Questions related to Earthquake
Seismic moment gives us the release of the energy during earthquake. If this could relate to the PGA expected at site, we could estimate the PGA from moment magnitude itself. Probabilistic seismic hazard analysis is an elaborate procedure to get this but a direct relation can save a lot of time and calculations.
I am doing my MTech thesis on topic “ANALYSIS OF SEISMIC SEPARATION GAP BETWEEN TWO ADJACENT REINFORCED CONCRETE BUILDING” and i am planning to use FVD250 between two adjacent buildings, so what will be the cost of one single viscous damper and is it good idea to use FVD between building?
Geothermal energy is a renewable energy generated from earth's heat which can be harvested for human use. However, my first question is about is there any solution for absorbing and utilizing the earthquake energy and if possible can that be done by using geothermal energy. I know that earthquake energy is quite immense and difficult to do this practical which requires high technology and more expensive too but is there any possibility even though to resolve this issue?. Please, kindly respond.
In his name is the judge
I want design cotroller in to control active force of damper.
On this purpose, i analyzed structure with damper, wich is tlcdg, and get data whic use for generate controller. data are accleration and velocity of damper as input and dampers force as output ( i mean force wich made by own damper under earthquake excitation, not active force).
here is anfis properties :
number of inputs are 2
number of outputs is 1
generate fis method is grid partition
number of membership function are 4 for each input
input membership function type is guass2mf
output membership function type is linear
opt method is "hybrid".
(have to say i tried different epochs membership function , .....)
Unfortunately anfis toolbox in matlab refuse to train and build Suitable fuzzy controller wich means error is too much in training, so this answer is not acceptable.
i have some idea for make it true but i'm not sure.
here is my ideas :
* first i think train controller with more or less data ( training data are about 2000 wich is under 100s earthquake excitation but when i reduce earthquake excitation to 10 or 15 seconds the error is acceptable however i think this solution is not good.)
* second maybe i must try one damper for training.
* the last idea is to assign force on the damper location and get acceleration and velacity for generate trianing data.
here is my data and shot frome my try.
Any help is greatly appreciated.
Take refuge in the right.
In a way to understand the seismic response of underground structures, researchers mostly define the maximum thrust or maximum bending moment against PGA (Peak Ground Acceleration) as intensity measure. But, there are other ground motion parameters like PGD (Peak Ground Displacement), PGV (Peak Ground Displacement) or any tectonic characteristics (i.e. fault length; source to site distance, focal depth, fault or thrust type) etc.
Why PGA is most dominating measuring factor among all, so as to represent the earthquake induced intensity?
We can calculate the dimension of a fault plane for a particular magnitude earthquake using Wells and Coppersmith (1994) relation. But how can we locate it on map.
I'm currently do my final year project, I use time integration method to solve linear dynamics structure.
I am Abdollah, senior member of Engineering Seismology and Earthquake Engineering Research (eSEER) group, Universiti Teknologi Malaysia, leading by Prof. Azlan Adnan. Currently, we are working to propose Malaysian National Annex to BS EN 1998-2:2005, Eurocode 8: Design of structures for earthquake resistance -Part 2: Bridges.
In this regard, it would be appreciated if everyone could guide us on how to define the Distance (Lg) parameter beyond which the seismic ground motions may be considered as completely uncorrelated. Regarding the EC8-2, the parameter is defined based on the ground type. Now, we would like to know that how these values (e.g., 600 m for ground type A, or 500 m for ground type B) have been derived? We are waiting for your kind reply. Thank you very much for your contribution. Best Regards
I am looking for some references relating directly the fault rise time (or earthquake rise time) to the moment magnitude. Suggestions?
If a rigid plate is bounded by two transform faults and the plate is moving, with the translatory motion of the plate will there be oscillatory motion as well? If not, why and if there is an oscillatory motion then what will be the mechanism of it?
Different database provides Shear wave velocity profile (Vs) (and sometimes P-wave velocity ) for most countries, for eg. ESM (Engineering Strong-Motion) provides Vs and Vp for Europe. However, these data are in graphical format. Is there any way to get these data in the digitized format ?
The prestressing plus the anchoring of the sides of the walls from their highest level with the foundation ground ensures in all sections of the bearing during the earthquake a small deformation and eliminates the correct forces (N), the moments (M) and the shear (Q) It deflects the inertia tensions in the ground, increases the active cross-section of the wall, provides a strong foundation ground, corrects the oblique tensile arrows, restores the construction to its original position even after an inelastic leak. It ensures less displacement of the ground, so less acceleration, reduces the cost of construction .... and no one cares!
I need the digitized data (Acceleration time history) of 1968 Tokachi-Oki Earthquake (Hachinohe harbor).
