Questions related to Seismic Hazard
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.
How to develop a limit state equation ( in terms of capacity and demand) for bridge components such as deck, pier, and foundation in the event of a seismic hazard. My goal is to evaluate the reliability associated with it utilizing various reliability approaches. I can do it with fragility analysis or even modelling, but I'm looking for an equation that I can use to numerically measure reliability. Can someone recommend some research papers or any book anything related to the same?
The purpose of earthquake engineering is not to build strong and earthquake-resistant buildings that do not experience the slightest damage in rare and severe earthquakes. The cost of such structures for the vast majority of users will have no economic justification.
Instead, engineers focus on buildings that resist earthquakes' effects and do not collapse, even in severe external excitations. It is the most important goal of international standards in the seismic design of buildings.
Below I have mentioned some crucial points in reducing the seismic demand in reinforced concrete structures. If there is anything else that is not on the list, feel free to append:
1- Selecting suitable construction conditions with the desired soil type of seismic design
2. Avoid using unnecessary masses in the building
3- Using simple structural elements with minimal torsional effects
4. Avoid sudden changes in strength and stiffness in building height
5. Prevent the formation of soft-story
6. Provide sufficient lateral restraint to control drift through shear walls
7- Preventing disturbance in the lateral behavior of the structure by non-structural components
For instance, while comparing the response spectrum curve in IS 1893-2002 with that of ATC-40, Ca = Z/2 and Cv is either of Z/2, 1.36·Z/2 and 1.67·Z/2 for hard, medium and soft soils respectively for DBE.
While doing the pushover analysis using capacity spectrum method (ATC 40), what would be the values for Ca and Cv with respect to the response spectrum curve given in NBC 105:1994???
As the values are expressed in terms of coefficients, it's rather confusing to figure out the value of intensity of ground acceleration.
Risk-Adjusted Maximum Considered Earthquake (MCER) Ground Motion, which considers structural collapse risk of each site in seismic hazard analyses, is used to prepare seismic hazard maps provided in United State Geologic Survey 2010 (USGS 2010).
The mentioned collapse risk are considered in MCER through risk coefficients and applying to Maximum Considered Earthquake Geometric Mean (MCEG).
How these coefficients are calculated and applied to seismic hazard maps?
I am using R-CRISIS for seismic hazard map creation. I know how to use the given attenuation model in R-CRISIS but I want to use an attenuation model from a published article. How to make such an input file? Also, I would like to know, how to find out suitable spectral ordinate parameters for each zone for R-CRISIS? (It will be so helpful if you explain the later one in detail)
Hope Somebody can help me with this.
I went through FEMA-356 and FEMA-440 for target displacement and I cam across the formula as well but it wasn't helpful as i'm not able to understand it completely and I wasn't able to find all of the coefficients. It would be great if i can get a solution for that.
I need to asses what would be the consequences of earthquakes over a cylindrical water tank embedded in soil (roof is at the surface of the soil).
I was wondering to do a spectral response analysis but does this makes sense if the whole structure is below the surface?
What analysis can I do over the structure to asses seismic risk? Any recommendation is appreciated!
Based on landslide scaling relationship, we observed that a transition zone exists in the NW Himalaya that differentiates the landslide volume capacity of the hillslopes and possibly landslide frequency.
The most probable reason could be spatial variability of the Indian Summer Monsoon that depletes in the Indian Himalaya in a ESE-NW direction. The other potential reason could be seismic activity. My question seeks the explanation in seismic context.
Building exhibit torsional rotation under seismic loading due distance between the center of mass and center of rigidity. According to building codes, does this distance or torsional rotation have any limitations? And if not, how could I check the capacity of building for large torsional rotation?
Good morning everyone;
I have a synthetic PGV values for my study area, that I generated only for rock soils, I was wondering if there is a way to apply some perturbations on my results in order to reflect the basin's effect or the shallowest layers.
I do have a Vs30 map of my study area. Is there a link between Vs30 and the PGV that allows me to tell how far the PGV can amplify (or not) according the Vs30 values.
