Entry roof of Radisson Bay View Hotel

Description

Structural system
Chittagong city is located close to the sea and is quite windy. The structural design of the 8 tensile cones are done according to BNBC code considering 260km/hr wind speed. The membrane roof is consisted of 8 cones of 8mx8m sizesize, 20m above ground level and 15m above entry porch level. Each cone is supported by a flying mast of 4m height which is suspended by 4 PVC coated 12mm wire cables. The membrane material of the cones is PVDF coated white polyester fabric. The profile of the supporting steel structure is H which acts as a gutter to drain out rain water to adjacent terraces. The supporting steel structure is painted in black while the flying mast and top ring are painted in white color. The top ring of the flying mast is weather protected by acrylictransparent sheet which allows daylight and air circulation into the space beneath it. There is a 65mm air gap between the acrylic sheet and the top ring to allow air flow. Acrylic sheet is extended 150mm to protect interior from rain water.
Impact and impression
The 15m high and 24m wide entry porch gives a grand impression while entering the building. The translucency of the white fabric creates an excellent impression. The shadow of the concrete beam frames from background creates an ever changing play of shadow from morning to afternoon on the tension fabric of the entry porch. At night LED lights illuminate the Tensile Membrane which is also very pleasing to see. In terms of thermal quality the white color and conical shape of the membrane reflects most of the solar radiation and keep the interior cool.
Also due to the height of the entry porch, which is 15m above the floor, a gentle, cool, airy environment is created in the entry lobby.
Construction & Erection
Construction of the steel is done locally. The erection procedure was labor intensive since labor is cheap and the location of the inner cones were very difficult to be reached by heavy crane since there was little effective work space for crane. The steel scaffolding was done on the entire lobby area. A temporary deck was built on the scaffolding 13.5m above the floor level. With the help of chain pulley and temporary scaffolding the steel and fabric was erected in place. It took about a week to fit and erect all
8 cones.
Conclusion
The tensile Membrane Entry Roof is the largest tensile membrane structure ever constructed in Bangladesh. As tensile structures are quite new as system in Bangladesh it was difficult to manage and to coordinate this project. After all it is successfully completed. People who were involved in this project are delighted to see the happy faces of the visitors while entering the building.

Description of the environmental conditions