Here you can see the graph of this record (Acc. time history) that used in this article:
And also an old report of this event is available in Port and Airport Research Institute of Japan website: [pari.go.jp] (Strong-Motion Earthquake Records on The 1968 Tokachi-Oki Earthquake And Its Aftershocks)
I wonder if someone can help me find this record. Thanks.
The foundation of the wall has a large tread area, in order to distribute the loads on a large ground surface in order to increase the bearing capacity. This really happens when the construction is at rest and all the loads are directed vertically to the ground. When the construction receives lateral loads from the earthquake, the wall along the entire height of the floors, together with its base, tends to overturn. The beams with which it is connected to the nodes react and prevent the overturning of the walls in height. However, the cross sections of the beams are strained with torques and if the torques are large then they fail and we have the collapse of the construction. The weight of the base and the foot girders are not able to stop the overturning in large earthquakes, because the entire height of the walls are huge levers and lower huge torques that the foot girders are unable to receive. It is very important to stop the wall overturning if we want the beams and foot girders not to break We can only do this if we lock the sides of the wall with the ground, as we lock the steering wheel of the car so that it is not stolen from us.
When driving and wanting to turn one hand pushes one side of the steering wheel up and the other down. In the same way it turns the wall in the earthquake and breaks the beams and the foot girders. The vertical force of the side of the wall is received by the base and transmitted to the ground. The upward force of the other side is picked up by the beams and foot girders and they break. If we anchor the sides of the wall with the ground, we will stop the upward force and we will help the beams and the foot girders not to break. It is simple. We remove the base in width, and we make bases in depth, anchored to the ground, so that we receive the vertical forces and the forces that are directed upwards successfully, so that we do not strain the beams and foot girders and break them. The beams also break when the pillar or wall is deformed due to bending. To prevent the bend we use elongated walls with multidimensional cross sections so that they can receive all the horizontal directions of the earthquake.
The walls did not bend easily. If we want to reduce any bending of them, we impose on them by pre-tension compression in the cross section + anchoring in the ground. The pre-tension in the cross section of the wall also increases the elastic displacement, because the cracks that are created are not inelastic but close due to pre-tension and return the wall to its original position. On the other hand they increase the active cross section of the wall due to compression. The shear failure that exists at the concrete and steel interface in the relevance mechanism does not exist since there is no relevance to the prestressing. The foundation soil becomes stronger as the anchorage transfers loads to the lower and stronger compacted soils. The control of coordination and seismic duration is now possible because we control them with external forces coming from the ground.
Vs from the geophysical method relate with the low strain values; however, liquefaction induced from the earthquake is related to high strain values. Is it worth calculating the liquefaction potential using the Vs values of geophysical methods?
Regarding strain values, it shows the contradiction about the available collections.
( For example, SPT N is based on the high strain, whereas Vs from MASW is based on the low stain. Both SPT and Vs depend on the density, soil type, plasticity index, effective overburden pressure, etc)
I am doing psha analysis of a site in Indian peninsular region using R-crisis software. I have devided the site with various seismic zones. Maximum credible earthquake is 6.8. I have calculated a b value of each zone.
During PSHA analysis my site is located inside the one seismic zone, with lamda =0.12, beta 1.953, Mmin4.8, and Mmax 6.8. with PSHA with return period 10000 years, I am getting pga value nearly 0.48 to 0.58 g. Which is very high value for any stable continent. I think is I am getting that much high value because my site is located inside the source zone and made some gross mistake in defining the problem. (Source parameters are correct).
Kindly give your comments and suggestions.
In R-crisis software, in have define site location,
Source geometry as area source,
Attinuation relationship ( Pezeshek et.al. 2011, and Atkinson Boots 2006, ENA).
Depth of source 10km.
If other software is available kindly inform
I am looking for recorded earthquake rotational time history (ground motion) data; both torsional and rocking. Is there any database to procure these data ?
One of the assumptions of the masonry structures analysis is "Sliding will not occur" (Heyman`s assumptions).
In near field domain, the wave P has a strong role. It throws the objects and structures up which leads to decreasing the friction. For example, in the Bam earthquake vertical PGA was almost g: no friction. In this case, it seems that in the near field domain this analysis method is meaningless and the masonry buildings will be destroyed.
This query is very important, because in my country Iran, most of the rural houses are in near field domain.
I simulate a pile embedded in multi-layer soil (Five Layers: 3 layers of clay, and 2 layers of sand ), subjected to earthquake (El-Centro earthquake) as solid elements by using Abaqus. Why the present curve gives a good agreement at the beginning only? How could I improve the model?
I need help on getting a research topic for my PhD dissertation, in the fields of seismics and earthquake geophysics. I will also appreciate suggestions in the field of hydrogeology.
I need help on getting a research topic for my PhD dissertation, in the fields of seismics and earthquake geophysics. I will also appreciate suggestions in the field of hydrogeology.