Thank you very much.
Historic earthen structures are a significant part of the built heritage worldwide and are associated with intangible building techniques, wide material availability and low cost construction. Nonetheless, due to their low mechanical properties and, often, poor connections, historic earthen structures are susceptible to early structural damage and even collapse in areas of high seismic hazard. InIn additionthe lack of maintenance can further reduce structural performance and durability.
The PGV to PGA ratio is known as a significant parameter for the damage assessment of structures under earthquake shakings. As a matter of fact, it is considered as a descriptor of the frequency contents of the seismic input motion. I am interested in understanding the physical and seismological significance of that ratio, and finally the engineering meaning, and its correlation with the structural damage.
I could not find technical treatments except empirical measurements.
Many thanks in advance for your contribution.
I use Atkinson and Boore (2011), Chiou andd Yaungs (2008), Campbell and Bozorgnia (2008) eauations for seismic hazard assessment.
some parameters at these equations like type of faulting, dip angle, rupture width, depth to top of rupture... are identified for linears sources, however, sources of my zone are area sources.
would you please let me know how to use those parameters for area sources using attenuation equations?
does anyone please know to help me?
The design response spectrum provides a general procedure to estimate the expected dynamic load on a structure which is expressed as a function of natural period. Thus knowing the period of the structure, design load could be calculated. It well known that the deterministic (DSHA) and probabilistic (PSHA) seismic hazard maps provide prediction of peak ground acceleration and ground motions for a specific site. As per NEHRP guidelines, design response spectrum is developed from the PSHA framework. The 2% pr 10% probability hazard level can be used for development of design response spectra which is actually satisfying a MCE level condition.
The accuracy in determination of PSA is very important in calculating the final shear load. Could you explain how to estimate such value for a given site?
How to calculate spectral acceleration (design acceleration) for the each type of site class?.
In statistical and probabilty anslyses we are asked to compute error and uncertainty curves and values.
Do you think there are absolute fixed error or uncertainty? Do we reach the time to say what error exist in our answers?
Recently, there are many earthquake cluster (if can be called) or earthquake sequence happened in a short time and at a same place. I have used the ETAS (only time analysis) model study the characteristic of the sequence, but the result is not good to give a complete decision. So i ask some advice to you who study this problem or some scientist major in time data analysis. If you have any good advice or have known some better analysis tools, please let me know or sent me a message directly. Thank you!
As we know, there are many software for 1D site response analysis, namely SHAKE, DEEPSOIL...
Now, I need a software for 3D site response analysis. Is there any commercial software for 3D analysis of basin response to ground motion?
Can we use ANSYS or ABAQUS or PLAXIS for 3D analysis of basin response to long-period ground motion?
Is Main central Thrust (MCT) or Main Boundary Thrust (MBT) active or both are active in Bhutan Himalayan region?What is the impact of these two thrusts on nearby hydropower projects or other construction projects?Is it related with the failure of rockbolts of the powerhouse of Tala Hydropower plant?
Hope everything is going well. I need help. I prepared seismic source zonation map of my country. Now I want to prepare seismic hazard map using zonation. Can you provide me any code and manual to prepare such map? It will be very much helpful for me. Thank you.
I want to investigate the linear as well as non-linear responses of earthquake events, regarding this is there any other available tools such as NERA and EARA.
The earthquake occurrence is more complicated than the models on which hazard maps are based. Hazard maps often depend on poorly constrained parameters, whose values are chosen based on the mapmakers' preconceptions. When these are incorrect, maps do poorly.
What to do to improve seismic hazard maps?
I would like to estimate Vs30 for seismic hazard assessment in the NW Himalaya using proxies some like Geo morphology or Topographic slope complementary with strong motion data in that region. This is part of my PhD work, kindly suggest me. I would very thankful to you.
In regard with the Attenuation Relationship for Seismic Hazard Analysis, with scenario below:
Site selection for seismic hazard: located on stable continent.
