Capital City Towers Moscow
Yuri Starodubtsev - Special Projects Design Manager - Capital Group, Larry Goetz - Principal, Joey Meyers - Senior Project Designer, NBBJ.
With its compressed schedule, achieving this unique structure at this point in Moscow's history required innovation and collaboration. The design introduced advanced engineering and capabilities while building upon local construction expertise. Developed by Capital Group, a Moscow-based company responsible for more than 5 million square meters (53.8 million square feet) of residential, commercial and mixed-use development, Capital City's completion represents an exchange of highrise design and construction expertise that will influence future construction and building standards in Russia.
Anchoring A New District
The idea of a new business district in Moscow first emerged after the completion of the Expocenter in 1980. With the Expocenter drawing new activity to the area, attention turned to the adjacent site, then a declining industrial area. By 1990, a master plan for a new international business center was in place, but it would take the sustained economic growth of the past decade to finally catalyze developments.
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.
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 highrise 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 the 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.
|Completion Date:||December 2010|
|Height to Architectural Top:||302m (989ft) Moscow – 257m (843ft) St. Petersburg|
|Stories:||76 (Moscow), 65 (St. Petersburg)|
|Total Area:||288,000 sq. m (3.1 million sq. feet)|
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 nothing but typical. The tower pile caps were installed during continuous, 33-hour mid-winter pours in temperatures ranging from -32 to -34oC (-25 to 30oF), 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 (65.5 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 comprised circulation and the basement-level program. The six-level basement includes more than 2,200 parking spaces, electrical equipment and enlarged file compartments.
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.
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.
One of the project's more complex curtain wall systems is the folded, angled curtain wall covering the retail atrium and spa pool and making the main entrance (see Figure 6). The curtain wall's geometry tapers in plan and angles in section, allowing for water drainage and ice collection and removal. The glass panels are heated to adapt to Moscow's winter climate. The skylight system - an undulating, folding clear and translucent glazing - also resonates with the interior pedestrian "fashion street" at the ground level by creating a fashion/fabric analogy.
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 finalizations. Wind tunnel tests and computer analyses were performed to determine areas of positive and negative pressure, after which on-site mock-ups provided critical feedback dictating the use of thicker glass in certain locations. After several tests, the necessary thickness for the exterior glass on the upper floors of the St. Petersburg and Moscow Towers was deemed to be 8 millimeters (0.25 inches) and 10 millimeters (0.375 inches), respectively.
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 agencies - represents a foundation of exchange between the global and local tall building industries that paves the way for future advances.