The Seismic Regulation say that even without an anchoring mechanism, the structures are considered to be anchored to the ground. Right or wrong?
Are the constructions anchoring with the ground Yes or No?
The anchors in the space commit the six degrees of freedom.
The reaction of an anchor consists of one or more component moments.
If these torques are not able to stop the rotation of the walls then it is not anchoring it is a articulation.
At small accelerations the foot girders are able to stop the rotation of the columns.
We know, however, that the pillars are intended to carry only static loads and not seismic ones in which they are completely weak.
The elongated walls, the correct dimensioning per direction and shape of the cross-sections of the floor plan of the walls, and their correct placement in the space, is the correct design that resists seismic shifts.
In an earthquake, the walls lose their eccentricity and their bases are lifted, creating twisting in all of the nodes of the structure. There is a limit to the eccentricity, that is, there is a limit to the surface area of the base which is lifted by the rollover moment. To minimize the twisting of the bases, we place strong foot girders in the walls.
In the large longitudinal columns and walls, due to the large moments which occur during an earthquake, it is practically impossible to prevent rotation with the classical way of construction of the foot girders.
The result is that the foot girders fail and the anchoring turns into a joint with disastrous results for the elements of the nodes.
So the question comes in.
Is there anchoring of the walls at high accelerations or is it turning into a articulation,?
Because if there is a articulation,, then the anchoring of the base to the ground with the mechanism of my invention is imperative.
I am an M.Tech structural engineering student working on the project ' Numerical analysis of Kath-kuni architecture ( a common masonry typology ) in Himachal Pradesh region of India subjected to earthquake loading in ABAQUS software' . The question of concern is that I am finding it difficult to input plasticity parameters for timber/ wood material that I have used in my model even after searching in various research papers. I have got only elasticity parameters and wood being an orthotropic material requires plasticity parameters and a plasticity damage model to be defined in order to understand the actual material behavior in ABAQUS software. So, kindly help me in finding the plastic properties and a damage model for timber, it would be very helpful to proceed in my current project.
Thanks and regards
Please before any of you find my question incorrect or even blame me for it, be patient until this conversation continues!
Today, for scholars, earthquake is an understandable concept, somewhat of course non unique and imprecise. If it is true, please stay with me!
This natural phenomenon varies greatly in size. Occurs at different depths of the earth's crust or lithosphere. They have different mechanisms. They can happen anywhere and anytime. Although the location of many of them is explained by plate tectonic theory, their occurrence is possible anywhere on Earth. Their magnitude on the known Richter scale can vary from small numbers (negative) to about 10. It can be happen even if be greater than 10!?!
In seismology, where the magnitude of an earthquake is proportional to the moment (Mo=µSD relation), by the same value of the shear modulus (µ) the amount of area (S) as well as the amount of displacement (D) at their very low level is ambiguous (for examples, a bulk of materials and grains size, crystal or molecule-atom scales). They are also very different in terms of origin. They originate by falling caves, erupted volcanoes and around the magma chambers, between plate boundaries (Interplate), induction such as around dam reservoirs, vary in focal depth from a few kilometers to several tens of kilometers. They also occur inside lithospheric plates (Intraplate), which may not be well understood in relation to the plate tectonics theory. In terms of duration time on waveforms (seismograms), they fluctuate between less than 10 seconds to more than 1 minute and have variation in frequencies from 0.001 up to 1000 Hz and more between 0.01 up to 100 Hz. By improvement of instruments and methods, can be sensed and detected as small amplitude as possible. If they consider as strong ground motion in earthquake engineering views because of human and financial losses (greater than 4 up to 4.5 as threshold magnitude), the task is somewhat clear. But this limitation in magnitudes does not solve the scientific problem of the source and the initiation of this phenomenon and how it was really created. Should they be considered as the propagation of elastic waves on the ground? Do they come only from the release of the elastic energy of the strain of the crust materials? As the famous scientist Reid said? Apart from breaking (fault and failure), can other phenomena produce such violent and destructive waves? As we know, Aki and Richards in their effort “Quantitative Seismology” tried to point out that seismology is the scientific study of mechanical vibrations of the Earth due to earthquakes. We also know that any small earthquake can be a pre-earthquake (foreshock) or a post-earthquake (aftershock) of a larger earthquake. Without knowing which of them, are the main earthquake (main shock), it will take a long time (hours to several days) to distinguish it. I have not yet found a powerful answer for the question. I will be very grateful if someone can satisfy me with a reasonable answer. If is not, I together with interested researchers ready to define it as a joint project for finding the proper answer.
I am trying to model the impact element having non linear stiffness in Abaqus. I want to model the pounding force between two frames under earthquake excitation. For this I am using Axial connecter element and defined elastic behavior and reference length equal to gap. Under elastic behavior I have input the table of Force vs Relative displacement in such a way that force is zero in tension and remains zero until gap closes. But after running the analysis my pounding force value is comming less than expected.
