.45m x 0.42m = 4.85m³

1 x 10.97m x 0.45m x 0.42m = 2.07m³ 

1 x 10.82m x 0.45m x 0.42m = 2.04m³

2 x 3.63m x 0.45m x 0.42m = 1.37m³

Internal beams (IB):

1 x 11.48m x 0.35m x 0.35m = 1.41m³

1 x 10.97m x 0.45m x 0.35m = 1.73m³

1 x 4.61m x 0.45m x 0.35m = 0.73m³

Patio slab

5.17m x 0.35m x 0.1m = 0.18095m³

[(1.32m x 6.35m) – (0.35m x 0.24m)] x 0.1m = 0.8298m³ 

Pad footings

2 x 0.9m x 1.2m 0.45m = 0.972m³ 

The net measure of SL72 reinforcing mesh is determined by calculating the net area of ground floor slab and patio slab as follows

Ground slab:

11.93m x 10.97m = 130.87m²

3.63m x 4.61m = 16.73m²

Patio slab:

5.17m x 0.35m = 1.81m²

[(1.32m x 6.35m) – (0.35m x 0.24m)] = 8.3m² 

Bulk excavation

Net ground area = 130.87m² + 16.73m² + 1.81m² + 8.3m² = 157.71m²

The number of sheets needed to complete the ground slabs is determined by dividing the net ground area by the effective cover of one sheet. The effective cover of reinforcing mesh sheet is 5.8m x 2.2m with 400mm lap. Thus the number of sheets is calculated as follows

The length of trench mesh needed is determined by calculating the total length of trenches needed for the ground slab. The trench lengths are determined as follows:

3 x 12.83m = 38.49m

3 x 10.97m = 32.91m

2 x 4.08m = 8.16m

1 x 4.61m = 4.16m

Total = 38.49m + 32.91m + 8.16m + 4.16m = 83.72m

The structural steel bars used are of diameter 12 mm and spaced at 200mm apart. The weight of this bars is 0.89kg or 0.00089 tonnes per meter.

 (Civilology, 2019)

Length of main bars = no. of main bars x length of one main bar (Hamakareen, 2018); (Krishna, 2019).

Length of main bars = (32 x 5.11m) + (32 x 4.97m) = 163.52m + 159.04m = 322.56m

Length of main bars = (27 x 5.11m) + (27 x 4.97m) = 137.97m + 134.19m = 272.16m

Length of main bars = (19 x 4.51m) = 85.69m

Length of main bars = (8 x 5.45m) = 43.6m

Total length of main bars = 322.56m + 272.16m + 85.69m + 43.6 = 724.01m

Length of distribution bars = no. of distribution bars x length of one distribution bar

Length of distribution bars = (29 x 6.2m) + (29 x 5.08m) = 179.8m + 147.32m = 327.12m

Length of distribution bars = (26 x 6.2m) + (26 x 5.08m) = 161.2m + 132.08m = 293.28m

Length of distribution bars = (24 x 3.63m) = 87.12m

Length of distribution bars = (29 x 1.32m) = 38.28m

Total length of distribution bars = 327.12m + 293.28m + 87.12m + 38.28m= 745.8m 

Net measure

The net measure includes the area of walls of the first floor rooms excluding wet areas. The height of the first floor rooms is 2450mm.

Rumpus: 4.5m + 5.52m + 1.99m + 3.36m + 1.71m = 17.07m x 2.45m = 41.82m²

Gallery: 6.06m + 4.16m = 10.22m x 2.45m = 25.04m² 

Bed 1: 10.54m + 8.12m = 18.66m x 2.45m = 45.72m²

Bed 2: 7.08m + 6.98m = 14.06m x 2.45m = 34.45m²

Bed 3: 3.54m + 3.23m + 2.14m + 2.22m + 2.15m = 13.28m x 2.45m = 32.54m² 

Bed 4: 2.66m + 3.34m + 3.03m + 3.34m = 12.37m x 2.45m = 30.31m²

Net area of walls = 41.82m² + 25.04m² + 45.72m² + 34.45m² + 32.54m² + 30.31m² = 209.88m²

Number of plasterboard sheets

Standard size of plasterboards is 2400mm long and 1200mm wide. Area of one sheet is:

2.4m x 1.2m = 2.88m²

The length of skirting needed for the first floor rooms is as follows:

Rumpus: 4.5m + 5.52m + 1.99m + 3.36m + 1.71m = 17.07m

Gallery: 6.06m + 4.16m = 10.22m

Bed 1: 10.54m + 8.12m = 18.66m

Bed 2: 7.08m + 6.98m = 14.06m

Bed 3: 3.54m + 3.23m + 2.14m + 2.22m + 2.15m = 13.28m

Bed 4: 2.66m + 3.34m + 3.03m + 3.34m = 12.37m

Ensuite: 6.8m + 8.12m + 3.62m + 4.98m = 23.52m

Bath: 6.06m + 6.52m = 12.58m

Hall: 4.16m + 2.22m + 4.3m + 3.04m + 1.59m = 15.31m

Balcony: 11.04m + 3.04m = 14.08m

Total = 17.07+10.22+18.66+14.06+13.28+12.37+23.52+12.58+15.31+14.08 = 151.15m   

The length of one skirting is 2.7m 

First is to calculate the floor area of the individual gro9und floor rooms

Family room: 4.08m x 5.03m = 20.52m² 

Meals room: 2.17m x 4.589m = 9.96m²

Kitchen: 4.589m x 5.87m = 26.94m²

Foyer/stairs: 5.5m x 1.71m = 9.41m²

Net floor area = 20.52+9.96+26.94+9.41 = 66.83m²

Allow 10% wastage =

Size of tiles used is 20cm by 20cm

Area of one tile = 0.2m x 0.2m = 0.04m²

No of tiles =

Table 1: Material quantities take-off

Civilology. (2019). How to Calculate Steel Quantity for Slab? – Reinforcement Calculation . Retrieved from Civilology: https://www.civilology.com/bar-bending-schedule-for-slab/

Hamakareen, M. (2018). How to calculate steel quantity for slab, footing and column? Retrieved from The Constructor: https://theconstructor.org/practical-guide/calculate-steel-quantity-slab-footing-column/25533/

Krishna. (2019, January 12). Bar Bending Schedule [BBS] Estimate of Steel in Building Construction. Retrieved from Civil Read: https://civilread.com/bar-bending-schedule-bbs/