# Questions tagged [seismic]

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### Would a larger building more safely or smoothly ride the seismic waves of an earthquake?

If larger ships are less affected by ocean waves, and tend to ride smoothly through them, would that same principle influence the survivability of a larger building when weathering the seismic waves ...
• 113
1 vote
34 views

### Most effective bracing arrangement for resisting seismic forces? [closed]

Which bracing arrangement is most effective for resisting seismic forces?
1 vote
22 views

### 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 $EI$ ...
• 1,186
62 views

### how can i find Spectral Acceleration (Sa(T1; 5%))?

I want to do incremental dynamic analysis (IDA) for my project and for hunt and fill algorithm i need the 5% damped Spectral Acceleration at the structure’s first-mode period (Sa(T1; 5%)) . Can i find ...
21 views

### 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.
• 101
1 vote
67 views

### 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 ...
74 views

### 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 ...
• 219
1 vote
59 views

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 ...
• 467
374 views

### Seismic Design Changes between ASCE and UBC Code?

what is the difference between the seismic design between ASCE and UBC code? from load combinations to loads applied to the history between the sudden shift or change in the code. and which one of the ...
• 503
147 views

### Slab Stiffness Modifiers applied in Vertical Elements design but not in Slab design?

Why in the design of vertical elements (columns and walls) for a structure against lateral loads (such as seismic and wind) we use a slab (or shell) with a stiffness modifiers (such as 0.25 according ...
• 503
24 views

### Wave train 200 m/s meaning

I ran a 60 m seismic line. Energization with hammer. 12 (10 hz vertical 5 m spaced) geophones and 5 shots (15 m spaced). Record length 0.5 s. Thanks to a borehole near a estrata of gravelly silt man-...
1 vote
116 views

### 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. ...
• 503
1 vote
556 views

### How to handle modal combination in response spectrum analysis for member forces for member with more than 1 element?

My textbook says for mode combination, the peak value $r$ of each response quantity is determined by combining the peak values $r_n$ of the modal contributions to the same response quantity. From ...
• 1,254
2k views

### 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 ...
• 3,587
1 vote
283 views

### 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 ...
• 113
841 views

### 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 ...
• 1,254
3k views

### 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. ...
• 1,254
665 views

### 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 ...
• 1,254
5k views

### 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 ...
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