Affiliations: [a] Department of Civil Engineering, Tafresh University, Tafresh, Iran
| [b] Permayon Advanced Strengthening Co., Tehran, Iran
Correspondence:
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Corresponding author. A. Moslehi Tabar, Assistant Professor, Department of Civil Engineering, Tafresh University, P.O. Box: 3951879611, Tafresh, Iran. Tel.: (Fax):+98 862 6241250; E-mail: amoslehi@tafreshu.ac.ir.
Abstract: Lightly reinforced mass concrete piers are seismically vulnerable due to their excessive weight and inadequate reinforcement. The present paper aims to outline an innovative method for seismic rehabilitation of such piers using post-tensioning technique. In the numerical case study carried out in the paper, it is shown that a prescribed compressive stress about five percent of the pier axial strength can promote the lateral load-carrying capacity by 60 percent. Moreover, the piers with originally brittle behavior show proper ductility applying adequate prescribed compression. The capability of the rehabilitated piers to reveal stable non-linearity is resulted in a minimum seismic response modification factor of 3.0, approximately. This value is comparable with unity considered for the existing piers. The nonlinear analysis conducted under cyclic loading confirms that the efficiency of this method does not considerably degrade during the loading excursions. Finally, a simplified method is proposed to estimate the amount of compression needed to achieve required strength and ductility.
