Project Brief
In Imphal, a hospital is being developed including a Critical Care Block with a total built-up area of 1.5lacs sqft. This structure is designed as per IS800, IS 875, and IS 1893 using STAAD-Pro Connect and has been built using structural steel tubes.
The focus of this project is to reduce the project duration and to optimize the design.
How Tubes can help?
Time Saving
The main focus of the project is to reduce the overall project duration. To ensure faster construction, structural steel tubes are the best solution. Studies suggest that tubular construction requires approximately 8-10 days to complete one slab. Hence, the total time it would take for the superstructure to get ready for a 4-storey building would be around 35-40 days. While for built-up sections it requires approximately 15-20 days to construct 1 slab, in the case of RCC it would need a minimum of 20-30 days for the construction of one slab. Hence, with tubes, there is around 50 to 70 percent time saving as compared to any other conventional method.
According to the plan, the entire building will be ready in approximately 18 months. Starting from the foundation stage to the erection of the tubes to the final finishing; this is possible solely with the usage of tubes. While constructing the built-up, a minimum of 9 months extra would be required to complete the superstructure and then finish which would therefore take more than 2 years to complete.
Design Optimization
Tubes have a better load-bearing capacity as the weight is divided equally into all 4 sides of the tube, thus reducing the stress in the center. A better strength-to-weight ratio helps to reduce the total steel tonnage per square foot, making the structure lighter as compared to a conventional built-up steel structure. This leads to the reduction of the total steel consumption per kg by 7 to 10 percent, which reduces the overall cost of the project. In this case, the overall steel tonnage came out to be 656 MT, while in conventional built-up it would have been around 700 MT.
Steel tubes also give more carpet area since the column size in tubes is around 500×500 mm, as compared with RCC and in built-up sections, the column sizes are 800×800 mm and 650×650 mm respectively, so with tubes 1 to 2 percent additional carpet area is gained, providing more usable area.
Additionally, in conventional steel buildings, steel columns need to get encased with concrete/Gypsum board which requires more carpet area while in the case of structure tubes, such encasing is not required, which in turn leads to a smothering area around the column corners with a higher carpet area and reduced finishing cost.
Stocking & Logistics
For construction in hilly areas, logistics is always a major concern as freight is very high and the site is very compact with hardly any space for storage. For conventional construction, transportation of materials is very difficult as huge quantities of concrete, cement rebar, etc., are needed to be transported which requires more space on site for preparation and stocking once the material is delivered. On the other hand, with tubes, construction is much easier and it hardly takes around 7-8 days per slab. Every day fabricated ready sections can be transported on-site and can be erected the next day, this makes the process more efficient and faster, with minimum stocking requirement on site.
In Conclusion
After having a detailed analysis, we arrived at the conclusion that we can optimize the steel structure by using tubes as it reduces the construction time while giving us extra carpet area. It makes the structure lighter, reducing the total cost of the project while ensuring faster IRRs.