Page 17 - Open-Access-June-2020

TECHNICAL PAPER

(a) (b)
Figure 4: Typical Hysteresis loop of (a) RC and (b) RECC Beams [79]

Unlike RC beams, the brittle failures such as shear failure and 9.2.4 Cracking Behavior and Failure Mode
bond splitting failure were eliminated in RECC beams . In
[78]
RECC beams, the failure modes depends upon the shear-span In ECC beam-column joint, the major crack was observed in
ratio. The flexure and shear failure modes were observed for joint zone and spread into dense tiny cracks with reduced crack
[83]
larger and shorter shear-span ratios, respectively . Diagonal spacing . Spalling or bond splitting was eliminated by the use
[79]
tension failure was observed in RECC coupling beams . of ECC in the beam-column joint [82,84] .
[80]
The ECC beam-column joint failed in ductile failure mode
9.2 Seismic Behavior of Beam-Column Joints
unlike concrete beam-column joint, which fails in brittle shear
Beam-column joint with ECC exhibits enhanced seismic failure . Flexure failure mode exist for both with and without
[83]
response in terms of hysteresis loop, energy dissipation, the transverse reinforcement, which indicated ECC could render
cracking and failure mode. Some of the research works (see sufficient shear strength .
[13]
Table 8) from the literature are discussed below.
9.3 Seismic Behavior of Columns
9.2.1 Influence of shear Reinforcement
ECC columns exhibits enhanced seismic response such as
ECC beam column joint specimens showed comparable peak increased load carrying capacity, energy dissipation, cracking
loads with and without transverse reinforcement suggesting that behavior and failure modes compared to concrete columns.
the ECC can replace the reinforcement [13, 82] . Some of the notable research works (see Table 8) available in
literature are presented in this section for more understanding.
9.2.2 Influence of Hysteresis Loop
9.3.1 Influence on the Hysteresis Loop
The hysteresis loop of ECC beam column joint was more stable
and full without any apparent pinching effect unlike concrete In RECC columns, the transverse reinforcement does not have
beam column joint [82,83] . ECC beam column joint, with transverse any significant effect on the hysteresis loop unlike RC columns
[85]
reinforcement showed higher positive cycles than other due to the confinement effect of PVA fibers in ECC . Pinching
specimens due to the higher compressive strength of ECC . effect was not observed in the hysteresis loop of ECC encased
[13]
CFST columns . In case of short columns, the hysteresis loop
[86]
9.2.3 Energy Dissipation Capacity of ECC columns was superior to the RC columns . The ECC/
[87]
RC composite short columns also exhibits full and more stable
Replacement of concrete joint by ECC joint in beam-column hysteresis loop compared to concrete columns. In addition,
joint exhibits enhanced energy dissipation . In addition, the decrease in stirrup ratio does not have any influence . The area
[83]
[88]
energy dissipation is more when there was a reduction or of the hysteretic loops of ECC short columns became narrower
elimination of transverse reinforcement than the specimen with with increase of axial load and the stirrup spacing and the
transverse reinforcement . area of the hysteretic loops decreased with smaller shear-span
[13]
18 The IndIan ConCreTe Journal | June 2020