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.

Damped outrigger semi-active control for seismic vibration mitigation

In earlier days, the only way to resist the lateral loads was to increase the lateral strength of the structure obtained by making larger cross sections and massive buildings. Structural control is one of the solutions and important topics in both points of view of security and comfort in recent years. To reduce the effect of seismic energy, one of the structural forms used is the outrigger. In recent years, supplementary devices are installed into the outrigger structure so that damping of the structure increases and helps in mitigating the vibration, this concept is called damped outrigger. In this study, a damped outrigger structure replicating St. Francis Shangri-La Place skyscraper is excited for the El-Centro earthquake, and the Kobe earthquake is numerically modeled with viscous dampers and Magneto-Rheological damper to compare its effectiveness. The finite element approach is used for the analysis of the structure using Bernoulli’s Euler beam theory in modeling the core of the structure as a beam element. The state-space approach is used in modeling the structure, dampers, and controller interface in MATLAB and Simulink, then results are obtained for the peak value of displacement, acceleration, and mean values of the response of the structure. The results are discussed, which shows the significant distinction between uncontrolled and controlled responses.

Demolition traditions: Isozaki and Sakaguchi

If ever an architect bit the hand that fed, it was the young Arata Isozaki, a mercurial and uncompromising architectural talent who would go on to secure establishment respectability with the Pritzker Prize of 2019. But he made his renown with designs and exhibitions exploring themes of death and destruction, not least his ‘Fractures’ pavilion for the 1996 Venice Biennale, which sought to stage the aftermath of the Kobe earthquake from a year earlier, while also being a leading proponent of a playful, almost saccharine postmodernism, with projects including the Team Disney HQ of 1991. Immersed in the leading currents of Japanese architecture from the 1960s onwards, his tendency to snipe at the motives of his collaborators was legendary. Commentators have tried to account for these professional shifts and antagonisms, his dour and contrarian thematic obsessions, as well as his critiques of architectural traditionalism and technological progressivism. Why did he conduct his professional life and art this way? The conclusion seems to be that he was a nihilistic maverick pushing at the outer limits of architectural culture and even taste.

Radon degassing triggered by tidal loading before an earthquake

The presence of anomalous geochemical changes related to earthquakes has been controversial despite widespread, long time challenges for earthquake prediction. Establishing a quantitative relationship among geochemical changes and geodetical and seismological changes can clarify their hidden connection. Here we determined the response of atmospheric radon (222Rn) to diurnal tidal (K1 constituent) loading in the reported 11-year-long variation in the atmospheric radon concentration, including its anomalous evolution for 2 months before the devastating 1995 Kobe earthquake in Japan. The response to the tidal loading had been identified for 5 years before the occurrence of the earthquake. Comparison between these radon responses relative to crustal strain revealed that the response efficiency for the diurnal K1 tide was larger than that for the earthquake by a factor of 21–33, implying the involvement of crustal fluid movement. The radon responses occurred when compressional crustal stress decreased or changed to extension. These findings suggest that changes in radon exhaled from the ground were induced by ascent flow of soil gas acting as a radon carrier and degassed from mantle-derived crustal fluid upwelling due to modulation of the crustal stress regime.

Hard and soft measures for earthquake and tsunami disaster mitigation

A destructive earthquake struck the Kobe region on January 17, 1995, and a massive earthquake and tsunami struck eastern Japan on March 11, 2011. We present an overview of the casualty aspects of the 2011 Tohoku earthquake compared with those of the 1995 Kobe earthquake. In the Tohoku disaster, some water gates and seawalls saved some villages from the tsunami effects, though some did not. Based on these examples, we discuss the efficiency of soft and hard measures and consider their respective merits and demerits. The main causes of death in the Kobe and Tohoku EQs were, respectively, collapsing buildings and drowning in the tsunami. Although the time to death was very short in both cases, people often have more time to evacuate in the case of an interplate earthquake leading to a tsunami. Basic countermeasures against tsunamis include such hard measures as water gates, seawalls, and embankments. Soft measures need to be implemented in areas where hard measures are insufficient