journal article
LitStream Collection
Home
doi: 10.1002/eqe.3216pmid: N/A
Ground‐motion models (GMMs) are widely used in probabilistic seismic hazard analysis (PSHA) to estimate the probability distributions of earthquake‐induced ground‐motion intensity measures (IMs) at a site, given an earthquake of a certain magnitude occurring at a nearby location. Accounting for spatial and cross‐IM correlations in earthquake‐induced ground motions has important implications on probabilistic seismic hazard and loss estimates. This study first develops a new Italian GMM with spatial correlation for 31 amplitude‐related IMs, including peak ground acceleration (PGA), peak ground velocity (PGV), and 5%‐damped elastic pseudo‐spectral accelerations (PSAs) at 29 periods ranging from 0.01 to 4 seconds. The model estimation is performed through a recently developed one‐stage nonlinear regression algorithm proposed by the authors, known as the Scoring estimation approach. In fact, current state‐of‐practice approaches estimate spatial correlation separately from the GMM estimation, resulting in inconsistent and statistically inefficient estimators of interevent and intraevent variances and parameters in the spatial correlation model. We test whether this affects the subsequent cross‐IM correlation analysis. To this aim, based on the newly developed GMM, the empirical correlation coefficients from interevent and intraevent residuals are investigated. Finally, a set of analytical correlation models between the selected IMs are proposed. This is of special interest as several correlation models between different IMs have been calibrated and validated based on advanced GMMs and global datasets, lacking earthquakes in extensional regions; however, modeling the correlation between different IM types has not been adequately addressed by current, state‐of‐the‐art GMMs and recent ground‐motion records for Italy.
Lu, Xinzheng; Liao, Wenjie; Cui, Yao; Jiang, Qing; Zhu, Yaning
doi: 10.1002/eqe.3218pmid: N/A
The frame‐core tube‐outrigger structural system is widely used in tall buildings, in which outriggers coordinate the deformation between the core tube and the moment frame, leading to a larger structural lateral stiffness. Existing studies indicate that outriggers can be designed as “fuses” of tall buildings through dissipating seismic energy after yielding, to protect the main structure. To date, both conventional and buckling‐restrained brace (BRB) outriggers have been applied in practice. Subjected to the maximum considered earthquake (MCE), the hardening effect of BRB outriggers increases the damage of other structural components. Meanwhile, conventional outriggers are difficult to repair, owing to the local buckling‐induced severe deterioration and damage. To overcome these problems, this study proposes a novel sacrificial‐energy dissipation outrigger (SEDO) to improve the seismic resilience of tall buildings. The chords of SEDO are made of high‐strength steel and remain elastic. The inclined braces of the SEDO are composed of a sacrificial part and an energy‐dissipating part. Therefore, the SEDO remains elastic under design‐based earthquakes (DBEs) and dissipates inelastic energy under MCEs. Moreover, the detailing of this novel SEDO is proposed on the basis of experimental studies. The optimal strength ratio between the sacrificial part and the energy‐dissipating part is determined in the range of 6:4 to 4:6 on the basis of nonlinear time history analyses (THAs) and parametric studies. Afterwards, the SEDOs are used in an actual tall building to verify their seismic performances through nonlinear THAs. The results indicate the proposed SEDO is able to protect other structural components and effectively improve the seismic resilience of tall buildings.
doi: 10.1002/eqe.3219pmid: N/A
Accurate prediction of the dynamic responses of a high‐rise building subjected to dynamic loads such as earthquake and wind excitations requires the information of its structural dynamic properties such as modal parameters including natural frequencies and damping ratios. This paper presents the identification results of the modal parameters based on field vibration tests on a 600‐m high skyscraper. A set of tests, including ambient vibration test (AVT) and free vibration test (FVT), were conducted on the skyscraper to identify its modal parameters. Firstly, this paper presents and discusses the modal parameters of the skyscraper assessed by several identification methods applied to the AVT measurements. These methods include the wavelet transform (WT) method, the stochastic subspace identification (SSI) method, and the random decrement technique (RDT). Secondly, an active mass damper (AMD) system with total mass 1000 tons equipped into the skyscraper was used to excite the building for estimation of the modal parameters by FVT. Thirdly, this paper presents observations on the structural dynamic behavior of the skyscraper with the operation of the AMD system during a typhoon event. The field measurement results show that the AMD system functioned efficiently for suppression of the wind‐induced vibrations of the skyscraper during the typhoon. This paper aims to further understand the structural dynamic properties of super‐tall buildings and provide useful information for structural design and vibration control of future skyscrapers.
Showing 1 to 5 of 5 Articles