In the past, there were civil engineers who argued that construction should be designed rigidly, and other civil engineers argued that it should be designed with great flexibility. The great rigidity is achieved when the building is constructed with walls entirely of reinforced concrete, completely eliminating the brickwork masonry to fill the panels. The rigid construction has great dynamics. The great elasticity is achieved with the columns which have a small and square cross section. Plasticity is a method that allows the wall and column to deform beyond the elastic displacement area in which no leaks occur, but without losing its ability to accept loads. Basically, when the deformation of the bearing body passes through the elastic rocking area, it enters the inelastic rocking area where cracks begin to appear in this area. To achieve plasticity we place a lot of concentrated horizontal reinforcement near the nodes. This contributes to the entrapment of concrete and vertical reinforcement in the cross section resulting in increased cohesion as well as showing many but very small harmless cracks instead of showing few but large and dangerous cracks, when the construction is rocked in the early stages of inelastic displacement. And the prestressing is achieved by the application of compressive stresses in the cross sections, small cracking and great elasticity in the trunk of the pillar. After all, which construction survives best in a strong earthquake, the rigid or the elastic?
Answer
Elongated walls have a cost but express the complete anti-seismic design which is clearly superior to the partial anti-seismic design expressed by the elastic columns. The walls may be located around the perimeter of the building (excluding storefronts) surrounding the stairwell and elevator (strong cores) and may be internal walls (eg partition walls) throughout the height of the building. The installation of many strong walls implies, of course, due to their great rigidity, a significant reduction of the fundamental eigenperiod of construction. This, in combination with the view q = 1, leads to a correspondingly large increase in the seismic loads of the structure. However, it should not be overlooked that precisely because of the many and strong walls, the strength increases more or, conversely, the cross-sectional loads decrease despite the increase of seismic loads. The large walls in high-rise structures also predispose a complete reversal of the building construction, which is prevented by the anchoring of the construction to the ground. This is exactly what my patent does.
I don't know the answer to the question you asked but I have another question. If you build a monument without pillars instead have springs made of an alloy composed of Fe attached below , what material would be preferable?
Dear Rumani Dey
Sorry. I did not understand your question and I do not see the attached below.
On springs I would prefer a solid and light material
I mean if you use springs below a monument made of Fe/iron , will it be earthquake resistant ? And if so ,of what material would the house be built of ?
Hi Ioannis Lymperis,
Is it practically possible with all the alloys and metals we have ? Say a house with 1 room only , what would be your choice of metal to build the house ? Earthquake doesn't conduct electricity. But will lightning or rain or storm cause any devastation to the structure? This is superficial though
Dear Rumani Dey
My opinion is.
The answer depends on the size of the cross section and the height of the structure. High-rise structures on springs have the problem of overturning by air and earthquake. Short constructions on springs are ok. I would build on springs what light and strong material there is, or I would build it from reinforced concrete walls and hollow inside.
Dear Rumani Dey
I do not know from constructions with metal alloys. I only know about concrete constructions. If I made with metal I would prefer metals that do not pull lightning. There are also lightning rods
Elongated walls have a cost but express the complete anti-seismic design which is clearly superior to the partial anti-seismic design expressed by the elastic columns. The walls may be located around the perimeter of the building (excluding storefronts) surrounding the stairwell and elevator (strong cores) and may be internal walls (eg partition walls) throughout the height of the building. The installation of many strong walls implies, of course, due to their great rigidity, a significant reduction of the fundamental eigenperiod of construction. This, in combination with the view q = 1, leads to a correspondingly large increase in the seismic loads of the structure. However, it should not be overlooked that precisely because of the many and strong walls, the strength increases more or, conversely, the cross-sectional loads decrease despite the increase of seismic loads. The large walls in high-rise structures also predispose a complete reversal of the building construction, which is prevented by the anchoring of the construction to the ground. This is exactly what my patent does.
It is surely the elastic construction that survives best in earthquake prone areas. The elastic construction provides some degree of flexibility right from the foundation to the roof of the building. This helps to take up shocks and allow for sone degree of movement in the structure without fracture to the elements if the building.
