PETRONAS TWIN TOWER 2: TECHNICAL REVIEW AND SPECIFICATIONS

Petronas Twin Tower 2 forms one half of the iconic Petronas Towers complex in Kuala Lumpur, Malaysia. Standing at 451.9 meters (1,483 feet), it held the title of the worlds tallest building (along with its twin) from 1998 to 2004. While the towers appear identical, Tower 2 possesses a distinct construction history and operational profile that distinguishes it from Tower 1.

This technical review focuses on the specific engineering challenges faced by Tower 2, the structural systems employed, and the unique dynamics of the inter-tower Skybridge.

CONSTRUCTION HISTORY: THE TOWER 2 RACE

A defining feature of the project was the competitive construction strategy. To ensure rapid completion, the developers awarded contracts to two different consortia. Tower 1 was built by a Japanese consortium led by Hazama Corporation, while Tower 2 was assigned to a South Korean consortium led by Samsung C&T and Kukdong Engineering & Construction.

Although construction on Tower 2 began a month after Tower 1, the South Korean team utilized advanced self-climbing formwork systems to accelerate the concrete pouring process. Consequently, Tower 2 was the first to reach the pinnacle, completing its spire installation before the Japanese team on Tower 1. This "race to the sky" resulted in significant innovations in high-speed vertical construction management.

STRUCTURAL SYSTEM: HIGH-STRENGTH CONCRETE

Unlike most supertall skyscrapers of its era which relied on steel frames, Petronas Tower 2 is constructed primarily of high-strength reinforced concrete. This decision was driven by the high cost of importing steel and the ready availability of local concrete expertise.

The structural core is a "tube-in-tube" system. It consists of a massive central concrete core (23 by 23 meters) and an outer ring of 16 cylindrical perimeter columns made of high-strength concrete. These perimeter columns are spaced widely at the base and taper as they rise.

To handle the immense vertical loads, the engineers utilized concrete with compressive strengths reaching 80 MPa (Grade 80), a material specification that was unprecedented in Malaysia at the time. This mass of concrete provides exceptional dampening characteristics, significantly reducing sway and improving occupant comfort compared to steel structures.

FOUNDATION AND GEOTECHNICAL ENGINEERING

The Petronas Towers sit on the worlds deepest foundations. The site presented a major geotechnical hazard: it straddled a cliff where limestone bedrock met soft soil (Kenny Hill formation). Building directly on this mixed geology would have caused catastrophic differential settlement.

To resolve this, the entire complex was shifted 60 meters to sit entirely on the soft soil. The engineers then drilled friction barrettes (rectangular piles) to depths of up to 120 meters (394 feet). These piles do not rest on bedrock but rely on skin friction against the soil to support the towers 300,000-tonne weight. A massive 4.5-meter thick concrete raft foundation caps these piles, one of the largest continuous concrete pours in history.

THE SKYBRIDGE CONNECTION

The Skybridge connects Tower 2 to Tower 1 at the 41st and 42nd floors. Structurally, this bridge is not rigidly attached to both towers. If it were, the differential swaying of the two buildings during high winds would tear the bridge apart.

Instead, the bridge is anchored to each tower using a complex system of "slide bearings" and centering pins. The legs of the bridge are bolted to a ball bearing system at level 29. This design allows the bridge to slide in and out and pivot, accommodating independent movements of up to 500 millimeters between Tower 2 and Tower 1 without compromising structural integrity.

VERTICAL TRANSPORTATION

Tower 2 is serviced by a double-deck elevator system supplied by Otis. The main bank of elevators allows passengers to embark on two levels simultaneously (ground and concourse), significantly increasing passenger throughput during peak hours.

The tower is zoned vertically, with a sky lobby at the 41st floor (accessible via the Skybridge level) serving as a transfer point for the upper zones.

TECHNICAL DATA SHEET

Official Name: Petronas Twin Tower 2
Location: Kuala Lumpur City Centre (KLCC), Malaysia
Architect: Cesar Pelli
Contractor (Tower 2): Samsung C&T, Kukdong Engineering & Construction
Completion Year: 1998
Architectural Height: 451.9 meters (1,483 feet)
Floor Count: 88
Structural Material: High-strength Reinforced Concrete
Foundation Depth: Up to 120 meters (Barrette Piles)
Occupancy: Multi-tenant (unlike Tower 1 which is fully Petronas)

FREQUENTLY ASKED QUESTIONS

Who occupies Petronas Tower 2?
While Tower 1 is fully occupied by Petronas (the national oil and gas company), Tower 2 is leased to various multinational corporations, including Microsoft, Reuters, and Al Jazeera.

Why is Tower 2 famous in construction history?
Tower 2 is famous because the South Korean contractors (Samsung C&T) started one month late but finished the spire installation before the Japanese team building Tower 1, effectively winning the construction race.

Is the bridge part of the structure?
The Skybridge is structurally independent. It does not provide structural support to hold the towers together; rather, it "floats" between them on slide bearings to allow for movement.

How many corners does the floor plan have?
The floor plan is based on an 8-point star (Rub el Hizb), a symbol of Islamic unity. To increase floor space, 8 semicircles were added between the points, creating a 16-lobed geometric shape.