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I-girder Composite Bridges with Lateral Bracing: Improved load distribution
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Byggkonstruktion och brand.ORCID-id: 0000-0002-9627-4713
2023 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

This thesis deals with the subject of lateral bracing between the bottom flanges of I-girder composite bridges. The focus is on the impact of adding lateral bracing on existing bridges, as well as on new bridges. Experience and knowledge from bridge projects around the world are investigated and implemented in the evaluation of the research subject.

Many existing bridges are in need of being strengthened or replaced, due to the increased traffic volume and heavier traffic loads. Different approaches can be used to prolong the lifetime of existing bridges. The approach is different depending on the cause, but for increasing the lifetime regarding fatigue some of the most suitable options are described in this thesis. A proposed concept is presented, in this thesis, along with some research questions to be answered.

The use of lateral bracings in composite bridges varies between different parts of the world. In one country it can be a requirement/common praxis for long span composite bridges with two I-girders, in other countries there are no requirements of using them. Some parts of these regulations and requirements can be traced back to the tradition in both manufacturing and construction of this type of bridges. This thesis investigates how lateral bracing is used around the world to distribute eccentric loads between primary longitudinal structural members, provide resistance to lateral loads, and to permit an existing two-girder structural system to be retrofitted to behave similarly to an often more expensive closed steel box girder.

Furthermore, several case studies have been conducted to investigate the impact on the structural behavior of composite bridges where a lateral bracing is implemented in the structure. The results from these case studies are presented in the thesis and show the advantages of the quasi-box section for which the lateral bracing is closing the composite cross section. By making the I-girder composite cross section acting more like a box-section, the distribution of eccentric loads between the girders is improved. The impact on longitudinal stresses from traffic loads and the additional effects on internal sectional parts are also evaluated and discussed.

Furthermore, proposals of the connection design for lateral bracings in existing bridges are suggested. Finally, conclusions from the results are stated.

sted, utgiver, år, opplag, sider
Luleå: Luleå University of Technology, 2023.
Serie
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Emneord [en]
assessment, bridge, composite bridge, steel-concrete composite, I-girder, case study, horizontal trusses, lateral bracing, rehabilitation, strengthening, torsional stiffness, upgrading
HSV kategori
Forskningsprogram
Byggkonstruktion
Identifikatorer
URN: urn:nbn:se:ltu:diva-96212ISBN: 978-91-8048-286-8 (tryckt)ISBN: 978-91-8048-287-5 (digital)OAI: oai:DiVA.org:ltu-96212DiVA, id: diva2:1745142
Presentation
2023-05-12, F1031, Luleå tekniska universitet, Luleå, 10:00 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2023-03-22 Laget: 2023-03-22 Sist oppdatert: 2023-12-18bibliografisk kontrollert
Delarbeid
1. Lateral trusses between I-girders introducing torsional stiffness to a composite bridge in Guatemala
Åpne denne publikasjonen i ny fane eller vindu >>Lateral trusses between I-girders introducing torsional stiffness to a composite bridge in Guatemala
2023 (engelsk)Inngår i: Eurosteel 2023: September 12–14, 2023, Amsterdam / [ed] Milan Veljkovic; Trayana Tankova; Florentia Kavoura; Andreas Taras; Vlad Silvestru; Valentino Vigneri, John Wiley & Sons, 2023, s. 1049-1054Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

The ways of designing and building steel girder bridges with a composite concrete deck vary much between different parts of the world. A bridge system with twin steel I-girders or a concept with multiple (more than two) girders can be used. The design and use of details and secondary systems also vary a lot. In order to give horizontal stabilization and distribute horizontal loads, bracing between the I-girders bracings are often used. Although not so common, the bracing can also be used to distribute vertical loads between the main girders. To describe and to analyze the possible impact from using a lateral bracing, this paper describes the design of a curved bridge in Guatemala City and its challenges. The new Bridge over the Pinula River is designed as a steel-concrete composite bridge with multiple steel girders with a concrete deck on top and has lateral bracing between the girders. The bridge is used as a case study to analyze the impact from a lateral bracing system on the vertical load distribution between the longitudinal girders. The bridge was designed with lateral bracing between the top flanges along the whole bridge and with bracing between the lower flanges near the supports. The case study shows that the distribution of eccentric vertical loads between the longitudinal girders can be improved by using lateral bracing between the lower flanges for multiple girders. In some cases, it may not be beneficial to use lateral bracings along the whole bridge length, like for example this bridge. In this case due to the governing design cases in the construction stages where these bracings influenced the torsional stiffness of the bridge in such way that an unfavorable distribution of the support reactions between the six girders at some supports was achieved.

