Development of seismic retrofitting technology by spraying PVA fiber-reinforced mortar


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Development of seismic retrofitting technology by spraying PVA fiber-reinforced mortar

Masato Iso1,*, Koichiro Ishikawa1, Keiich Inoue1, Ayato Honma1, Atsuhisa Ogawa2

HIGHLIGHTS

  • PVA-FRM was developed as a material of seismic retrofitting method.
  • The appropriate amounts of fibers were investigated.
  • The retrofitting effect of PVA-FRM was verified by RC columns retrofitted with additional wing walls.
  • The appropriate volume content of PVA fibers was 0.3%.
  • The retrofitting effect of RC columns retrofitted with additional wing walls using PVA-FRM was almost the same as normal concrete one.

ABSTRACT

In Japan in particular, the Hyogo-ken Nanbu earthquake, the Tohoku earthquake off the Pacific coast, and the Kumamoto earthquake occurred in 1995, 2011 and 2016, respectively. Since many reinforced concrete (RC) buildings designed by the abolished Japanese seismic codes before 1981 were severely damaged by these earthquakes, the necessity of a seismic diagnosis and a seismic retrofit for the existing buildings was strongly recognized. On the other hand, noise and vibrations will occur upon doing work for the seismic retrofit. Furthermore, the work pollutes the environment, and requires usage restrictions and the temporary evacuation of the building. Therefore, these become a large burden for the building residents and tenants. The objective of this research is to develop premix “polyvinyl alcohol fiber reinforced mortar (PVA-FRM)” that is utilized for the seismic retrofitting material of existing buildings, and to propose a new seismic retrofitting method by spraying PVA-FRM. At first, the various tests, which were a compressive test, a split tensile test, a flow test, a test of dry shrinkage cracking, a spraying test, a bonding test and an adhesion test, were conducted to clarify the material properties, the fresh properties and the filling performance of PVA-FRM. Furthermore, the existing RC column retrofitted with the additional wing walls, which used the developed PVA-FRM, was tested to reveal the reinforcing effect and the structural performance. In addition, RC bare column without strengthening, and the existing RC column retrofitted with the additional RC wing walls were prepared to compare with test specimen using PVA-FRM. As the results of these material tests, the material properties of PVA-FRM were almost same as normal concrete. The appropriate volume content of PVA fibers was decided at 0.3% due to tests of flow, dry shrinkage cracking and spraying. On the results of structural testing, the proposed seismic retrofitting method using PVA-FRM could enhance the seismic behavior of the existing RC column. The effect of seismic retrofit using PVA-FRM was almost the same as normal concrete.

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To cite this article: Iso M, Ishikawa K, Inoue K, Honma A, Ogawa A. Development of seismic reinforcement technology by spraying PVA fiber-reinforced mortar. Journal of Advanced Civil Engineering Practice and Research 2017;5:7-16.

To link this article: http://ababilpub.com/download/jacepr5-3/