An experimental investigation of the effects of imperfections on the strength of steel box girders

1988 ◽  
Vol 15 (3) ◽  
pp. 443-449 ◽  
Author(s):  
R. M. Korol ◽  
E. G. Thimmhardy ◽  
M.S. Cheung
Keyword(s):  
Experimental Investigation ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Scale Model ◽  
Bridge Structure ◽  
Box Girders ◽  
Box Girder ◽  
Geometric Imperfections ◽  
Longitudinal Stiffeners ◽  
The One

As part of a major study, an experimental box girder having nominally identical cantilever sections was constructed to model the geometry of a pier girder of the Hunt Club–Rideau Bridge structure in Ottawa. The one-fourth scale model did not, however, replicate the varying depth of the prototype. The objective was to determine whether a deliberate reduction in the gross heat input for welds attaching longitudinal stiffeners to the flange plates for one end of the girder (and hence would incur reduced plate distortions and residual stresses) could augment the carrying capacity of a statically loaded box girder. In fact, the results from the two tests are such as to suggest that inward bent transverse stiffeners may account for a greater reduction in strength than do the imperfections of local plate panels of compression flanges. Key words: box girders, bridges, experiments, geometric imperfections, residual stresses, strength, structural steel.

scholarly journals Influence of executive imperfections of railway steel bridges construction on operational capacity and fatigue capacity

2013 ◽  
Vol 12 (2) ◽  
pp. 071-078
Author(s):  
Adam Wysokowski
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
Steel Bridges ◽  
Load Carrying Capacity ◽  
Bridge Structure ◽  
Geometric Imperfections ◽  
Theoretical Methods ◽  
Critical Elements ◽  
Load Carrying ◽  
Operational Capacity

In recent years, in our country are modernized and rebuilt several sections of railway lines, mainly main lines. The greater part is adapted to increased speeds. However, such an adaptation involve the reconstruction or construction of new bridges including steel ones. The paper concerns the executive imperfections of constructions of steel bridges which in recent years have been built in the modernized main railway lines. These imperfections consist of, among others, the geometric imperfections from the assumed construction project. This also applies to defects in welds of various types that occur in critical elements of bridge structure. The aim of this paper is to demonstrate the influence of imperfections on the load carrying capacity and fatigue of these structures. Author showed that the observed imperfections have a significant impact on the fatigue life - especially for weld defects, in the case of load carrying capacity their importance is much smaller. These analyses are performed by using the theoretical methods developed in previous reports. In the analysis new standards for the design of steel structures from Eurocodes group were used.

Bracing for composite box girder bridges

1984 ◽  
Vol 11 (4) ◽  
pp. 844-853 ◽  
Author(s):  
Fernando A. Branco ◽  
Roger Green
Keyword(s):  
Torsional Stiffness ◽  
Scale Model ◽  
Box Girders ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Finite Strip ◽  
Girder Bridges ◽  
Open Section ◽  
Box Beams ◽  
Construction Loads

For steel–concrete composite box girder bridges, the steelwork is generally erected first and then the concrete deck cast. During construction the girder may be subjected to a variety of construction loads. If the girder is a flexible open section, and lacks distortional or torsional stiffness, the cross section will deform or twist excessively; such difficulties with box girder construction have been reported. Bracing systems should be installed to increase the torsional and distortional stiffness of the open section during construction. A finite strip analysis of the influence of bracing systems on open section box girders is presented and compared with test results obtained using a one-quarter scale model. With the analysis, the influence of ties, distortional bracing, torsion boxes, and top chord bracing on the behaviour of torsionally open box girders is examined. Simplified design methods are also presented whereby the bracing forces and the stresses arising from the distortion of the section can be computed. Key words: bridges (box girder), bridges (steel), box beams, torsional distortion, bending distortion, bracing, construction safety.

