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𝗟𝗲𝘀𝘀𝗼𝗻𝘀 𝗟𝗲𝗮𝗿𝗻𝗲𝗱 𝗳𝗿𝗼𝗺 𝗣𝗮𝘀𝘁 𝗘𝗮𝗿𝘁𝗵𝗾𝘂𝗮𝗸𝗲𝘀 Earthquakes have taught us invaluable lessons about the resilience and vulnerability of our built environment. Key takeaways from past events underscore the importance of continuous innovation and stringent building codes. ➜ 𝗕𝘂𝗶𝗹𝗱𝗶𝗻𝗴 𝗖𝗼𝗱𝗲𝘀 𝗠𝗮𝘁𝘁𝗲𝗿 🏢 Earthquakes like the 1994 Northridge in California and the 2011 Christchurch in New Zealand highlighted the critical role of modern, well-enforced building codes. Structures adhering to updated codes fared significantly better. ➜ 𝗥𝗲𝘁𝗿𝗼𝗳𝗶𝘁 𝗢𝗹𝗱𝗲𝗿 𝗕𝘂𝗶𝗹𝗱𝗶𝗻𝗴𝘀 🏚️ The 1995 Kobe earthquake in Japan emphasized the need for retrofitting older buildings. Many of the buildings that collapsed were constructed before modern seismic codes were implemented. ➜ 𝗦𝗼𝗶𝗹-𝗦𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗲 𝗜𝗻𝘁𝗲𝗿𝗮𝗰𝘁𝗶𝗼𝗻 🌍 Events such as the 1985 Mexico City earthquake showed how local soil conditions can amplify seismic waves, necessitating tailored engineering solutions. ➜ 𝗡𝗼𝗻-𝗦𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗮𝗹 𝗘𝗹𝗲𝗺𝗲𝗻𝘁𝘀 🛠️ Damage isn't limited to the structure itself. Several seismic events revealed that securing non-structural elements like ceilings, partitions, and equipment is vital for safety. ➜ 𝗖𝗼𝗺𝗺𝘂𝗻𝗶𝘁𝘆 𝗣𝗿𝗲𝗽𝗮𝗿𝗲𝗱𝗻𝗲𝘀𝘀 🚨 The 2011 Tōhoku earthquake in Japan underscored the importance of public awareness and preparedness. Education and regular drills can significantly reduce casualties and improve response times. These lessons remind us of the ongoing need for vigilance and improvement in earthquake engineering. By learning from the past, we can strive to mitigate the impact of future seismic events and enhance our communities' resilience. #StructuralEngineering #EarthquakeEngineering #Seismic #StructuralDesign #SeismicDesign

This time, Dr. Rami Ousta and I would like to share our discussion about the case study of the collapsed building in Wijima, Japan, just to illustrate the power of the resonance of the ground, even if it is not compatible with the natural design of the building. It is about the collapse of the Wijima Building in Japan. A building with 7 floors above ground and 1 floor below. It was built in 1972 on pile foundation. Prof. Kusunoki/Tokyo University's/ said: "Since the Great Hanshin Earthquake in 1995, I have not seen such damage from an earthquake in Japan. There was a lot of shaking in the building, both vertically and horizontally. The western side was separated from its piled foundations and the building began to topple to the east. The structural elements of the underground vault on the east side also suffered from some damage. " In other website i had information that the building had settlements already before the 2024 earthquake. other websites suspect that it was the 2007 noto earthquake that made a damaged already. Some photos by closer look show no big rebars anchored to pile cap for fixation seems filled w wooden chips or seems to have a typical small wire strand only from pile? Does not seem to be intended to overturn. other discussed a case with a stratified soil profile, including non-liquefiable and liquefiable soil layers, and with or without lateral spreading. Others compared the case to other historical case studies such as: The collapse mechanism of the Kandla Port building in India due to lateral spreading soil. according to Prof. Kusunoki, "We have not yet reached where we can be sure of anything". As a geotechnical engineers, we would like to point out the following : Considering the soil profile and the corresponding shear velocity shown in figures, the characteristic period of the layered soil is about 0.13 sec. The measured period corresponding to the maximum Sa:g is 0.12-0.1 sec due to the measurements of WAJIMA (ISK 003).This means that the soil column was in resonance. The building was subjected to a large amount of shaking. Even this was not its natural period, which should be 0.73 sec. If the characteristic period of the site soil profile does not match the natural period of the building, no resonance will occur in the building. However, if it is close to the applied ground motion period, the ground motion wave will be amplified at the surface. Even if there is no resonance in the building, this will exert large forces on the building and may exceed the design forces. The worst thing that can happen is the amplification at small period. This means stronger shaking for one- or two-story buildings.

