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.

Geometric Imperfection Sensitivity and Effect of Constraint Conditions of H-Section Columns under Compression

2010 ◽  
Vol 102-104 ◽  
pp. 140-144
Author(s):  
Yi Ping Wang ◽  
Yong Zang ◽  
Di Ping Wu
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
Load Carrying Capacity ◽  
Imperfection Sensitivity ◽  
Geometric Imperfection ◽  
Manufacture Process ◽  
Buckling Behavior ◽  
Load Carrying ◽  
Thin Walled ◽  
Tolerance Control

The buckling behavior of thin-walled steel structures under load is still imperfectly understood, in spite of much research over the past 50 years. In this paper, the buckling behaviors of H-section columns under compression have been simulated with ANSYS. In the analysis, contact pairs between column ends and end blocks have been introduced into the model, and the load carrying capacity of the columns with four kinds of end constraint conditions and various typical initial geometric imperfections has been calculated and discussed. The results indicate that the load carrying capacity is most sensitive to the flexural imperfection, and the constraint condition cannot change the imperfection sensitivity of a column under compression, but improving restrain condition can heighten the load carrying capacity. They are helpful to the use and the tolerance control in the manufacture process of thin-walled H-section steel structures.

Parametric Study of Tendon Profiles in Prestressed Steel Plate Girder

2002 ◽  
Vol 5 (2) ◽  
pp. 75-85 ◽  
Author(s):  
G. N. Ronghe ◽  
L. M. Gupta
Keyword(s):  
Carrying Capacity ◽  
Steel Plate ◽  
Steel Structures ◽  
Prototype Model ◽  
Load Carrying Capacity ◽  
Prestressing Steel ◽  
Analysis And Design ◽  
Prestressing Force ◽  
Load Carrying ◽  
Plate Girder

The concept of prestressing steel structures has only recently been widely considered, despite a long and successful history of prestressing concrete members. Several analytical studies of prestressed steel plate girder were reported in the literature, but much of that work was not studied with reference to different parameters like tendon profile, eccentricity, partial span to full span ratio, prestressing force, load carrying capacity etc. associated with prestressing. This paper examines analytically a comparative study of various tendon configurations and prestressing parameters on over all analysis and design of prestressed steel plate girder. The output from the computer Program for analysis and design of steel plate girder prestressed with different tendon configurations are compared among each other. As a Case-study, a prototype model of Prestressed Steel Testing Frame with straight tendon has been designed, constructed and tested in the laboratory for its safe load carrying capacity and maximum deflection.

On the Choice of Initial Geometric Imperfections in Externally Pressurized Shells

1999 ◽  
Vol 121 (1) ◽  
pp. 71-76 ◽  
Author(s):  
J. Błachut ◽  
O. R. Jaiswal
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Carrying Capacity ◽  
Circular Cross Section ◽  
Load Carrying Capacity ◽  
Geometric Imperfections ◽  
Elliptical Cross ◽  
Buckling Strength ◽  
Load Carrying ◽  
Initial Geometric Imperfections

Localized and global, of eigenmode type, initial geometric imperfections were superimposed on perfect torispherical, ellipsoidal, and toroidal shells of circular and elliptical cross section. Reduction of the load-carrying capacity was then calculated numerically for various geometries and the yield point of material which was assumed to be mild steel. Results show that the buckling strength of torispheres and ellipsoids could be strongly affected by imperfections, but reduction of its magnitude was dependent on the choice of imperfection shape and, more importantly, on the imperfection’s location. Calculations carried out for closed toroids of circular cross section show that these shells are not sensitive to eigenmode-type imperfections, while toroids with elliptical cross sections are sensitive to eigen-imperfections.

Safety Assessment of Bridge Structures Using Ambient Vibration

2012 ◽  
Vol 83 ◽  
pp. 151-156
Author(s):  
Chin Hyung Lee ◽  
Young Jun You ◽  
Ki Tae Park ◽  
Bong Chul Joo ◽  
Bo Mi Lee ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Evaluation System ◽  
Safety Assessment ◽  
Ambient Vibration ◽  
Load Carrying Capacity ◽  
Bridge Structure ◽  
Efficient Manner ◽  
Load Carrying ◽  
Bridge Structures ◽  
Estimation System

In this study, relative load-carrying capacity (RLC) evaluation system in which the change of load-carrying capacity of a bridge structure can be estimated through the variation of the dynamic property, which is induced by the stiffness change due to the deterioration of the bridge, by using ambient traffic-induced vibration was proposed. The system uses the natural excitation technique in conjunction with the eigensystem realization algorithm for identification of modal parameters. Indoor test using a truss-typed model bridge and field measurement were performed to verify the suggested system and it was shown that the RLC estimation system is suitable for the safety assessment of bridge structures in a simple and efficient manner.

scholarly journals Design Reliability Analysis of Cold-Formed Thin-Walled Steel Members with Lipped Channel Sections Considering Distortional Buckling

