FATIGUE BEHAVIOR AT THE UPPER END OF VERTICAL STIFFENERS CONNECTED WITH SWAY BRACINGS

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Chihiro Sakamoto ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Masahiro Koyama
Keyword(s):  
Fatigue Behavior ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Large Specimen ◽  
Cracking Behavior ◽  
Girder Bridges ◽  
Bead Surface ◽  
Rc Slab ◽  
Vertical Stiffener

Lots of fatigue crackings were reported at the upper end of vertical stiffeners connected to sway bracings in steel highway girder bridges. In this study, we investigate fatigue cracking behavior at the upper end of vertical stiffeners under RC slab, through fatigue tests using a large specimen with three main girders under alternative loading using two actuators. As a result, alternative loading can reproduce the alternative stress at the upper end of vertical stiffener in the middle girder when vehicles run on the driving lane and passing lane alternatively. Root cracks were initiated after 0.1 Mcycles loading and appeared on the bead surface when 0.6 Mcycles.

FATIGUE TEST OF STEEL GIRDER WEB PENETRATION DETAILS WITH A SLIT

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Naoto Yoshida ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Takashi Fujii
Keyword(s):  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Fatigue Cracking ◽  
Highway Bridges ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Bottom Surface ◽  
Steel Girder ◽  
Propagation Behavior

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. A one-meter-long crack was detected in Yamazoe Bridge in 2006. Since a number of highway bridges with such web penetration details may exist in Japan, it is of urgent importance to understand these fatigue-strength properties. However, few fatigue tests have been reported on steel girder web penetration details. The purpose of this study is to clarify fatigue behavior of steel girder web penetration details with a slit through fatigue tests of specimens with these details. We designed and fabricated girder specimens that have steel girder web penetration details, in which cross-beam bottom flanges are connected to each top or bottom surface of a slit by welding. First, we conducted static loading tests to understand the stress distributions around web penetration details. Second, we conducted fatigue tests to examine fatigue crack initiation and propagation behavior and fatigue strength.

Cumulative Damage Behavior of Anisotropic Al-6061-T6 as a Function of Axial-Torsional Loading Mode Sequence

1994 ◽  
Vol 116 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Hong Lin ◽  
Hamid Nayeb-Hashemi ◽  
Charles A. Berg
Keyword(s):  
Damage Accumulation ◽  
Low Cycle Fatigue ◽  
Constitutive Relations ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Cracking Behavior ◽  
Al 6061 ◽  
Damage Models ◽  
Loading Mode

Two types of low cycle fatigue tests were conducted along two principal orthotropic directions of an orthotropic Al-6061-T6 plate in strain control at room temperature: (1) reference fatigue tests under three loading conditions: push-pull, torsion, and combined push-pull/torsion in-phase; (2) sequential fatigue tests in which different sequences of push-pull and torsion were performed. Fatigue cracking behavior was observed during all of the fatigue tests. Shear cracking dominated the damage of the material. Anisotropic constitutive relations of the material were used in the evaluation of several multiaxial fatigue damage models. The predictive capabilities of these models were assessed based on the results of reference fatigue tests. The damage accumulation behavior of the material was found to depend on the sequence of the loading mode. For the sequence of torsion then push-pull, the damage summation was greater than unity. However, for the sequence of push-pull then torsion, the damage accumulation was near unity as predicted by the linear damage rule. A nonlinear damage accumulation rule could represent the results of the sequential fatigue tests.

RETROFITTING METHODS AGAINST FATIGUE CRACKING IN STEEL GIRDER WEB PENETRATION

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Chihiro Sakamoto ◽  
Masahiro Sakano ◽  
Hideyuki Konishi ◽  
Takashi Fujii
Keyword(s):  
Fatigue Life ◽  
Fatigue Cracking ◽  
Highway Bridges ◽  
Lower Surface ◽  
Strength Properties ◽  
Fatigue Tests ◽  
Stress Distributions ◽  
Steel Girder ◽  
Cracking Behavior ◽  
Weld Toe

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties and develop effective retrofitting methods. In a previous report, we investigated the stress distributions around web penetration details, and fatigue cracking behavior, using steel girder specimens with web penetration details. In this study, we investigate effects of retrofitting methods against fatigue cracking in web penetration details through fatigue tests using large girder specimens with web penetration details in which cross beam lower flanges are connected to lower surface of a slot by welding. Principal results obtained through this study are as follows: (1) Weld toe grinding can extend fatigue life more than 5 times, (2) Two-face attachment can extend fatigue life more than 10 times, and (3) Two-face attachment with weld toe grinding can extend fatigue life more than 25 times.

