scholarly journals Classical and innovative methods of fatigue and fracture repairs in navigation steel structures

2021 ◽  
Author(s):  
Lozano Christine ◽  
Riveros Guillermo
Keyword(s):  
Fatigue Cracking ◽  
Steel Structures ◽  
Load Carrying Capacity ◽  
Limit States ◽  
New Methods ◽  
Innovative Methods ◽  
Design Life ◽  
Load Carrying ◽  
Fatigue And Fracture ◽  
The U.S

Most of the hydraulic steel structures (HSS) in the U.S. have reached or have past their design life, which leads to unsatisfactory performance. Welded connections with low fatigue resistance, poor weld quality, unanticipated structural behavior, or unexpected loading due to the deterioration of the design boundary conditions are the causes of fatigue cracking. The purpose of this report is to identify and evaluate the traditional and new methods used for fatigue and fracture repairs in navigation steel structures to restore their load carrying capacity and fatigue and fracture resistance. The final objective was to generate a guidance report comprising of recommended and more efficient repair methods for the different fatigue limit states observed in navigation steel structures.

scholarly journals The Effects of Deteriorated Boundary Conditions on Horizontally Framed Miter Gates

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 37
Author(s):  
Guillermo A. Riveros ◽  
Felipe J. Acosta ◽  
Christine M. Lozano ◽  
Eileen Glynn
Keyword(s):  
Analytical Solutions ◽  
Steel Structures ◽  
River System ◽  
Limit States ◽  
Design Life ◽  
Fundamental Understanding ◽  
Bolt Failure ◽  
Shear Cracking ◽  
Different Levels ◽  
The U.S

The U.S. navigable infrastructure is a system of waterways dependent upon hydraulic steel structures (HSS) to facilitate the passage of ships and cargo. The system is linear in the sense that if one HSS is impassable, the entire river system is halted at that point. The majority of the HSS in this system were built in the first half of the 20th Century, and over seventy percent of them are past or near past their design life. Miter gates are critical HSS components within the system and many are showing signs of structural distress from continued operation past their design life. Common distress features include shear cracking within the pintle socket, partially missing Quoin blocks, fatigue fracturing, and bolt failure in the pintle region. This article focuses on gaining a fundamental understanding of the consequences of quoin block deterioration on a miter gate. The work was conducted by developing a computational model of a miter gate with different levels of quoin block deterioration. This model was validated using analytical solutions. The deterioration results demonstrated that the miter gate thrust diaphragm and quoin post experienced changes in their limit states due to deterioration. The results also demonstrated that the miter gate could overcome up to 10% of quoin block deterioration.

Flexural strengthening of pre-cracked RC slabs with prestressed NSM CFRP laminates and evaluation of strain loss

2021 ◽  
pp. 136943322110105
Author(s):  
M.R. Mostakhdemin Hosseini ◽  
Salvador J.E. Dias ◽  
Joaquim A.O. Barros
Keyword(s):  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Transfer Length ◽  
Rc Structures ◽  
Cracked Concrete ◽  
Flexural Strengthening ◽  
Cfrp Laminates ◽  
Load Carrying ◽  
Rc Slabs

The strengthening intervention of RC structures often involves already cracked concrete. To evaluate the effect of the level of damage prior to the strengthening (pre-cracks) on the behavior of the flexurally strengthened RC slabs with prestressed NSM CFRP laminates, an experimental research was carried out. Two pre-cracking levels of damage were analyzed and, for each one, three levels of prestress were tested (0%, 20% and 40%). The obtained results showed that the strengthening of damaged RC slabs with prestressed NSM CFRP laminates results in a significant increase on the load carrying capacity at serviceability limit states. Pre-cracked RC slabs strengthened with prestressed NSM CFRP laminates presented a load carrying capacity almost similar to the corresponding uncracked strengthened slabs. To determine the effective prestress level in CFRP laminates, the variation of strain over the length of the CFRP and over time was experimentally recorded. The prestress transfer length was also evaluated. The experimental results revealed that the transfer length of CFRP laminates was less than 150 mm, and the maximum value of strain loss out of transfer length (around 14%) was measured close to the cracked section of the damaged RC slabs. Significant part of strain loss in CFRP laminates occurred during 24 h after releasing the prestress load.

