Council on Tall Buildings and Urban Habitat
 

Capital City Towers, Moscow
Written by Yuri Starodubtsev, Capital Group,
Joey Myers, NBBJ, & Larry Goetz, NBBJ
Posted May 2011
This paper was originally featured as a case study in CTBUH Journal 2011 Issue II and is also available as a PDF download.

Other Featured Tall Buildings
“As a pioneering project in Moscow, Capital City has forged many new pathways for the city’s real estate and construction industries. Through its integrated design and engineering, the project provides a model for mixed-use development, which remains rare in the city, and further establishes a new identity for Moscow.”
Location
Moscow
Completion
December 2010
Height
302 m (989 ft) (Moscow)
257 m (843 ft) (St Petersburg)
Stories
76 (Moscow), 65 (St. Petersburg)
Area
288,000 sq. m.
Primary Use
Residential

Owner/Developer

Capital Group
Design Architect
NBBJ
Structural Engineer
Arup
MEP Engineer
Arup
Main Contractor
Inrecon

After more than a decade in the planning, Moscow City, a new mixed-use business district rising 4 kilometers (2.5 miles) west of the Kremlin, is a symbol of Russia’s ascent in the global economic playing field. The Capital City mixed-use development, completed in 2010, is the fourth to be realized among more than 20 projects which comprise Moscow City and, at 302 meters (989 feet) in height, it is currently the tallest building in Europe.


Anchoring a New District

Capital City’s mix of residential, office and retail distinguishes Moscow City from precedents like Canary Wharf in London and La Défense in Paris, which were planned primarily as commercial districts and are only now working to increase their residential components. Set on the Presnenskaya embankment overlooking the Moscow River, Moscow City was envisioned from the outset as a place for business, living and leisure. More than 3 million square meters (32.6 million square feet) of residential, office, hospitality and entertainment uses – including Capital City’s 288,000 square meters (3.1 million square feet) – are planned for the 60-hectare (247-acre) district. Similar to London and Paris, Moscow City is intended to provide a vitalizing expansion of commercial office space while preserving the character of Moscow’s historic center.

The luxury residences that comprise the bulk of Capital City’s program are contained within the 76-story, 302-meter (989-foot) Moscow Tower and the 65-story, 257-meter (843-foot) St. Petersburg Tower. Both are joined through their first 18 floors by a podium building (see Figure 2), creating the larger floor plate desired by commercial office tenants. A “lifestyle marketplace,” a fitness spa with indoor pool, and residential lobbies occupy the first three floors.

Together with the two other completed mixed-use towers – the Naberezhnaya Tower (completed 2007) and Imperia Tower (completed 2010) – Capital City provides a firm anchor for the nascent Moscow City.


Figure 1. A view of the towers
Collaborative Process

While any project of this complexity requires collaboration, fulfilling the vision for Capital City on a fast-track schedule in a district with few architectural precedents required extreme agility and innovation on the part of the project team, which spanned 11 time zones from Seattle, to London, to Moscow.

Another complication was the absence of applicable local building codes. When the development of Moscow City began, local building codes dated back to 1950, when the average building height did not exceed 75 meters (246 feet) and codes for high-rise housing did not exist. In order to address the structural and life-safety requirements for Moscow City’s tall buildings, rigorous codes modeled after British standards were adopted for all projects in the new district, including Capital City. These codes establish high standards for fire safety, and include 4-hour structural fire resistance, the use of 30-minute fire-rated glass, ample refuge areas, redundant fire elevators and exit stairs, and rooftop platforms for lightweight refuge cabins that can be delivered by helicopter.

To begin construction on schedule, NBBJ and Arup elected to complete the structural design while the architectural design was still in process. The superstructure and raft foundation design was developed on a fast-track schedule that was locked in place after early design development, allowing architectural façade design to continue while detailed structural design was completed. Refuge floor locations in the two tall towers were finalized along with vertical mechanical and fire separations to allow structural design of the superstructure to be coordinated quickly with the design of the structural out-riggers and core.