Length Effects on Fatigue Behavior of Longitudinal Pipeline Dents

2002 ◽  
Author(s):  
Adam J. Rinehart ◽  
Peter B. Keating
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Experimental Evidence ◽  
Parametric Study ◽  
Fatigue Behavior ◽  
Fatigue Cracking ◽  
Finite Element Models ◽  
Cracking Behavior ◽  
Stress Behavior ◽  
Length Effects

Dent length has been shown to have a significant effect on the fatigue cracking behavior of pipeline dents. Long dents, which experience rerounding and center cracking, have a dramatically shorter fatigue life than otherwise similar short dents, which experience peripheral cracking and little rerounding. Because the fatigue lives of long dents are much shorter than those of short dents, both safety and economy would benefit from improvements in the ability to distinguish long dents from short dents. Based on experimental evidence, a transition between short and long dent behavior is shown to exist. Finite element models are used to further explore the nature of this transition by allowing the examination of cases not available in the experimental record and by permitting stress behavior to be studied. A parametric study is used to quantify the nature of the short dent to long dent transition for a range of cases. Relative dent lengths that bound short and long dent regions of behavior are proposed for these cases.

scholarly journals Influence of Shot Peening on the Isothermal Fatigue Behavior of the Gamma Titanium Aluminide Ti-48Al-2Cr-2Nb at 750 °C

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1083
Author(s):  
Christoph Breuner ◽  
Stefan Guth ◽  
Elias Gall ◽  
Radosław Swadźba ◽  
Jens Gibmeier ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Shot Peening ◽  
Elevated Temperatures ◽  
Stress Amplitude ◽  
Negative Impact ◽  
Fatigue Behavior ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Positive Effects ◽  
Isothermal Fatigue

One possibility to improve the fatigue life and strength of metallic materials is shot peening. However, at elevated temperatures, the induced residual stresses may relax. To investigate the influence of shot peening on high-temperature fatigue behavior, isothermal fatigue tests were conducted on shot-peened and untreated samples of gamma TiAl 48-2-2 at 750 °C in air. The shot-peened material was characterized using EBSD, microhardness, and residual stress analyses. Shot peening leads to a significant increase in surface hardness and high compressive residual stresses near the surface. Both effects may have a positive influence on lifetime. However, it also leads to surface notches and tensile residual stresses in the bulk material with a negative impact on cyclic lifetime. During fully reversed uniaxial tension-compression fatigue tests (R = −1) at a stress amplitude of 260 MPa, the positive effects dominate, and the fatigue lifetime increases. At a lower stress amplitude of 230 MPa, the negative effect of internal tensile residual stresses dominates, and the lifetime decreases. Shot peening leads to a transition from surface to volume crack initiation if the surface is not damaged by the shots.

Fatigue behavior of precipitation strengthened Cu–Ni–Si alloy modified by Cr and Zr addition

2020 ◽  
Vol 11 (6) ◽  
pp. 861-873
Author(s):  
Ş. Hakan Atapek ◽  
Spiros Pantelakis ◽  
Şeyda Polat ◽  
Apostolos Chamos ◽  
Gülşah Aktaş Çelik
Keyword(s):  
Design Methodology ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Lower Stress ◽  
Content Type ◽  
Hardened Alloy ◽  
Zr Addition ◽  
Nucleation Sites ◽  
The Matrix ◽  
Lower Stress Level

Purpose The purpose of this paper is to investigate the fatigue behavior of precipitation-strengthened Cu‒2.55Ni‒0.55Si alloy, modified by the addition of 0.25 Cr and 0.25 Zr (wt%), using mechanical and fractographical studies to reveal the effect of microstructural features on the fracture. Design/methodology/approach For strengthening, cast and hot forged alloy was subjected to solution annealing at 900°C for 60 min, followed by quenching in water and then aging at 490°C for 180 min. Precipitation-hardened alloy was exposed to fatigue tests at R=−1 and different stress levels. All fracture surfaces were examined within the frame of fractographical analysis. Findings Fine Ni-rich silicides responsible for the precipitation strengthening were observed within the matrix and their interactions with the dislocations at lower stress level resulted in localized shearing and fine striations. Although, by the addition of Cr and Zr, the matrix consisted of hard Ni, Zr-rich and Cr-rich silicides, these precipitates adversely affected the fatigue behavior acting as nucleation sites for cracks. Originality/value These findings contribute to the present knowledge by revealing the effect of microstructural features on the mechanical behavior of precipitation-hardened Cu‒Ni‒Si alloy modified by Cr and Zr addition.

Gigacycle Fatigue of Welded Joints of Structural Materials (A Review)

2016 ◽  
Vol 17 ◽  
pp. 14-30 ◽  
Author(s):  
Okechukwu P. Nwachukwu ◽  
Alexander V. Gridasov ◽  
Ekaterina A. Gridasova
Keyword(s):  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Structural Materials ◽  
Fatigue Tests ◽  
Material Defects ◽  
Graphite Cast Iron ◽  
Ultrasonic Fatigue ◽  
Materials Used ◽  
Fatigue Failures

This review looks into the state of gigacycle fatigue behavior of some structural materials used in engineering works. Particular attention is given to the use of ultrasonic fatigue testing machine (USF-2000) due to its important role in conducting gigacycle fatigue tests. Gigacycle fatigue behavior of most materials used for very long life engineering applications is reviewed.Gigacycle fatigue behavior of magnesium alloys, aluminum alloys, titanium alloys, spheroid graphite cast iron, steels and nickel alloys are reviewed together with the examination of the most common material defects that initiate gigacycle fatigue failures in these materials. In addition, the stage-by-stage fatigue crack developments in the gigacycle regime are reviewed. This review is concluded by suggesting the directions for future works in gigacycle fatigue.