If your world started shaking, would the foundation under your feet stand firm or fall apart? The recent tragic earthquake in Japan has provided a stark reminder of the enormous dangers seismic activity poses to buildings and infrastructure. In Japan's case, despite the brutal intensity of the earthquake they suffered comparatively few fatalities. Of course even a single fatality is heart breaking, but it proves that preparing (and planning) for seismic events absolutely saves lives. A major part of being prepared is taking a hard look at how we can build smarter, stronger buildings capable of withstanding increasingly powerful earthquakes. That starts with the foundation. In this blog post, we dive deep into how helical pier foundations perform during seismic activity. You'll discover: 🟢 The forces behind earthquakes and why they're so devastating 🟢 Why and how foundations fail during seismic events 🟢 How soil liquefaction is lethal to foundations - and what you can do about it 🟢 Scientific evidence that uncovers helical pier performance during earthquakes It's only a matter of time before we see another major earthquake in the continental United States. The question is... How prepared will we be? #earthquake #engineering #construction #preparedness

Dramatic video footage shows large movements of a seismically isolated building in the 3 April 2024 Hualien Mw 7.4 Earthquake. The video below along with four additional video clips by Taiwan Matsuzawa Base Isolation Co., Ltd. can be seen at this link: https://lnkd.in/gYqFqb6a Clips show the movement of lead-rubber bearings, LRBs, (two views of one bearing in 1st and 2nd videos), elastomeric sliding bearings (two views of one bearing in the 3rd and 4th videos), and a view inside the building lobby (5th video) where movement of expansion joint covers can be seen. A few observations: the views of the bearings, from cameras mounted on the underside of the isolated floor level highlight the dramatic movement of the ground relative to the isolated building; significant shaking lasts approximately 1.5 minutes, with discernible movement for nearly 2 minutes; prominent in the views of the sliding bearing are the dust covers on the sliding plate being pushed around during large movements; and finally, the movement of building staff around the expansion joint covers, even while shaking is occurring, highlights the need for full functionality design of critical architectural components.

Must see: Real-life performance of seismic base isolation bearings 👇 #Seismic #SeismicDesign #EarthquakeEngineering

Pioneering Seismic Research in New Zealand

See lead-rubber bearings (LRBs) and elastomeric sliding bearings move up to 39 cm during the Mw 7.4 Hualien earthquake. As large as these movements appear to be, they are only about half the bearing maximum design displacement of 80 cm.

Ever wonder how base isolation works as a way to resist building damage during strong earthquake shaking? Check out the video below to see one in action! The basics on how this works? Base isolation is a system where the building sits on a series of structures that are able to move during ground shaking. When the ground shakes, it accelerates side to side in all directions, and up and down - but the building above it doesn't move, just the ground. Building like this in earthquake country is one of the best ways to mitigate against shaking damage in buildings. #Earthquake #Mitigation

Common Misconceptions About Modal Analysis in Earthquake Engineering Modal analysis stands as a critical step in computing earthquake loads on buildings and structures. However, despite its widespread application, there are several misconceptions that persist in the industry. Let's address and clarify a few of these: Misconception 1: Modal Analysis is Only for Complex Structures While it's true that modal analysis is essential for complex structures, it's equally important for simpler structures. Earthquake loads can impact buildings of all sizes and complexities, and modal analysis helps in understanding how these structures might respond to seismic events. Misconception 2: The First Mode Dominates the Response Many believe that the first mode of vibration is the most significant and solely required for design. However, higher modes can contribute significantly to the response in taller and irregular structures. Neglecting them may result in underestimating the seismic demand. Misconception 3: More Modes Means More Accuracy Intuitively, it might seem that including a large number of vibration modes would yield more accurate results. However, there's a point of diminishing returns. The contribution of higher modes may be minimal, and including too many can complicate the analysis without significant benefits. Let's continue the conversation. What other myths have you encountered regarding modal analysis for seismic design? Share your thoughts in the comments below! #ModalAnalysis #EarthquakeEngineering #StructuralEngineering #SeismicDesign #CivilEngineering #MythBusting #misconceptions