Earthquake-Resistant Design of RC Frame With “Dual Functions” Metallic Dampers

Abstract

Earthquake can make structures damaged and crumble. The traditional approach to seismic design has been based upon providing a combination of strength and ductility to resist the imposed loads. Thus, the level of the structure security cannot be achieved, because the disadvantage of the designing method is lack of adjusting capability subjected to an uncertain earthquake. The presence of some damping (energy dissipation) in buildings has been recognized and studied by professional researchers. Passive energy-dissipated system, as a category of vibration control methods, lead the inputting energy from earthquake to special element, thereby reducing energy-dissipating demand on primary structural members and minimizing possible structural damage. One of the most effective mechanisms available for the dissipation of input energy of a structure during an earthquake is through the inelastic deformation of metallic substances. Added damping and stiffness (ADAS) elements are designed through the flexural yielding deformation of steel plates. Metallic material is a popular (and inexpensive) choice for an energy dissipation device because of its relatively high elastic stiffness, good ductility and its high potential for dissipating energy in the post-yield region. The idea of utilizing separate metallic dampers in a structure to absorb a large portion of the seismic energy began with the conceptual and experimental work by Kelly et al.. Numerous different types of energy-absorbed devices have been proposed, for example, X-shaped and triangular plate dampers by Whittaker et al. The normal metallic damper is to use the out-of-plane bending deformation of metallic plate to provide damping for structure to reduce its dynamic response to environmental loadings. Since the bending curvature produced by a force, which is perpendicular to the metallic plates of damper applied at the ends is uniform over the full height of the plate, the plate can inelastically deform well without deflection concentration. However, the inelastic deformation of the damper may occur even subjected to a relatively small disturbance (wind or earthquake) since the out-of-plane stiffness of metallic plates of damper is very small. As a result, it has to be replaced after the disturbance. How to improve the stiffness of metallic dampers is an important issue. In this paper, a new idea of designing the metallic damper is presented, i.e. the metallic damper with “dual functions”, and the quasi-static tests with the dampers are carried out. Design and fitting process of the reinforced concrete frame with dual functional metallic damper are introduced. A three-dimensional frame structure model is made with ADPL language in ANSYS program. Seismic responses of the structure with and without metallic damper are calculated and compared. The results show that the metallic dampers with the “dual functions” presented here not only provide certain stiffness in the normal application, but also are of good ability of the seismic energy dissipation.