The earthquake imposes an oscillation back and forth in construction.
This displacement varies from earthquake to earthquake.
This displacement has an oscillation amplitude, an acceleration, a duration, a direction, a frequency, a transmission medium (rock soil) from the epicenter of the earthquake to the construction, a distance from the epicenter of the earthquake to the construction.
These factors vary from earthquake to earthquake and one of them to change, differently affect the different construction structures.
The structures on the other hand have a different height and number of floors, a different seismic protection design each, a specific shape each, and each react differently depending on their design and depending on the unbalanced seismic factors that will arise.
That is chaos.
The statement of absolute seismic protection is false. Other constructions respond well to some earthquake factors, others to other earthquake factors.
But no construction is sure that because it withstood a big earthquake it will withstand the next one with different characteristics.
Opposite each construction in the next earthquake remembers the damage it had suffered from the previous earthquake.
There is a design problem with all constructions today and that is that they can not prevent damage.
Damage to structures comes from two causes.
1) From inelastic deformation
2) From rigidity.
If a structure is designed to be elastic, it will not be easily overturned, but in small earthquakes nothing will happen, in medium-sized earthquakes it will have some failures and in large earthquakes it can stand but it can collapse, and that depends on unbalanced factors. of the earthquake. On the other hand, tall structures are vulnerable to a large amplitude of oscillation, ie from distant earthquakes.
Now what a big earthquake is and what a small one depends not on the magnitude of the Richter scale, but on the mentioned unbalanced factors that affect the magnitude of the acceleration and the frequency of the ground that will reach under each structure.
If a structure is designed to be rigid and slightly elevated, it will be dynamic but will present a total reversal of the total area of the base of the structure, or a reversal of the base of the walls.
That is, it will show either total overturning torque, or overturning torque of the walls or both.
In this phase the construction loses its support from the ground and its loads themselves break it in two.
That is, overturning torque - reverse torque of loads due to loss of ground support = failure over doors and windows where the weakest cross section is located.
Basically the problem in large earthquakes is that the current seismic design can not control the inelastic displacement of the floors in the elastically designed structures, while in the rigid it can not control the overturning moment of the walls or the total tendency of the structures to overturn.
That is, when we design the construction to be elastic, we have a problem after the elastic displacement area.
We design rigidly and dynamically, you have a problem supporting the loads because they lose their contact with the ground, or we have the wall overturned and a great strain on the beams.
Front cliff and back stream.
There is a solution?
Yes there is and it is the one I suggest.
They must control the inelastic displacement and overturning torque of the wall or the overturning of the entire structure.
The solution is to apply pre-tension on the sides of the walls to avoid bending, + anchoring to the ground to eliminate the retraction of the base of the wall and the area of construction.
I present you three suggested design methods in the videos below.
https://www.youtube.com/watch?v=RoM5pEy7n9Q&t=27s
https://www.youtube.com/watch?v=Q6og4VWFcGA&t=6s
https://www.youtube.com/watch?v=IO6MxxH0lMU&t=51s
We cannot prevent natural earthquakes from occurring but we can significantly mitigate their effects by identifying hazards, building safer structures, and providing education on earthquake safety. By preparing for natural earthquakes we can also reduce the risk from human induced earthquakes.
Interesting topic and useful informative links and analysis ...... Thanks for sharing
We cannot prevent natural earthquakes from occurring but we can significantly mitigate their effects by identifying hazards, building safer structures, and providing education on earthquake safety. By preparing for natural earthquakes we can also reduce the risk from human induced earthquakes.
https://www.google.com/search?q=The+solution+to+the+earthquake+problem.&rlz=1C1RXQR_enUS939US939&oq=The+solution+to+the+earthquake+problem.&aqs=chrome..69i57j69i60.735j0j9&sourceid=chrome&ie=UTF-8
El terremoto es un desastre natural que no se puede prevenir. Hay que crear estructuras más fuertes para las viviendas en lugares donde es frecuente que ocurran por ejemplo Haití recientemente ocurrió un sismo de 7..3 grados.
Thank you for this well informative essential text.
Useful links I shall recommend it to all seimic prone regional subject experts.
Regards
Fatema Miah
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