As part of IAStructE’s ongoing efforts to increase interest in the area of structural engineering and foster original thought and innovation, IAStructE is conducting the National Awards Competition and Innotech has won outstanding structure award 2020 (Buildings) for Embassy Lake Terraces Bengaluru, India
Project Details:
Architectural excellence, Innovations & Life Cycle Cost aspects
Embassy Lake Terraces melds form and function inseparably, with its twisted design to create the Sky Blocks, maximizing the views of the Nagavara and Hebbal lakes. This has been achieved by aligning the plane of the floors towards the lakes and the Central Meadow creating a facade that’s the embodiment of aesthetic beauty.
At the 13th floor level where the building twists by 30 degrees, the slab is designed as a Post Tension Voided Slab. The slab system adopted for the apartment floors is the wall and slab system. The major innovation required was to have as system to accommodate the typical unit walls planting above, integrate services requirement and to handle the loads and deflections whilst maintaining the aesthetic aspect.
The challenge led us to use voided system innovatively, which helped integrate the structural & services requirement to give a clear soffit at the sky deck level maintaining the aesthetic value of the floor. The use of progressive tensioning helped control deflections and loads.
The use of formwork system and advanced concrete helped achieving the desired architectural intent along with meeting required structural, services and maintenance aspect of the structure through its life cycle.
Functional efficiency
Basements, Ground and 22 upper levels twisted at 13th level with the sky deck level at 11th floor. The Units are planned to have large openings at all levels to allow the natural lighting and ventilation at all levels. This creates a healthy and wellness environment.
Sky deck level has been designed as an active zone which consists of jogging track, Yoga center, Havana, Water bodies, landscapes and Gymnasium.
Favorable environmental impact
The use of Self dynamic concrete(SDC) helped in reducing the quantity of plastering for the walls, giving it a fine finish thereby reducing wet works, labour and avoiding debris arising due to hacking of concrete walls, hence reducing dust.
The Post tensioning along with progressive stressing was used to control various deflections and loads along with optimization of steel quantity. The use of SDC and PT helped achieve high early strength, earlier demoulding, and lesser wastages with reduced labour which was a good value addition to the project With the use of voided slab system and with the deck having a form finish and the services addressed, false ceiling was avoided completely thereby reducing environmental impact.
The waffle slab system was used in the basements and podium where landscape, fire tender driveway and other amenities were located. The waffle slab system helps in controlling the vibrations arising due to the vehicular movement and addresses the various loads. The system helped in optimization of steel & concrete.
Integration of structure and services to meet architectural requirements & Innovative ideas in structural system used
The plane of the floor changes at the 13th floor which results in floor plate projecting out of the lower level plan. The cantilever at the transfer level slab is 7 meters from the column face which was a huge challenge to design the slab for above floor loads as well as the cantilever. To achieve this, columns at the transfer level were flared to accommodate the walls above.
Since the structure changes its profile and requirement wrt services at 11th floor due to the twist towers starts from 13th floor, voided slab system was provided as a structural girder system to transfer the walls starting from 13th to terrace.
The structural system adopted for transfer is PT voided slab varying from 900mm to 1000mm. it was a challenge to the services and structural team to integrate the scheme which is cost effective and error free.
Hence in coordination with services structural team proposed MS sleeve for the toilets, balconies and utilities through the void slab with minimum sunk (this helped in restricting the girder depths). Same is executed at site to the precision with proper detailing and is working perfectly.
The staging to support the formwork for the projected slab was taken from the founding level which was nearly 13 stories. This posed a challenge in itself which was executed perfectly in consultation with the contractor.
The basements and the podium level which has the landscape and other amenities have been designed with waffle slab system.
Efficiency of design & detailing, Constructability Sustainability
The transfer level voided slab was designed in a manner that the construction methodology involved was casting the entire slab monolithically. The quantum of the concrete pour for this slab required the concrete to be easy flowing, to increase the speed of the concreting process and to avoid any choking of concrete pumped to the 13th floor and above. The desired quality of surface finish for the voided slab to have an exposed soffit without additional false ceiling works was achieved with the use of SDC.
Efficiency of the design & detailing was the key concern for this residential apartment wrt car parking efficiency and structural support system from the base to carry the load of twisting tower girder at 13th Floor.
Both design intents are met with effective structural designs systems &detailed planning along with the all stake holders from the inception of the project.
The constructability was achieved by using latest concrete technology i.e, SDC and high quality form finish which helped achieve early strength and form finish to avoid plastering. This helped in sustainability of the project