Seismic retrofit of rectangular RC bridge columns using wire mesh wrap casing

Abstract

Many bridges were constructed before a seismic design provision was implemented in Korea. Therefore, poor seismic response of non-seismically detailed RC bridge columns could be expected during a seismic event. The aim of this study is to report experimental results of a seismic retrofit method for the non-seismically detailed rectangular RC bridge columns by casing lap-splice region with a Stainless Steel Wire Mesh (SSWM) and permeable polymer mortar. Total five reduced scale RC column specimens were tested to examine the seismic performance improvement due to the SSWM wrap casing for retrofitting the rectangular RC columns with an inadequate lap-splice length in the longitudinal reinforcement. The test results show that the non-seismically detailed rectangular RC column has poor seismic capacity. However, this deficient seismic capacity can be upgraded by applying an elliptical shape SSWM wrap and an elliptical shape mortar casing into the lap-splice region of rectangular RC column.

Retrofitting of Infilled Frame in Reinforced Concrete Structure

“…Ferrocement overlay was used for the retrofitting of the damaged frames. According to the guidelines for application of reinforced plaster [14] the gauge and spacing of wires in a mesh should be such that to provide a minimum reinforcement ratio of 0.05% of the gross area of masonry. A corrosion resistant welded steel wire mesh of gauge 18 (diameter = 1.18mm) with a spacing between two alternative wires of 19.05mm having reinforcement ratio of 0.05% was used which was compliance with the guidelines for application of reinforced plaster.…”

“…[17] recommended that grout injection is effective for cracks having a thickness ranging from 0.08-12 mm. As recommended by [6 -7] cracks with width less than 10 to 12mm were repaired according to the guidelines for application of grout injection [14]. Holes were drilled in mortar joints along the crack length and injection nozzles of length 101.6mm and diameter of 9.525mm were fixed at the drilled holes using fast binding cement paste (1:2).…”

“…With a minimum of 14 days plaster curing, grout comprised of ten parts of ordinary Portland cement, one part of slacked lime and an ultra-expansion agent at the rate of 0.005% of Portland cement was prepared based on penetrability, stability and affectivity [14]. The water to cement ratio used in grout was 0.9.…”

Shear strengthening of reinforced concrete beams with high-strength steel wire and engineered cementitious composites

“…High-strength steel wires are often used in combination with polymer mortar to strengthen RC structures. Previous studies have proven it to be an effective method for flexural, shear and seismic retrofitting (Kim and Kim, 2011; Kim et al, 2007; Nie et al, 2005a, 2005b; Yang, 2012; Yang et al, 2009). However, this strengthening method also has the problem of poor durability under severe corrosion environment due to the poor crack control ability of polymer mortar.…”

Enhancement of circular RC columns using steel mesh as internal or external confinement under the influence of axial compression loading

“…The results proved that the SWM has a mightily effective repair technique for RC columns that have insufficient lap splices under earthquake load, where the peak load, flexural strength, energy dispersion, stiffness, and the displacement ductility of the rehabilitated columns were larger than those of the unrepaired columns. Kim and Kim [19] tested RC bridge columns retrofitted using SM and a porous polymer mortar. This study indicated that the improvement in the retrofitted columns ductility was greatly satisfactory, and their seismic behavior was extremely enhanced compared to the original columns without SM.…”