Two landmark projects completed with the participation of the School of Civil Engineering and Water Resources at Tsinghua University—"Fire Safety Design of Large Concrete-Filled Steel Tubular Columns in Terminals T1 and T2 of Chengdu Tianfu International Airport" and "Beijing Chaoyang District CBD Core Area Plot Z15 Project (CITIC Tower)"—received the ASCE Greater China Project Excellence and Innovation Award and the China Civil Engineering Zhan Tianyou Award, respectively. Professor Han Linhai of the School of Civil Engineering and Water Resources at Tsinghua University served as the lead of the participating party.

China Civil Engineering Zhan Tianyou Award

Chengdu Tianfu International Airport is a national key project and officially began operations in June 2021. The total construction area of Terminals T1 and T2 of Tianfu International Airport exceeds 700,000 m², with a maximum span of 72 m and a maximum cantilever of 32.8 m. The main vertical load-bearing structure of the terminals consists of concrete-filled steel tubular columns, with a maximum outer diameter of 2.3 m. As large main structural components of this important public building, the fire protection design of the concrete-filled steel tubular columns is extremely challenging and must comprehensively balance structural reliability, economy, and architectural aesthetics. To this end, Professor Han Linhai led a research team in close cooperation with the China Southwest Architectural Design and Research Institute Corp. Ltd. and other units. Based on the multi-field coupling effect of "load-temperature-time" under fire, they conducted fire resistance analysis of concrete-filled steel tubular columns and bearing capacity calculations for the entire fire process, and ultimately determined a design scheme using an intumescent fireproof coating system. This overcame the difficulty of lacking design basis for such schemes and achieved good architectural and technical-economic results.

Aerial panoramic view of Chengdu Tianfu International Airport

This technology also provided a basis for the formulation of fire protection design provisions in the national standard "Technical Standard for Concrete-Filled Steel Tubular Hybrid Structures" GB/T 51446-2021 and the international standardDesign of concrete-filled steel tubular (CFST) hybrid structures ISO 16521:2024. It is reported that the fire protection design of concrete-filled steel tubular components in the Chongqing Jiangbei International Airport T3B Terminal project (completed acceptance in January 2025 and officially put into use in April 2025) also adopted this technology.

Interior view of the hall of Terminals T1/T2 of Chengdu Tianfu International Airport

The Beijing Chaoyang District CBD Core Area Plot Z15 Project (CITIC Tower), 528 m tall, is the world's first 500 m-class super high-rise building in a high seismic intensity area (seismic fortification intensity ≥ 8 degrees), and was completed in October 2018. The building adopts a dual lateral force-resisting structural system composed of a mega outer frame tube and a core tube, in which the main vertical load-bearing components of the outer frame tube adopt multi-cell polygonal concrete-filled steel tubular mega-columns, with a maximum cross-sectional area of 62.3 m².

Beijing CITIC Tower

In this project, how to ensure the reliability of the seismic performance of the concrete-filled steel tubular mega-columns is one of the core challenges faced by the project design. To this end, Professor Han Linhai worked jointly with Beijing Institute of Architectural Design Co., Ltd., China Construction Third Engineering Bureau Co., Ltd., and other units to carry out experimental research and refined simulation of the mechanical performance of multi-cell polygonal concrete-filled steel tubular mega-columns and their key joints, such as mega-column branching joints and column base connection joints, and proposed their seismic design methods and joint detailing measures, providing a basis for the engineering structural design. In addition, the research team led by Professor Han Linhai has carried out in-situ field testing on the long-term performance of the concrete-filled steel tubular mega-columns since September 3, 2014, for more than 10 years, verifying the mechanical reliability of the mega-columns. As of the time of publication, the testing is still ongoing, providing an important basis for full-life-cycle performance analysis and engineering practice verification of large concrete-filled steel tubular structures.

Award certificate for the innovation group of the China Civil Engineering Zhan Tianyou Award