Seismic Behavior of Stone Pagoda Structure by Shaking Table Test

In general, the stone pagoda structures with discontinuous surfaces are vulnerable to lateral forces and are severely damaged by earthquakes. After the Gyeongju earthquake in 2016 and the Pohang earthquake in 2017, numerous stone pagoda structures were damaged due to slippage, rotation, and the separation of stacked stone. To evaluate seismic resistance of masonry stone pagoda structures, we analyzed the seismic behavior of stone pagoda structures using the shaking table test. Shaking frequency, permanent displacement, maximum acceleration, rocking, and sliding were assessed. Responses to simulations of the Bingol, Gyeongju, and Pohang earthquakes based on the Korean seismic design standard (KDS 41 17 00) were analyzed for return periods of 1000 and 2400 years. We found that the type of stylobate affected the seismic resistance of the stone pagoda structure. When the stylobates were stiff, seismic energy was transferred from lower to upper regions of the stone pagoda, which mainly resulted in deformation of the upper region. When the stylobates were weak, earthquake energy was absorbed in the lower regions, which was associated with large stylobate deformations. The lower part of the tower body was mainly affected by rocking, because the structural members were slender. The higher part of the stone pagoda was mainly affected by sliding, because the load and contact area decreased with height.

Seismic Behavior of Stone Pagoda Structure by Shaking Table Test

In general, the stone pagoda structures with discontinuous surfaces are vulnerable to lateral forces and are severely damaged by earthquakes. After the Gyeongju earthquake in 2016 and the Pohang earthquake in 2017, the earthquakes damaged numerous stone pagoda structures due to slippage, rotation and the separation of stacked stone. To evaluate seismic resistance of masonry stone pagoda structure, we analyzed the seismic behavior of stone pagoda structure using shaking table test. Shaking frequency, permanent displacement, maximum acceleration, rocking, and sliding were assessed. Responses to simulations of the Bingol, Gyeongju, and Pohang earthquakes based on Korean seismic design standard (KDS 41 17 00) were analyzed for return periods of 1,000 and 2,400 years. We found that the type of stylobate affected the seismic resistance of stone pagoda structure. When the stylobates were stiff, seismic energy was transferred from lower to upper regions of the stone pagoda, which mainly resulted in deformation of the upper region. When the stylobates were weak, earthquake energy was absorbed in the lower regions; this was associated with large stylobate deformations. The lower part of tower body was mainly affected by rocking, because the structural members were slender. The higher part of the stone pagoda was mainly affected by sliding, because the load and contact area decreased with height.

MACROSEISMIC EVIDENCE OF SEISMIC EVENTS CAUSED BY INFLUENCE OF GROUND CONDITIONS AND FORMATION OF MAPS OF SEISMIC MICROZONATION

Проявление каждого ощутимого землетрясения несет в себе уникальную информацию о его реальном проявлении на исследуемой территории. Поэтому сбор и анализ всех имеющихся данных о проявлении сейсмически событий на исследуемой территории является важным по оценке сейсмической опасности. В работе рассмотрено проявление наиболее сильного землетрясения, произошедшего в современное время – Рачинского землетрясения 29 апреля 1991 г. на территории г. Амбролаури. Показано усиление сейсмического эффекта, обусловленного влиянием грунтовых условий. Рассмотрено проявление слабого землетрясения 2005 г. на территории г. Владикавказа и выполнено сопоставление с действующей картой сейсмического микрорайонирования. Использование современных информационных технологий позволило по признакам проявления слабых воздействий выделить отдельные участки, в которых сейсмический эффект может быть обусловлен индивидуальными локальными особенностями грунтовых условий, а также спектральными особенностями воздействия и состояния застройки Macroseismic evidence of each significant earthquake carries a unique information about its actual impact on the investigated territory. Therefore, the collection and analysis of all available data on the occurrence of seismic events in the study area is important in assessing seismic hazard. The paper shows the manifestation of the strongest earthquake that occurred in modern times – the Racha earthquake on April 29, 1991 in the territory of Ambrolauri city. The increase in the seismic effect due to the influence of ground conditions is shown. The manifestation of a weak earthquake in 2005 in the territory of the city of Vladikavkaz is considered and a comparison is made with the current seismic microzoning map. The use of modern information technologies made it possible, on the basis of manifestations of weak effects, to single out individual areas in which the seismic effect can be caused by individual local features of ground conditions, as well as the spectral features of the impact and building conditions

Rethinking earthquake-related DC-ULF electromagnetic phenomena: towards a physics-based approach

Numerous electromagnetic changes possibly related with earthquakes have been independently reported and have even been attempted to apply to short-term prediction of earthquakes. However, there are active debates on the above issue because the seismogenic process is rather complicated and the studies have been mainly empirical (i.e. a kind of experience-based approach). Thus, a physics-based study would be helpful for understanding earthquake-related electromagnetic phenomena and strengthening their applications. As a potential physics-based approach, I present an integrated research scheme, taking into account the interaction among observation, methodology, and physical model. For simplicity, this work focuses only on the earthquake-related DC-ULF electromagnetic phenomena. The main approach includes the following key problems: (1) how to perform a reliable and appropriate observation with some clear physical quantities; (2) how to develop a robust methodology to reveal weak earthquake-related electromagnetic signals from noisy background; and (3) how to develop plausible physical models based on theoretical analyses and/or laboratory experiments for the explanation of the earthquake-related electromagnetic signals observed in the field conditions.