Dear Humphrey Danso
Your point of view is respected. My opinion is that elasticity in construction has no dynamic. Elongated walls, on the other hand, drop large torques at the base and tip over easily. I have a patent that joins (by pre-tensioning) all the sides of the elongated walls from the top level of the nodes together with the ground, in order to deflect the tipping moments into the ground preventing the moments at the nodes.
Experiment Findings EXPERIMENTAL ELEMENTS
Elasticity what a nice word! Like your flexible friend MasterCard. The question that arises is whether in a large earthquake with high acceleration and duration we can keep the construction within the range of elastic displacement. No we can not. The construction will go into inelastic displacement and then if the breaking point passes, the construction will collapse.
Do you want me to tell you how we will control the inelastic displacement, or do we want the structures to be demolished?
The wall is more rigid than the pillar. The wall is a double lever arm that if you apply pre-tension on all its sides between its upper ends and the ground, then all the right compressive and tensile forces are deflected into the ground, preventing them from going to the cross-sections around the nodes. In order to achieve this, the appropriate conditions must be in place. First, if we place a prestressing in a small column cross section, we will give compressive intensities to the cross section and it will not withstand them. The wall will withstand them. Secondly, the wall under the imposition of compressive stresses will not bend its trunk. The pillar will bend. Thirdly in the pillar we can place only a pre-tensioning tendon in its center. On the wall we can place at least two tendons at its ends and this allows it to work as a double lever alternately during rocking. All this effectively removes seismic intensities and sends them into the ground. Elastic displacement will exist but never inelastic because the anchoring to the ground in combination with the pre-tension controls the displacement from the nodes of the upper level, and does not allow leaks. It moves flexibly but so far. Pretension + anchoring together on the ground with the same tendon.Experiment Findings EXPERIMENTAL ELEMENTS
I don't know much about this issue. Sorry.
Best regards,
Ildefonso
Elastic, but flexible in some designed, planned way. Of course, the structure must not be too flabby and slender. Forms of vibration (deformation) should be determined in dynamic analysis and the shape, mass distribution and stiffness of the structural members should be optimized. The stability criteria must of course be fullfiled. The method of foundation is also important. The answer to this question - could be an extensive lecture with many examples. There is no simple answer to the question "elastic - rigid".
Dear Piotr Bętkowski
A completely rigid construction gathers trends in a few areas. A rigid wall lowers high torques at the base, as does the lever arm, or the behavior of the bending cantilever. So if it fails it will fail near the base sole, or the cantilever near the anchorage point. In a strong earthquake we need a large number of plastic joints, and not a single failure as shown by the rigid wall. The truth is that the small elastic columns, properly equipped with very horizontal steel reinforcement present the desired number of plastic joints - cracks. The walls struggle and absorb the seismic shear in which the columns are unable to receive it. Basically, structures with many walls have the behavior of a bending cantilever, while without walls with columns we go to shear ... The golden section of design today is the coexistence of flexible elements with walls that will simultaneously absorb most of the seismic shear. The above applies today with the existing design. But the pre-tensioning + anchoring of the walls to the ground changes the behavior of the wall which works just like the protruding cantilever. A complex design proposal of my own frame construction which includes as a core a wall (or walls) extended with the ground as an independent support and around it a plastic elastic structure separated by a seismic joint that grows in height, placed at the height of the bulkheads, and also includes horizontal seismic insulation.
https://www.youtube.com/watch?v=IO6MxxH0lMU&t=14s
Dear Ioannis Lymperis. You are right that "The golden section of design today is the coexistence of flexible elements with walls that will simultaneously absorb most of the seismic shear". A rigid structure in seismic areas works well if the connection to the ground is flexible, such as in the video you indicated (https://www.youtube.com/watch?v=IO6MxxH0lMU&t=14s)
Dear Hassan Izzeddin Sarsak and Ali A. Al-Homaidan
Do you think that the elastic construction would withstand shifts better on this seismic base than the rigid construction of the experiment?
https://www.youtube.com/watch?v=RoM5pEy7n9Q&t=159s
According to the recommendation of the engineers, the best is to use reinforced concrete and steel so that the structure can balance without collapsing. The ductility of the materials is very important in this, that they are capable of deforming without breaking
Dear Celín Pérez Nájera
The truth in this question is somewhere in the middle.
Read here.
https://www.researchgate.net/post/My_method_or_existing_seismic_technology_is_the_best
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