After working closely together to develop highly efficient and integrated structural and mechanical systems, the design team worked with Moscow authorities to verify that the project would fulfill the new building codes. Expert panels in structural engineering and life-safety reviewed the proposed design.
Figure 2. Typical residential plans
Design Concept

Capital City’s bold architectural form takes as its conceptual inspiration “Corner Counter Relief” of 1914 by Vladimir Tatlin, often heralded as the father of Russian Constructivism. Tatlin’s experimental work in the early 20th century marked an attempt to redefine sculpture’s relationship to built space. Slung between two perpendicular walls, Corner Counter Relief breaches the orthogonal shape of a typical room in order to introduce a taut, interstitial geometry. A similar effect is created by the offset rotation of Capital City’s tower segments which create a dynamic departure from the stability of a square.   

This rotational effect, achieved through a slight cantilever on only two façades of each vertical segment, does not compromise the regularity of the towers’ structure. A mechanical floor demarcates each 15-floor segment and integrates the structural system. The Moscow Tower contains five such segments while the St. Petersburg Tower contains four.

The two-tower typology had several benefits over a single tower of the same square footage. It allowed for a slender, elegant massing that maximizes the perimeter-to-floor plate ratio and also eliminated corridors and provided a more intimate relationship between the elevator lobby and the five to six units per floor.
The two-tower typology had several benefits over a single tower of the same square footage. It allowed for a slender, elegant massing that maximizes the perimeter-to-floor plate ratio and also eliminated corridors and provided a more intimate relationship between the elevator lobby and the five to six units per floor.

Unlike typical real estate practices in Moscow, where residential units are typically delivered unfinished, nearly all Capital City’s 474 rental apartments are fully fitted out with finished interior walls, stone and parquet floor, high-end appliances and fixtures, etc. This change in practice allowed residential units to be leased ready for immediate occupancy and eliminated any reduction in lift service that could occur during a simultaneous fit-out of so many units once the building began to be occupied.

The 18-story podium building has inclined façades and a curvilinear ground plan that alludes to Moscow’s concentric ring roads and creates a welcoming space for the public amenities on the first three floors. Upon entering from the porte-cochere, visitors are welcomed into the lifestyle marketplace on the first two levels and a world-class fitness spa and pool facility on the third. Organized around a central north-south pedestrian axis that defines a “main street” of shops and restaurants, the retail floors culminate in an expansive, day-lit atrium near the base of the towers.
Figure 3. Building section
Integrated Engineering

Eight mega-columns – arranged to maximize open interior space and permit large windows in the façade – transfer loads for each tower segment through a series of connections. At each mechanical floor, the vertical load is transferred from the corner and central columns to the eight mega-columns through a perimeter belt truss that also connects to an outrigger structure. These outriggers in turn tie back into the core for wind load transfer.

Integrating the tower structure with the podium building structure required significant analysis. Structurally separating the two towers would have necessitated placing a movement joint through an entire floor. More significant than loss of usable space, this approach would result in a compromised experience since the independent movements of the towers would be noticeable during windy conditions and interior finishes, exterior cladding and waterproofing would have to accommodate this movement.

Arup elected instead to treat the towers as a fully contiguous, single structure through the first 19 floors (including the podium building roof) and conducted complex dynamic analysis in order to determine the forces acting between the linked structures. The resulting structural analysis designated a slightly thicker, more reinforced slab at Level 18, with lower floors also performing as continuous concrete diaphragms.
Figure 4. Entry Figure 5. Mat foundation
Foundation Construction

The ready availability and local production of concrete, coupled with a local building industry skilled in its use, gave reinforced concrete construction a significant advantage over other options. From an engineering and design perspective, it also allowed for minimal floor depth, maximum fire resistance, and adequate acoustic separation necessary in residential multi-story buildings.

Despite the common use of reinforced concrete in the region, critical portions of Capital City’s concrete construction work were carried out in conditions that were anything but typical. The tower pile caps were each installed during continuous, 33-hour mid-winter pours in temperatures ranging from -32 to -34°C (-25 to -30°F, under a large heated tent to keep the concrete from freezing. Running five meters deep and measuring 6,500 cubic meters (230,000 cubic feet) and 6,000 cubic meters (212,000 cubic feet) for the Moscow and St. Petersburg Towers, respectively, the foundation utilized a relatively standard rebar cage and wooden formwork.