Reliability analysis of wood I-joists

1993 ◽  
Vol 20 (4) ◽  
pp. 564-573 ◽  
Author(s):  
R. O. Foschi ◽  
F. Z. Yao
Keyword(s):  
Reliability Analysis ◽  
Carrying Capacity ◽  
Failure Modes ◽  
Limit State ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Element Analysis ◽  
Strength Limit ◽  
Reliability Method ◽  
Load Carrying

This paper presents a reliability analysis of wood I-joists for both strength and serviceability limit states. Results are obtained from a finite element analysis coupled with a first-order reliability method. For the strength limit state of load-carrying capacity, multiple failure modes are considered, each involving the interaction of several random variables. Good agreement is achieved between the test results and the theoretical prediction of variability in load-carrying capacity. Finally, a procedure is given to obtain load-sharing adjustment factors applicable to repetitive member systems such as floors and flat roofs. Key words: reliability, limit state design, wood composites, I-joist, structural analysis.

STABILITY PROBLEMS OF STEEL‐CONCRETE MEMBERS COMPOSED OF HIGH‐STRENGTH MATERIALS

2010 ◽  
Vol 16 (3) ◽  
pp. 352-362 ◽  
Author(s):  
Zdeněk Kala ◽  
Libor Puklický ◽  
Abayomi Omishore ◽  
Marcela Karmazínová ◽  
Jindřich Melcher
Keyword(s):  
Theoretical Analysis ◽  
Experimental Research ◽  
Carrying Capacity ◽  
High Strength ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Load Carrying ◽  
Geometrical Imperfections

The presented paper deals with the stochastic analysis of the ultimate limit states of steel‐concrete building members. The load carrying capacity of steel‐concrete columns, comprising of steel profiles encased in high strength concrete, in compression is analyzed. The first part of the paper lists assumptions for the determination of the theoretical load carrying capacity of the column. Principles of elasticity and plasticity are used to determine stresses in the concrete and steel sections. Statistical characteristics of input material and geometrical imperfections are listed. Results of the theoretical analysis are then compared with results of experimental research. Statistical characteristics of obtained results of the theoretical analysis were verified using statistical characteristics obtained from experimental research. Numerical simulation LHS and Monte Carlo methods, which take into account the influences of variability of input imperfections, were employed. The influence of the utilization of the plastic reserve in the determination of the load carrying capacity of the analysed strut is shown. The influence of the initial geometric imperfections of initial strut curvature on the load carrying capacity is also presented. Santrauka Straipsnyje pateikta plienbetonio pastatu elementu didžiausiu ribiniu būkliu stochastine analize, analizuojama plienbetonio kolonu, sudarytu iš plieniniu profiliuočiu, padengtu didelio stiprio betonu, laikomoji galia gniuždant. Pirmoje straipsnio dalyje išvardytos kolonos teorines laikomosios galios nustatymo prielaidos. Tamprumo ir plastiškumo principai taikyti itempiams betono ir plieno skerspjūviuose nustatyti. Nustatytos medžiagu ir geometriniu defektu statistines charakteristikos, teorines analizes rezultatai palyginti su eksperimentiniu tyrimu rezultatais. Teorines analizes metu gautu rezultatu statistines charakteristikos patikrintos taikant iš eksperimentiniu tyrimu gautus statistinius rodiklius. Pritaikytas skaitinis modeliavimas LHS ir Monte Karlo metodais, kurie ivertina pradiniu defektu kintamumo itaka. Parodyta plastiškumo atsargos naudojimo itaka, nustatant analizuojamojo statramsčio laikomaja galia, pateikta pradinio statramsčio išlinkio pirminiu geometriniu defektu itaka laikomajai galiai.

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.

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.

Actual Effects of Local Buckling of Thin-Walled Metal Roof Decking: Control Experimental Verification Performed during Structure Realization

2013 ◽  
Vol 368-370 ◽  
pp. 1503-1506
Author(s):  
Marcela Karmazínová ◽  
Jindrich Melcher
Keyword(s):  
Experimental Verification ◽  
Carrying Capacity ◽  
Failure Process ◽  
Local Buckling ◽  
Load Carrying Capacity ◽  
Limit States ◽  
Loading Test ◽  
Actual Behaviour ◽  
Load Carrying ◽  
Thin Walled

Experimental verification of structural members can be the necessary part of the structural design of load-carrying civil structures, mainly in the period of last two decades. In some cases, the knowledge obtained from the tests is the sole source of the reliable information about actual behaviour of structural member in strain and failure process and about its objective load-carrying capacity. The paper is specifically aimed at the control experimental verification of roof decking based on thin-walled metal profiled sheets. Loading test has been performed during structure erection, as additional resource for the verification of actual behaviour and objective load-carrying capacity and for the confirmation or refinement of static design assumptions and results, within the ultimate and serviceability limit states. The subject of the control experimental verification was roof decking composed of thin-walled metal cassettes with thermal insulation at its upper side, used for the university lecture room roofing.

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.

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