The Earthquake Engineering Online Archive

Experimental and analytical studies on the seismic behavior of lightweight concrete panels with friction energy dissipators

Sasani, Mehrdad; Popov, Egor P.

UCB/EERC-97/17, Earthquake Engineering Research Center, University of California, Berkeley, 1997-12, 177 pages (517.6/S27/1997)

As part of the seismic retrofit plan of the Rivera Library at the University of California at Riverside, an energy-dissipating system was designed. The system uses nonstructural lightweight reinforced concrete panels as structural elements that not only carry some portion of the lateral load but also dissipate energy as a result of relative displacements between adjacent floors. A full-scale model of the panels and the energy-dissipating devices was tested under different types of motions. By modifying the types of anchor bolts used to connect the steel elements to the concrete, a more efficient energy-dissipating system has been proposed. To study the response of the panel and the importance of different elements of the energy-dissipation system, an analytical model has been developed. A new element is introduced to model the lateral movement of an anchor bolt in a concrete hole, i.e., the impact when the bolt hits the hole and the extension of the hole as a result of the impact. The analytical results show good agreement with the experimental results. Since the new element used in this study could be categorized as an endochronic model, theoretical aspects of endochronic models with regard to violation of certain postulates of plasticity are discussed. A definition of dissipated energy over any time interval is proposed that not only leads to a non-decreasing time history of dissipated energy but also results in a better understanding of how and to what extent endochronic models violate some plasticity postulates. Corrosion-related problems are discussed. In order to reduce the risk of corrosion, alternative materials are considered based on experimental evidence. The effects of material type on the mechanical response of friction-based energy-dissipating devices are discussed. The results of tests on brake lining pads, as an alternative non-metallic material, are also presented.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-97-17.pdf (28 MB)