The HVSR (Horizontal to Vertical Spectral Ratio) is used to determine the site period. As a very crude explanation, you can think about the site period as the period/frequency that the ground will most dominantly shake in. Like a plate of jello moved back and forth. If that Jello has a structure on top of it with the same natural period, that structure will see some really large movements. My video on Natural Period and Resonance links these two ideas. I have colleagues who have done a lot of work using HVSR to map the depth of soft soil basins in and around New Zealand cities to determine site class and site period. Then as a structural engineer, I can then use that information to see if my building is likely to see an increased level of shaking. This phenomenon was really evident after the 2016 Kaikoura earthquake in which the taller buildings along the waterfront that were sitting on soft soils saw much larger shaking than the buildings sitting on rock. Subsequent HVSR measurements confirmed this.
@@evazhang3232 Because the period of vibration is only dependent on the mass and the stiffness of the system, if you make the system more flexible (i.e. lower its stiffness) you will increase the period. Most earthquake have lower energy content at higher periods (lower frequencies) so structural engineers can take advantage of this fact and put the building on isolators which are stiff in the vertical direction so the building doesn't sink, but are very flexible in the horizontal direction which increases their natural period compared to if the building were just fixed to the ground.
@@lucasshogan Thank you!!! lower the stiffness to increase the building period so it may receive an earthquake have lower energy content! Thank you for your timely respond!!! Love your videos!
GREAT TUTORAIL. We want more of this kind of videos that makes our basic stronger
Great tutorial! Thanks Lucas
Thanks a ton
thanks a lot bro, great help
what are the units of k and m to get Tn in seconds ?
Thanks Lucas! this natural period also comes from HVSR measurement?
The HVSR (Horizontal to Vertical Spectral Ratio) is used to determine the site period. As a very crude explanation, you can think about the site period as the period/frequency that the ground will most dominantly shake in. Like a plate of jello moved back and forth. If that Jello has a structure on top of it with the same natural period, that structure will see some really large movements. My video on Natural Period and Resonance links these two ideas.
I have colleagues who have done a lot of work using HVSR to map the depth of soft soil basins in and around New Zealand cities to determine site class and site period. Then as a structural engineer, I can then use that information to see if my building is likely to see an increased level of shaking. This phenomenon was really evident after the 2016 Kaikoura earthquake in which the taller buildings along the waterfront that were sitting on soft soils saw much larger shaking than the buildings sitting on rock. Subsequent HVSR measurements confirmed this.
@@lucasshogan thanks for response.. then you can use HVSR period for analize the target spectrum? for you structural design..?
Thank you.
tnks alot
Thank you for the video!! May I ask, how would I relate the natural period to the seismic isolator?
How to understand period shift?
@@evazhang3232 Because the period of vibration is only dependent on the mass and the stiffness of the system, if you make the system more flexible (i.e. lower its stiffness) you will increase the period. Most earthquake have lower energy content at higher periods (lower frequencies) so structural engineers can take advantage of this fact and put the building on isolators which are stiff in the vertical direction so the building doesn't sink, but are very flexible in the horizontal direction which increases their natural period compared to if the building were just fixed to the ground.
@@lucasshogan Thank you!!! lower the stiffness to increase the building period so it may receive an earthquake have lower energy content! Thank you for your timely respond!!! Love your videos!
Unit of natural period??
seconds
great tutorial mate