Structural Challenges with the SOCAR Tower in …global.ctbuh.org/resources/presentations/structural-challenges...Structural Challenges with the SOCAR Tower in ... Per SNiP code 2.01.07-89

Structural Challenges with the SOCAR Tower in Baku, a New Megacity in the Caspian Region 巴库SOCAR大厦中的结构挑战—一座里海地区的新兴大都市

Hi Sun Choi, Senior Principal, Thornton Tomasetti, Inc. Hi Sun Choi,高级总监，宋腾添玛沙帝

SOCAR Tower (Source: Heerim Architects & Planners)

SOCAR Tower Team Client: The State Oil Company of Azerbaijan Republic (SOCAR) Architect and Project Management: Heerim Architects & Planners General Contractor: Tekfen Construction and Installation Structural Engineering: Thornton Tomasetti, Inc. Opus Pearl Structural Engineering

© Council on Tall Buildings

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Recent Tower Development along Heydar Aliyev Avenue (Source: Heerim Architects & Planners)


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Tower Zoning Planning (Source: Heerim Architects & Planners)

Project Brief 38-stories Tower: Height = 200.45-meter GFA = ~100,000 m2. class-A office space guest houses conference rooms, sky-lounge fitness centers underground parking 3-stories Amenity Podium: conference rooms Restaurants Cafeteria + retail fitness club


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SOCAR Tower is inspired by the motifs of

Architectural Design Motives and Design Process

FIRE = Azerbaijan WIND = Baku

ENERGY = SOCAR

(Source: Heerim Architects & Planners)


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Tower Construction Photograph (Source: Thornton Tomasetti, Inc.)

Structural Design Criteria: Building Codes: International Building Code (IBC 2006) Reference to ASCE 7-05. Design Codes: For Concrete: ACI-318-05 For Steel: AISC LRFD 13th ED

Concrete Strength: Core Wall: C50 (f’c = 50 MPa) Slab on Metal Deck: C30 (f’c = 30MPa) Basement Structure: C30 (f’c = 30MPa) Mat: C35 (f’c = 35MPa) Steel Strength: Fy = 345 MPa


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Typical Floor Framing System

Composite infill steel beams typically spaced at 3m. The vibration due to walking excitations was checked with reference to AISC Design Guide 11. Wide flange columns and moment connected beams are used for the perimeter frames.


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Tower Section View of Sloping Column Geometry (Source: Thornton Tomasetti Inc )

Diaphragm Forces Due to Sloping Columns


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Photograph of Downtown Baku (Source: Thornton Tomasetti, Inc.)


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Wind Loads

The City name Baku means “wind-pounded city”. Per SNiP code 2.01.07-89 , a uniform service wind pressure of 6kPa (120 psf) for full height of the tower. Per recommendations from the Wind Tunnel Consultant, Basic wind speed: 53 m/s for 50 yrs. Wind Exposure: C. Importance factor: 1.0 Design Wind Pressures: similar to those in the coastal regions of Alaska. Street Level Wind Pressure: 3kPa (60 psf) = 3x or 4x of major city


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Azerbaijan Baku

PGA for 475 Year Return Period in the Peninsula of Asheron (Source: Akhundov, 2011)

Seismic Loads ASCE 7-05 seismic design parameters provided by the local expert committee and the geotechnical engineer. Ss=1.545g and S1 =0.6g, essentially the same as those at the center of San Francisco. Sds = 1.03g. Later, site specific ground acceleration studies were conducted at several construction sites in Baku that showed maximum design spectrum values approximately 25% less than the assumed values for SOCAR Tower.


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Wind Loads Seismic Loads

Basic Wind Speed, Vo = 53 m/s (50 years, 3 sec.) Dual System with RC Core and Special Moment Frame, R=7

Wind Exposure C

Soil Site Classification D

Seismic Design Category D

Ss= 1.545g Sd=0.6g

Importance Factor, I=1.0 Importance Factor, I=1.0

Vx = 1,830 T (service) Vux = 2,152 T (ultimate)

Vy = 2,030 T (service) Vuy = 2,152 T (ultimate)

My = 146,640 T-M (service) Muy = 160,015 T-M (ultimate)

Mx = 196,400 T-M (service) Mux = 132,815 T-M (ultimate)

Summary of Lateral Load Parameters


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SOCAR Tower Lateral Resisting System

Fundamental Bldg Periods: T1 = 4.71sec in EW T2 = 2.84 sec in NS T3 = 1.39 sec in Torsion

Wind Overall Deflection: Less than H/500 Seismic Inelastic Story Drift: Less than 0.02 per IBC 2010


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Special Moment Frames: Typical Beam Design: - W920 (W36 AISC) with RBS (Reduced Beam Section) - Approximately 25% ~ 30% reduction in flexural

strength at the critical zone for RBS. - A separate model was generated to confirm that the

Special Moment Frames would be capable of resisting 25% of the design seismic forces independently, dual system requirement.

