A new type of steel plate shear wall has been devised which resists out--of--plane buckling without requiring stiffeners. The ring--shaped steel plate shear wall (RS--SPSW) includes a web plate that is cut with a pattern of holes leaving ring--shaped portions of steel connected by diagonal links. The ring shape resists out--of--plane buckling through the mechanics of how a circular ring deforms into an ellipse. It has been shown that the ring's compression diagonal will shorten a similar amount as the tension diagonal elongates, essentially eliminating the slack in the direction perpendicular to the tension field. Because of the unique features of the ring's mode of distortion, the load--deformation response of the resulting RS--SPSW system can exhibit full hysteretic behavior and possess greatly improved stiffness relative to thin unstiffened SPSW. The concept has been validated through testing on seven 34 in x 34 in panels. General conclusions about influence of different geometric parameters on plate behavior have been made.iii

This paper presents the design and experimental investigation of a miniature buckling-restrained brace (MBRB) which can act as a hysteretic damper to dissipate energy when subjected to inelastic axial deformations. The MBRB is similar to a buckling restrained brace (BRB) with a yielding steel core plate restrained from buckling by a grouted restraining tube. The MBRBs, however, are designed to have shorter lengths, smaller steel core dimensions, and smaller yield capacity as compared to a typical BRB. As a result, careful consideration is required for the detailing at the ends and the stability of the MBRB. Small capacity BRBs can be useful in a range of applications as a primary energy dissipating structural fuse or supplementary axial hysteretic damper in seismic force resisting systems. The design, construction, and testing of six MBRB specimens with nominal axial yield forces between 30 kN and 95 kN is reported. Issues related to global stability of the MBRBs are discussed and a stability criterion to prevent global buckling was adopted to design the MBRB end connection pieces. The MBRBs exhibited cumulative plastic deformations between 181 and 400 times the yield deformation and cumulative plastic strain between 46% and 106%. Conclusions about the behavior and recommendations for the design of the MBRB are presented.

Although several self-centering seismic systems have been developed in the past, their implementation in practice has been relatively limited. Unusual field construction practices, perceived initial cost premiums and deformation incompatibility with the gravity framing are some of the issues that may be factors. A self centering beam moment frame (SCB-MF) has been developed that mitigates several of these issues. The self-centering beam (SCB) can be shop fabricated with a restoring force mechanism which eliminates deformation incompatibility and allows conventional field construction methods. The strength and stiffness of the beam are decoupled resulting in a cost-effective system that may be competitive with conventional moment frames. This paper describes an experimental program on two-thirds scale one-bay SCB specimens. Parameters that were varied in these tests include SCB depth, initial post-tensioning stress, ratio of initial post-tensioning force to fuse yield capacity, and nominal moment strength of the system. A detailed description of the test setup, post-tensioning procedure, and implementation of the energy dissipation fuse will be presented. Finally, the testing results including the behavior of the individual components (energy dissipation fuse, PT strands and beam) and global system behavior will be summarized.

Although several self-centering seismic systems have been developed, their use in practice has been relatively limited. Complicated or unusual field construction, perceived initial cost premiums, and deformation incompatibility with the gravity framing may be some of the factors restricting their use. A self-centering beam moment frame (SCB-MF) has been developed that mitigates several of these issues.The self-centering beam (SCB) can be shop fabricated with self-contained restoring force which eliminates deformation incompatibility and allows conventional field construction methods. The strength and stiffness of the SCB are decoupled resulting in a cost-effective system that may be competitive with conventional moment frames. This paper describes the SCB-MF concepts, construction and modeling. An upcoming experimental program on two-thirds scale test specimens will also be presented. Computational simulations of the SCB-MF are presented and the results are analyzed.