Commerzbank, Frankfurt, Germany

Commerzbank -Frankfurt, Germany

Architect: Sir Norman Foster and Partners ClientPartners Client: Commerzbank

Structural Engineer : Arup & PartnersConstruction started: 1994Year Completed : May,1997Occupancy Type: OfficeConstruction type: Mixed (reinforced concrete foundation, steel frame with vierendeel principle)Height: 258.7 metres (853.71 feet) 298.74 metres (985.8 feet) up to the top of AntennaStories: 63Area: 120,736 sq m(1,314,815 sq ft)

Structure Foundation type: pile raft foundationGravity force systems type: perforated tube structure (corner columns with link frames)Lateral force systems type: vierendeel truss systemsecondary structure/ backup: continuous floors at every fourth floor act as a stiffening diaphragm

EnvelopeGlazing type: identify double-glazed operable window w/ outer skin of fixed glass & ventilated cavitySkylights: full-height atrium with glass decks every twelve floorsCladding type: identify double-skinned aluminium framed curtain wallRoof: glazed roof over plaza & atrium, high albedo concrete above remaining program

Passive systemDay lighting: sky gardens, atrium, & floor-to-floor glazingHeating: passive solar gain, heat generated from office machinery & building occupantsCooling: natural ventilation, stack effect

HVAC

Equipment list: cooling towers, absorption chillers, central building management system (BMS)Cooling system type: water-cooled, chilled-panel ceiling systemHeating system type: thermostatically controlled radiant heating systemDuct yes/no: yesVertical Chases yes/no: no

construction phase

structural system

Perforated Tube StructureThe perforated tube structure of the Commerzbank is made up of two primary structural elements: the eight-storey Vierendel trusses, and the corner columns. These two elements provide the primary gravity and lateral load resisting members of the building. To add stiffness and stability to the structure, every fourth floor is continuous throughout the building.

Two storey high link frames that connect the main composite ‘mega columns ’Picture

Mega-Column

The “mega-columns” of the Commerzbank tower encompass a response to structural, environmental, and construction ideas.Even though the building’s foundation consists of piles bearing on fairly stable limestone, it has to be as light as possible. The “mega-columns” of the building consist of two vertical steel ʻHʼ-section members that rise from the foundation to the top of the building. The members are stabilized by beams and diagonal bracing and encased in reinforced concrete. This creates a very light but strong structure to carry the gravitational loads of the tower. Consequently, the concrete also acts as a damper to reduce vibration in the steel from wind.

Exploded axon of major structural members:Red corner: columnsBlue: Vierendeel framesGreen: floor structure

Diagram of how concrete can be poured while steel frame is still being constructedabove it

Diagram of wind vibration in structure with or without concrete encasement

Exterior Office Glazing Panels

Design Analysis-Floor Plan organization

Floor plan of the tower is an equilateral triangle (each side approximately 64 meters) with rounded corners and slightly convex sides.

Floors of the building as well as the cores at the three corners are organized around the central atrium.

Each floor has three wings, two of which serve as office “villages”; the third forms part of one of the 4-story-high “sky gardens”.

Atrium is separated horizontally every 12-storeys at the ‘village’ boundaries to limit stack pressures and smoke spread.

Principal entrance to the new tower is from the north, up a grand flight of stairs.

Water is shed away from glazing toAerofoil sections and the location of the operable glazing

Ventilation allows air intake at thebottom sill and exits at the head of thewindow

Passenger lifts in each core serve a distinct group of floors

the combined service/firemen’s lifts in the north and west cores stop at every level

interchanges at levels 7,19 and 35 simplify travel between floors for those people working in the building

Construction: The Foundation

The long piles led to high torsion stresses during drilling, causing restrictions on their overall diameters.They used telescopic piles-dia 1.5 m.