ANALYTICAL STUDY ON SEISMIC RETROFITTING OF RC RIGID FRAME VIADUCT WITH MID-LEVEL BEAMS

Abstract

 After 1995 Southern Hyogo Earthquake, the seismic retrofitting of railway structures has been prioritized specially the structures with low design performance, but the number of columns to be retrofit is huge, and construction is difficult if the space under the viaduct is in commercial use. In this study, with the aim of improving the effectiveness of seismic retrofitting, a 3D finite element analysis with material nonlinearity is carried out on three-span RC rigid frame viaduct with mid-level beams with the parameters such as shear reinforcement of the columns and the presence or absence of seismic retrofitting of columns. As a result, it was confirmed that in unstrengthen viaducts where mainly the lower columns are damaged, retrofitting of only the lower columns can sufficiently improve performance, and that retrofitting of only the end or middle columns can significantly reduce the amount of top surface settlement. On the other hand, it is also confirmed that when the shear strength before retrofitting is small, retrofitting only the lower columns may increase the damage of the upper columns.