Basaksehir City Hospital; Basaksehir City Hospital;

Başakşehir Pine and Sakura City Hospital, Istanbul

Bringing to life the largest base-isolated building in the world

As one of the world’s most populous cities, Istanbul saw the need to expand their healthcare offerings with a new large-scale hospital to serve its growing population. In addition to providing world-class healthcare services, the hospital needed to be seismically secure, as Istanbul is located near the North Anatolian fault and has suffered highly destructive earthquakes in the past.

Working with Rönesans Holding, currently operating in the roles of main contractor and investor in 28 countries around the globe and ranked 33rd in ENR’s list of the world’s largest construction companies, Arup designed Başakşehir Pine and Sakura City Hospital. Opened in May 2020, the hospital was jointly built by Rönesans Holding and Sojitz Corporation, a Japanese investment and trade corporation, using a Public-Private Partnership (P3) model. The hospital is the largest base-isolated building in the world, and features more than 2,000 seismic isolators, as well as one million m2 of construction area.

The engineering behind the seismically resilient hospital was no small feat – it involved evaluation of hundreds of structural configurations, including multiple seismic isolation schemes and concrete wall layouts. For many decades, engineers have based analysis and validation on available computational methods or algorithms, as well as the available computational processing speed, or hardware firepower. However, Arup has for years embarked on a journey to leverage cloud computing to transform traditional workflows. By using LS-DYNA, an advanced finite element analysis software, in conjunction with cloud computing, Arup was able to expedite the non-linear analysis workflow by 50% in comparison with traditional non-cloud-based workflows.

Başakşehir Pine and Sakura City Hospital features three hospital towers, six clinic buildings, and five auxiliary facility buildings that provide 2,682 beds divided between the main hospital, psychiatric hospital, and the physical treatment and rehabilitation facility. The hospital partially opened in April 2020 to assist with the ongoing COVID-19 pandemic.

Project Summary

1,000,000 construction area

2,068 seismic isolators

2,682 beds

Leveraging digital technology

The hospital’s large-scale structure and location in a highly active seismic region made it challenging to analyse. Earthquakes release large amounts of energy that travel through a structure in the form of seismic waves. However, in non-isolated buildings, when conventional elements such as beams, columns, and walls go beyond their elastic capacities, they begin to exhibit distress in the form of cracks and may render the building unusable due to safety concerns. To avoid this, buildings in highly seismic regions benefit from the use of seismic isolators that allow buildings to move safely and absorb and dissipate energy. Use of seismic isolation in Başakşehir Pine and Sakura City Hospital reduced the earthquake forces used in the design of the superstructure by a factor of 3.

Arup conducted a wall optimization study in which a total of 180 different wall thickness configurations were evaluated. Performance results of each configuration and the associated concrete quantities were shared with the client via a web interface developed by Arup. The unique interface allowed Rönesans Holding to be engaged in the engineering design and to leverage this information as part of their procurement strategy and process.  

Our digital and cloud-based workflows expedited the process from the concept phase through documentation, facilitating the completion of the design of the hospital within one year and significantly reducing the amount of time typically associated with such large-scale projects. Ultimately, the design aims to ensure that the hospital can remain operational after an earthquake, allowing for critical and life-saving services for its patients and adding to the overall resiliency of Başakşehir and İstanbul. ” Atila Zekioglu Atila Zekioglu Principal

To further help the client, Rönesans Holding, decide on the most feasible isolator type for the project, Arup ran a full building performance evaluation using nonlinear time history analyses on six different isolation schemes. Through traditional means of analysis and post-processing, this process would have taken approximately six to seven months. However, by leveraging digital technology and cloud computing, Arup was able to go beyond standard computational limits and finish this evaluation within two months. This enabled Rönesans Holding to choose the most optimum isolation scheme based on performance, cost, and schedule. 

Use of cloud computing and in-house developed digital tools throughout the project not only made the analysis of this large-scale structure possible, but also significantly improved the efficiency of the design process. By conducting the rapid seismic isolation and structural optioneering studies at the outset of the project, Arup was able to complete the design of the hospital in less than a year.

This project is of significant importance to me not only for the vital service that it will provide Istanbul and its surrounding areas, but also because it is located near my hometown. After experiencing firsthand the devastating 1999 earthquake in Izmit, it is rewarding to be able to give back to my community by ensuring that critical medical services can be provided even after a destructive earthquake. ” Aysegul Gogus Aysegul Gogus Associate

Designing for resilience

The hospital is designed to satisfy ASCE 41 “Immediate Occupancy” seismic performance objective under a very rare earthquake event. To achieve this performance objective, the structure is supported by 2,068 triple-friction-pendulum (TFP) isolators, which can displace up to 700mm in a seismic event, allowing energy to be dissipated through this movement and thus reducing damage to the superstructure. 

The final design ensures that the hospital can remain operational, even for functions as delicate as surgeries, after a Maximum Considered earthquake, an event so rare that is expected to occur only once in approximately 2,500 years. Ensuring the hospital’s functionality is vital for not only patients who might need urgent treatment, but also for the resilience of the community and the city.

The completion of the world's largest base isolator structure with a great success, including all design disciplines, in a period of 32 months, could only be achieved by a great collaboration of Rönesans Holding's superior coordination and very high-quality construction speed capability and Arup's very advanced and innovative engineering solutions. ” Serdar Binzet President of Engineering Group / Rönesans Holding