Abstract:
The evaluation of seismic behavior in structures requires seismic experiments that simulate the true ground-structure interaction. The traditional method of conducting experiments with bolted bases (locking) leads to inaccurate results, as it does not replicate the real-world condition where the base does not carry moments and other dynamic forces. This paper proposes the correct methodology for conducting seismic experiments, using only two stops at the ends of the specimen to limit sliding without restricting the natural movement of the base. This method allows for the proper distribution of moments to the joints of the structure and an accurate representation of seismic behavior.
Introduction:
The seismic behavior of structures is critical for the safety of buildings and infrastructure in areas with high seismic risk. Seismic shake tables are used to simulate the response of structures to seismic loading. However, an accurate representation of the ground-structure interaction is essential for correct seismic capacity assessment.
The common practice in most experiments is bolting the specimens to the base of the seismic shake table, effectively creating locking. This locking inhibits the normal movement of the structure and gives a false impression of the way forces are distributed, as in real conditions, the base does not carry moments.
Methodology:
To conduct accurate seismic experiments, we propose the following methodology:
Discussion:
Bolting the specimens to the shake table creates the illusion that the base is carrying moments and dynamic forces, which does not occur in reality. Locking restricts the natural movement of the base and prevents the proper distribution of moments to the joints, leading to inaccurate results for the seismic resistance of structures.
In reality, the base of structures does not carry moments, and the moments are distributed to the joints and connections of structural elements. Therefore, the use of stops to prevent sliding, without bolting the specimen to the base, provides a more realistic representation of seismic behavior.
Thus, seismic experiments should be conducted without bolting the specimens to the base to replicate the natural interaction between the ground and the structure. This allows the moments to be properly distributed to the joints and provides accurate results for seismic performance.
Conclusions:
Experiments with bolting the structure to the seismic base lead to inaccurate results, as the base carries moments that are not transferred from the ground in real-world conditions. The correct methodology for conducting seismic experiments is avoiding locking, using stops at the ends to prevent sliding while allowing the structure to move freely on the base. This method better replicates the natural seismic behavior of structures and leads to more accurate and reliable results for assessing their seismic capacity.
Keywords:
Seismic experiments, locking, bolting, ground-structure interaction, moments, joints, seismic resistance, accurate results.
Dear prof. Ioannis Lymperis
Reply to Discussion: Correct Execution of Seismic Experiments and the Importance of Ground-Structure Interaction Without Locking in Seismic Behavior
Thank you for initiating this important discussion on the methodology of seismic experiments and the implications of ground-structure interaction. Your insights into the limitations of traditional bolting methods are particularly relevant, as they highlight a critical aspect of seismic testing that can significantly affect the accuracy of results.
Further Considerations:
Real-World Applicability: The distinction between bolted and unbolted conditions is crucial for ensuring that experimental results can be reliably translated to real-world scenarios. In practice, structures are designed to allow for some degree of movement and flexibility, which is essential for dissipating seismic energy. By allowing the structure to move freely on the shake table, we can better understand how it will behave under actual seismic conditions.
Dynamic Response: The dynamic response of a structure is influenced not only by its mass and stiffness but also by how it interacts with its foundation. The proposed methodology of using stops to limit sliding while allowing for free movement is a significant improvement. It acknowledges the importance of dynamic effects, such as inertia and damping, which are critical in understanding how forces are transmitted through the structure during an earthquake.
Data Interpretation: The interpretation of data from seismic experiments is heavily influenced by the experimental setup. By eliminating the locking effect, researchers can obtain more accurate data regarding the distribution of forces and moments within the structure. This can lead to better-informed design practices and improved safety standards in seismic-prone areas.
Future Research Directions: It would be beneficial to explore the effects of different types of stops and their configurations on the seismic response of various structural systems. Additionally, incorporating advanced monitoring techniques, such as real-time data acquisition and analysis, could enhance our understanding of ground-structure interaction during seismic events.
Broader Implications: The implications of this methodology extend beyond just experimental setups. It can influence building codes and standards, encouraging a shift towards more realistic testing practices that prioritize safety and resilience in seismic design.
In conclusion, your proposal for a revised methodology in seismic experiments is a significant step towards improving the accuracy of seismic behavior assessments. By prioritizing realistic ground-structure interaction and avoiding the pitfalls of locking, we can enhance our understanding of seismic performance and ultimately contribute to safer building practices. I look forward to further discussions on this topic and the potential for collaborative research to refine these methodologies.
Dear prof. Pooria Kianoush
Thank you very much for your insightful response and your interest in the methodology of seismic experiments and ground-structure interaction. I would like to clarify that I am not a university professor; I am an independent researcher in seismic technology. I fully agree that realistic simulation of interaction conditions is crucial for drawing reliable and practically applicable conclusions.
My experiments include comparative tests with different support methods to highlight the effects of fixation on the seismic response of structures. Specifically, I have conducted experiments concerning:
- Bolted base: The structure is fully anchored to the base, resulting in some of the seismic energy being transferred to the ground instead of being absorbed exclusively by the structural joints. This differentiates the dynamic response compared to a free or partially constrained structure.
