Clause 2.6 Precast Hollow Core Household Shelters (Precast HS)

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2.6.1 Design of Precast Hollow Core Household Shelters (Precast HS)

Precast hollow core household shelter shall be designed as a complete HS. For two adjoining HS, they can be formed by a complete HS and a C-shaped HS.

The various designs of precast hollow core HS are as follows:

a. Precast HS with HS door on longer wall and one of the ventilation sleeves above the door. See FIGURE 2.6.1(a).

b. Precast HS and C-shaped Precast HS connected at the shorter wall and with HS door on longer walls. See FIGURE 2.6.1(b).

c. Precast HS and C-shaped Precast HS connected at the longer wall and with HS door on longer walls. See FIGURE 2.6.1(c).

d. Precast HS and C-shaped Precast HS with connection between longer and shorter walls respectively and with HS doors on long wall. See FIGURE 2.6.1(d).

e. Precast HS adjoining cast in-situ walls/ columns. See FIGURE 2.6.1(e).

2.6.2 Dimensions

a. The internal length (L) and width (w) of the HS Walls shall be modular in size with an increment of 50mm.

b. Precast HS showing the arrangement of hollow cores in HS wall with its dimension as shown in FIGURE 3.5.6.1(a) to (h) and spacing, wall thickness, blast door, ventilation sleeves and electrical services shall be designed with dimensions as shown in Tables 3.5.6(a), 3.5.6(b) and 3.5.6(c).

c. Hollow cores shall be modular in size with an increment of 100mm for its length and 25mm for its width. See FIGURE 2.6.2(c).

d. The spacing between two adjacent hollow cores in HS wall shall be 100mm.

e. There shall be a minimum 150mm reinforced concrete nib next to vertical edge of the HS door frame.

f. Shear key of 35mm high shall be provided on wall above the HS door. See FIGURE 2.6.2(f).

TABLE 3.5.6(a) DIMENSION OF PRECAST HOLLOW CORES HS
Precast Hollow Core Household Shelter	Minimum Dimension (mm)	Maximum Dimension (mm)
Length of Hollow Core (a*)	200	500
Width of Hollow Core (b^)	150	200
Distance between the nearest hollow core and internal wall (c1^ / c3^)	25	50
Distance between two hollow cores (c2)	100
Distance between the nearest hollow core and edge of door frame (d1^)	250	300
Distance between the nearest hollow core and edge of door frame with internal electrical fixture between them (d2^)	375	450
Distance between the adjacent HS wall and edge of door frame for door on short wall of dimension 1200mm, 1250mm, 1300mm and 1350mm (d3#)	150	450
Distance between the nearest hollow core and centre of ventilation sleeve (e^)	150	200
Distance between the nearest hollow core and edge of a C-shaped HS wall (f^)	250	350
Note: *Dimensions with increment of 100mm #Dimensions with increment of 50mm ^Dimensions with increment of 25mm

TABLE 3.5.6(b) HS WALL THICKNESS AND SIZES OF HOLLOW CORES
HS Wall Thickness, t (mm)	Size of Hollow Core
	b (mm)	a (mm)
250	150	200
		300
		400
		500
275	175	200
		300
		400
		500
300	200	200
		300
		400
		500

TABLE 3.5.6(c) MINIMUM REINFORCEMENT BARS IN HOLLOW CORES
HS Wall Thickness, t (mm)	Size of Hollow Core		Minimum Reinforcement Bars in Hollow Cores	Minimum Links for Reinforcement Bars in Hollow Cores
HS Wall Thickness, t (mm)	b (mm)	a (mm)
2400 < Ht ≤ 3000	150/175/200	200	4H20	H8 - 250
		300	6H16	H8 - 250
		400	8H16	H8 - 250
		500	10H16	H8 - 250
3000 < Ht ≤ 3900	150/175/200	200	4H25	H8 - 250
		300	6H20	H8 - 250
		400	8H20	H8 - 250
		500	10H20	H8 - 250
Note: If larger size of reinforcement bars are required in the hollow cores, the number of such reinforcement bars shall remain the same as stipulated in the table above.

FIGURE 2.6.1(a) PRECAST HS WITH HS DOOR ON LONGER WALL AND ONE OF VENTILATION SLEEVES ABOVE THE DOOR

FIGURE 2.6.1(b) PRECAST HS AND C-SHAPED PRECAST HS CONNECTED AT THE SHORTER WALL AND WITH HS DOOR ON LONGER WALLS

FIGURE 2.6.1(c) PRECAST HS AND C-SHAPED PRECAST HS CONNECTED AT THE LONGER WALL AND WITH HS DOOR ON LONGER WALLS

FIGURE 2.6.1(d) PRECAST HS AND C-SHAPED PRECAST HS WITH CONNECTION BETWEEN LONGER AND SHORTER WALLS RESPECTIVELY AND WITH HS DOORS ON LONG WALL

FIGURE 2.6.1(e) PRECAST HS ADJOINING CAST IN-SITU WALLS/COLUMNS

FIGURE 3.5.6.1(a) to (h), Tables 3.5.6(a), 3.5.6(b) and 3.5.6(c).

FIGURE 3.5.6.1(a) PRECAST HS WITH HS DOOR ON LONGER WALL AND ONE OF VENTILATION SLEEVE ABOVE THE DOOR (TYPE 1)

FIGURE 3.5.6.1(b) PRECAST HS WITH HS DOOR ON SHORTER WALL AND ONE OF VENTILATION SLEEVE ABOVE THE DOOR (TYPE 2)

FIGURE 3.5.6.1(c) PRECAST HS SHOWING VENTILATION SLEEVE AND INTERNAL ELECTRICAL FIXTURES ON THE SAME WALL (TYPE 3)

FIGURE 3.5.6.1(d) PRECAST HS AND C-SHAPED PRECAST HS CONNECTED AT THE SHORTER WALL AND WITH HS DOORS ON LONGER WALLS (TYPE 4)

FIGURE 3.5.6.1(e) PRECAST HS AND C-SHAPED PRECAST HS CONNECTED AT THE LONGER WALL AND WITH HS DOOR ON LONGER WALLS (TYPE 5)

FIGURE 3.5.6.1(f) PRECAST HS AND C-SHAPED PRECAST HS CONNECTED AT THE LONGER WALL AND WITH HS DOOR EACH ON LONGER WALL AND SHORTER WALL (TYPE 5A)

FIGURE 3.5.6.1(g) PRECAST HS AND C-SHAPED PRECAST HS WITH CONNECTION BETWEEN LONGER AND SHORTER WALLS RESPECTIVELY AND WITH HS DOORS ON LONGER WALL (TYPE 6)

FIGURE 3.5.6.1(h) PRECAST HS AND C-SHAPED PRECAST HS WITH CONNECTION BETWEEN LONGER AND SHORTER WALLS RESPECTIVELY AND WITH HS DOOR EACH ON LONGER WALL AND SHORTER WALL (TYPE 6A)

TABLE 3.5.6(a) DIMENSION OF PRECAST HOLLOW CORES HS

TABLE 3.5.6(b) HS WALL THICKNESS AND SIZES OF HOLLOW CORES

TABLE 3.5.6(c) MINIMUM REINFORCEMENT BARS IN HOLLOW CORES

FIGURE 2.6.2(c) PRECAST HS DIMENSIONS

FIGURE 2.6.2(f) SHEAR KEY ON WALL ABOVE HS DOOR

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