Advanced

Analysis of Jointless Bridges due to Horizontal Actions and Soil-Structure Interaction

Christensson, Pontus LU (2016) In TVBK-5251 VBK920 20161
Division of Structural Engingeering
Abstract
Bridges constructed without joints function to take care of forces by introducing bending moments to the stiff connections. Jointless bridges, also called integral bridges, in different appearances are built all over the world, and are popular due to their advantages regarding life cycle cost. Usually the dimensions of the structural parts, especially the backwalls, tends to be large and the elements are heavily reinforced. By crediting the interaction between a bridge and the surrounding soil in the design work, material can be saved. Soil-structure interaction is a complex phenomenon where the boundary between soil and bridge may be modelled as springs with the same stiffness as the soil. The dissertation studies a method of FE modelling... (More)
Bridges constructed without joints function to take care of forces by introducing bending moments to the stiff connections. Jointless bridges, also called integral bridges, in different appearances are built all over the world, and are popular due to their advantages regarding life cycle cost. Usually the dimensions of the structural parts, especially the backwalls, tends to be large and the elements are heavily reinforced. By crediting the interaction between a bridge and the surrounding soil in the design work, material can be saved. Soil-structure interaction is a complex phenomenon where the boundary between soil and bridge may be modelled as springs with the same stiffness as the soil. The dissertation studies a method of FE modelling of the deformations and section forces, and also the extent of the soil-structure interaction, by introducing linear springs at the surface between soil and structure.

The work is carried out by investigating two bridges, one fully integrated abutment bridge and one bridge with backwalls (sv. ändskärmsbro). The bridges are solely loaded by horizontal forces, e.g. braking forces, temperature movements and earth pressure. An initial stiffness of the soil is chosen, and from there, with some help from measurement data, the results from the FE model has then been compared to both calculations of a simple load case, as well as measured data, to find the proper soil stiffness.

It is found that no sufficiently good convergence of the stiffness can be found from the measurement data, but the method shows good potential of working if more and more detailed analyses are made. (Less)
Popular Abstract (Swedish)
Broar som konstrueras utan kopplingar och lager fungerar så att de ska ta upp krafter via moment i ramhörn eller liknande. Integrerade broar i olika utformningar byggs över hela världen, och är populära på grund av dess enkla utformning och fördelar rörande livscykelkostnader. Vanligtvis tenderar dimensionerna, då i synnerhet ändskärmarna, att bli väldigt tunga och tungt armerade. Genom att tillgodoräkna sig interaktionen mellan jord och konstruktion kan man minska momenten, och således också dimensionerna. Jord-konstruktion-interaktion är ett komplext fenomen där man till exempel kan modellera kontaktytan med ett fjädrande upplag, som innehar samma styvhet som jorden. Avhandlingen undersöker modelleringsmetoden genom att jämföra... (More)
Broar som konstrueras utan kopplingar och lager fungerar så att de ska ta upp krafter via moment i ramhörn eller liknande. Integrerade broar i olika utformningar byggs över hela världen, och är populära på grund av dess enkla utformning och fördelar rörande livscykelkostnader. Vanligtvis tenderar dimensionerna, då i synnerhet ändskärmarna, att bli väldigt tunga och tungt armerade. Genom att tillgodoräkna sig interaktionen mellan jord och konstruktion kan man minska momenten, och således också dimensionerna. Jord-konstruktion-interaktion är ett komplext fenomen där man till exempel kan modellera kontaktytan med ett fjädrande upplag, som innehar samma styvhet som jorden. Avhandlingen undersöker modelleringsmetoden genom att jämföra förskjutningar och moment för olika lastfall, och genom att jämföra både en beräkningsmodell genom ett simpelt lastfall samt mätdata från horisontella rörelser i en verklig bro.

Två broar undersöks, en bro med fullt integrerat landfäste samt en ändskärmsbro, och broarna är enbart belastade i horisontalled. Exempel på laster som kan påverka broarna är bromskraft från trafikerande bilar, temperaturförändringar eller jordtrycket som omgivande jord påverkar ändskärmen med. En initialstyvhet definieras och med hjälp av förskjutningarna givna av mätdata kan sedan rätt styvhet på jorden i FE-modellen hittas.

Det framgår av undersökningarna att ingen tillräckligt bra styvhet kan hittas för given metod, men att detta troligtvis är möjligt om hänsyn tas till de osäkerheter och fel som har identifierats. (Less)
Please use this url to cite or link to this publication:
author
Christensson, Pontus LU
supervisor
organization
alternative title
Analys av skarvfria broar på grund av horisontella krafter och jord-konstruktion-samverkan
course
VBK920 20161
year
type
H3 - Professional qualifications (4 Years - )
subject
keywords
Jointless bridges, integrated abutment bridges, backwall, soil-structure interaction, FE modelling
publication/series
TVBK-5251
report number
TVBK-5251
ISSN
0349-4969
language
English
additional info
Examinator: Roberto Crocetti
id
8886197
date added to LUP
2016-07-01 09:29:01
date last changed
2016-07-01 09:29:01
@misc{8886197,
  abstract     = {Bridges constructed without joints function to take care of forces by introducing bending moments to the stiff connections. Jointless bridges, also called integral bridges, in different appearances are built all over the world, and are popular due to their advantages regarding life cycle cost. Usually the dimensions of the structural parts, especially the backwalls, tends to be large and the elements are heavily reinforced. By crediting the interaction between a bridge and the surrounding soil in the design work, material can be saved. Soil-structure interaction is a complex phenomenon where the boundary between soil and bridge may be modelled as springs with the same stiffness as the soil. The dissertation studies a method of FE modelling of the deformations and section forces, and also the extent of the soil-structure interaction, by introducing linear springs at the surface between soil and structure.

The work is carried out by investigating two bridges, one fully integrated abutment bridge and one bridge with backwalls (sv. ändskärmsbro). The bridges are solely loaded by horizontal forces, e.g. braking forces, temperature movements and earth pressure. An initial stiffness of the soil is chosen, and from there, with some help from measurement data, the results from the FE model has then been compared to both calculations of a simple load case, as well as measured data, to find the proper soil stiffness.

It is found that no sufficiently good convergence of the stiffness can be found from the measurement data, but the method shows good potential of working if more and more detailed analyses are made.},
  author       = {Christensson, Pontus},
  issn         = {0349-4969},
  keyword      = {Jointless bridges,integrated abutment bridges,backwall,soil-structure interaction,FE modelling},
  language     = {eng},
  note         = {Student Paper},
  series       = {TVBK-5251},
  title        = {Analysis of Jointless Bridges due to Horizontal Actions and Soil-Structure Interaction},
  year         = {2016},
}