Geometric imperfections and tolerances for steel box girder bridges

1988 ◽  
Vol 15 (3) ◽  
pp. 437-442 ◽  
Author(s):  
Eugene G. Thimmhardy ◽  
Robert M. Korol
Keyword(s):  
Measurement Data ◽  
Field Measurements ◽  
Highway Bridges ◽  
Statistical Interpretation ◽  
Box Girders ◽  
Box Girder Bridges ◽  
Box Girder ◽  
Geometric Imperfections ◽  
Girder Bridges ◽  
Plate Panels

An investigation to determine the magnitude of geometric imperfections induced during the fabrication of welded steel box girders is reported for nine highway bridges constructed in Canada. Measurement data were collected to compare the significance of dead load on initial imperfections obtained following fabrication. Existing bridges were found to have out-of-plane deviations of plate panels about 10% higher than unloaded bridge values. A statistical interpretation of measurements of initial plate imperfections and out-of-straightness of stiffeners culminates in tolerance levels, deemed to be appropriate for Canadian-built box girders, and well within the capability of the fabricating industry to achieve. Key words: box girder, bridges, field measurements, geometric imperfections, plate panels, stiffeners, structural steel, tolerances.

scholarly journals Shear cutting induced residual stresses in involute gears and resulting tooth root bending strength of a fineblanked gear

2021 ◽  
Author(s):  
Daniel Müller ◽  
Jens Stahl ◽  
Anian Nürnberger ◽  
Roland Golle ◽  
Thomas Tobie ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Near Surface ◽  
Load Carrying ◽  
Involute Gears ◽  
Cut Surface

AbstractThe manufacturing of case-hardened gears usually consists of several complex and expensive steps to ensure high load carrying capacity. The load carrying capacity for the main fatigue failure modes pitting and tooth root breakage can be increased significantly by increasing the near surface compressive residual stresses. In earlier publications, different shear cutting techniques, the near-net-shape-blanking processes (NNSBP’s), were investigated regarding a favorable residual stress state. The influence of the process parameters on the amount of clean cut, surface roughness, hardness and residual stresses was investigated. Furthermore, fatigue bending tests were carried out using C-shaped specimens. This paper reports about involute gears that are manufactured by fineblanking. This NNSBP was identified as suitable based on the previous research, because it led to a high amount of clean cut and favorable residual stresses. For the fineblanked gears of S355MC (1.0976), the die edge radii were varied and the effects on the cut surface geometry, hardness distribution, surface roughness and residual stresses are investigated. The accuracy of blanking the gear geometry is measured, and the tooth root bending strength is determined in a pulsating test rig according to standardized testing methods. It is shown that it is possible to manufacture gears by fineblanking with a high precision comparable to gear hobbing. Additionally, the cut surface properties lead to an increased tooth root bending strength.

scholarly journals Stability of a one-dimensional morphoelastic model for post-burn contraction

2021 ◽  
Vol 83 (3) ◽  
Author(s):  
Ginger Egberts ◽  
Fred Vermolen ◽  
Paul van Zuijlen
Keyword(s):  
Wound Healing ◽  
Residual Stresses ◽  
Truncation Error ◽  
Signaling Molecules ◽  
Discrete Problem ◽  
One Dimensional ◽  
Stability Constraint ◽  
Biological Interpretation ◽  
The Stability ◽  
The One

AbstractTo deal with permanent deformations and residual stresses, we consider a morphoelastic model for the scar formation as the result of wound healing after a skin trauma. Next to the mechanical components such as strain and displacements, the model accounts for biological constituents such as the concentration of signaling molecules, the cellular densities of fibroblasts and myofibroblasts, and the density of collagen. Here we present stability constraints for the one-dimensional counterpart of this morphoelastic model, for both the continuous and (semi-) discrete problem. We show that the truncation error between these eigenvalues associated with the continuous and semi-discrete problem is of order $${{\mathcal {O}}}(h^2)$$ O ( h 2 ) . Next we perform numerical validation to these constraints and provide a biological interpretation of the (in)stability. For the mechanical part of the model, the results show the components reach equilibria in a (non) monotonic way, depending on the value of the viscosity. The results show that the parameters of the chemical part of the model need to meet the stability constraint, depending on the decay rate of the signaling molecules, to avoid unrealistic results.

