Ph.D. defense of Alonso Pizarro

1. ON A NEW HYDRAULIC APPROACH
FOR BRIDGE-PIER DESIGN
_______________________________
Matera, 23 October 2018
Alonso Pizarro
alonso.pizarro@unibas.it
https://sites.google.com/site/alonsopizarrov/

2. Contents
• INTRODUCTION
• EFFECTIVE FLOW WORK, W*, AND
SIMPLIFIED HYDROGRAPH
• BRISENT MODEL: SCOUR MODEL UNDER
COMPLEX HYDRAULIC SCENARIOS
• THEORETICALLY DERIVED DISTRIBUTION OF
SCOUR (TDDS)
• APPLICATION TO A REAL CASE STUDY
• CONCLUSIONSSOURCE: Prendergast & Gavin (2014)
Emol (2004)
Reichelt and Richter (2003)
2/16

3. q Worldwide problem
2. Motivation
3/16

4. q Why is important to study Bridge-pier scour?
SOURCE: Reichelt and Richter (2003) SOURCE: Ettmer (2006)
SOURCE: Emol (2004)
COSTS
SOCIALS
HUMANSECONOMICS
SOURCE: Prendergast & Gavin (2014)
2. Motivation
4/16

5. q Complex process
2. Motivation
SOURCE: May et al. (2015)
5/16

6. q Hydraulic loads on bridges during their service life
Variability across all temporal scales
Necessity of new approaches
Climate Change effects on the
hydrological regimen…
Complex hydraulic and erosional
patterns around bridges
2. Motivation
SOURCE: Tubaldi et al. (2017)
6/16

7. q Effective flow work Parameter W*: Definition
3.1 Energy concepts applied to local scour
!∗ = $
%
&'() 1
+,
- − 0.5-2
-,
3
4 5+
Ø Stream Power concept applied to local
scour.
ØGeneralization of the Flow intensity
parameter
6
67
Ø Useful for complex hydraulic conditions
SOURCE: Pizarro et al. (2017a)
7/16

8. q Effective flow work Parameter W*: Properties
3.1 Energy concepts applied to local scour
!∗ = $
%
&'() 1
+,
- − 0.5-2
-,
3
4 5+
Data source: Lança et al. (2013)
Ø Simple: energy-based parameter
allowing fast calculations.
Ø Powerful: it explains the influence of
hydraulic loads on bridge scour
Ø Parsimonious: Time dependent scour
depends on W* and D/d50
8/16

9. q BRISENT model
1. Effective flow work W*.
2. Principle of Maximum Entropy ( )
*
* *
max*
max
1
ln 1 exp 1
W
Z Z
W
l
l
ì ü
é ù= + -í ýë û
î þ
3.2 Energy concepts applied to local scour
SOURCE: Pizarro et al. (2017b) 9/16

10. q General Concept:
4. TDDS Formulation
10/16

11. q Coupling hydrological, hydraulic, and erosional models…
4. TDDS Formulation
Ø Gumbel Distribution for floods
Ø Velocity-Are Rating Curve
Ø BRISENT model
SOURCE: Manfreda et al. (2018b) 11/16

12. q Real Application:
5. Real Case Study
SOURCE: Manfreda et al. (2018b) 12/16

13. qTheoretically derived probability distribution of scour (TDDS):
5. Real Case Study
SOURCE: Manfreda et al. (2018b) 13/16

14. 8. Conclusions
q General Conclusion:
Ø Bridge scour is a complex process which is the consequence of
the interaction among different hydraulic and hydrological
loads at different spatial and temporal scales.
Ø New approaches integrating and exploiting different scour
controlling sources are a current necessity for a scientific and
practitioner point of view.
Ø The TDDS is the first attempt in integrating hydraulic,
hydrological, and erosional models in a closed and analytical
way.
14/16

15. 9. References
15/16
1. Prendergast, L. J.; Gavin, K. A review of bridge scour monitoring techniques. J. Rock Mech. Geotech. Eng.
2014, 6, 138–149.
2. Manfreda, S. On the derivation of flow rating-curves in data-scarce environments. J. Hydrol. 2018a,
562, 151–154.
3. Manfreda, S.; Link, O.; Pizarro, A. A Theoretically Derived Probability Distribution of Scour. 2018b
(Accepted to Water MDPI)
4. Tubaldi, E.; Macorini, L.; Izzuddin, B. A.; Manes, C.; Laio, F. A framework for probabilistic assessment of
clear-water scour around bridge piers. Struct. Saf. 2017, 69, 11–22.
5. Pizarro, A.; Ettmer, B.; Manfreda, S.; Rojas, A.; Link, O. Dimensionless Effective Flow Work for
Estimation of Pier Scour Caused by Flood Waves. J. Hydraul. Eng. 2017, doi:10.1061/(asce)hy.1943-
7900.0001295.
6. Pizarro, A.; Samela, C.; Fiorentino, M.; Link, O.; Manfreda, S. BRISENT: An Entropy-Based Model for
Bridge-Pier Scour Estimation under Complex Hydraulic Scenarios. Water 2017,
doi:10.3390/w9110889.
7. May, R. W. P.; Ackers, J. C.; Kirby, A. M. Manual on scour at bridges and other hydraulic structures; Ciria
London, 2002; Vol. 551.
8. Reichelt, A.; Richter, S. Hochwasserschäden im Vorlandbereich der Elbebrücke Riesa - Maßnahmen zu
deren Beseitigung. TU Dresden und der Verein der Freunde des Bauingenieurwesens 2003, 13. Dresdn,
157–187.

16. ON A NEW HYDRAULIC APPROACH
FOR BRIDGE-PIER DESIGN
_______________________________
Matera, 23 October 2018
Alonso Pizarro
alonso.pizarro@unibas.it
https://sites.google.com/site/alonsopizarrov/