sted, utgiver, år, opplag, sider
John Wiley & Sons, 2023
Serie
c/e papers - Proceedings in civil engineering, E-ISSN 2509-7075 ; 6
Emneord
Bridge, I-girder, lateral bracing, launching, steel-concrete composite, torsional stiffness
HSV kategori
Forskningsprogram
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-96210 (URN)10.1002/cepa.2684 (DOI)
Konferanse
10th Eurosteel conference, (EUROSTEEL2023), Amsterdam, Netherlands, September 12-14, 2023
Merknad

Full text license: CC BY

Tilgjengelig fra: 2023-03-22 Laget: 2023-03-22 Sist oppdatert: 2023-11-24bibliografisk kontrollert
2. Torsion of a Norwegian bridge with partial box-action - a case study
Åpne denne publikasjonen i ny fane eller vindu >>Torsion of a Norwegian bridge with partial box-action - a case study
2022 (engelsk)Inngår i: IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures - Report, International Association for Bridge and Structural Engineering, 2022Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Some old bridges have a truss between the bottom flanges not intended for torsional effects but for transferring horizontal forces. This paper describes the effects of the truss on torsion for a Norwegian three span bridge from 1967, without composite action. Furthermore, the effects of post-installed shear connectors are investigated. For composite bridges without intended composite action in bending, the effects of the slab preventing the top flanges from moving laterally should not be ignored, since this is important for the deformations of the girders under eccentric loading. Furthermore, the load distribution between the girders for an eccentric load is significantly enhanced if the horizontal truss is considered. The paper also investigates and presents the effects of post-installed shear connectors, with respect to bending stresses in the bottom flanges (moderate effects) and the top flange (large effects). 

sted, utgiver, år, opplag, sider
International Association for Bridge and Structural Engineering, 2022
Emneord
Composite bridge, strengthening, horisontal bracing, composite action, box-action
HSV kategori
Forskningsprogram
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-91424 (URN)2-s2.0-85133548852 (Scopus ID)
Konferanse
IABSE Symposium Prague 2022: Challenges for Existing and Oncoming Structures, Prague, Czech Republic, May 25-27, 2022
Tilgjengelig fra: 2022-06-15 Laget: 2022-06-15 Sist oppdatert: 2023-09-05bibliografisk kontrollert
3. Box-action giving new life-time to old steel bridges
Åpne denne publikasjonen i ny fane eller vindu >>Box-action giving new life-time to old steel bridges
2018 (engelsk)Konferansepaper, Oral presentation only (Fagfellevurdert)
Abstract [en]

When strengthening existing I-girder composite bridges one idea is to make the cross section act like a box section, by adding a horizontal truss between the bottom flanges. This means that eccentric loads produce a torque that is transferred by shear forces around the section. The magnitude of the effects coming from introducing such a framework between girders is addressed in this article. The fatigue resistance will be improved by the reduced stress ranges and increased amount of tolerated load cycles and extend the lifetime of the details, and by so the lifetime for the bridge. The work described in the paper is part of the European R&D project Prolonging Life Time of Old Steel and Steel-Concrete Bridges (ProLife), RFCS 2015-00025.