2017 ◽  
Vol 11 (1) ◽  
pp. 906-918
Author(s):  
Yao Xingyou
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
External Loading ◽  
Material Strength ◽  
Load Carrying Capacity ◽  
Distortional Buckling ◽  
Partial Coefficient ◽  
Load Carrying ◽  
Cold Formed Steel ◽  
Thin Walled

Introduction: Based on the experimental results of cold-formed thin-walled steel lipped channel sections, the uncertainty of calculating mode of load-carrying capacity using effective width method considering distortional buckling for different material types cold-formed steel compressed members was researched, and the uncertainties of material strength and geometric characteristics of the typical sections were statistically analyzed. Methods: According to the recommended resistance of partial coefficient in the draft of Technical code of cold-formed steel structures (GB50018-), the reliability indexes of cold-formed thin-walled steel lipped channel sections under compression were investigated using the improved first-order second-moment method considering different possible external loading combinations. Results: The analyzed results show that, using the recommended resistance partial coefficient in the code draft, the reliability indexes of the compressed members with width-thickness ratio within the limitation of code draft can well met the target reliability index. The suitability of the corresponding calculating modes of load-carrying capacity considering distortional buckling was established.

scholarly journals Development of Light Weight and Seismic Performance of Light Gauge Cold Formed Steel Structures by Different Types of Moment Resistant Steel Connection

2020 ◽  
Vol 8 (6) ◽  
pp. 2879-2885
Keyword(s):  
Seismic Performance ◽  
Carrying Capacity ◽  
Minimum Weight ◽  
Steel Structures ◽  
Cost Ratio ◽  
Load Carrying Capacity ◽  
Base Shear ◽  
Load Carrying ◽  
Steel Connection ◽  
Cold Formed Steel

Structural steel has many advantages over other construction materials by its high strength and ductility. It has a higher strength to cost ratio in tension and a slightly lower strength to cost ratio in compression when compared with concrete. This paper is intended to evaluate the beam column rolled and cold formed steel connection experimentally by moment resistant connection such as stiffened, un stiffened and splices connection. At the present, in most of the countries, the use of light gauge cold formed steel section has been developed for economical and best seismic performance by different shape of cross sectional area and various types of connections are used. These results to study the seismic performance of cold form steel sections area using various moment resistance connections. Finally the report result the splice connection has best moment resistance connection, seismic resistant of structures, load carrying capacity is high and minimum weight compare with other types of connections. The splice connection has load carrying capacity is high, so we can reduced the size of section and prevent the base shear due to reduced the weight of structures.

Parametric study of truss bridges by the post-tensioning method

2005 ◽  
Vol 32 (2) ◽  
pp. 420-429 ◽  
Author(s):  
Kyoung-Bong Han ◽  
Sun-Kyu Park
Keyword(s):  
Carrying Capacity ◽  
Steel Structures ◽  
High Strength ◽  
Elastic Behavior ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Prestressing Force ◽  
Load Carrying ◽  
Post Tensioning ◽  
Post Tensioned

The post-tensioning method has been successfully used to improve the performance of existing concrete structures. Applications of the method are rare in steel structures, however. Post-tensioning using high-strength cables or bars can be effectively used to increase the working load carrying capacity of steel structures. In this paper, the elastic behavior of post-tensioned trusses with straight and draped tendon profiles for truss strengthening is examined. The effects of design parameters such as the tendon profile, truss type, prestressing force, and tendon eccentricity on working load and deflection of trusses are studied. The results show that the allowable load of a truss increases proportionally with the increase in prestressing force and eccentricity. Post-tensioning enlarges the elastic range, increases the redundancy, and reduces the deflection and member stresses, eventually increasing the load-carrying capacity of truss bridges.Key words: post-tensioning method, steel structures, post-tensioned trusses, truss strengthening, design parameters, load-carrying capacity.

On Structural Redundancy in Space Trusses

1988 ◽  
Vol 3 (4) ◽  
pp. 237-241 ◽  
Author(s):  
Ariel Hanaor ◽  
An-Fu Ong
Keyword(s):  
Carrying Capacity ◽  
Collapse Mechanism ◽  
Load Carrying Capacity ◽  
Allowable Stress ◽  
Structural Redundancy ◽  
Critical Elements ◽  
Design Load ◽  
Compression Members ◽  
Load Carrying ◽  
Space Trusses

Static redundancy does not ensure structural redundancy in cases where the collapse mechanism involves instability. Structural redundancy is defined here as the ability of the structure to sustain its design load with the loss of one or more critical elements. The parametric investigations on a square on square double-layer grid presented here, suggests that the loss of one critical member from this type of structure typically entails a loss of 20% to 30% of load carrying capacity. To allow for structural redundancy, as well as for loss of carrying capacity due to the effect of imperfections, it is recommended to reduce compression members' buckling (or allowable) stress by a corresponding value or, alternatively, to perform a suitable analysis.

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