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China is now undergoing the largest and fastest urbanization process in the world, developing various reinforced concrete high-rise buildings during this process. Most high-rise structures are constructed in densely populated and economically active areas and earthquakes pose a potential possibility of serious economic loss and casualties, which cannot be ignored. This paper conducts on-site dynamic tests on 129 high-rise RC buildings in eastern China by utilizing ambient vibration measurement. Fundamental vibration periods, second vibration periods, and third vibration periods are statistically analyzed in translational directions based on two high-rise building types: shear wall slab building and shear wall tower building (including framed shear wall structures and framed tube structures). After fully considering building usage conditions and comparing the fitting formulas in existing codes, fitting empirical formulas of the vibration periods in two translational directions based on the above structural types are given. The ratio distribution ranges of vibration periods are calculated by utilizing the vertex displacement method, concentrated mass method, and Rayleigh-Ritz energy method. In addition, by analyzing the vibration period ratio in horizontal directions of 543 high-rise RC buildings, different ranges are distinguished as well as suggested boundaries are given. The conclusion of this paper provides a reference and convenient method for future on-site dynamic testing and a new proposal is provided to the empirical formula of vibration period in the current building seismic design code. [ABSTRACT FROM AUTHOR]

This study is carried out based on field investigation data obtained over more than 20 days after the 20 April 2013 Lushan Ms7.0 earthquake in Sichuan Province, China. The investigation includes detailed seismic damage data from 3,684 buildings in 428 districts. This research summarizes the seismic characteristics of buildings with different structures in this area and systematically analyzes the cause of damage. Based on this analysis, the seismic vulnerability of various structural forms in different intensity regions is systematically assessed. The damage characteristics are summarized for several types of the structures typical in the region: constrained masonry structures designed following current standards, unengineered constrained masonry structures, unreinforced masonry structures, brick-wood structures, brick-concrete structure, traditional Chinese timber frame structures, reinforced concrete frame structures, tall buildings, and industrial plants. Moreover, the causes of damage to these structures are investigated. Furthermore, through statistical analysis, this study develops a vulnerability matrix for the main building types and compares their vulnerabilities of similar buildings in regions with different earthquake intensities. The research results provide an important reference for earthquake engineers to recognize failure modes in different types of structures (especially those reconstructed after the Wenchuan earthquake, Sichuan Province, China), revise seismic design codes, and formulate future disaster-reduction plans. [ABSTRACT FROM AUTHOR]

The post-earthquake rapid accurate assessment of macro influence of seismic ground motion is of significance for earthquake emergency relief, post-earthquake reconstruction and scientific research. The seismic intensity distribution map released by the Lushan earthquake field team of the China Earthquake Administration (CEA) five days after the strong earthquake ( M7.0) occurred in Lushan County of Sichuan Ya'an City at 8:02 on April 20, 2013 provides a scientific basis for emergency relief, economic loss assessment and post-earthquake reconstruction. In this paper, the means for blind estimation of macroscopic intensity, field estimation of macro intensity, and review of intensity, as well as corresponding problems are discussed in detail, and the intensity distribution characteristics of the Lushan '4.20' M7.0 earthquake and its influential factors are analyzed, providing a reference for future seismic intensity assessments. [ABSTRACT FROM AUTHOR]