The foundation pile cap tops 215 piles beneath the Moscow Tower and 191 piles beneath the St. Petersburg Tower. An additional 76 piles for the combined-pile raft foundation support the podium building. Each pile measures 1.2 meters (47.25 inches) in diameter and 20 meters (65.6 feet) in length, and is drilled down through the site’s thick layer of clay to the underlying limestone bedrock. The alternative – a shallow foundation at the bottom of the basement that would act as a big raft in the clay layer – would have required large stabilizing walls in the basement that would have significantly compromised circulation and the basement-level program. The six-level basement includes more than 2,200 parking spaces, electrical equipment and enlarged fire compartments.

The basement also accommodates an unusual site runoff management facility that responds to the limited capacity of Moscow’s sewer system to absorb large surges of water. Rainwater collection tanks located in the basement temporarily retain runoff water before it is slowly discharged into the municipal system at a manageable rate. While such measures are unusual for Moscow, this system protects Capital City and the immediate site from flooding. Additionally, a water retention pond for fire defense minimizes on-site water and energy consumption.

Typical cast-in-place concrete construction utilizing pumps to move the concrete to upper floors was utilized for the towers and podium building and towers.
Figure 6. The towers at night

Curtain Wall

The design team collaborated with German curtain wall specialist Schüco to create a dynamic façade for the towers and podium building. The towers are enclosed in a unitized panel system with four-sided structural-silicone glazing. The aluminum panels compose a shifting super grid that resonates with the towers’ shifting blocks. The panels also shift in plan, some protruding outward while others are slightly inset to accommodate vertical LED lighting. Within this shifting grid, silver-reflected glass panels alternate between shadow box construction and ceramic frit coating to control solar heat gain. The curtain wall also integrates electronically operable windows in all apartments. These windows are designed for use in accordance with the mechanical systems, offering residents flexible control over their interior environment.
The podium building’s façade establishes a more striking presence, utilizing two systems: a structural silicone stick system and a point-supported planar glass system. The main three walls to the south incline at a 10-degree slope and are constructed of a four-way glazing system with sunshades on the south side. The remaining vertical curtain walls are fabricated with flat and curved aluminum panels with vision glass that form a gently curving wall extending from south to north. The three retail and spa floors are denoted by a point-supported planar façade system with stainless steel spider supports and specially designed glass columns. Three automatic revolving doors with air curtains provide the primary means of entry.
The realization of the curtain wall was a global effort. Designed in Germany, fabricated in Turkey, tested in England at Taylor Woodrow Technology Centre, supervised by US consulting firm Israel Berger & Associates, and assembled in Moscow by Aygun Aluminum; the curtain walls are one of Capital City’s more complex elements and necessitated multiple iterations before finalization.

Conclusion
As a pioneering project in Moscow, Capital City has forged many new pathways for the city’s real estate and construction industries. Through integrated design and engineering, the project provides a model for mixed-use development, which remains rare in the city, and further establishes a new identity for Moscow.
As much as the project demanded innovative solutions and processes, an equally important legacy of Capital City’s development is the design, construction and procedural precedents it helped to establish in Moscow. The collaboration throughout the project – between the client, design team, and local engineering, construction and agencies – represents a foundation of exchange between the global and local tall building industries that paves the way for future advances.

Figure 7. Capital City Towers

Related Links
CTBUH Skyscraper Center Profile:
Visit Capital City Moscow Tower's profile
Visit Capital City St. Petersburg Tower's profile

Capital City Towers featured as a Case Study:
Download the Paper
2011 CTBUH Journal Issue II

Capital City Towers featured as 8th and 17th tallest in Tallest 20 in 2010:
Press Release
Tallest 20 in 2010 Poster

The authors would like to thank Yosh Asato for editorial support on this paper.
The CTBUH would like to thank Capital Group and NBBJ for their assistance with this article. Images/drawings
© NBBJ.