A Simple Strengthening Method for Preventing Collapsed of Vulnerable Masonry Infills

Abstract

A series of structural tests were conducted to examine the seismic performance of masonry infills strengthened with particular materials on infilled reinforced concrete (RC) frame structures. Six 1:4 scaled-down RC frame specimens had been prepared, including one brick-infilled frame without strengthening and five brick infills strengthened with innovative strengthening materials. The materials were steel wire mesh, chicken hexagonal wire mesh, plastic wire mesh, fiber-reinforced polymer (FRP), and plastic stretch film. The strengthening was diagonally applied on both surfaces of the masonry infill. The steel wire mesh, chicken hexagonal wire mesh, and plastic wire mesh were sewn using steel wire, while the FRP sheet was glued using epoxy resin and the plastic stretch film was glued using synthetic rubber adhesive. The specimens were tested following the FEMA 461 standard testing protocol, which involved applying lateral static cyclic loading to the specimens. The displacement transducer apparatus measured the deformations of the specimens, and crack propagation was observed during experimental works. The experimental results showed that most specimens exhibited an increase in their lateral strength, secant stiffness, deformation capacity, and energy dissipation. Among all prepared specimens, the specimen using plastic stretch film showed the best and most promising results, i.e., long deformation and steady lateral strength after yielding. This result suggests that using plastic stretch for strengthening can increase ductility performance. It is expected to withstand earthquake shaking, has low application costs, and is feasible for application even by unskilled local laborers.

Keywords

• cyclic loading test
• energy dissipation
• masonry infill
• retrofit
• seismic performance
• secant stiffness