Typical Column Design: - W350 (W14 AISC) - Strong Column Weak Beam (SCWB) check to ensure

the beam exhibits nonlinear behavior before the columns.

- ETABS design module is not able to calculate the reduced flexural strength of the beams for SCWB Check, a separate in-house spreadsheet was used.


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Core Wall: Detailed to accept significant inelastic deformations under seismic events, working with perimeter steel special moment frames. The Core wall thickness: - Foundation to Level 6: 1000mm - Level 6 to Level 24: 800mm - Level 24 to Roof: 600mm Reinforcement was dictated by the seismic detailing requirements: - Heavy confinement rebar was provided around

the vertical reinforcement to prevent sudden crushing of concrete during an earthquake.

- Link beams were designed as steel embedded reinforced concrete (SRC) members rather than diagonally reinforced link beams due to dimensional constraints.


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Foundation Plan (Source: Heerim Architects & Planners)

Raft pile system: A 3.5-meter-thick mat with total 70 piles: 2m & 1.5m dia. RCD piles under the tower footprint

- 2m dia Pile Capacities: 2,400 tons @Compression 600 tons @ Tension - 1.5m dia Pile Capacities: 1,300 tons @Compression 335 tons @ Tension

Foundation Design


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Pile Construction Photograph (Source: Tekfen Construction and Installation)


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Foundation Construction Challenges - Thick limestone layer situated directly below the street

level was removed by saw-cutting - Procurement of piling equipment for the 2m and 1.5m

dia. pile installation under the Tower. - Redesigned with a maximum diameter of 1.2m. - Realized while the piling was under-going construction

at the podium area that the redesign would cause a further significant delay on the foundation construction.

- Purchased a new machine from overseas to make the 2.0-meter diameter pile installation possible.


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Tuned Mass Damper (Source: Heerim Architects & Planners)

Tower Motion (Acceleration) Control

Tower Acceleration without TMD: 28.5 milli-g for 1-yr, 47.3 milli-g for 5-yrs, 58.8 milli-g for 10-yrs winds with 1.5% of critical damping inherent.

Bldg Acceleration with a 600 tons supplementary TMD: 12 milli-g for 1-yr 17 milli-g for 5-yrs wind.

Does not Satisfy the International Organization for Standardization (ISO) 10137 and 6897 (ISO 2007; ISO 1984).


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Facade Design Free formed spiral shape to express the basic design concepts of fire, wind, and energy. Maximizing usable space and minimizing the gap between the building skin and the slab edge were top design priorities. Rectangular typical curtain wall unit following smooth curvature exterior lines except for corner conditions. Entire units are equipped with LED lights.

Photograph of Exterior LED Lighting (Source: Heerim Architects & Planners)


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Implement higher security measures reflecting the strategic importance of the SOCAR Tower. Anti-blast design was studied by the special consultant retained by the client and redundant structural load paths were considered in the final structural design. Refuge area and structural upgrades provided to primary structural elements. The newly added special refuge area located in the basement is shielded by thick reinforced concrete fin walls painstakingly tied to the already installed building structure.

Blast Resistant Improvement Design


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Conclusion and Acknowledgements - SOCAR Tower became the tallest

tower in Azerbaijan and a national landmark.

- Its design was inspired by the motifs of fire, wind and energy, which represent Azerbaijan, Baku and SOCAR, respectively.

- SOCAR Tower has introduced new innovative design and construction technologies related to high rise buildings such as 2m dia RCD and TMD.

- Dual system of Special Reinforced Concrete dual system and Special Steel Moment Frames.

- Received the ENR 2016 Global Best Projects Award in Office Category

- Special thanks to SOCAR, Heerim, and Tekfen


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Documents

Structural Challenges with the SOCAR Tower in …global.ctbuh.org/resources/presentations/structural-challenges...Structural Challenges with the SOCAR Tower in ... Per SNiP code 2.01.07-89