Impact of Extreme River Flows on Bridges An Application to River Lagan in Ljungby Municipality, Sweden Using HEC RAS
(2022) In TVVR 5000 VVRM01 20211Division of Water Resources Engineering
- Abstract
- The role of bridges in the transportation network has become increasingly important as they ensure the smooth and safe passage of people and goods across rivers and other bodies of water. Flowing water impacts bridges over rivers primarily in two ways: (1) Hydrodynamic forces that directly impact the structure and (2) scouring at the pier and abutment, including contraction scour. The design principles for bridges in Sweden are relatively simplistic, including both impacting forces and local scour. Therefore, the purpose of this thesis is to examine the impact of extreme river flows on bridges, particularly in circumstances beyond the design flow, using as a case study Ljungby Municipality, Skåne. Ten bridges are located across 6 km of the... (More)
- The role of bridges in the transportation network has become increasingly important as they ensure the smooth and safe passage of people and goods across rivers and other bodies of water. Flowing water impacts bridges over rivers primarily in two ways: (1) Hydrodynamic forces that directly impact the structure and (2) scouring at the pier and abutment, including contraction scour. The design principles for bridges in Sweden are relatively simplistic, including both impacting forces and local scour. Therefore, the purpose of this thesis is to examine the impact of extreme river flows on bridges, particularly in circumstances beyond the design flow, using as a case study Ljungby Municipality, Skåne. Ten bridges are located across 6 km of the Lagan River within the municipality area. Although applications are made regarding Swedish conditions, the work is primarily based on international literature and experiences. An overview of the literature on the impacts of extreme river flows on bridges was conducted, as well as an analysis of the most common equations that have been used to model these impacts. Several countries, including the United States and Australia, have studied this topic extensively and recommended design and analysis procedures. Additionally, corresponding Swedish techniques were reviewed. This was followed by evaluation of HEC RAS (1D - steady flow) model for its ability to simulate the impact of extreme flows on bridges, including scour predictions using the Froehlich equation. This resulted in inundation and flood hazard maps for the study area (Ljungby Municipality), as well as the determination of overflowed bridges. A 100-year event resulted in the overflowing of Ljungsätersbron. During the 200-year event, Ljungsätersbron and Söderbron overflowed. Also, abutment scour analyses have been performed for all bridges. Overall, the model provided a satisfactory estimation of the potential threats posed by scouring at bridges abutments during extreme flow conditions. (Less)
- Popular Abstract (Swedish)
- Strömmande vatten påverkar broar över vattendrag huvudsakligen genom: (1) hydrodynamiska krafter med direkt effekt på konstruktionen och (2) lokal erosion kring bropleare och sidostöd, inkluderat erosion på grund av flödeskontraktion. Utformning och dimensionering av broar i Sverige med avseende på direkt flödespåverkan och lokal erosion är relativt förenklad och täcker inte alla aspekter av problemet. Syftet med föreliggande studie är att undersöka påverkan på broar från extrema flöden i vattendrag, speciellt när det dimensionerande flödet överskrids, med Ljungby kommun som studieobjekt. Även om fokus i studien är svenska förhållanden är arbetet i stor utsträckning baserat på internationell litteratur och erfarenheter. Först ges en kort,... (More)
- Strömmande vatten påverkar broar över vattendrag huvudsakligen genom: (1) hydrodynamiska krafter med direkt effekt på konstruktionen och (2) lokal erosion kring bropleare och sidostöd, inkluderat erosion på grund av flödeskontraktion. Utformning och dimensionering av broar i Sverige med avseende på direkt flödespåverkan och lokal erosion är relativt förenklad och täcker inte alla aspekter av problemet. Syftet med föreliggande studie är att undersöka påverkan på broar från extrema flöden i vattendrag, speciellt när det dimensionerande flödet överskrids, med Ljungby kommun som studieobjekt. Även om fokus i studien är svenska förhållanden är arbetet i stor utsträckning baserat på internationell litteratur och erfarenheter. Först ges en kort, generell beskrivning av effekten på broar från extrema flöden med utgångspunkt från en litteraturgenomgång. Därefter beskrivs resultatet av simuleringar med den numeriska strömningsmodellen HEC RAS (1D – stationära förhållanden) för att uppskatta effekten på broarna i Ljungby vid extrema flöden. Från dessa simuleringar konstruerades översvämningskartor och tillhörande riskzoner tillsammans med broar som utsätts för överströming. Ett flöde med 100-års återkomsttid resulterade i överströmning av Ljungsätersbron. Vid ett flöde med 200-års återkomsttid observerades överströmning av både Ljungsätersbron och Söderbron. Erosion vid sidostöden analyserades också för samtliga broar. Generellt gav modellen tillfredsställande resultat vad gäller hur exponerade broarnas sidostöd är för erosion vid extrema flöden. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9103663
- author
- Mohammad Tahir, Assad LU
- supervisor
- organization
- alternative title
- Extrema flödens påverkan på broar. En studie av Lagan i Ljungby kommun med modellen HEC RAS.
- course
- VVRM01 20211
- year
- 2022
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- HEC RAS, Extreme River Flow, River Bridges, Ljungby, Lagan, Climate Change.
- publication/series
- TVVR 5000
- report number
- TVVR22/5016
- ISSN
- 1101-9824
- language
- English
- additional info
- Examiner: Prof. Ronny Berndtsson
- id
- 9103663
- date added to LUP
- 2022-12-05 14:18:00
- date last changed
- 2022-12-05 14:18:00
@misc{9103663,
abstract = {{The role of bridges in the transportation network has become increasingly important as they ensure the smooth and safe passage of people and goods across rivers and other bodies of water. Flowing water impacts bridges over rivers primarily in two ways: (1) Hydrodynamic forces that directly impact the structure and (2) scouring at the pier and abutment, including contraction scour. The design principles for bridges in Sweden are relatively simplistic, including both impacting forces and local scour. Therefore, the purpose of this thesis is to examine the impact of extreme river flows on bridges, particularly in circumstances beyond the design flow, using as a case study Ljungby Municipality, Skåne. Ten bridges are located across 6 km of the Lagan River within the municipality area. Although applications are made regarding Swedish conditions, the work is primarily based on international literature and experiences. An overview of the literature on the impacts of extreme river flows on bridges was conducted, as well as an analysis of the most common equations that have been used to model these impacts. Several countries, including the United States and Australia, have studied this topic extensively and recommended design and analysis procedures. Additionally, corresponding Swedish techniques were reviewed. This was followed by evaluation of HEC RAS (1D - steady flow) model for its ability to simulate the impact of extreme flows on bridges, including scour predictions using the Froehlich equation. This resulted in inundation and flood hazard maps for the study area (Ljungby Municipality), as well as the determination of overflowed bridges. A 100-year event resulted in the overflowing of Ljungsätersbron. During the 200-year event, Ljungsätersbron and Söderbron overflowed. Also, abutment scour analyses have been performed for all bridges. Overall, the model provided a satisfactory estimation of the potential threats posed by scouring at bridges abutments during extreme flow conditions.}},
author = {{Mohammad Tahir, Assad}},
issn = {{1101-9824}},
language = {{eng}},
note = {{Student Paper}},
series = {{TVVR 5000}},
title = {{Impact of Extreme River Flows on Bridges An Application to River Lagan in Ljungby Municipality, Sweden Using HEC RAS}},
year = {{2022}},
}