My whole objective is to model the gap element and it should work in a way that when two frames collide, the gap element becomes active else it should transfer no force?
Please somebody tell me where I am doing wrong or if there is another way of modelling gap in abaqus?
Thanks in advance.
Soil-structure interaction effect increases (i.e. increasing the natural period of the structure and effective damping )with the structure-to-soil stiffness ratio. Similarly, I want to know does Soil-structure interaction effect increase with earthquake intensity?
Hi for all,
How can I calculate the amount of loss in the materials strength (the residual strength of the compressive strength of concrete fc and yield strength of steel) for any structural element under earthquake effect or multiple earthquake effects?
If we want to look at the universe we can not ignore the force that moves everything.
No one knows where this force that moves molecules and atoms comes from.
But we do know some physical properties of power.
Power = energy, which changes form, but is not lost.
Two equal and opposite forces, balance.
The force is diverted, that is, it changes direction
The force is broken down into components or multiplied by component forces, with the lever arm.
Power is everywhere but it is invisible and appears only from the effect it causes.
In the science of civil engineering there are static forces which are managed in order to achieve a balance of forces, and non-linear variables which are caused by the displacement of the ground in a seismic event.
When mass is stationary it is easier to calculate the forces of mass and contrast opposing forces to achieve equilibrium.
When an earthquake occurs, additional forces appear which are often three times the size of the static mass loads, because they are multiplied by the magnitude of the ground acceleration, the duration of the earthquake, and the height of the mass X its weight
These forces on the load-bearing structure of the building multiply, change their direction, and diffuse into all areas of the cross-sections of the structure, which are weak and can not react, creating equilibrium forces.
The result is that there is a breakage and collapse of the structure.
There are six solutions to balance and consume energy.
a) To increase the dynamics of materials without increasing their mass which is a factor of multiplication of intensities.
b) To convert the force of an earthquake from kinetic to thermal
c) To reduce the acceleration of the ground to be transferred to the construction using horizontal seismic insulation (bearings)
d) To make a rubber unbreakable bearing body from rubber or sponge.
And two other systems you do not know are ...
e) To put independent parts of the construction, to collide with each other, on elastic joints and in this way one part to neutralize the forces of the other.
g) To deflect the forces from the structure into the ground before they multiply through the lever mechanism and diffuse over the cross sections of the bearing body.
All but all of these systems that I mentioned contribute to the response of the construction to the seismic shifts and are concentrated in the anti-seismic design that I designed, for the first time in the world and is in this video.
How will temperature of submarine sedimentary strata change after it suffers from earthquakes? Will the elastic source give rise to a temperature field?
I tried converting seismic SAC data into SAF using Geopsy, but the results were not satisfactory. Is there any other way to do that conversion from SAC to SAF?
The steel itself does not receive the tensile if it is not well anchored somewhere; For example, if the steel reinforcement of a balcony is not well fixed inside the slab, it will reach the ground floor. Why not connect the structure to the ground, and simply place it on the ground? You will tell me ... that no material receives any charge unless the carrier is statically defined. Yes in the case of the balcony the anchoring is necessary. All intense states (Tension, Compression, Bending, Shear, Torsion, etc.) imply the assumption of static equilibrium, otherwise they would not make sense. "It's not the same as a cantilever with a foundation." Answer In the earthquake a balcony - cantilever, and a wall are the same. Moments received by the cantilever moments are presented in the earthquake and on the wall. Unless you insist on breaking the cross-sections on the beams. '' for our own good ''
.How to calculate the shear strain in a multilayer soil profile based on a half-space under a seismic action?
While adding dashpots error i am getting is the spring/dashpot element is not available.
And should I provide space for soil to flow to other region. I am considering very thin strip of soil and providing earthquake load to it.
And if I am assigning dashpots I would have to assign it to every node(except surface since it's open to air) So what size should I take for the mesh.
In DEEP SOIL, there are several earthquake data available like Kobe or Chichi earthquakes. These input data are used in the examples, however, the information of the recording station is not available.
Simulate or evaluate the ground motion characteristics (acceleration time history, response spectrum, etc.) of future destructive earthquakes (set earthquakes or scenario earthquakes), and how to judge the reliability or rationality of the simulation results, because there is no actual earthquake record for reference. Therefore, how to verify the reliability of the results from what other angles?
I am doing some research on seiches and hydrodynamic effects caused by earthquakes in reservoirs, and need some data on oscillation frequency (alongside peak acceleration), to make some simplified models (to start with).
I have found a few sources for acceleration time histories (e.g: https://www.strongmotioncenter.org/index.html), but aside from crudely counting the oscillations per second, the data isn't clearly marked.
I don't mind if the data is recent or historical, I just need a fairly wide range of intensities.
