DISTINCTIVE-FREQUENCY-BASED SIMILITUDE LAW FOR EARTHQUAKE SIMULATION TEST OF BUILDING STRUCTURES

摘要

This paper presented a Distinctive-Frequency-Based similitude approach of earthquake simulation test for down-scaled building structures on shaking table. Due to the limitation of the load capacity (not more than 1000KN) of most shaking tables (not larger than 6m× 6m), small scale model structures have to be used to simulate the seismic behavior of their prototype counterparts in almost all earthquake simulation tests. And so far kinds of equivalent linear similitude law (Bocking-Ham π theory based) also have to be adopted in destructive earthquake simulation tests due to the slow developing of the non-linear similitude theory. Actually, in earthquake simulation test for a certain model structure, its' natural frequency or so-called distinctive frequency can be measured before each test case no matter how high the next excitation level or how severe of the model structure will be damaged. The measured distinctive frequencies reflect the non- linear changing of the tested structure relatively exactly. Using the measured distinctive frequency in each test phase, corresponding equivalent secant modulus of the model material can be estimated, as consequence, the new secant modulus based dynamic similitude relationship can be determined easily for each test phase. Case study is provided in this paper for illustrating how the new developed similitude approach is used in test practice.