Takamatsu et al. 2008
The authors propose an energy absorbing wedge device to be used in structures as an earthquake resistance element. In this study, new structural elements: a non-slip-type column base, a non-compression brace, a self-centering beam-to-column connection and a non-compression knee-brace were studied under cyclic loading to clarify their earthquake-resistant performance, restoring force characteristics and applicability to rehabilitation.
System Concept
Non-Slip Type Column-Base: A wedge device between the nut and the base plate prevent slip behavior. Any gap generated between the nut and the base plate due to plastic elongation of the anchor-bolt can be eliminated by the wedge moving into the gap under spring compression. The anchor-bolt can absorb plastic energy without pinching behavior.
Non-Compression Braces: This structure consists of a slender rod with tensile-connected ends equipped with a wedge device. One end of the brace is pinned and the other (with the wedge device) is designed as a roller moving only in the compressive direction. The brace can thus resist only tensile force. The plastic deformation capacity and energy absorption capacity of the non-compression brace depends on the sliding displacement of the wedge.
Non-Compression Knee-Brace: This specimen consists of a rigid connection with non-compression knee braces.
Experimental Study, Results and Discussion
Horizontal actuators were used in all experiments to laterally load the systems.
Non-Slip Type Column-Base: In this test, anchor bolts are considered as the yielding elements, and the base plate, column member and foundation are considered as elastic elements. Test results show that the column base was able to self-center until the elastic limit of rotation was exceeded. No looseness was generated in the column base due to the lack of a gap between the nut and base plate.
Non-Compression Braces: Under cyclic loading tests, the braced frame showed spindle-type restoring force characteristics at each loading cycle, and constant elastic-stiffness curves.
Non-Compression Knee-Brace: Members other than the knee-braces showed behavior in the elastic region. Under cyclic loading, the restoring force characteristics became bi-linear curves.
Reference
Takamatsu, T., Tamai, H., Yamanishi, T., and Matuo A. (2008). “Rehabilitation of Steel Structure by Means of Wedge Device,” Proceedings of the 14th World Conference on Earthquake Engineering 2008, Beijing, China, October 12-17.