Challenges in Construction of a High-Rise Building in the Central Business District (CBD) area of Bangalore
High-rise buildings are built to achieve high density projects due to rapid growth of population and lack of available land for development. Their design is the outcome of various technological and social developments, often led by demand for a large residential building or a prestigious head office.
The most important mechanism of high-rise buildings is stability. They need a sound structural design with a strong foundation (based on geotechnical investigation), efficient vertical transportation, larger façade area, etc. Their construction requires special engineering systems due to their height and complexity. Fire and earthquake resistance are important considerations, as is the safety of the labourers during construction, and regular maintenance and safety of the occupants, post construction.
The Prestige Trade Tower, in the Central Business District (CBD) area of Bangalore, is constructed as an A-grade office building. The ~2.5 acre property with 2 basements + ground + 23 storeys is situated on the Palace Road in the eastern boundary, with apartments in the southern boundary, and a school on the northern boundary.
Unique Features of Prestige Trade Tower
Prestige Trade Tower is one of the tallest composite structures in Bangalore. It is LEED GOLD certified having achieved remarkable results in terms of energy efficient design, water consumption reduction, sustainable site selection and development, responsible material selection, waste management, and interior quality improvement.
- All four elevations illuminated by Linear LED Lights & lit Logo.
- All elevations done with unitized curtain wall system.
- Stack and puzzle parking system provided for organized parking and management.
- Slip form technique used for main tower core walls and tower crane with lifting capacity 6 ton at tip of jib.
- Helipad constructed as per norms.
- Centralized air-conditioned system with 100% captive power back-up.
- Forced ventilation provided wherever necessary.
- Around 15 thousand sqm of external glazing.
- Special roof top structure on which cooling towers are placed and covered with aluminium louvers.
- Project has used 1750 RMT of Linear LED strips on four elevations, and were designed by international façade lighting consultants.
- Electrical Power Distribution
- Air Conditioning
- Captive Power Generation
- HSD Yard
- Fire Detection & Protection
- Elevators and Escalators
- BMS & CCTV
- Façade Cleaning
MAJOR MATERIALS CONSUMED
- Executing a Composite Structure
- Working in CBD area
- Concrete pour
- Large Façade
- Wind and Earthquake Resistant Design
- Geotechnical Investigations
- To Achieve the Required Car Parks
- Efficient Vertical Transportation System
- Construction and Fire Safety
- Speed of Construction
- Provision of Efficient Plumbing Services
Mass excavation was one of the most difficult jobs since the project is located in the middle of the city with many buildings surrounding it. There was always a threat of the neighbouring buildings getting damaged. MS touch piles were used to protect the earth. Also, the excavated earth could not be stacked in the premises and had to be sent out. This was a time-consuming process and resulted in some delay. The work was carried out efficiently and without any damage to the neighbouring buildings.
Vacuum dewatering system technique was adopted for dewatering to avoid basement floatation and upheaval failure.
Executing a Composite Structure
A composite structure is a structure in which two different materials are used and are bound together in such a manner that they act as a single unit structurally. The prime objective of using composite structure is to enhance the structural performance of steel and concrete so that the two materials act as a single unit with better compression and tensile strength, and thereby give more stability to the structure, attain the required architectural view, and save time. The execution process starts with using steel as a support system. Poor installation of steel structural members will affect the stability of the structure so optimum care was taken right from the excavation and installation of waler & strut beam support.
Working in CBD area
CBD had additional challenges like lack of working space, dense population, and heavy vehicular movement. Restriction in vehicular movement during the day by the authorities was a challenge as the transit mixers and vehicles carrying construction materials were allowed only during the limited movement hours. So, their movement was managed in a way that most of the materials would reach the site at night and get unloaded during the day, and leave the site again at night. If any critical activity had to be executed, it was done only after obtaining special permission from the police department.
Also, as per the company policy, no labour sheds were allowed in the site during the construction period; so the contractors would transport the workers from the labour camps to the site and drop them off at their camps after working hours. Labours were allowed to work in eight hour shifts or a few hours more. Work that created noise was carried out in during the day and at night the work was restricted to soundless activities.
During mass concreting there were issues like neighbour complaints, 24x7 vehicular traffic movement which would obstruct the flow of concrete vehicles, government guidelines etc. All these issues were handled well resulting in successful completion of the work within the stipulated time.
Large façade area
Safety against falling objects during construction and maintenance of high-rise buildings was important. The materials for the external facades were carefully selected according to the needs and properties of the building. Weekly site meetings were held to discuss design and project monitoring with the contractors, and specialists were called in for façade installation. About 15,000 sqm of a watertight façade was installed all around the building with unitised glass and granite fixed in panels, along with LED illumination.
Wind and Earthquake Resistant Design
Earthquake and wind forces are the major loads that require lateral design of structures. Prestige Trade Tower was designed to take the wind and seismic loads as per the Indian Standard Codes IS:875 and IS:1893. A third party consultant was appointed for checking and validating the design given by the principal structural consultant.
The foundation of high-rise structures needs special consideration, both in geotechnical investigation and in construction. The basic principle of geotechnical investigation is to go deep into the ground till we get a hard stratum whose capacity to take the building load should be sufficient.
Since there is a great need for parking services in high-rise buildings, the provision of more than one basement has become necessary. Over 800 car parking slots were provided in two basements with a combination of stacked and puzzled parking system. The required car parking as per government norms was achieved.
Vertical Transportation System
Vertical transportation systems must be highly efficient and fast in high-rise buildings, especially when used in a single run. Extra care was taken to ensure that the building’s VT system was designed to the maximum efficiency. The holistic design approach of the project from Day 1 helped achieve this.
Construction and Fire Safety
Safety in high-rise buildings includes structural safety, occupational safety during construction and maintenance, safety against falling components, protection against fire and lightning, etc. The project achieved 5 million accident-free manhours during its construction and there were zero casualties throughout the construction period.
Speed of Construction
New construction technologies in high rise buildings are enabling speedier construction along with quality, safety and economic viability. Steel, composite and RCC constructions with high-strength self-compacting concrete and latest formwork (Slipform) technology were used. Pumping concrete, lifting materials and equipment, and working at higher levels were some of the biggest challenges which resulted in some delays in the project’s completion.
Efficient Plumbing Services
Designing water tanks, ensuring water pressure on different floors, water recycling system, soil and sewage drainage, and rainwater pipes were some of the challenging tasks which were efficiently executed.
- Adequate planning before kickstarting the construction on site.
- Follow a holistic approach starting from day 1 to avoid any kind of challenges arising at a later date.
- Work out a detailed schedule and not deviate from the critical path to ensure timely completion of project.
- Know the restrictions and limitations of working in CBD area and plan the flow of material accordingly.
- Work out a proper logistic plan and ensure free flow of manpower and material within the site.
- Repair and rehabilitation work is not only expensive, but also technically demanding.
- Challenges should be thoroughly evaluated and executed in the initial stage of construction.