A 10 X 10 three-story precast building with a floor area of 100 m2 with 30 cm thick concrete walls in a large earthquake with an acceleration of 1.5g has some overturning moment tendency.
Wanted 1. how much does the precast weigh
2.the inertia and shear base created at the 1.5g acceleration
3. plus the magnitude of the overturning moment of the entire building.
The building weighs 340 tons
Payload is 80kg/m2 = 24 tons
The floors another 24 tons
The building finally weighs 340+24+24= 388 tons without the base.
Inertia and base intercept = mass X acceleration = 388 ton X 1.5g = 582 tons
Overturning moment = height X inertia = the first floor is 3 m high the second 6 and the third 9 total 3+6+9 = 18m
Each of the three floors has an inertia of 582/3 = 194 tons
18mX194ton = 3492 ton overturning moment
But the precast as a rigid structure has a double lever arm, that of the height and that of the width.
So we divide the torque of 3492 tons by the width of the building which is 10 meters 3492/10 = 349 tons.
Every single anchor I have can withstand 100 tons of torque at two meters depth.
If we place 8 anchors around the perimeter, we will not have any loss of support from the ground due to the total withdrawal of the area of the base of the building, so no damage in the earthquake of 1.5g acceleration.
A 300 sq.m pre-fab house costs 310,000 euros finished today + 30,000 the eight anchors = 340,000 euros and you have the most earthquake-proof house in the world.
A conventional house today costs 2,000 euros per sq.m when finished, 300 sq.m costs 600,000 euros.
Choose.
https://www.youtube.com/watch?v=XsHC9WJwgyU
My proposal for anti-seismic constructions is to prestress the sides of the reinforced concrete walls as well as to compact them with the foundation soil at the same time.
Prestressing + compaction on the sides of the walls Prestressing (generally compression) on the sidewalls has very positive effects, as it improves the oblique tensile trajectories. On the other hand you also have the other good thing... the non-shear failure of the cover concrete due to the high tensile strength of the steel, the reduced cracking and the increase in the elastic and dynamic displacement area due to compression, which increases the effective cross-section and stiffness of the structure, and most importantly increases the response of the cross-section to the intersecting base. If prestressing is combined with compaction in the soil then we divert the seismic loads into the soil, prevent the moments at the nodes, control the eigenperiod and ensure soil samples and a strong foundation.
https://www.youtube.com/watch?v=zhkUlxC6IK4&t=72s
The response to your question:
How we increase the seismic resistance of buildings by reducing costs? is simply.
They will talk to both of us and we will solve it.
Regards,
Laszlo
Dear Aparna Sathya Murthy Pre-built house means that machines and computers do most of the building work. Man cannot compete with machines. This lowers the cost of prefabrication by 30 to 50% But prefabs have a problem. They are rigid and easily overturned in an earthquake when they have many floors. For this reason, in areas with frequent earthquakes, they do not allow many floors in rigid prefabs, only two (ground floor and first floor) The compaction mechanism I have stops the prefabs from tipping over
Conclusion Using the compaction mechanism I have in the rigid prefabricated houses makes them earthquake resistant and increases the number of floors above two. A prefabricated house bolted to the ground with the compaction mechanism I have is much more earthquake resistant than a conventional house. It is also cheaper because it is manufactured
Prestressing method.
Dear László Attila Horváth
My proposal for anti-seismic structures includes prestressing + compaction with the foundation soil of the sides of the reinforced concrete walls using mechanisms and adhesion grouts.
If we applied the prestressing from the roof of the structure to open the compaction mechanism that you find in the depths of a borehole it would be wrong because 1. the structure would receive large vertical loads which would harm it. 2. with the first shaking of the earthquake, the ground beneath the base would give way and the tendon would loosen and no longer serve. For this reason there is a method by which we do the prestressing. To ensure a strong foundation soil and not to overload the structure with excessive loads we do the following. a) If the overturning moment derived from the calculations is of the order of 100 tons, we apply a preload of 200 tons on the cap of the borehole from the ground surface in order to expand the mechanism towards the slopes of the borehole and to succeed strong compaction
https://www.youtube.com/watch?v=V5X2zsMQ92c
b) The second prestressing is done by the roof of the structure and its intensity should not exceed 70% of the breaking point of the material. Everything is simple
Dear László Attila Horváth
I'd rather you talk to me and tell me if you find anything wrong with what I'm saying.
Dear Ioannis Lymperis ,
My answer is in private.
It is essential that the building adapts to the area!
Regards,
Laszlo
Interesting question but it is out of my field . Thanks for sharing dear Dr Ioannis .
Best regards
Dear Samy Elhadi Oussadou
1. A 21 m high structure is a six-storey structure.
2. A 10x10 rigid prefabricated house of three storeys in height has a double lever arm, that of height and that of width.
The total overturning moment of 3492 tons must be distributed differently because of the double lever arm.The height together with the other factors of mass and acceleration increase the moment, while the width together with the other factors of mass decrease the overturning moment, so the tensions that the anchorage mechanisms will have to receive will be much lower from 100 tonnes.
This is the footing mechanism, I have it, and I have tested it experimentally at two meters depth and it has withstood 100 tons on its own without concrete grout I don't know how much it really withstands because I don't have powerful jacks to test it.
https://www.youtube.com/watch?v=XsHC9WJwgyU&t=4s
I have done my own measured experiments with an acceleration of 2,41g
https://www.youtube.com/watch?v=RoM5pEy7n9Q
And without the method I suggest, the results were disastrous
https://www.youtube.com/watch?v=l-X4tF9C7SE&t=7s
In a simulation I have, shown me that when I apply quantitative compression to the walls with tension at 50% of the breaking point, the shear strength increases quantitatively by 31% and when the tension reaches 70% of the breaking point, the shear strength increases quantitatively by 40%
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