After completing this PEB project, Cipla’s manufacturing unit became the first of its sort in Sikkim.

Kirby International, one of the leading PEB design experts, have recently successfully completed setting-up of manufacturing unit for Copal Limited, in Sikkim. The set-up was partially built using RCC, i.e.., the foundation, basement and the ground floor. This building was a mixed-use structure because of the severity of seismic forces in the area. They wanted to urgently start this manufacturing uniting its location and planned to build second unit. The upper three floors were designed as structural steel floors to make the structure more earth quake resistant.

Since the site was located in a heavily seismic-prone and hilly region, a pre engineered steel building (PEB) was the ideal choice as it would provide better strength to the building since, with greater number of floors, the structure becomes more vulnerable during an earthquake.

Project initialisation

The first step was understanding and optimising the architectural layout to achieve good structural optimisation. Thereby structure was designed in 3D, and detailed specifications, load details, and a complete cost estimation were prepared. All the agencies involved in the project—the architect, the RCC design agency, and the site execution team understood the PEB construction details to ensure the proper fitment of various services. Designs and details were checked to ensure compliance with technical requirements and to ensure they were compatible with all supported services. Connections between RCC and the steel structures were checked to ensure they were connected and finished within the set time.

Structural details of the project undertaken.

The new manufacturing unit of Copal has been designed as a basement + ground floor + 3 storeys.

• All the primary and secondary framing members used were PE Bgirders.
• The total structural steel consumption was 3500 MT.
• For time and cost optimisation, the foundation, basement, and the first slab were planned in RCC, and all the components above have been planned in steel.
• All the columns have been designed as “+” columns for better seismic resistance and are provided with rib plates at every meter for better torsional strength.
• The building has large unsupported spans ranging up to 18 meters, and it has heavy live/collateral load requirements up to 20KN/M2.
• Toto restricts the size of the concrete columns; all steel columns have been designed as pinned bases. RCC members have also been modelled to get more accurate support reactions for the RCC design.
• Since this was a pharma manufacturing unit, no bracing could be permitted inside the building. All the beam-column junctions have been designed as moment connections to take very heavy horizontal loads.
• Massive connections have been used for heavier connections with 42nos. and 40 die bolts.
• All the hardware has been torque tightened.
• The maximum member lengths restricted to 6 meters to allow transportation in the hilly region.
• The entire structure has been repainted after the erection at the site to give it a new look.
• A 28-meter clear height has been kept for the automated storage and retrieval system (ASRS).
• Numerous 4-tiered pipe racks run along and across the floor to accommodate multiple service lines.
• All the utility support has been well planned and detailed to allow future expansion and easy maintenance.
• The entire roof of the building has been designed to take the load of solar panels.
  

Featured highlights

• The façade of the building is a very sophisticated sandwich panel within insulation and PVDF coated steel sheets, which are economical and maintenance-free.
• A minimum number of down-take pipes has been provided to avoid the growth of micro-organisms. All the gutters and down-take pipes have been kept outside and covered with PUF panels to give the façade and ensure a completely clean room inside.

Challenges dealt with during design and project commencement

During the design process, the 3Drendering of the PEB structure was Avery large STAAD model with many load combinations, which took more time fora complete run of the STAAD model.

Since the site was located in a hilly area, transportation was limited. The maximum member length needed to be restricted to 6 meters even though the clear spans required in the structure went up to 18 meters long. This required additional designs for numerous connections. Since the site was located in an army-controlled region, transhipment was necessary. The first shipment of materials was from our PEB factory at Haridwar, Uttarakhand, to Siliguri, West Bengal. Then the materials were shipped in different trucks from Siliguri to the site. All the materials that were shipped to the site needed approximately 1,000 trucks.

Another challenge that was overcome was that parts of the building required an ASRS height of 22 meters, while the clear height of the building in those parts was 28 meters. Each floorplate of the structure was 100 meters 100 meters, which meant that the erection could only be done from the outside, and a large tower crane oat least 50 meters boom length was required. Taking into consideration these requirements and limitations, the design and erection needed to be carefully planned accordingly. Numerous service lines needed to be supported on each floor and cater to future changes, and be easily maintained. The entire building was designed to comply with clean room requirements.

STAAD Pro has been used to create the 3D model of the pre-engineered structure. Conclusion The project was a challenge, given the region it was in and the restrictions that came with it. Having completed the project, this manufacturing unit of Copal became the first-of-its-kind factory in Sikkim. It set an example that many other pharma companies followed and constructed steel buildings in Sikkim.