Overall Conceptual Seismic Design and Local Seismic Capacity Design for Components of Bridges - Structural Seismic Design Optimization and Earthquake Engineering - page 295

Figure 24. Capacity curve comparisons between piers wholly and locally reinforced with SFRC

Table 14. Curvature ductility comparisons between piers wholly and locally reinforced with SFRC

Pier model Yield

curvature (×10 -3 )

Ultimate
curvature (×10 -3 )

Curvature
ductility factor

Ratio of curvature ductility
factor (ii)/(i) (%)

(i) M3(WR-SFRC) 0.999 12.085 12.097 103.6

(ii) M3(LR-SFRC-4m) 1.047 13.111 12.522

(i) M4(WR-SFRC) 1.046 10.769 10.295 106.2

(ii) M4(LR-SFRC-5m) 1.038 11.344 10.929

Plastic Hinge Length and Reasonable
Range Locally Reinforced with SFRC

tively at the pier bottoms. For another compared
group of piers M3 and M4 (Table 12), it is assumed
that the piers are wholly reinforced with SFRC
(WR-SFRC). Based on pushover analyses, the
capacity curve comparisons are shown in Figure
24 and the curvature ductility comparisons are
shown in Table 14 between the piers wholly and
locally reinforced with SFRC. It can be seen that
applying the SFRC locally in a reasonable region
at the bottom of the single-column pier almost
has the same effect in improving the ductility and
the bending strength as applying the SFRC in the
whole pier. So considering the economy, it is more
advantageous to applying SFRC in a local region
of the bridge pier rather than applying SFRC in
the whole pier.

For the third group of piers M3 and M4 (Table
12), the lengths of the local region reinforced
with SFRC are assumed to be 2.0 m and 2.5 m
respectively at the pier bottoms. Based on push-
over analyses, the results show that a local CRC
region above the CRC-SFRC interface has already
yielded, while the pier bottom range reinforced
with SFRC has not yet yielded. It is obvious that
the local region reinforced with SFRC has not
attained the predicted aim to increase the sec-
tion capacities for the third group of pier models
because of the unreasonable range reinforced
with SFRC.
So, it is very important to determine the reason-
able range of the local region reinforced with SFRC
for bridge piers, namely the plastic hinge lengths.
While referring to the present seismic guidelines