I appreciate anything you can send my way,
TL;DR: Looking for earthquake data that includes how many oscillations occur per second.
Let's say some truths that we hide under the carpet, but come to the surface after every big earthquake. Do the newly built structures withstand the earthquake? Yes, they can withstand the seismic acceleration of design. The Greek area is divided into three seismic hazard zones. The values of design ground accelerations are 0.16g (percentage of gravity acceleration g) for the first zone, 0.24g for the second zone and 0.36g for the third zone. Yes, they can withstand these earthquake accelerations. However, historically earthquakes of the order of 1 g have been recorded in Greece with much greater territorial acceleration. What happens to these earthquakes that are greater than the design acceleration? The largest earthquake in the world had an acceleration of 2.9 g At these accelerations, the constructions have absolutely no luck That's why you need my patent. There are also projects of extreme importance such as nuclear power plants, hospitals, schools. In these projects, how do we prevent disaster?
The purpose of the modern seismic regulation is to construct structures that: a) In frequent earthquakes most likely to happen nothing will happen, b) In earthquakes of medium probability to occur will suffer small, repairable damage and c) In very strong earthquakes of low probability to occur we will have no loss of human life. So we should not use the term "absolutely" in seismic constructions. We should use the term "quality" constructions which means application of at least the requirements of all modern regulations. The quality of constructions and their safety is also a function of the economic situation of the countries, among other factors. It is understandable that poor countries cannot be compared to countries where they have strict modern seismic regulations. Conclusion… there is no absolute seismic design today, and we should not refer to absolute seismic design. So there is a great need today to invent a more modern anti-seismic design that meets the ultimate anti-seismic design, with lower construction costs.
Hi Research Gate family,
I am curious to see how GPS data can be used for earthquake early warning systems. Feel free to share your experience and knowledge.
This is Dileep Kumar Chandragiri, Did my Masters in Structural engineering from NIT Allahabad, India in the year 2007. I have around 14+ years of experience as a structural engineer in India, with experience gained a lot of exposure to economic design and good detailing.
- I have hands on experience in Structural analysis, Design & Detail drawings of Hydro Power, Metro & Road Tunnels, Residential, Commercial, Educational & Industrial Building Structures.
- I'm planning to do Master's in earthquake engineering (Research) from New Zealand. I'm interestingly looking for exceptional concept/research work to do. Please guide/suggest me on the project selection/topic which will be more beneficial for career prospective based on my experience.
My Proposal :
The area of my experience always governs the earthquake design. The Design of all Hydro power projects are in high seismic zones (Himalayan region) and the area is porn to large earthquakes in India.
Dam, Intake and powerhouse operation sustainability is a major concern for the Hydro power Projects in India.
I would like to contribute to the field through meaningful research in Earthquake Engineering on “Seismic risk assessment of Hydro Power components Dam, Intake and Powerhouse". Which includes detailed structural modeling, risk analysis in order to develop high-level retrofit strategies to save loss of life.
Please suggest on my proposal as well.
I want to make further study about the material point method in Geotechnical Engineering (such as earthquake), but I don't know which software to choose. I contacted anura3d first, but I still need secondary development to realize the loaded seismic wave boundary conditions(versus time). I just knew the CB-Geo MPM and found that this software seems to meet the requirements. This is my first time learning FORTRAN and C + + , so I want to ask which one is a better choice.
I want to perform time history analysis on an RCC frame structure for earthquake loading in the transient module of ANSYS mechanical. From the input table of applied acceleration, when I turn on the base excitation option, I can not select the boundary conditions and the direction of applied acceleration; while I turn off the base excitation option, the software selects all bodies, but I am also not able to select any direction. Can anyone explain how to figure this out?
Please have a look at the snapshots of both cases.
When it comes to placing the column longitude bars in a foundation, an old wrong belief says that a column's longitude bars should be bent outward (like Figure 1). However, due to the force transmission mechanism and the cohesion stress in the bent part of longitude bars, in my opinion, It makes perfect sense to bend the column's longitudinal bars inward (like Figure 2).
The argument of those who consider Figure 1 to be correct usually refers to the roots of trees in nature.
Is this argument correct?
Please share your opinion about this with others.
What is your opinion about the criterion recommended in seismic codes for determining scaling period, which are used to scale ground motion records?
As you know, the mentioned criterion is the period of the structure’s dominant mode, which has the largest modal participating mass ratio (usually the first vibration mode). Hence, the period of the mode with the second largest modal participating mass ratio is not considered in the scaling process. Consequently, although this criterion usually results in the largest value of scaling period, it is not logical ones.
This is especially important when Tuned Mass damper (TMD) or Base-Isolation system is utilized, which cause the modal properties of the structures to change.
I used a new criterion based on the weighted mean value of the periods for the structures equipped with TMD.
Have you used any criteria other than the criterion mentioned in the seismic codes?