Source zones: At subduction zone approximately 500++km away from the site.
Which attenuation relationship that is suitable to be used for seismic hazard analysis on stable continent with sources from subduction zone/shallow crustal zone?
I tried different Attenuation Relationship which derived for stable continent, subduction zone and shallow earthquake and get a different result but not exactly sure which relationship that represent the best with the above scenario.
I’m planning to investigate damage increasing of concrete frame structures subjected to seismic sequence.
I have to identify the region where seismic activity occur within a depth of 200m and estimate the seismic hazard in and around a closed mining area.
How many minimum geophone stations are required for the estimation of seismic hazard in an area of 5Km by 2Km?Are five number of triaxial geophones sufficient for this?
Neo Deterministic Seismic Hazard (NDSHA) is compared to PSHA asserting that the latter overestimates observed PGA values for medium-weak earthquakes (Italy case) and, more seriously, PSHA does not provide preventive values for large earthquakes (underestimation of PGA values). I am interested in a comment or opinion from both engineers and seismologists.
In EOS recent issue ( https://eos.org/opinions/reality-check-seismic-hazard-models-you-can-trust ).
Hypothetically calculating the impact of a co-seismic landslide on a railway bridge we have: (the probability of the earthquake multiplied by the models epistemic uncertainty multiplied by the probability of a landslide multiplied by its associated epistemic and aleatoric uncertainties. Are the latter two uncertainties dealt with as separate entities or should they be combined before running the entire equation?
So should it be Peq X Peqepi X Pls X Plsepi X Plsale = Hazard exposure
Peq x Peqepi x Pls x (Plsepi x Plsale) = Hazard exposure
where Peq = prob earthquake, PZepi is PZ epistemic uncertainy & PZale = aleatoric uncertainty
Furthermore should the aleatoric uncertainty be a larger decimal or a smaller one for seismic hazard as this will impact the model severly? ie 0.9 or 0.1.
In Building code, there is only response spectrum for short to medium period (<1s) for site A,B,C,D,E.
In case of deep soil basin (Osaka, Kanto, Los Angeles... basins), the predominant period may be up to several seconds. It is very dangerous for high-rise buildings in these regions if there is a large earthquake which releases long-period energies.
How is the design response spectrum? Is it mentioned in any code or document?
We all work around Seismic Risk. Structural Behaviour, Retrofit Techniques, Scenario Simulation, Loss Quantification and so on. But. Do people feel at Risk? If not, how can citizens be willing to pay Seismic Risk Reduction policies and practices? Do people know about Feasible Risk Reduction Strategies and actions? If not, how can people be willing to pay Seismic Risk Reduction policies and practices. If someone has any ideas about this, please share.
I have been working in PSHA (Probabilistic seismic hazard analysis) and I could not find information about the Stepp´s method, mentioned in the question, used in the completeness analysis process of seismic catalogs. I will appreciate if someone could help me onto this.
3D-1D broadband simulations of ground motion are normally performed by using a hybrid approach where full wave numerical methods are used for the low frequencies and a stochastic contribution has added a posteriori to achieve high frequencies. The cross-over for hybridization is established empirically in a band between about 0.5 Hz and 2 Hz depending on the earthquake magnitude size, distance, local structure and shape of Fourier spectra of low frequency synthetic seismograms.
For micro seismic zonation, lateral variation in the P-wave velocity is an important parameter because the unconsolidated zones having lower velocities are supposed to have higher amplitude response during the earthquakes. Sometimes, for shallow subsurface investigations, procuring equipments for seismic surveys prove to be cost prohibitive. However, electrical resistivity is a much cheaper means to investigate shallow subsurface stratigraphy. The problem is can we compare the velocity information with resistivity?
I know openSHA allows to select deterministic or probabilistic approach, but their open source Java code does not reveal much of deterministic approach. I want to know if any other software is available.
We are investigating Volcano Monitoring using WSN, we actually need to adapt geophones to our wireless network and we need to buy some of them, or maybe there is an institution interested in participating as a sponsor.