Seismic Performance of Beam-Column Joint Connections With Reduction in Transverse Reinforcements in Rigid-Framed Railway Bridges By Using Pp-Ecc


Abstract eng:
Bridges are vital components of transportation that requires a high degree of protection to ensure their safety during a strong earthquake. The extensive damages of RC bridges observed in the past earthquakes such as Northridge, Kobe and 2011 Great East Japan earthquakes triggered extensive researches on the behavior of beam–column joint connections for designing and constructing a safer infrastructure, which further resulted in the improvements of design codes focusing on providing sufficient ductility in the vulnerable structural member to prevent its brittle failure during a major seismic event. Accordingly, for reinforced concrete (RC) structures, a considerable amount of steel reinforcements are required to be provided in these vulnerable regions, such as the plastic hinge in the beam end adjacent to the column face in a beam–column joint connection in the rigid-framed railway bridges, to confine the concrete to realize the formation of ductile inelastic behavior in the plastic hinge. However, the increased and elaborated reinforcement details bring the difficulties in fabricating this complicated steel reinforcement cage as well as placing and consolidating concrete in it during the construction phase. The contradiction between increased high cost for design and construction due to these complicated reinforcements with accordingly raised requirements on seismic performance becomes more and more apparent. In this research, a cementitious composite combined with fabricated polypropylene fibers named Polypropylene Fiber Reinforced Engineered Cementitious Composites (PP-ECC) with improved bond properties exhibiting the pseudo strain hardening and multiple fine cracking of ECC was utilized to reduce the transverse reinforcements in beam–column joint connections of rigid-framed bridges. Compared with widely used polymer fibers such as polyvinyl alcohol (PVA) fibers or polyethylene (PE) fibers, polypropylene (PP) fiber is softer, costs lower and disperses faster, which all results in better workability. In addition, because of the hydrophobic and non-polar nature of PP fiber, PP-ECC has better durability in an alkaline environment. The loading tests including two phases were conducted: the basic mechanical properties of PP-ECC in compression and tension were confirmed by cylinder compression and uniaxial tensile tests in the first phase and a total of three one-sixth scaled T-shaped beam–column joint connections which were prepared based on the design standards for existing railway bridges in Japan were tested under the applied reversed cyclic load to verify the possibility of reducing transverse reinforcements. The experimental results reveal that the PP-ECC is effective in replacing transverse reinforcements in the beam-column joint connections of railway rigid-framed bridges without deterioration of seismic performance.

Contributors:
Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
Rights:
Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 4090.:
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