Actual earthquake motion induces inertial forces as well but quasi-static loading doesn't account for them. Any explanation please?
Full scale dynamic load test of a large structure requires a specially designed, large size and costly shaking table facility, and only few countries have the facility.
To match the frequency of earthquake force vibration, we must use high speed actuators which is quite difficult to obtain using hydraulic jack which has slow response inherently. Alternatively, we can use a pneumatic jack system, but it has lower load capacity and more difficult to control. For small size shaking table, we can use electric motor to simulate the high frequency vibration of earthquake. These are some reasons why many still use quasi-static loading.
Nathan Madutujuh
Dear Sir,
Thank you much for your very informative reply. May I please ask whether the application of quasi-static loading approximates the earthquake loading or not. Of course, it doesn't account for inertial effects but how accurately can it approximate to earthquake effects?
The inertial and dynamic effect of earthquake load is already included in the dynamic analysis to get the maximum load used for testing using quasi-static equivalent load.
If the structure does not have a moving member (pendulum) or any kind of damper, using quasi static is acceptable for structure until 460m height, because the wave propagation speed in concrete is 4600m/s and the max frequency of earthquake vibration is about 10hz.
- Badges
- Science topic
- Similar topics
- Analytical Chemistry
- Column