Seismic Monitoring of Super High-Rise Building Using Ambient Noise with Dense Seismic Array

We report the first thorough seismological study of the Shanghai Tower, the second tallest building in the world, by applying seismic interferometry to ambient noise recorded by a dense seismic array. We extract the building responses by deconvolution of the seismic vibrations for three components of the impulse response functions (IRFs), and retrieve two wave types corresponding to vertical and horizontal wave components that travel along the core tube of the tower. Five new resonant modes are identified here for the first time between 1 and 5 Hz. Displacements for the resonant modes around 1 Hz are strongly attenuated by the passive damper system installed on the top floor of the building. Refuge floors connected to the outrigger trusses system have unique structural properties, characterized by a specific resonant mode, which apparently shifts from 1.8 Hz at the base of the building, to ∼3 Hz at the top. The most interesting observation is the diurnal variation in both the seismic velocities and the mechanical response of the building, which correlates with temperature, and was detected by repeated measurement of coda waves for the IRFs and the horizontal-to-vertical spectral ratio. Seismic velocity appears to increase for the structure at midnight due to cooling that drives an increase in rigidity, which reaches a local maximum in the early morning and decreases after sunrise. In summary, our study demonstrates the effective application of seismic ambient-noise interferometry for structural health monitoring and for hazard assessment for super high-rise buildings worldwide.