Vizag Airport terminal roof after the cyclone
On 12th October 2014, a very severe cyclonic storm Hudhud made landfall in the coast of Andhra Pradesh over Visakhapatnam. During landfall, the cyclone had a maximum sustained wind speed of 180 kmph. The cyclone also caused heavy rainfall with strong gale winds leading to large scale structural damage over Visakhapatnam and along the cost of Northern Andhra Pradesh and adjoining Orissa. The strong gale winds caused heavy damage to the terminal roof and adjoining buildings. Although the terminal roof was designed for such heavy wind pressures, the entire roofing sheet of the terminal was blown away. This was largely because the roof at the time was made of thin GI roofing sheets and the connections between the roofing sheet and the roof purlins were not designed or sufficiently enough to resist the extreme gale forces. As a result the connection between the roofing sheet and the purlins failed and sheets was blown off. Subsequently the roof insulation, false ceiling and HVAC installments got exposed to very severe wind and rain causing these items to be completely blown away. However, once the roofing sheet failed and was blown off, the wind fore on the roof truss reduced considerably and therefore the roof truss was largely intact and undamaged.
Since the terminal roof frame was virtually undamaged and replacing the entire roofing frame will take considerable amount of time, the authorities decided to install a new roofing sheet on the existing roof truss. Also, replacing the roof truss will severely affect the daily operations at the airport during the construction and will leave most part of the terminal exposed to the elements of nature for several weeks or months. Hence the best viable option was to make use of the existing frame work. However to do so, the roof frame should be verified for its strength and stability. Further the region being cyclone prone, the roof should be checked and certified to resist cyclonic winds and to satisfy functional requirements and ensure structural integrity of the structure as envisaged in the applicable safety standards.
