To calculate the dead , live and wind load for RC residential structure and to apply them using TSD
1.
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Finishes: The finishes in the building include plaster, tiles, and paint. Assuming a thickness of 50mm for these finishes, the weight of the finishes can be calculated using the density of the material and the area covered. For example, if we assume a density of 2000 kg/m3 for plaster, the weight of plaster per square meter would be 0.05m x 1m x 2000 kg/m3 = 100 kg/m2.
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Slab thickness: The weight of the slab depends on its thickness, and we need to assume a thickness as per the design. Let's assume a thickness of 150mm for the slab. The weight of the slab per square meter can be calculated using the density of the concrete and the thickness. Assuming a density of 2500 kg/m3 for concrete, the weight of the slab per square meter would be 0.15m x 1m x 2500 kg/m3 = 375 kg/m2.
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Brick wall load: The weight of the brick wall depends on its thickness and height. Assuming a thickness of 230mm for the wall and a height of 3 meters, the weight of the wall per square meter would be 0.23m x 3m x 1920 kg/m3 = 1324.8 kg/m2.
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Roofing load: The weight of the roofing depends on the type of roofing material used. Assuming a flat roof with a thickness of 150mm and a density of 1200 kg/m3, the weight of the roofing per square meter would be 0.15m x 1m x 1200 kg/m3 = 180 kg/m2.
Once we have calculated the dead load for each element, we can add them up to get the total dead load on the building. Let's assume the dimensions and material properties for each structural element as follows:
- Column: 400mm x 400mm x 4m, reinforced concrete
- Beam: 300mm x 500mm x 6m, reinforced concrete
- Slab: 150mm thick, reinforced concrete, span of 6m x 6m
- Foundation: 1000mm x 1000mm x 2m, reinforced concrete
Based on these dimensions and material properties, we can calculate the dead load for each structural element using the density of concrete, which is assumed to be 2500 kg/m3. The dead load for each element would be:
- Column: 0.4m x 0.4m x 4m x 2500 kg/m3 = 1600 kg
- Beam: 0.3m x 0.5m x 6m x 2500 kg/m3 = 2250 kg
- Slab: 6m x 6m x 0.15m x 2500 kg/m3 = 8100 kg
- Foundation: 1m x 1m x 2m x 2500 kg/m3 = 2500 kg
Adding up the dead load for each element and the loads from finishes, brick wall, and roofing, we get the total dead load on the building as:
Total dead load = 100 kg/m2 (finishes) + 375 kg/m2 (slab) + 1324.8 kg/m2 (brick wall) + 180 kg/m2 (roofing) +
2.
Assuming a residential building, we can apply a live load of 2.0 kN/m2 on the floor slabs. The live load on the roof can be assumed to be 1.5 kN/m2.
Once we have calculated the live load for each element, we can add them up to get the total load on the building. Let's assume the dimensions and material properties for each structural element as given below:
- Column: 400mm x 400mm x 4m, reinforced concrete
- Beam: 300mm x 500mm x 6m, reinforced concrete
- Slab: 150mm thick, reinforced concrete, span of 6m x 6m
- Foundation: 1000mm x 1000mm x 2m, reinforced concrete
Based on these dimensions and material properties, we can calculate the live load for each element using the live load on the floor slabs and roof. The live load for each element would be:
- Column: (2.0 kN/m2 x 6m x 6m) = 432 kg
- Beam: (2.0 kN/m2 x 6m x 6m) = 432 kg
- Slab: (2.0 kN/m2 x 6m x 6m) = 432 kg
- Foundation: 0 kg (no live load on the foundation)
Adding up the live load for each element and the dead load, we get the total load on the building as:
Total load = 100 kg/m2 (finishes) + 375 kg/m2 (slab) + 1324.8 kg/m2 (brick wall) + 180 kg/m2 (roofing) + 432 kg (live load on column) + 432 kg (live load on beam) + 432 kg (live load on slab)
Total load = 2856.8 kg/m2
We can now apply the total load on the model by adding it as a load case. The model can be analyzed and designed to ensure that it can resist the combined effect of the dead load and live load.
To generate manual wind loading in the design report based on IS code, we need to consider the wind speed and the terrain category of the site. Let's assume the following input for the wind loading calculation:
- Site location: Chennai, Tamil Nadu, India
- Wind speed: 50 m/s
- Terrain category: 3 (sub-urban)
- Building height: 20m
- Building width: 15m
- Building length: 30m
Based on the above input, we can calculate the wind pressure on the building using the following steps:
Step 1: Determine the basic wind speed (Vb) based on the site location and return period. For Chennai, the basic wind speed with a return period of 50 years is 50 m/s.
Step 2: Determine the importance factor (I) based on the intended use of the building. For a residential building, the importance factor is 1.0.
Step 3: Determine the topographic factor (K1) based on the site location and terrain category. For Chennai with terrain category 3, the topographic factor is 1.0.
Step 4: Determine the wind directionality factor (Kd) based on the shape of the building. For rectangular buildings, the wind directionality factor is 0.85.
Step 5: Determine the gust factor (G) based on the building height and exposure category. For a building with a height of 20m and exposure category C, the gust factor is 0.85.
Step 6: Determine the velocity pressure (qz) using the formula:
qz = 0.613 x Vb^2 x K1 x Kd
Substituting the values, we get:
qz = 0.613 x 50^2 x 1.0 x 0.85 = 1642.4 N/m2
Step 7: Determine the net pressure (pn) using the formula:
pn = qz x G x Cp x Ce
where Cp is the pressure coefficient and Ce is the terrain and height factor.
For the walls and roof of the building, we can assume a pressure coefficient of -0.6 for the windward side and +0.6 for the leeward side. For the side walls, we can assume a pressure coefficient of -0.6 for the windward side and -0.2 for the leeward side.
For the terrain and height factor, we can use the values given in IS 875 Part 3:
- For a height of 20m, the terrain and height factor (Kh) is 1.0
- For a sub-urban terrain category, the terrain and height factor (Kz) is 1.0
Substituting the values, we get:
- Net pressure on windward wall: pn = 1642.4 x 0.85 x 0.6 x 1.0 = 699.2 N/m2
- Net pressure on leeward wall: pn = 1642.4 x 0.85 x (-0.6) x 1.0 = -699.2 N/m2
- Net pressure on roof: pn = 1642.4 x 0.85 x 0.6 x 1.0 = 699.2 N/m2
We can now apply these net pressures as load cases on the model to analyze and design the building for wind loading.