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Showing posts from February, 2016

Response Spectrum Analysis - I

"Response" is what an object, living or nonliving, gives to a certain situation. It can be passive response or active response but it doesn't matter. What matters is how the buildings respond to earthquakes. Let us say for an example, you take a pendulum and you pull it to a certain height and leave it for free oscillation. What you will see is the mass attached at the end of the pendulum moving back and forth constantly, such motion is simple to understand as it is clearly visible to your eyes. The time a pendulum takes to complete one oscillation is called the time period of a pendulum. This factor, "time period" is very important characteristic of a building, it can tell you everything about the building, every ins and outs. Coming back to pendulum and time period, when you plot the motion of pendulum with respect to time it will give you a sinusoidal curve called the response of the pendulum to the disturbance. It will look something like this: Angl

Taiwan Earthquake 2016

Every time an earthquake strikes, we learn something new from it. As a structural engineer it is always difficult to explain people as why a building collapsed. The only reason is we cannot predict earthquakes. But wait I am not done here, yet..!! Let us take a deep breath and jump into the possibilities of failure of buildings in the city of Tainan which is located just at a distance of 48km (30 miles) from the epicenter. Let us take a look at USGS map of the affected zone. Now the earthquake was a very strong earthquake of category 7 which describes the wave velocity of 20 cm/s and a peak acceleration of 0.22g. One more thing to keep in mind is that the earthquake was a shallow earthquake which means that the intensity of the earthquake might have amplified.  Talking about the building collapses in Tainan, we cannot directly blame at design engineers and the only reason I am saying this is because Taiwan has been famous for earthquakes and not small intensity but the la