Effect of corrosion and sandblasting on the high cycle fatigue behavior of reinforcing B500C steel bars

2017 ◽  
Author(s):  
Marina C. Vasco ◽  
Panagiota Polydoropoulou ◽  
Apostolos N. Chamos ◽  
Spiros G. Pantelakis
Keyword(s):  
Mass Loss ◽  
High Cycle Fatigue ◽  
Fatigue Behavior ◽  
Salt Spray ◽  
Fatigue Tests ◽  
Tensile Behavior ◽  
Loading Frequency ◽  
Reinforcing Steel ◽  
Cycle Fatigue ◽  
Steel Bars

In a series of applications, steel reinforced concrete structures are subjected to fatigue loads during their service life, what in most cases happens in corrosive environments. Surface treatments have been proved to represent proper processes in order to improve both fatigue and corrosion resistances. In this work, the effect of corrosion and sandblasting on the high cycle fatigue behavior reinforcing steel bars is investigated. The investigated material is the reinforcing steel bar of technical class B500C, of nominal diameter of 12 mm. Steel bars specimens were first exposed to corrosion in alternate salt spray environment for 30 and 60 days and subjected to both tensile and fatigue tests. Then, a series of specimens were subjected to common sandblasting, corroded and mechanically tested. Metallographic investigation and corrosion damage evaluation regarding mass loss and martensitic area reduction were performed. Tensile tests were conducted after each corrosion exposure period prior to the fatigue tests. Fatigue tests were performed at a stress ratio, R, of 0.1 and loading frequency of 20 Hz. All fatigue tests series as well as tensile test were also performed for as received steel bars to obtain the reference behavior. The results have shown that sandblasting hardly affects the tensile behavior of the uncorroded material. The effect of sandblasting on the tensile behavior of pre-corroded specimens seems to be also limited. On the other hand, fatigue results indicate an improved fatigue behavior for the sandblasted material after 60 days of corrosion exposure. Martensitic area reductions, mass loss and depth of the pits were significantly smaller for the case of sandblasted materials, which confirms an increased corrosion resistance.

High-cycle fatigue tests of pretensioned concrete beams

PCI Journal ◽  
2022 ◽  
Vol 67 (1) ◽  
Author(s):  
Jörn Remitz ◽  
Martin Empelmann
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Concrete Beams ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Design Methods ◽  
Test Results ◽  
Cycle Fatigue ◽  
Pretensioned Concrete ◽  
Current Design

Pretensioned concrete beams are widely used as bridge girders for simply supported bridges. Understanding the fatigue behavior of such beams is very important for design and construction to prevent fatigue failure. The fatigue behavior of pretensioned concrete beams is mainly influenced by the fatigue of the prestressing strands. The evaluation of previous test results from the literature indicated a reduced fatigue life in the long-life region compared with current design methods and specifications. Therefore, nine additional high-cycle fatigue tests were conducted on pretensioned concrete beams with strand stress ranges of about 100 MPa (14.5 ksi). The test results confirmed that current design methods and specifications overestimate the fatigue life of embedded strands in pretensioned concrete beams.

scholarly journals Changing in Fatigue Life of 300 M Bainitic Steel After Laser Carburizing and Plasma Nitriding

2018 ◽  
Vol 165 ◽  
pp. 21002 ◽  
Author(s):  
Antonio J. Abdalla ◽  
Douglas Santos ◽  
Getúlio Vasconcelos ◽  
Vladimir H. Baggio-Scheid ◽  
Deivid F. Silva
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Plasma Nitriding ◽  
Fatigue Behavior ◽  
High Strength ◽  
Tensile Tests ◽  
Steel Sample ◽  
Fatigue Tests ◽  
300M Steel ◽  
Structural Applications

In this work 300M steel samples is used. This high-strength steel is used in aeronautic and aerospace industry and other structural applications. Initially the 300 M steel sample was submitted to a heat treatment to obtain a bainític structure. It was heated at 850 °C for 30 minutes and after that, cooled at 300 °C for 60 minutes. Afterwards two types of surface treatments have been employed: (a) using low-power laser CO2 (125 W) for introducing carbon into the surface and (b) plasma nitriding at a temperature of 500° C for 3 hours. After surface treatment, the metallographic preparation was carried out and the observations with optical and electronic microscopy have been made. The analysis of the coating showed an increase in the hardness of layer formed on the surface, mainly, among the nitriding layers. The mechanical properties were analyzed using tensile and fatigue tests. The results showed that the mechanical properties in tensile tests were strongly affected by the bainitic microstructure. The steel that received the nitriding surface by plasma treatment showed better fatigue behavior. The results are very promising because the layer formed on steel surface, in addition to improving the fatigue life, still improves protection against corrosion and wear.

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