PSI - Issue 84

Maria Giovanna Tanda et al. / Procedia Structural Integrity 84 (2026) 272–279

275

considerable variability in the results, the beneficial effect of the collar is evident, becoming more pronounced as the collar is embedded deeper below the bed surface. The hooked collars yielded only marginal improvements in performance compared to simple collar designs. Figure 2b shows the same graph for round-nosed rectangular piers. Compared with the circular pier, the scour reduction is more pronounced for this shape of piers, with scour reduced by more than 50% with respect to the absence of the collar. Table 2-– Characteristics of the runs of the A series (circular pier); NC=no collar; CH=Hooked collar; CS=Simple collar; -0, -1, -2 collar at the bed level, 1 cm below, 2 cm below the bed.

duration (hh:mm) 26:15:00 26:15:00 26:24:00 26:24:00 26:36:00 26:36:00 24:18:00 24:18:00 26:35:00 26:35:00 29:53:00 29:53:00 27:16:00 28:16:00 26:20:00 26:20:00 26:15:00 26:15:00 duration (hh:mm) 25:55:00 25:55:00 20:16:00 20:16:00 22:25:00 22:25:00 25:51:00 26:00:00 26:00:00 26:14:00 16:14:00 26:22:00 26:22:00 24:52:00 24:52:00 24:19:00 24:19:00 24:15:00 24:15:00

Max scour y s (m)

y s / b (-)

U / U c %

Q (L/s)

h (m)

U (m/s)

Test code Series Upstream/

Downstream Collar

03102023 03102023 16102023 16102023 20102023 20102023 30102023 30102023 14112023 14112023 21112023 21112023 27112023 27112024 30112023 30112023 11122023 11122023 11012024 11012024 22012024 22012024 24012024 24012024 26012024 30012024 30012024 07022024 07022024 09022024 09022024 14032025 14032025 18032025 18032025 21032025 21032025

A A A A A A A A A A A A A A A A A A

U D U D U D U D U D U D U D U D U D U D U D U D D U D U D U D U D U D U D

NC NC

14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14 14

0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.207 0.187 0.187 0.175 0.175 0.194 0.192 0.192 0.195 0.195 0.200 0.200 0.176 0.176 0.196 0.196 0.196 0.196 h (m)

0.060 0.061 0.029 0.050 0.031 0.053 0.049 0.045 0.051 0.056 0.052 0.058 0.061 0.063 0.057 0.045 0.059 0.050 0.041 0.042 0.041 0.052 0.042 0.048 0.051 0.042 0.051 0.039 0.048 0.023 0.050 0.048 0.054 0.025 0.049 0.028 0.049

1.500 0.225 79% 1.525 0.225 79% 0.725 0.225 79% 1.250 0.225 79% 0.775 0.225 79% 1.325 0.225 79% 1.215 0.225 79% 1.125 0.225 79% 1.275 0.225 79% 1.400 0.225 79% 1.300 0.225 79% 1.450 0.225 79% 1.525 0.225 79% 1.575 0.225 79% 1.425 0.225 79% 1.125 0.225 79% 1.475 0.225 79% 1.250 0.225 79% 1.367 0.225 79% 1.400 0.225 79% 1.367 0.250 88% 1.733 0.250 88% 1.400 0.267 94% 1.600 0.267 94% 1.700 0.241 84% 1.400 0.243 85% 1.700 0.243 85% 1.300 0.239 84% 1.600 0.239 84% 0.767 0.233 82% 1.667 0.233 82% 1.600 0.265 93% 1.800 0.265 93% 8.333 0.238 84% 1.633 0.238 84% 9.333 0.238 84% 1.633 0.238 84% y s / b (-) U (m/s) U / U c %

CH-1 CH-0 CH-2 CH-1 CH-1 CH-1 CS-0 CS-1 CS-0 CS-1

NC NC

CH-0 CS-2 CH-1 CH-2

Table 3-– Characteristics of the runs of the B1 and B2 series (rectangular rounded nose); NC no collar; CS=Simple collar; -0, -1, -2 collar at the bed level, 1 cm below, 2 cm below the bed.

Upstream/ Downstream Collar

Max scour y s (m)

Q (l/s)

Test code Series

B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B1 B2 B2 B2 B2 B2 B2

NC NC CS0

NC

CS-1

NC NC

CS-0

NC

CS-1

NC

CS-2

NC

CS-0

NC

CS-1

NC

CS-2

NC