12m span of concrete roof slab

In summary, the conversation discusses the design of a concrete roof slab for a living area that is 12m long and 9m wide. The slab is supported by columns in each corner and cantilevered out by 1.8m on three sides. The top floor of a 3-storey house is located on a hill top with support columns on a 35 degree angle. The surrounding area is a non-active seismic zone with lots of loose rocks and an average of 2m depth to the bedrock. The structure will also have 30 pile caps on an 8m grid. The questions raised include whether the imposed load of 2.5kN/m2 for lounge decking needs to be taken into account
  • #1
Hafiz Rafar
1
0
Hi,
I am designing a concrete roof slab that span across 12m long and 9m width for my living area. The support columns are placed in each 4 corners and they are 300mm x 300mm size. The concrete slab roof is cantilevered out by 1.8m on 3 sides (not all 4 sides) with the thickness of 150mm.
At the moment, the beams are connected to each corners with dimension of 150mm x 400mm thickness and height respectively.
This living area is placed on the top floor of 3-storey house. The house itself is sitting on support columns alongated on the side slope of 35degrees angle (perpendicular to the slope). The top floor is on the hill top. the lowest floor is at the bottom of slope.
Briefly about the surrounding. It is going to be built in non active seismic zone. there are lots of loose rocks/boulders. The entire hill is actually a granite. some of bedrocks are exposed. An average of 2m depth to the bedrock. Soil is sand/silt/clayey.
There will be at least 30 pile caps on 8m grid.
Questions,
a) the idea of concrete roof slab is mainly for lounge decking. Might have some flower pots and a set of breakfast table. Do I still need to design the structure by taking into account the imposed load of 2.5kN/m2 to meet the requirement.
b) Are my beams, columns configuration and size correct? How many secondary beams do I need? Do I need more columns? my idea is to build with conventional way with reinforced concrete beam and column with conventional rebars.
c) is the column size good enough to support all the floors? does it need bigger size at the bottom? Considering they are supporting 2 floors above.
Please advice.
 
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  • #2
Hafiz Rafar said:
Hi,
I am designing a concrete roof slab that span across 12m long and 9m width for my living area. The support columns are placed in each 4 corners and they are 300mm x 300mm size. The concrete slab roof is cantilevered out by 1.8m on 3 sides (not all 4 sides) with the thickness of 150mm.
At the moment, the beams are connected to each corners with dimension of 150mm x 400mm thickness and height respectively.
This living area is placed on the top floor of 3-storey house. The house itself is sitting on support columns alongated on the side slope of 35degrees angle (perpendicular to the slope). The top floor is on the hill top. the lowest floor is at the bottom of slope.
Briefly about the surrounding. It is going to be built in non active seismic zone. there are lots of loose rocks/boulders. The entire hill is actually a granite. some of bedrocks are exposed. An average of 2m depth to the bedrock. Soil is sand/silt/clayey.
There will be at least 30 pile caps on 8m grid.
Questions,
a) the idea of concrete roof slab is mainly for lounge decking. Might have some flower pots and a set of breakfast table. Do I still need to design the structure by taking into account the imposed load of 2.5kN/m2 to meet the requirement.
b) Are my beams, columns configuration and size correct? How many secondary beams do I need? Do I need more columns? my idea is to build with conventional way with reinforced concrete beam and column with conventional rebars.
c) is the column size good enough to support all the floors? does it need bigger size at the bottom? Considering they are supporting 2 floors above.
Please advice.

Welcome to the PF.

You need to get a licensed structural engineer to help you with these plans. And you need to get a building permit from your local Building Inspection office based on those plans. We cannot help you with such a potentially dangerous project over the Internet. Thread is closed.
 

1. What is the purpose of a 12m span of concrete roof slab?

A 12m span of concrete roof slab is used to provide structural support and create a flat, solid surface for a building's roof. It helps distribute the weight of the roof evenly and prevents sagging or collapsing.

2. How is a 12m span of concrete roof slab constructed?

A 12m span of concrete roof slab is typically constructed using reinforced concrete, which involves placing steel bars or mesh within the concrete to provide additional strength. The concrete is then poured and allowed to cure, forming a solid and durable roof slab.

3. What factors affect the design of a 12m span of concrete roof slab?

The design of a 12m span of concrete roof slab is affected by various factors such as the load it will need to support, the climate and weather conditions in the area, and the type of building it will be used for. The design also takes into account the type and amount of reinforcement needed for the slab to withstand the expected loads.

4. How is the structural integrity of a 12m span of concrete roof slab ensured?

The structural integrity of a 12m span of concrete roof slab is ensured through proper design and construction techniques. This includes using the correct amount and type of reinforcement, ensuring proper curing of the concrete, and regular maintenance and inspections to identify any potential issues or damages.

5. Can a 12m span of concrete roof slab be used for all types of buildings?

While a 12m span of concrete roof slab is commonly used for a wide range of building types, it may not be suitable for all situations. Factors such as the building's location and the expected load it will need to support may affect its suitability. It is important to consult a structural engineer to determine the best type of roof slab for a specific building.

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