| 1. |
- Axhag, F., et al.
(författare)
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Tension flange instability of I-beams
- 1999
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 49:1, s. 69-81
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Tidskriftsartikel (refereegranskat)abstract
- The possible lateral-torsional instability of an I-beam with braced compression flange is studied. It is shown that taking the sagging prior to lateral-torsional buckling into account gives a finite critical moment. A solution for a uniform I-beam under uniform bending is presented. It is further shown that this solution can be approximated by a simple geometrical relation for the critical strain. This approximation is a lower bound also where the bending is causing inelastic deformations. For normal structures tension flange instability will not be a problem but it may be necessary to consider it for very high strength shallow beams or if plastic rotations occur in the sagging region.
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| 2. |
- Collin, Peter, et al.
(författare)
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Lateral-torsional buckling of continuous bridge girders
- 1998
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 45:2, s. 217-235
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Tidskriftsartikel (refereegranskat)abstract
- The resistance of bridge girders with respect to lateral-torsional buckling at support is strongly influenced by the moment gradient. In most design methods this influence is taken into account by the use of a correct critical bending moment in the slenderness parameter λ. This critical moment is influenced by the shape of the moment diagram as well as the distortion of the cross-section and the restraint from the web and stiffeners, if any. In this paper, a method for the calculation of the critical moment is presented. A further effect of the moment gradient is that the stresses due to lateral bending of the flange in connection with lateral-torsional buckling does not coincide with the maximum of stresses caused by bending in the vertical plane. This is taken into account by performing the check for lateral-torsional buckling in a design section at some distance from the support. A design procedure based on this concept has been introduced in Eurocode 3 Part 2: Steel Bridges
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| 3. |
- Graciano, Carlos, et al.
(författare)
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Critical buckling of longitudinally stiffened webs subjected to compressive edge loads
- 2003
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 59:9, s. 1119-1146
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Tidskriftsartikel (refereegranskat)abstract
- The resistance of steel plate girders subjected to concentrated load can be described using a strength curve, which includes a gradual transition from yielding to buckling depending on the slenderness ratio of the web. The slenderness is a function of the ratio of the yield resistance to the critical buckling load. This paper describes a methodology for the determination of buckling coefficients for longitudinally stiffened plate girders subjected to partial edge loading or concentrated loads. After an extensive parametric analysis, the optimum parameters that govern the change from a global buckling mode to a more local buckling mode were found. As in similar buckling problems, the results show that the location and the relative flexural/torsional rigidity of the stiffener are relevant parameters that govern the final buckling shape. Finally an expression for the buckling coefficient used to determine the critical buckling load for longitudinally stiffened girder webs is presented.
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| 4. |
- Graciano, Carlos, et al.
(författare)
-
Failure mechanism of slender girder webs with a longitudinal stiffener under patch loading
- 2003
-
Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 59:1, s. 27-45
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Tidskriftsartikel (refereegranskat)abstract
- The failure mechanism of slender girder webs stiffened by a single longitudinal stiffener under patch loading is addressed. Experimental results have shown that failure is due to crippling in the web panel formed between the loaded flange and the stiffener. This mechanism is similar to the one for unstiffened webs, which is characterized by the presence of elastoplastic deformations in the compression flange (plastic hinges) and in the web (yield lines). A longitudinal stiffener with normal position, b1 less than or equal 0.3hw, and rigidity restricts the size of the buckle in the upper web panel, and in some cases the distance between the outermost plastic hinges in the loaded flange is reduced. Based on the upper bound theorem of plastic collapse an expression for the patch loading resistance of webs stiffened by a single horizontal stiffener is presented. Theoretical predictions are in good agreement with experimental results. © 2002 Elsevier Science Ltd. All rights reserved.
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| 5. |
- Graciano, Carlos, et al.
(författare)
-
Resistance of longitudinally stiffened I-girders subjected to concentrated loads
- 2003
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 59:5, s. 561-586
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a design procedure for the determination of the ultimate resistance of longitudinally stiffened girder webs to concentrated loads. The influence from the longitudinal stiffener is considered in the slenderness parameter λ, through the buckling coefficient kf. This procedure is harmonized with other design procedures currently used for describing buckling problems in steel structures. An expression is developed for the buckling coefficient based on finite element analysis. The interaction between the web plate with flanges and a longitudinal stiffener was considered in the analysis. The ultimate strength according to the design procedure presented herein and the results are compared with available experimental results. The interaction with bending is also investigated
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| 6. |
- Granath, Per, et al.
