Answer to Quora question, "What is 'spectral acceleration' in structural analysis?"

Quora's bots asked me to answer the above question, and below is my response. What do you think of my response? Did it answer the question? Is there anything incorrect with what I said? How would you have answered the question? Let me know in the comments.

"What is 'spectral acceleration' in structural analysis?"



It's risky to miscommunicate risk

In a previous post, I asked that we take caution how we communicate a certain risk. That example talked about the location of the "Valley Fault System," previously called the Marikina Fault, which obviously presents a certain disaster risk. One problem was that risk wasn't quantified then -- how close should one be to the fault lines to be at risk? It wasn't very clear, but people could readily assume that if they are clearly not along the fault lines, they should be safe. If they're not sure, they should consult PHIVOLCS (not PHILVOLCS, by the way), who can provide information on distance of a certain property from the nearest fault line.


Metrology is not the same as meteorology #didyouknow

I know that the word "meteorology" is difficult to pronounce and sometimes even spell. But some, whether unintentional or otherwise, pronounce it like "metrology," or its descriptive form "meteorological" as "metrological." It might be all right, because not so many people know about metrology, and even some spell checkers think it is a misspelling. But in fact, this is how it is defined:


Damping in buildings for wind-resistant design based on a stick-slip model

I am posting a download link to a copy of my dissertation here for those of you who are interested.




Damping is said to be one of the most important parameters in the wind-resistant structural design of buildings. But, damping is also known to have high uncertainty, which leads to low reliability in the design. Current estimation formulas and early research on structural damping, particularly, are associated with stick-slip mechanism. But these current models have only shown this qualitatively. In the end, these models fitted formulas to databases of full-scale experimental data. This dissertation therefore aims to quantitatively study the stick-slip mechanism itself to derive a theoretical expression, and finally, to apply the derivation to actual physical structure data to illustrate that stick-slip damping is indeed a valid model. The study starts from a very simple one-degree-of-freedom (1DOF) system with one stick-slip component (1SSC), to a more complicated 1DOF system with a large number of SSC (NSSC). The study also briefly touches on the damping of SSC inside MDOF systems. The study of MDOF with NSSC systems is necessary because actual physical structures are such.


Your house is not along the faultline. What now?

A friend linked to this blog article:
Obviously, the author has good intentions, although he is seemingly not an engineer (or maybe still a young engineer?). The impression I'm getting though is that the article is suggesting to check whether your house/property is along one of the published faultlines. If it is, you're obviously in danger. But it might also give the impression that if you are a good distance away, you probably shouldn't worry.


In the eye of Super Typhoon Yolanda

Well, not exactly. But pretty close -- this is a 12-minute compilation of videos taken by the folks at iCyclone.com of STY Yolanda's fury right in Tacloban City.

WARNING: You are risking your life when you try to do this. Technically, the city should have been evacuated already. When authorities (e.g. PAGASA) warn of an impending storm, follow their instructions! You might say that they been "wrong" before... But it's because this is nature we're talking about. No one can very accurately predict nature. We can only prepare for the worst.


Do we need to increase the code-required minimum design wind speed now after Yolanda?

The answer to this question is NO, there is no need to provide NEW wind load code requirements for higher wind speeds.


Response to students' questions on NSCP 2010 wind loading provisions

These are actually in the comments, but I thought I should promote them to a full post. The first asks about leeward wall pressures:
Are the values for the Leeward wall pz really constant with elevation?


Response to a reader question regarding using the NSCP for estimating wind loads on irregular shapes

A reader asked:
How would you evaluate the pressure coefficients for structures with irregular polygon shapes. An example would be those structures with a plan shape resembling the letters "W" or "K." Most of the pressure coefficients in the code are for uniform cross-sections such as circle, rectangle, square, and so on. I have my own approach on this (mostly based on engineering judgement), but I would like to hear first on a wind load aficionado, such as yourself.


2013-2014 1st Sem CE 197 Final Grades

Another semester has gone. I feel that this class has learned things that they wouldn't have otherwise been taught, and yet there is a lot more to know. Even I am still learning! What I did was I only penalized those who did not follow instructions, such as rounding off, etc., or those who did not even try at all. That said, complaints will not be entertained. These grades are final.