An Iconic, large, free flowing space being built at the ground floor of J W Marriott hotel in Kolkata is an epitome of technology. The Diagrid, coming up at the entrance lobby, is a triple height structure and on completion, it would be an architectural marvel. Free flowing space is enclosed with a mesh of rectangular tubes (Diagrid) which is glazed with laminated double glass units. The intent of the designers is to have a minimalistic support frame for the entire 2000 sq m of the Diagrid façade, hence there is no structural member supporting this façade. While the span is very large yet the intent was to have as less frame element as possible with a very high performance and acoustic insulated façade.
For the façade contractors Glasswall systems, diagrid project for J W Marriot was a challenging project, though they have taken up lot of complex projects in their carrier of 12 years as façade contractors. What is peculiar about the structure is the simplicity in form yet it needs a highly complex engineering and expert execution. The diagrid is designed as a mesh of tubular profile which curves in 3-dimension. It is 12m high and does not have any intermediate support.
The mesh forms node joints on the entire surface with six glasses meeting at every node (Fig 2). Each glass is a laminated double glass unit. Each glass is angled to the adjacent glass as the diagrid is curving in 3-dimensions. This makes each node very complex and needs high precision designing, fabrication and execution.
Designing the fabrication drawing was a challenge as it needed a good understanding of the challenges to be faced by the execution team. So the designing was fine tuned to suit a realistic execution methodology. Considering that there are more than 1000 different sizes of glass the precision required is the highest at every level of its construction.
The biggest task in the construction was the location of each node to the accuracy of a millimeter without any reference point in 3-dimension due to absence of any floor slab except the ground floor (Fig 3). This was meticulously planned out at design stage and executed at site by highly qualified engineers and the survey team by use of latest in laser survey techniques.
At the completion of diagrid structure, the high performance glass is fitted in conventional stick system with triple silicone barrier and pressure plate and capping to ensure that the structure will not leak as this is a high premium area of the hotel (Fig 4).
The structure is tested with water pressure before the final caping is done to seal the glass joints with pressure plate.
Client: J W Marriot hotel Kolkata
Architect: H Architects
Façade Consultant: BES
Façade Contractors: Glasswall systems