(författare)
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Behaviour of girder webs subjected to patch loading
- 1999
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 50:1, s. 49-69
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the behaviour of bridge girder webs subjected to concentrated forces that are introduced in the web during launching, a load case usually referred to as patch loading. So far, this type of loading has, in engineering practice, been dealt with using formulas originating from investigations concerning the ultimate load carrying capacity. Numerous bridge launchings have, however, led to unwanted damages of the girder web, i.e. plastic deformations of such magnitudes that the webs had to be repaired. To avoid these damages it is necessary to have a design method, for launching situations, which focuses more on avoiding some irreversible behaviour than on the ultimate load carrying capacity. Such a design method has to be based on a deeper understanding of the behaviour of the girder. In Ref. [1] the first author discusses the fact that yielding of the flange occurs only after the web plate has been severely damaged. This paper describes the deformation behaviour of the web plate due to patch loading. For small loads the deformations will be similar to the first linear buckling mode. As the load increases a smaller buckle, in the opposite direction, will start to develop in the web plate close to the load. This behaviour, which may be named post-critical buckling, occurs also for girders of a perfectly elastic material. The investigations are based on laboratory tests and non-linear finite element analyses of three typical girders representing different slenderness categories.
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| 7. |
- Granlund, Jan, et al.
(författare)
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Modelling of the plastic behaviour of structural steel based on biaxial testing
- 1998
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 46:1-3, s. 404-405
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Tidskriftsartikel (refereegranskat)abstract
- The biaxial testing of structural steel in the principal plane σ1-σ2 is presented. The initial yield criterion of the steel falls between the von Mises and Tresca criteria. The subsequent yield criteria are characterized by a pronounced Bauschinger effect and more gradual transition into plastic state in subsequent loading opposite to preloading.
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| 8. |
- Johansson, Bernt, et al.
(författare)
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Current design practice and research on stainless steel structures in Sweden
- 2000
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 54:1, s. 3-29
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Tidskriftsartikel (refereegranskat)abstract
- The current design practice in Sweden is using codes for structural steel also when working with stainless steel. For load cases governed by instability this may produce non-conservative errors amounting to 10% while it may greatly underestimate the ultimate resistance in cases when instability is not governing. Three ongoing research projects are briefly described, one on weldbonding, one on plastic forming and one on the behaviour of structural components. A part of the latter concerns fundamental work regarding the material behaviour which in general is described using too simple models. This is presented in some detail and its results will be used to provide improved finite element simulations.
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| 9. |
- Johansson, Bernt, et al.
(författare)
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New design rules for plated structures in Eurocode 3
- 2001
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 57:3, s. 279-311
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Tidskriftsartikel (refereegranskat)abstract
- This paper gives an overview of Eurocode 3 Part 1.5 Design of Steel Structures. Supplementary rules for planar plated structures without transverse loading have been developed together with the Eurocode 3-2 Steel bridges. It covers stiffened and unstiffened plates in common steel bridges and similar structures. This paper presents the background and justification of some of the design rules with focus on the ultimate limit states. The design rules for buckling of stiffened plates loaded by direct stress are presented and explained. For shear resistance and patch loading the new rules are briefly derived and compared with the rules in Eurocode 3-1-1. Finally, the statistical calibration of the rules to tests is described.
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| 10. |
- Johansson, Bernt, et al.
(författare)
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Resistance of plate edges to concentrated forces
- 1995
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Ingår i: Journal of constructional steel research. - 0143-974X .- 1873-5983. ; 32:1, s. 69-105
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Tidskriftsartikel (refereegranskat)abstract
- The prediction of the resistance of plate edges to concentrated loads has been dealt with in numerous studies of a more or less empirical nature. The normal approach is to use two criteria for the resistance, one based on yielding and one based on instability. This study aims at a procedure that is harmonized with those normally used for describing other buckling problems. It has been carried out as part of the work with drafting Eurocode 3 Part 2 and the paper is intended as a background document for the suggested design rules.
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