EARTHQUAKE RESPONSE BEHAVIOR ON STEEL FRAME WITH PARTIAL-STRENGTH CONNECTIONS AND COLUMN BASE DEFORMATION

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To estimate the seismic behavior of the SHS steel column specimen of structure with accuracy, free vibration, forced vibration tests, and earthquake monitoring were carried out. The response records monitored during natural earthquakes were used to identify the vibration property of the specimen. Identified system gain was approximated by a theoretical gain of linear SDOF system, and the response calculated based on such a linear SDOF system agrees with the monitored response fairly well. A series of test, which is performed on exposed-type steel column bases under static cyclic bi-axial bending, is carried out. Cold-formed square-tube columns with end-plate type connection specimens (19mm and 9mm thickness) with different failure types, anchor bolt yielding type and base plate yielding type, were tested under uni-axial, bi-axial but linear, and bi-axial circular cyclic loading programs. Shape of hysteresis loop, moment capacity including bi-axial interaction surface, and rotation capa … More city are examined experimentally. Moreover, to consider the interaction between the x-axis and y-axis bending moment in a partial-strength connection, we propose two different multi-spring models : one is base plate yielding type and the other is anchor bolt yielding type. In addition, efficiency of the proposed model is examined by comparing it with the test results.In order to reflect the nonlinear behavior of an exposed-type column base to design procedure, the exposed-type column base is modeled as a kind of the partial strength connection. From the test results of the experiments conducted in the past, a typical poly-line to characterize moment vs. drift angle rotation relationship of exposed-type column base is proposed. Also, a method to simulate the inelastic behavior of column base in case of biaxial bending by expanding uni-axial restoring force characteristic model to bi-axial model is proposed, with respect to anchor bolt yielding type and base plate yielding type, respectively. Less