Response of infilled frames using pseudo-dynamic experimentation

Abstract

SUMMARY An accurate and practical testing technique to study seismic performance of multi-storey infilled frames is formulated. This technique is based on the pseudo-dynamic method which can provide an acceptable approximation of the dynamic performance of structures under the influence of earthquake excitation. The pseudo-dynamic experimental technique is outlined and applied for testing a two-bay, two-storey gravity load designed steel frame infilled with unreinforced concrete block masonry walls. From the discussion of the results, the dynamic performance of the tested structure is assessed. ( 1998 John Wiley & Sons, Ltd. Pseudo-dynamic experimentation is a testing procedure in which the dynamic response of the structure is calculated and the obtained displacements are statically applied to the structure in an on-line procedure. This technique is essentially identical to traditional time domain analysis but rather than idealizing the non-linear sti⁄ness characteristics of the structure, the static restoring forces are directly measured from the specimen as the experiment proceeds. Computation of displacements is based on numerical integration of the governing second-order di⁄erential equations of motion of a system with assumed mass and damping properties and with a forcing function corresponding to a selected dynamic loading. During the test, actual displacements and restoring forces are measured using equipment normally used for static experiments. These measured quantitites are utilized in subsequent calculations. In this way, both dynamic e⁄ects and progressive damage of the specimen are included in the imposed displacements, and the procedure allows for an in-depth monitoring of the performance of the structure for the entire duration of realistic earthquake excitation. Infilled frames have been investigated experimentally by many researchers, most often with monotonic (see e.g. Reference 1) or quasi-static cyclic loading (see e.g. Reference 2), and in a few cases with actual dynamic