Questions tagged [seismic]
21 questions
12
votes
3 answers
How can large bridges be made resistant to earthquakes?
How can large bridges, with spans on the order of 1 km, be made resistant to earthquakes?
I'm no expert on quakes, but there are at least two kinds of shaking: lateral and vertical. The vertical shaking in particular really worries me. I don't know…
DrZ214
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11
votes
2 answers
Why are tremors of an earthquake felt more on upper floors?
Why are tremors of an earthquake felt most on the upper floors of a building in comparison to lower floors? Does this have something to do with a third class lever?
Debanshu Thakur
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6
votes
1 answer
How to derive Equivalent Static Load for irregular structure modeled with FEM?
Building codes such as the Uniform Building Code (UBC) or International Building Code (IBC) require the determination of Equivalent Static Lateral Forces in order to compute $P-\Delta$ effect and to perform checks on the structural design.
However,…
Graviton
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5
votes
2 answers
Generating a Blank Seismic Tripartite Graph
I am performing a calculation in which I need to plot a generated response spectrum to a seismic tripartite graph. However, I am having a heck of a time finding a blank tripartite graph online. A low-resolution example is shown below.
How might I…
grfrazee
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5
votes
1 answer
What drives improvements in seismic safety?
I get the impression that a lot of old buildings fail to meet modern earthquake safety norms, and need to be rebuilt or retrofitted. But what has changed in the last few decades that would make a building constructed today better than an older…
200_success
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4
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2 answers
Accidental Torsion and Equivalent Static Load for an irregular structure
Important note: I am writing a structural FEM software from scratch, so I won't able to use existing commercial FEM package. I would need to know how all the important quantities are calculated from the first principles.
I would need to determine…
Graviton
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4
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1 answer
How to calculate the relative contribution of each mode in seismic dynamic mode analysis?
In structural dynamic mode analysis, one would have to carry out modal analysis in order to get different modes that contribute to the response of the seismic ( or wind) force. Here is a nice summary.
In a large structural model, there are so many…
Graviton
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4
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1 answer
What is the frequncy range of seismic vibrations?
I'm working on a structure which needs to sustain common seismic vibrations due to earthquakes. So I want to do some modal analysis to find natural frequencies of the structure and make sure they are out of the range of seismic vibrations. I'm being…
Foad
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3
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1 answer
Seismic question
For a 3 stories building, in terms of seismic vertical instability which one is worse: a higher mass on Level 2 or, higher mass on the roof? Both are compared to L1 mass.
SSan
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1
vote
1 answer
Why is it useful to scale seismic ground motion data
I am learning by myself structural dynamics but confused about the concept of scaled ground motion data. I can't get the reason why the acceleration data should be scaled. I mean, isn't it better to use the original data "as it is" to compute the…
user123
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1
vote
1 answer
Most effective bracing arrangement for resisting seismic forces?
Which bracing arrangement is most effective for resisting seismic forces?
Sheikh Junaid Fayaz
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1
vote
0 answers
Definition of Mass in Multiple Mass Oscillators
In an exam on seismics and earthquake proof design I had a couple of days ago, there was a question on multiple mass oscillators in the form of a simply supported beam of length $L$, stiffness $EI$ and two point masses $M$ at the points…
Andrew
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vote
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Can the signal reflections from seismographic surveys be intercepted and interpreted to produce valid results
I am watching the news about Turkey conducting seismographic surveys in the Eastern Mediterranean and from day 1 I have been wandering if a "listener" can record the sound produced by the survey vessel using a hydrophone array and, knowing the…
Schizomorph
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1
vote
1 answer
Wind load vs Earthquake load and R factor
I read somewhere that if for instance for a building earthquake forces are expected to be much higher than wind loads, we can increase the R (response modification factor) value, so that we bring down the design earthquake force down to wind load…
upstream
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1
vote
2 answers
How to distribute moment from Lateral Load Method (Static Analysis IBC for example) to Each shear wall individually?
I have used the Equivalent Lateral Load Method from the IBC code to distribute forces and moments on each storey (level) but what I need to know is how to distribute the moment on each shear wall.
This maybe a stupid question, but I'm just a…
J.Daou
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