Hello my friends
ِI'm having trouble in how to use the command < his read 100 gilroy1.acc >.
Dose anyone Know that How do I Use from < his read 100 gilroy1.acc > Command in FLAC ?
I am looking for the latest approaches to find the band-gap of Phononic / Periodic materials. In this regard, if anyone knows a reference (in detail) for Finite Difference Time Domain (FDTD) theory along with the Bloch method, please share.
I really appreciate any help you can provide.
please consider my request and try to help me .
I want to distribute earthquake time series in a fuzzy membership function uniforly.
For example, I have displacement time series and need to give input to the fuzzy set in the form of gaussian membership function up to 5 membership functions, So now I need to distribute my signal in a fuzzy set uniformly. please give me some directions.
Thank you very much in advance
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.
Actually I've had done it, but the result only show tsunami generated by landslide. Somehow the earthquake just disappeared in the model.
I am currently working on earthquake risk perception. I have information of perceived probability of occurrence of an earthquake, perceived damage to property, perceived damage to life, perceived level of fear of earthquake (on an ordinal scale). All these four risk perception variables, loads into single latent variable.Let's name the factor score value from factor analysis as a variable Overall Risk Perception. I have information on sociodemographic factors, no of earthquake experienced, time gap from last earthquake experienced etc which I can hypothesize that influence these four risk perception variables. I found from Multiple logistic regression that risk perception parameters have significant relation with four risk perception parameters and overall risk perception.
I would like to hypothesis perceived damage to life and perceived damage to property are related with perceived fear (it would be a two way arrow) and develop a SEM. I do not have any other latent variable. As I have only one latent variable will it be possible to develop Structural Equation Modelling.
Archimedes was a Greek mathematician and the first to understand the operation of the lever arm mechanism. He had said the familiar phrase to show the power of the lever arm (It was said by Archimedes (287-212 BC) and it means "Give me a place to stand and I will move the earth" And we come to the current state of construction, where the load-bearing structure of reinforced concrete consists of columns, walls and beams, extending in height and width, ie by huge lever mechanisms that multiply the great forces of the earthquake. These huge levers of height (columns) and width (beams) join at the nodes creating a galaxy of opposite moments raised by seismic displacements and multiplied by the mechanisms of the levers. These torque forces are called to pick up the cross sections of reinforced concrete around the joints. Of course it is impossible to ignore these stresses concentrated at one point of the cross section (the one that fails first, critical failure area) and civil engineers have devised some techniques to trick the cross section failure at this point of the shear failure. One of these tricks is called elasticity. When the displacement of the structure is small, within the limits of the elasticity of the columns and beams the construction does not present failures. That is, they design the construction so that it works like a spring which stores and releases energy in the opposite direction. But when the earthquake is big and the displacements increase and the elasticity of the elements is not enough, they start to show leaks (small cracks) Here begins the second trick used by civil engineers to trick the great failure of cross sections and is called plasticity. Basically what they want to avoid is the creation of a large crack, which predisposes the collapse of the structure. They prefer to create many but much smaller cracks so that the construction does not collapse. They achieve this by placing dense transverse reinforcement (hoops) placed near the ends of the elements where they frame the node. If the earthquake is very large and the elasticity and plasticity are not enough then they use another trick which is called satisfactory design. Basically what they do is design the columns and the walls to be stronger than the beams. So the first thing that fails is the beam. And they do this because when the beam fails it releases seismic energy without falling because it hangs on the steel reinforcement, while if the pillar fails first with an oblique / form of failure it takes it all and leaves. These are the three defenses of construction today (elasticity, ductility, good design) that do nothing but try to overflow the displacement so that it is greater than the displacement of the earthquake.
There are a lot of studies using IKONOS or QuickBird images captured after the 2003 Bam earthquake. However, it seems that digitalglobe has removed the images from its website. Do you know by any chance where I can get the image?
Description in attached figure :
Translated in English from Nepali Language
Chungkang (Bhirkot) Information
Longitude: 28 DEG 11 MIN 22 SEC N
Latitude: 84 DEG 50 MIN 33 SEC E
EARTHQUAKE DATE: 2072, LOCAL TIME: 11:56 AM
80 meters hill collapsed, the whole hill was burned as volcano, during the earthquake, light transformed from Laprak and went to Barpak.
The earthquake through the foundation imposes a horizontal acceleration in the construction where, from its size, the destruction index depends.
Constructions had to fly or have the appropriate dynamic response to cope.
Unfortunately, the constructions do not fly and do not have the appropriate dynamic response to cope with large earthquakes.
There is no construction on the planet that can withstand an earthquake that will coordinate with the construction and will have great acceleration and duration.
Simply and fortunately, these three asymmetric factors rarely coincide.
But what will happen if these three asymmetric factors coincide and destroy projects of great importance such as hospitals, nuclear power plants?