HSV kategori
Forskningsprogram
Konstruktionsteknik; Stålbyggnad
Identifikatorer
urn:nbn:se:ltu:diva-87572 (URN)
Konferanse
9th International Symposium on Steel Bridges. Prague, Czech Republic (Steel Bridges 2018), September 10-11, 2018
Forskningsfinansiär
Swedish Transport AdministrationSvenska Byggbranschens Utvecklingsfond (SBUF)
Merknad

Funder: Research Fund for Coal and Steel; Transport Administration of Finland; Transport Administration of Norway; Ramboll

Tilgjengelig fra: 2021-10-21 Laget: 2021-10-21 Sist oppdatert: 2023-09-05bibliografisk kontrollert
4. Strengthening of a Composite I-girder Bridge by Trusses Introducing Box-Action
Åpne denne publikasjonen i ny fane eller vindu >>Strengthening of a Composite I-girder Bridge by Trusses Introducing Box-Action
2022 (engelsk)Konferansepaper, Oral presentation only (Annet vitenskapelig)
Abstract [en]

The increased amount of traffic and the increasingly heavier loads on the road network push the existing infrastructure to its design limit. Bridges, which are an important part of the road network, need to be adopted to the new traffic demands regarding both the load capacity and the fatigue limit state, FLS. Steel-concrete composite bridges, with twin steel I-girders, is a common bridge type in the Nordic countries. These bridges are often designed using beam models, assuming that the concrete deck is a statically determinate structure supported on the two steel girders in the transversal direction. This assumption implies that the most loaded girder can sometimes be subjected to even more than 100% of an eccentric load, e.g., the traffic loads in the design codes. If the girders are strengthened to be able to share the eccentric loads more equally, it would have a significant impact on the load capacity, especially for the fatigue limit state. By introducing horizontal trusses between the bottom flanges of the girders, making the cross-section act more like a box-girder, the torsional stiffness will increase so that the girders will share the eccentric loads more equally. The bracing system of the trusses can be designed in different shapes, each of them with pros and cons for the existing bridge structure. In this paper, the effects from different shapes of the bracing are evaluated of a single span I-girder composite bridge. The increased torsional stiffness and the change of the internal shear flow will increase the load capacity of the steel girders.

Emneord
bridge, steel-concrete composite, I-girder, case study, horizontal trusses, torsional stiffness, strengthening, composite bridges
HSV kategori
Forskningsprogram
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-96211 (URN)
Konferanse
10th International symposium on steel bridges – for A Green Planet, September 20 - 22, 2022 Istanbul, Turkey
Tilgjengelig fra: 2023-03-22 Laget: 2023-03-22 Sist oppdatert: 2023-09-05
5. Horizontal bracing between bottom flanges in composite I-girder bridges – A state of the art review
Åpne denne publikasjonen i ny fane eller vindu >>Horizontal bracing between bottom flanges in composite I-girder bridges – A state of the art review
Vise andre…
(engelsk)Inngår i: Practice Periodical on Structural Design and Construction, ISSN 1084-0680, E-ISSN 1943-5576Artikkel i tidsskrift (Annet vitenskapelig) Submitted
Abstract [en]

The tradition in how steel bridges are designed and built varies around the globe. These traditions can be based upon the accessibility to materials and products, but also the topographical conditions for the bridge locations. In the Nordic countries the most common type for the superstructure of steel girder bridges, is the welded steel girder. In contrary, steel girder bridges in many other European countries are more commonly built with rolled steel sections. Variations can also be seen in how details are designed, as on-site joints were a bolted or a welded connection are used. The difference in the use of a horizontal bracing between the main girders, often designed as a wind bracing, in different countries are not well known. The bracing is often used to distribute horizontal loads as wind and is then called a wind bracing. The bracing will also, and this is used in the design in some countries, distribute eccentric vertical loads due to its increase of the torsional stiffness of the structure.

This paper investigates the premise that the use of horizontal bracing between the bottom flanges of new I-girder bridges results in a cross-section that behaves similarly to a steel box-beam where the vertical webs share more equally in the applied loads. This concept lowers the beam stresses and is particularly beneficial for fatigue evaluation caused by eccentric loads. The concept is exemplified by in-service bridges in Finland, Guatemala, France, and the US. The potential to use horizontal bracing as a strengthening technique in existing steel two-girder composite bridges is also discussed.

Emneord
bridge, composite bridge, horizontal trusses, horizontal bracing, lateral bracing, strengthening, torsional stiffness
HSV kategori
Forskningsprogram
Byggkonstruktion
Identifikatorer
urn:nbn:se:ltu:diva-96209 (URN)
Tilgjengelig fra: 2023-03-22 Laget: 2023-03-22 Sist oppdatert: 2024-04-12

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