Trail Erection at Site
Those of you who know our Mivan system formwork will understand our hesitation. From the telephone conversation, it appeared that each floor was a totally different layout from the floor below and we all know that MFE formwork needs repetition in design to make it commercially viable. Upon seeing the drawings, we had three main concerns, how do we design our formwork for such a structure, what issues will we have manufacturing to the strict tolerances required and how do we devise a work cycle to achieve the contract programme?
On the design side, we first had to understand the philosophy of the structures. Due to the twisting geometry of the tower, the structure has a natural tendency to undergo additional twisting movement under gravity loads, including the self-weight of the cast in place concrete. After discussions, with the consultants, we decided to proceed with a new process for MFE and provide a 3D design, as we saw this as being the only way to provide the detail required to get approvals and to manufacture the special shaped panels properly. Gaining approval of the column rotation and transition could only be properly shown in 3D, also it would provide clear X/Y setting out dimensions for both the top and bottom of each column. 3D would also allow us to show the angle of rotation at each floor correctly.
Each column was colour coded and individually designed. The angle of the columns had to be slightly exaggerated to allow for the building settlement due to forces of gravity and the self-weight of the structure and we had to increase the offset angle of the sloping columns by approximately 4mm from its true shape.
Our technical site team's main concern from day one was the congestion of rebar at the main corner twisting columns and also at the spandrel edge beam as they feared this could delay the proposed 6-day per floor construction cycle. With the agreement of Arabtec, we supplied a corner section of the building and trial erected it at site, 2 months prior to the formwork being required.
The trail erection allowed us all to see the true angle and twist of the main columns and overcome any foreseen problems long before they happened on the working slab. It also ensured that our setup was much faster than anticipated and our client was able to resolve any rebar congestion problems long before they appeared on site.
MFE Formwork achieved on average, a 6-day per floor construction work cycle and in full flow was casting 7 floors per month and this was done by a mainly Indian workforce, completing the structure on time and within budget.