Of course, some techniques of horizontal seismic insulation and viscosity damping help, but they are very expensive and imperfect in tall buildings.
The good design of the nodes and the plasticity save some lives but completely destroy the buildings.
And the buildings in the next earthquake are remembered
Since the construction does not fly and is forced to rest on the ground the only solution is to increase the dynamic response.
But in order for something to be dynamic, it must be rigid and the rigid is overturned.
Something that is overturned is simply screwed
On the ground.
Believe me, there is nothing more powerful than which we can draw strength and transfer it to the structure to increase its response to the earthquake from planet earth!
Elasticity, viscosity damping, horizontal seismic insulation, plasticity, and dynamics are the useful factors that increase the response of the structure to seismic shifts.
how each of these properties of the structure works?
what are the failure limits?
and finally what is the most useful property that the structure must have to react better to the earthquake.?
I'm looking for a freely available software /tool/script for the detection and location of local earthquakes using data from my own network of more than 20 vertical component seismometers. Thank you for sharing your experiences.
Your suggestions and comments are heartily welcome.
In the last decade, several studies have concluded that elevated concentrations of radon gas in soil or groundwater could be the sign of an imminent earthquake. It is believed that the radon is released from cavities and cracks as the Earth's crust is strained prior to the sudden slip of an earthquake. I want to perform a study regarding this phenomena. I am looking for some data source (for nepal regions or any other region of the globe) of radon emission. :)
My research is related to the Ionospheric disturbances for an earthquake, and the point of my question is after I calculated and plotted the Ionospheric Pierce Point (IPP) & Sub-Ionospheric Point (SIP) trajectories, and the values of STEC and their anomalies from the closest satellite to the epicenter of an earthquake area by using several observation stations from sugar, I stopped on the step of calculating or plotting the STEC & VTEC for all my GPS stations because I don't know even I don't have the Matlab script for it. (please provide me a full Matlab script for it) with thanks
We provided a questionnaire including questions to scale the effect of an event (like an earthquake) on different psycho/mental indices. Our study is not of type pre-post because we have not collected data before the event of interest. Furthermore, it is not of type Control-Test trials because our sample is restricted to the people affected by the event of interest. There is around 40 questions (5-option Likert) classified into 4 categories. What is your suggestion for me to analyze this data?
Thank you very much
I added the following comparison to show what I mean.
According to the latest global seismic risk map (developped in GEM project, 2018) there are currently 17 megacities around the world with a population of more than 10 million that are placed at the highest risk level, including Tokyo, Jakarta, Delhi, Beijing, Manila, Mexico City, Osaka, Los Angeles, Dhaka, Chengdu, Karachi, Tehran, Istanbul, Lahore, Nagoya, Bogota, and Lima. One of the best efforts to address the impact of earthquakes on a region, especially in densely populated urban areas, is to conduct earthquake risk assessments. The megacities has normally a changing day/nith population. The population increases even up to 50% during working day time. This means that there are specially the periferal and suburban marginal towns around these megapoles. Therefore these towns are mostly the resting locations for the worker in the megapoles. The assessment of earthquake risk is mostly complicated specially in the megapoles in the underdevelopping countries. What are the major peririties for such assessments?
I am running a seismic analysis ( time history analysis). I applied the selfweight as a gravity load, in my Earthquake analysis step. I would like to apply additional concentrated forces in my model, that will contribute to the mass matrix of the system for the dynamic analysis. Is there a way to apply additional loads that will be converted to nodal masses .
I was validating a paper in ANSYS in which dynamic analyses was done using El Centro data with a PGA = 0.374g. But the record is not given in the paper. Can someone help me with this? Any sites or papers from which I may get the record?
A practical mathematical way to find the cubic meters of reinforced concrete in small structures is to multiply the number 0.245 by the floor area and the result shows the cubic meters of the structures (without the bases) Floor 100 sq.m. X 0.245 = 24.5 cubic meters. The specific weight of reinforced concrete is 2450 kg / m3 The 24.5 cubic meters X the 2450 kg = 6025 kg or close to 60 tons. A floor of 100 sq.m. only its concrete 24.5 m3 weighs 60 tons. Each cubic meter of reinforced concrete has a steel reinforcement of approximately 140 kg / m3 The 24.5 cubic meters of the floor of 100 sq.m. X 140 kg / m3 = 3430 kg of steel the floor of 100 sq.m. One of the thousands of prestressing steel available on the floor, with a cross section of 20 mm, has a lifting capacity of 63 tons. That is, a single steel raises the floor in the air, while in an earthquake the construction presents problems. Why so much waste on steel, and why do earthquakes fail?
