As an effort to minimize material utilization of metallic yielding dampers, steel dampers designed to deform inelastically in an in-plane flexural mode have attracted serious attentions recently. This paper presents a new type of in-plane flexural damper referred to as the in-plane archshaped damper modified from its portal frame-shaped counterpart to minimize the effects of stress concentration and warping, and to avoid premature failure as a result. Seismic performance assessment of the

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... ed damper was carried out via shaking table tests of a five-story model frame under the El Centro earthquake with various intensities. Significant reductions of the structural acceleration and displacement responses have been achieved with the proposed device implemented, and the equivalent damping ratios of all structural modes identified from the experimental data are considerably enhanced. Encouraging test results suggest the effectiveness and feasibility of using the proposed in-plane arch-shaped energy-dissipative device for earthquake protection of building structures. Moreover, a series of nonlinear time history analysis of the five-story model frame corresponding to the tests was further conducted. The inelastic behavior of the proposed dampers was simulated by the Bouc-Wen's model and the predicted acceleration and displacement responses were in turn compared with the experimental results. The simulated structural responses with properly selected parameters of the Bouc-Wen's model agree well with the experimental results, indicating that the proposed analytical model for nonlinear dynamic analysis of inelastic systems is adequate.  Index Terms-seismic, in-plane metallic damper, shaking table tests, Bouc-Wen's model, nonlinear dynamic analysis