Appraisal of Allowable Loads by Simplified Rules

1986 ◽  
Vol 108 (2) ◽  
pp. 131-137
Author(s):  
D. Moulin
Keyword(s):  
Experimental Investigation ◽  
Plastic Region ◽  
Thin Structures ◽  
Geometric Imperfections ◽  
Buckling Behavior ◽  
Simplified Method ◽  
Post Buckling ◽  
Initial Geometric Imperfections ◽  
Fast Breeder Reactors ◽  
Breeder Reactors

This paper presents a simplified method to analyze the buckling of thin structures like those of Liquid Metal Fast Breeder Reactors (LMFBR). The method is very similar to those used for the buckling of beams and columns with initial geometric imperfections, buckling in the plastic region. Special attention is paid to the strain hardening of material involved and to possible unstable post-buckling behavior. The analytical method uses elastic calculations and diagrams that account for various initial geometric defects. An application of the method is given. A comparison is made with an experimental investigation concerning a representative LMFBR component.

Prefabrication and Erection Technology of Wide Box Girders in Cross-Sea Bridge

2014 ◽  
Vol 1065-1069 ◽  
pp. 882-888
Author(s):  
Yue Huang ◽  
Xing Fa Wu
Keyword(s):  
Great Influence ◽  
Dead Load ◽  
Box Girders ◽  
Box Girder ◽  
Technical Problems ◽  
Line Segments ◽  
Temperature Load ◽  
Quanzhou Bay ◽  
Research Show ◽  
Better Than

In the approach spans of Quanzhou Bay Cross-sea Bridge, these standard spans are 50m or 70m , width is 20.05m.The approach spans have been built by using short Line segments precast and erection method. This is the first application in the cross sea bridges. According to characteristics of this project, the research on prefabrication and erection technology of wide box girders has been carried out to solve the technical problems in the process of construction. The research show that: 1)In precasting process , the vertical deformation of wide box girder is very small under dead load and temperature load etc. so the influence of prefabrication and erection accuracy can be ignored; 2)The temporary anchor using prestressed steel strand better than planished steel; 3) When using epoxy gasket to adjust geometric line shape, the thickness of cemented layer has a great influence on the linear adjustment;4)The epoxy gasket and bridge erecting machine should be used together, Alignment adjustmen could obtain satisfactory results.

scholarly journals Numerical Study of Pressure Attenuation Effect on Tunnel Structures Subjected to Blast Loads

2021 ◽  
Vol 11 (12) ◽  
pp. 5646
Author(s):  
Cheng-Wei Hung ◽  
Ying-Kuan Tsai ◽  
Tai-An Chen ◽  
Hsin-Hung Lai ◽  
Pin-Wen Wu
Keyword(s):  
Numerical Simulation ◽  
Orifice Plate ◽  
Experimental Result ◽  
Scale Model ◽  
Pressure Reduction ◽  
Expansion Chamber ◽  
Pressure Relief ◽  
Attenuation Effect ◽  
The One ◽  
Better Than

This study used experimental and numerical simulation methods to discuss the attenuation mechanism of a blast inside a tunnel for different forms of a tunnel pressure reduction module under the condition of a tunnel near-field explosion. In terms of the experiment, a small-scale model was used for the explosion experiments of a tunnel pressure reduction module (expansion chamber, one-pressure relief orifice plate, double-pressure relief orifice plate). In the numerical simulation, the pressure transfer effect was evaluated using the ALE fluid–solid coupling and mapping technique. The findings showed that the pressure attenuation model changed the tunnel section to diffuse, reduce, or detour the pressure transfer, indicating the blast attenuation effect. In terms of the effect of blast attenuation, the double-pressure relief orifice plate was better than the one-pressure relief orifice plate, and the single-pressure relief orifice plate was better than the expansion chamber. The expansion chamber attenuated the blast by 30%, the one-pressure relief orifice plate attenuated the blast by 51%, and the double-pressure relief orifice plate attenuated the blast by 82%. The blast attenuation trend of the numerical simulation result generally matched that of the experimental result. The results of this study can provide a reference for future protective designs and reinforce the U.S. Force regulations.

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