Answer. Seismic loads triple the intensities But this steel reinforcement is excessive even for a large earthquake. And yet, construction fails easily in a major earthquake. What's wrong? I will give answers to this big question below. Above I mentioned the tensile strength of steel. However, a reinforced concrete structure is also made of concrete. The compression concrete specifications are very good. It does not have good standards for all other forces such as shear, tensile strength. For example, the specifications of concrete in compression are 12 times stronger than in tensile strength. In reinforced concrete, steel and concrete work together with the mechanism of affinity. The cooperation between concrete and steel is achieved through the mechanism of relevance. When we say the mechanism of relevance we mean the combined action of the mechanisms which prevent the relative sliding between the bars of the steel reinforcement and the concrete that surrounds them. The mechanism of the connection consists of the adhesion, the friction and in the case of steel bars with embossed shape, the resistance of the concrete which is trapped between the ribs. The combined action of these mechanisms creates a radial development of shear stresses applied to the concrete and steel interface. When these stresses reach their limit value, the relevance is destroyed, by breaking the overlay concrete along the steel bars, and detaching the steel from the concrete. .
Shear stresses are created on the interface of the two materials. . The question is whether the concrete withstands the strong shear stresses imposed by the tensile strength of the steel; No it can not withstand and for this reason we have the pulling or otherwise slipping of steel through the concrete, and the destruction of the coating concrete around the steel. Conclusion 1) The premature shear failure of the coating concrete cancels the ability of the steel to tensile, because it does not manage to take on the tensile loads it can, because the cooperation wants two. Conclusion. The coherence mechanism is at least insufficient for these two materials. That is, if you put steel in butter, there will never be cooperation because butter does not withstand the pull of steel. If you put more pieces of steel in the butter or concrete you will have greater strength; Is it a Question? Solution There is also the concrete-steel co-operation mechanism of the prestressing which imposes compression on the concrete cross-section to equalize the tensile stresses that the affinity mechanism would receive. There is no steel-concrete connection in the prestressing mechanism, so the shear failure is non-existent. The prestressing mechanism strains the concrete only with compression which it can withstand because it can withstand 12 times more compression than it can withstand tensile stress, and it strains the steel only with tensile strength in which it is awesome. Even the protruding walls have a high rigidity, ie a small deformation, so they do not transfer deformation to the trunk of the beam with which it is connected to it at the node. Other causes of the relevance mechanism that pre-tensioning solves are as follows. A reinforced concrete wall, when its trunk is bent, one side is compressed and the other is stretched. That is, one side shrinks and the other grows. There is a point in its cross section where compression and tension have the maximum force. This point is the critical failure area. This point is responsible for the brittle failures of the structures in the earthquake. If we stop the bending of the wall we will eliminate the critical failure area. Is there a design method to stop the bending and the critical failure area? Yes there is. As we said the stretching side grows. If, with an unrelated tendon, we apply transverse compressive forces to the highest level of the cross-section of the wall side, greater than the tensile forces, then we have stopped the bending and the critical failure area. One problem was solved. Well now we have a rigid wall in terms of lateral earthquake strength without critical failure area. Like a rigid wall that is, its overturning moment will be transmitted through the nodes where it is connected to the beams, on their logs and after bending them easily as rigid as it is, it will break them. Another problem? There is a solution? Yes there is. If the protruding unrelated tendon that stops bending does not stop at the base foot of the wall, but extends and anchors into the ground, then the forces of the earthquake are deflected into the ground. The knots will not present great torques, capable of breaking the beams. For this reason I do not join the base of the sole with the ground but I join the upper ends of the sides of the walls with the ground with tense tendons without relevance. The reason is that with this method I stop both the torque of the nodes coming from the bend, and the critical failure area of the wall. The critical failure area of the walls is created in the cross section of the wall which is close to the base. This creates a potential difference in the adhesion of the reinforcement and the concrete. With the method of the invention, the tense unrelated tendon which is both embedded in the ground and the upper end of the wall, there is no potential difference or critical failure area. The problem of deformation with fringe failures is solved! In addition, the application of compressive stresses to the wall cross-section succeeds in increasing the cross-sectional strength of the developing floor and base intersections, increases the active cross-section, improves the sloping trajectories, and reduces cracks. The ground anchor mechanism increases the strength of the ground so that it can accept higher compressive loads. .
Why do we install steel reinforcement joining the construction of the beam and the slab with the balconies? Answer In order not to overturn. I do the same. I join the upper part of the wall with the ground so that it does not overturn in the earthquake ................................. ..............
. 2. Why do we apply prestressing to very large openings instead of simple steel reinforcement? Answer Because prestressing reduces flexion, and increases active cross-section. This is what I do to reduce the bending of the walls ...........
Why do I want to reduce the bending and torque of the walls? Answer Because the walls are connected to the beams and any change in the vertical position of the wall deforms the beams as well. The bending of the trunk of the wall and their overturning moment are the factors that break the beams and fall If we stop the overturning moment and the bending of the wall, how will the beam be deformed? .