Analysis Of 4.6.2 In Floor And Roof
4.6.2 In Floor and Roof:
Structural floors/roofs account for substantial cost of a building in normal situation. Therefore, any savings achieved in floor/roof considerably reduce the cost of building. Traditional Cast-in-situ concrete roof involve the use of temporary Shuttering which adds to the cost of construction and time. Use of standardized and optimized roofing components where shuttering is avoided prove to be economical, fast and better in quality. Some of the prefabricated roofing/flooring components found suitable in many lowcost housing projects are:
• Precast RC Planks.
• Prefabricated Brick Panels
• Precast RB Curved Panels.
• Precast RC Channel Roofing
• Precast Hollow Slabs
• Precast Concrete Panels
• L Panel Roofing …show more content…
Precast joist is rectangular in shape, 15 cm wide and the precast portion is 15 cm deep (Figure 2). The above portion is casted while laying in-situ concrete over planks. The stirrups remain projected out of the precast joist. Thus, the total depth of the joist becomes 21 cm. The joist is designed as composite Tee-beam with 6 cm thick flange comprising of 3 cm precast and 3 cm in-situ concrete (Figure 3). This section of the joist can be adopted up to a span of 400 cm. For longer spans, the depth of the joist should be more and lifting would require simple chain pulley block.
The completely finished slab can be used as intermediate floor for living also in residential buildings, balcony projections can be provided along the partially precast joists, designed with an overhang carrying super imposed loads for balcony as specified in IS: 875-1964, in addition to the self-load and the load due to balcony railings. The main reinforcement of the overhang provided at the top in the in-situ concrete attains sufficient …show more content…
(Figures 5 and 6). (P.K.Adlakha and H.C.Puri, 2002)
Figure 4.26 : Details of Precast Joist
Image source: Low Cost housing, ACSGE-2009, Oct 25-27, BITS Pilani, India
Structural design
The prefab brick panel for roof as well as for floor of residential buildings has two numbers 6 mm dia MS bars as reinforcement up to a span of 120 cms. The partially precast RC joist, is designed as simply supported Tee-beam with 3.5cm thick flange. The reinforcement in joist is provided as per design requirements depending upon the spacing and span of the joist.
An overall economy of 25% has been achieved in actual practice compared to cast-in-situ RCC slab. (P.K.Adlakha and H.C.Puri, 2002) iii. Precast curved brick arch panel roofing
This roofing is same as RB panel roofing except that the panels do not have any reinforcement. A panel while casting is given a rise in the centre and thus an arching action is created. An overall economy of 30% has been achieved in single storeyed building and 20% in two or three storeyed buildings (Figure 7). (P.K.Adlakha and H.C.Puri,
Structural floors/roofs account for substantial cost of a building in normal situation. Therefore, any savings achieved in floor/roof considerably reduce the cost of building. Traditional Cast-in-situ concrete roof involve the use of temporary Shuttering which adds to the cost of construction and time. Use of standardized and optimized roofing components where shuttering is avoided prove to be economical, fast and better in quality. Some of the prefabricated roofing/flooring components found suitable in many lowcost housing projects are:
• Precast RC Planks.
• Prefabricated Brick Panels
• Precast RB Curved Panels.
• Precast RC Channel Roofing
• Precast Hollow Slabs
• Precast Concrete Panels
• L Panel Roofing …show more content…
Precast joist is rectangular in shape, 15 cm wide and the precast portion is 15 cm deep (Figure 2). The above portion is casted while laying in-situ concrete over planks. The stirrups remain projected out of the precast joist. Thus, the total depth of the joist becomes 21 cm. The joist is designed as composite Tee-beam with 6 cm thick flange comprising of 3 cm precast and 3 cm in-situ concrete (Figure 3). This section of the joist can be adopted up to a span of 400 cm. For longer spans, the depth of the joist should be more and lifting would require simple chain pulley block.
The completely finished slab can be used as intermediate floor for living also in residential buildings, balcony projections can be provided along the partially precast joists, designed with an overhang carrying super imposed loads for balcony as specified in IS: 875-1964, in addition to the self-load and the load due to balcony railings. The main reinforcement of the overhang provided at the top in the in-situ concrete attains sufficient …show more content…
(Figures 5 and 6). (P.K.Adlakha and H.C.Puri, 2002)
Figure 4.26 : Details of Precast Joist
Image source: Low Cost housing, ACSGE-2009, Oct 25-27, BITS Pilani, India
Structural design
The prefab brick panel for roof as well as for floor of residential buildings has two numbers 6 mm dia MS bars as reinforcement up to a span of 120 cms. The partially precast RC joist, is designed as simply supported Tee-beam with 3.5cm thick flange. The reinforcement in joist is provided as per design requirements depending upon the spacing and span of the joist.
An overall economy of 25% has been achieved in actual practice compared to cast-in-situ RCC slab. (P.K.Adlakha and H.C.Puri, 2002) iii. Precast curved brick arch panel roofing
This roofing is same as RB panel roofing except that the panels do not have any reinforcement. A panel while casting is given a rise in the centre and thus an arching action is created. An overall economy of 30% has been achieved in single storeyed building and 20% in two or three storeyed buildings (Figure 7). (P.K.Adlakha and H.C.Puri,