The earthquake doesn't kill people but the bad design of the built structures that kills them, and that's what we learned from our teachers. In fact, it is known that seismic design requirements depend on the type of the structure, locality of the project and its authorities which stipulate applicable seismic design codes and criteria. However, if an earthquake occurred in such region, the most important step that must be done by the experts is to assess the damages caused by the earthquake and to report all the failure modes observed on damaged buildings. According to the expert studies conducted so far, I would like to know what is the most common failure mode in earth structures during an earthquake?
Hi,
I guess that by earth structure you mean the rocks ? If so, Mode-II is the most common. Here shear stress act parallel to the plane of the crack and perpendicular to the crack front. The famous San Andreas fault is a strike-slip fault, Mode-II. The faults causing the devastating earthquake in Mexico-2017 and Nepal-2015 were cause by thrust faults, also Mode-II.
Hope this helps
Amar
My father was to first to build anti-seismic structures in Greece in the 1920's. I am not the expert, but his design used iron bars in the floors and walls "bracing" the structure.
Two pictures: In this 1953 earthquake most buildings collapsed except the bank building which he built.
In the second photo he is standing on the roof before concrete is poured. The iron structure was unique at the time. The building has withstood numerous earthquakes since then and nothing happened to it.
Dear Dr. Amar Agarwal,
No, it is not what I meant, but I would like to thank you so much for the provided answer which was very interesting and I completely agree with you when you say the "Mode-II" is the most common. In fact, several civil engineering structures can be built on cracked rocks which can put them in a high risk if once an earthquake occurs, especially when it comes to a zone of a very high seismicity as the case of my country (Algeria). In Algeria, we register more than 20.000.000 inhabitants distributed on a littoral of 1200 km of length. According to your professional profile, I see that you're not a specialist in civil engineering but believe me your answer given previously led me to ask another question about the choice of a good foundation system on cracked rocks in a zone of a high seismicity. For this, I don't know if you have any idea about the construction techniques that can be used to ensure a good foundation for the built structures?
Thank you in advance
Dear Dr. Michael Issigonis,
I would like to thank you very much for the info given above especially for the two images dating several decades.
I don't know if your father has any scientific works or publications in relation with the anti-seismic construction?
Thank you in advance
Hello Dr. Hamid Gadouri,
No, my father did not have any publications on the anti-seismic construction subject. He learned it at the Lausanne Polytechnic where he graduated. He took numerous photos to demonstrate his method. He worked at the technical department of a bank. The bank undertook to build branches throughout the country with his method. In another earthquake his building was the only one standing after the quake. His bank president did not believe that the building was still standing and he hired a plane to go and see for himself. At that time anti-seismic construction was new.
Dear Dr. Michael Issigonis,
Believe me, I was very impressed when I read the lines that you wrote with your hands. I imagine and say what would have happened if your father had completed his university studies in order to make a deep study and scientifically prove that the construction that he built had resisted to earthquake effect at least twice. This confirms that the construction built by your father has not been resisted by coincidence, but there is a secret behind all this. So, I want to know if there were engineers who approached to your father to learn how to accomplish this type of construction that in my opinion became almost a miracle at a time when civil engineering was unable to find appropriate solutions to address earthquakes that killed many people due to the collapse of buildings? Or may be you've learned from him how to build?
Dear Dr. Hamid Gadouri,
I assure you there is no secrets in anti-seismic construction today. My father completed his university training in civil engineering and went on to build all kinds of structures, especially hydroelectric dams. I am sure the science of anti-seismic construction has expanded since then and is applied in many places around the world, such as Japan, USA, Mexico, etc
It is interesting to note that my father built his own house in an area with no previous earthquakes, so his house was not anti-seismic. However, in 1999 there was a "surprise" earthquake near Athens and some cracks appeared on the house, but there were no serious damage.
Recently, the Democritus University of Thrace in Greece had written about my father's contribution to the building industry, but all their data came from the family which was mainly pictures.
My father had numerous other proposals such as building trenches surrounding hills and mountains to collect water (which is scarce in Greece) and prevent floods at the same time. However, none of his proposals were adopted and years later many people lost their lives in floods in these areas.
Dear Dr. Michael Issigonis,
Thank you very much for the discussion made during this interesting dialogue, and I see that I'm very lucky to know you and your father who really, in my opinion, is one of the pillars of civil engineering. Waiting for further communication in the future, please accept my sincere respect for your honorable person. Also, I want that you pass my sincere greetings to your father if he is still alive.
Best regards
