Experiment as an aid to structural seismic design

An overview of the available methods for simulating or estimating seismic effects on buildings and similar structural models as well as onin situ structures is given. The motivation is provided by noting severe damage even to modern buildings in the wake of strong earthquakes. The complex inelastic behavior of members and connections must be determined experimentally. Such information is essential for developing mathematical design models. Four available test methods, with examples, are described. One of these is the pseudo-static method of testing where a specimen is subjected to apriori selected cyclic forces or displacements. The second, the pseudo-dynamic method of testing, combines the above procedure with an on-line computer. In employing this approach it is possible to apply a random sequence of displacements corresponding to a previously recorded earthquake while taking into account the continuously changing structural stiffness. The third procedure employs a shaking table programmed to apply scaled earth-quake input based on available accelerograms. The fourth, a nondestructive method of testing of actual structures, consists of recording and interpreting ambient or forced vibrations in the elastic regime.