- Free structure with stops at the ends: Where the structure can move freely within a controlled limit, better simulating real ground-structure interaction conditions.
The results of these experiments are revealing: the overturning moment in the free experiment with stops at the ends is significantly greater than that of the bolted experiment, demonstrating that the rigidity of the fixation dramatically reduces the actual dynamic response of the structure. This emphasizes the importance of correctly selecting experimental setups and the need to adjust tests to accurately reflect real seismic stress conditions.
Your observations regarding the dynamic response, data interpretation, and the impact of these methodologies on modern regulations are extremely important. I fully share your view that further investigation of ground-structure interaction, combined with advanced monitoring techniques, can lead to significant improvements in seismic design.
I look forward to further discussions and potential collaboration in developing a more comprehensive approach to seismic experiments. I would be particularly happy to explore new methodologies together and share knowledge and findings that can contribute to the advancement of our field.
Sincerely, Ioannis Lymperis
Dear Ioannis
Thank you for your thoughtful and detailed response. I appreciate the clarification regarding your role as an independent researcher, and I am glad to hear about your ongoing work in seismic technology.
Your experiments on the effects of different support methods on seismic response are indeed fascinating. The distinction you make between bolted bases and free structures with stops at the ends highlights the complexities of ground-structure interaction, and your findings regarding the overturning moments are particularly insightful. It is clear that your research is contributing valuable knowledge to our understanding of how fixation methods influence dynamic responses during seismic events.
I completely agree with your emphasis on the importance of selecting appropriate experimental setups to accurately reflect real-world conditions. As we both know, the implications of these findings can significantly impact seismic design regulations and practices.
I am very much looking forward to further discussions and the possibility of collaboration. Exploring new methodologies and sharing our findings could indeed lead to advancements in our field. Please let me know your availability for a meeting or a call to discuss this further.
Thank you once again for your engaging response. I look forward to our continued dialogue.
Best regards,
Pooria
Dear All,
Good opportunity of meeting:
"Will soon be an interesting event in Budapest, at which I will also be present:
Teknet Earth Global Science is proud to announce the first ever TEGS Conference; scheduled to commence May 30th 2025. Teknet Earth Global Science (TEGS) is a consortium of physicists from around the world, who conduct research into various aspects of theoretical physics including quantum mechanics, cosmology, general relativity, geophysics, and physical constants. The purpose of TEGS 2025 is to push the boundaries of our knowledge of the Universe and to gain a better understanding of our place within it.
TEGS 2025 will be held from May 30th to June 1st 2025. Location to be announced. For more information on our speakers visit our Speakers page and to keep up-to-date with the days scheduled events visit Schedule or use the links provided above. Registration for the conference is now available via the registration form. If you would like to present your own research at TEGS 2025, or if you have other questions or queries about the conference, you can contact us using the Contact page
Teknet Earth Global also curates a YouTube channel of the same name, which hosts presentations and discussions. To visit the channel, go to Teknet Earth Global" (attched file).
(http://tegs2025.scienceontheweb.net/index.html)
There personal we can speak about earthquake forecasting too
(Disasters require not only safe buildings, but also good disaster prediction methods... Certain types of disasters can be predicted, but only if there is the will.)
The Best Regards,
Laszlo
Dear prof. Pooria Kianoush
Thank you for your kind and detailed response. I truly appreciate your recognition of my research and the opportunity to discuss these critical issues in seismic technology.
I am particularly excited to share the results of the extensive research I have conducted as an independent researcher. My work focuses on developing innovative methods and techniques that can enhance the resilience and safety of buildings during seismic events.
A key aspect of my research involves the creation of an anchoring mechanism that is placed at the depths of boreholes and expands by pressing against the borehole walls using hydraulic jacks positioned at the surface. This technique achieves exceptionally strong anchorage, capable of withstanding tensile forces of hundreds of tons.
The potential applications of this mechanism are diverse and include:
- Anchoring wind turbines to the ground without the need for gravity-based concrete foundations, reducing support costs by up to 90%.
- Connecting the ground to the walls of buildings to counteract the overturning moment that causes beam failure and leads to structural collapse. By applying permanent compressive forces to the walls, I enhance their seismic resistance.
My research is not limited to theoretical models but also includes experimental tests that confirm the effectiveness of these technologies. Specifically, my experiments have revealed a significant difference in seismic response between a structure with a bolted base and a free-standing structure with stops at the ends. A crucial finding is that the overturning moment remains the same in both cases; however, in the case of the bolted base, a significant portion of the seismic energy is transferred to the ground, reducing the stress on the structural joints.
I strongly believe that implementing these methods in new or existing engineering projects, including bridges, could provide substantial practical benefits and contribute to the protection of structures and human lives.
I would be delighted to share more details and discuss potential collaborations or applications of these technologies. Please let me know your availability so we can arrange a meeting or a call.
I look forward to our continued exchange of ideas.
Best regards
Ioannis
email [email protected]
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