Seismic Ground Response Analysis of Input Earthquake Motion and Site Amplification Factor at KUET

Ground motion is the movement of the earth's surface due to explosions or the propagation of seismic waves. In the seismic design process, ground response analysis evaluates the impact of local soil conditions during earthquake shaking. However, it is difficult to determine the dynamic site response of soil deposits in earthquake hazard-prone areas. Structural damage has a great influence on the selection of input ground motion, and in this study, the importance of bedrock motion upon the response of soil is highlighted. The specific site response analysis is assessed through “DEEPSOIl" software with an equivalent linear analysis method. Furthermore, four input motions including Kobe, LomaGilroy, Northridge, and Chi-Chi were selected to obtain normalized response spectra. This study aims to obtain the site amplification of ground motion, peak spectral acceleration (PSA), and maximum peak ground acceleration (PGA) based on shear wave velocity from the detailed site-specific analysis of Bangabandhu Sheikh Mujibor Rahman hall at Khulna University of Engineering & Technology. The maximum shear wave velocity obtained was 205 m/s while the amplification factor varied from 4.01 (Kobe) to 1.8 (Northridge) for rigid bedrock properties. Furthermore, the Kobe earthquake produced the highest (4.3g) PSA and the Northridge earthquake produced the lowest (1.08g) PSA for bedrock, with Vs=205 m/s. The surface PGA values were acquired in the range of 0.254g (Northridge) to 0.722g (Kobe), and the maximum strain values for Kobe earthquakes were in the range of 0.016 to .303. Therefore, the surface acceleration values were very high (>0.12g) for the Kobe earthquake motion.

Decaying Post-Seismic Deformation Observed on the Korean Peninsula Following the 2011 Tohoku-Oki Earthquake

We investigated decaying post-seismic deformation observed on the Korean Peninsula associated with the 2011 Mw 9.0 Tohoku-Oki earthquake using Global Navigation Satellite System (GNSS). The GNSS velocity vectors were estimated in five periods from 2005 to 2019. A co-seismic offset of the Korean Peninsula caused by the 2011 earthquake was inversely proportional to epicentral distances. According to the temporal variations of two components (magnitude and direction) of the GNSS velocity vector with the epicentral distance, the difference between the eastern and western regions for the two components becomes smaller over time. For approximately nine years after the 2011 event, the direction for the crustal movement in South Korea showed a recovery pattern returning to the pre-earthquake motion. In addition, the recovery patterns of the crustal movement were observed differently with the regional geologic structure (e.g., the crustal thickness) and each period. Our estimates of the decay in post-seismic deformation of the Korean Peninsula suggest that post-seismic relaxation will be complete within 5–20 years after the 2011 earthquake. The results suggest that the crustal movement on the Korean Peninsula is gradually recovering to its pre-earthquake motion.

Geophysical and geotechnical factors in urban planing: Bursa (Nilüfer, Osmangazi, and Yildirim) cases

The study area covers the Central of Bursa, Osmangazi, Yildirim, Gürsü, Kestel and Nilüfer District boundaries in Bursa. The seismic process deals with the occurrence of an earthquake event and the process of wave propagation from the source to the site. Local amplification caused by surficial soft soils is a significant factor in destructive earthquake motion. In the first phase of this study, it is investigated the ground motion level and soil amplifications for Bursa city. For his aim, probabilistic and deterministic earthquake hazard analysis (including acceleration estimations) will be carried out for the region. Local amplification caused by surficial soft soils is a significant factor in destructive earthquake motion. In the first phase of this study, it is investigated the ground motion level and soil acharacterization for the region. For his aim, probabilistic earthquake hazard analysis (including acceleration estimations) was carried out for the region. Then, soil shear wave velocities were estimated from data obtained by MASW measurements. Soil liquefaction is a natural event in which the strength and stiffness of a soil are reduced by earthquake vibrations or other dynamic loadings. As it is known, liquefaction occurs in saturated soils, that is, soils in which the space between individual particles is completely filled with water. One of liquefaction evaluation methods is based on the cyclic stress approach. In this method, a safety factor is defined as CRR/CSR. CRR is a cyclic resistance ratio that represents soil liquefaction susceptibility, and CSR is the cyclic stress ratio that represents the earthquake effect. In the second phase of this study, possible soil potential index (PL) and ground induced settlements were estimated by using Isihara ve Yoshimine (1990) approach. All results on liquefaction potential index (Pl), liquefaction induced settlements and soil shear wave velocities in Bursa (Turkey) City were compared with each other. Finally, a seismic microzonation map was prepared by the integration of geophysical and geotechnical data for urban planning purposes.

Behaviour of RC Moment Resisting Regular and Irregular Framed Structures Situated Near and Far to Fault Zone

Near fault earthquake record are rich in high frequencies that effects structures for far fault earthquake record lower frequencies is not effects highly in structure. The objective of the study is to be investigating the effect of near-fault and far fault earthquake motion on the response of RC moment resisting regular and irregular structure considering Near and Far situated fault zones. Linear time history analysis G+10 building has carried out for two structures. The effects of Near and Far faults zones were evaluated for G+10 Two structure the ordinary moment resisting frame system was considered for two building as a lateral load-resisting system. For two building time, history analysis was performed under two example earthquake motion Uattarkashi (Almora and Bhatwari) magnitude 6.8 Mw. The peak acceleration v/s time response spectra of the two horizontal components of the two records for Near source earthquake records @ a distance 21.7 km Bhatwari and Far source earthquake records @ a distance 153.5 km of Almora records are taken in virtual data centre of India earthquake records COSMOS Virtual Data Center - Strong Motion Center. For two building and earthquake record, the analysis was carried out for both conditions and compared with fixed base results for all analysis both Near-field and Far-field earthquake were considered. The mainly evaluated parameter were storey drift, storey displacement and storey force, period vibration results based on linear time history analysis considering two structures. The comparative study of four parameters considers the graphs and curves shows higher and lower values higher values show that the earthquake effect of building and damages is more.