Fatigue Strength of Angle Shape Shear Connector used in Steel-Concrete Composite Slab

최성민,Kazuo Tateishi,Daisuke Uchida,Koichi Asano,Kiyoshi Kobayashi 한국강구조학회 2008 International Journal of Steel Structures Vol.8 No.3

Fatigue strength of welded joint between angle shape shear connector and bottom plate in steel-concrete composite slab was investigated by fatigue tests. Fatigue tests were performed on push-out shear specimens. Local stress around the welded joint was also investigated by FEA. In fatigue tests, fatigue cracks initiated and propagated at the welded toe. The fatigue cracks were caused by stress concentration at the welded joints due to the local bending deformation of bottom plate. This local bending deformation was analytically simulated by FEA carried out on slab members in practice. After these investigations, it was confirmed the stress level at the welded joint was small and much less than the fatigue limit even when the design truck loads were applied.

Fatigue Strength Improvement of U-type Trough Rib at Field Welded Joint in Steel Bridge Deck

최성민,Kazuo Tateishi,김인태,서원찬,이동욱 한국강구조학회 2008 International Journal of Steel Structures Vol.8 No.3

The influence of misalignment is investigated to improve the fatigue strength of U-type trough ribs at field welded joints in steel bridge decks. A 3-point bending fatigue test and finite element analysis were conducted on full-scale specimens. Small-scale specimens with a backing strip were also made and examined with a fatigue test and FEA to estimate the influence of misalignment. The result of the static loading test for the full-scale specimens showed that the position of maximum stress is in the bottom corners of the U-rib. It is known that fatigue cracks initiate from the inner surface of the U-rib and propagated to the outer surface, and larger misalignments contributed to a shorter fatigue life for the U-rib, based on the result of the fatigue test. The fatigue life is drastically reduced when the magnitude of misalignment is increased, as shown in the results of the fatigue test on small-scale specimens with a backing strip, and fatigue cracks usually occurred at the root of base metal. The result of stress analysis on small-scale specimens showed that the stress concentration at the root of base metal increases in proportion to larger misalignment, and the semicircular shape of the root is less subject to stress concentration than the right angle root type.

Fatigue Strength Improvement of Weld Joints with Cope Hole

최성민,Kazuo Tateishi,Takeshi Hanji 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.4

Weld joint with a cope hole has relatively low fatigue strength, since high stress concentration is generated due to local sheardeformation inside the cope hole. In this study, fatigue strength improvement for the cope hole joint by burr grinding isinvestigated. I-section beams with cope holes, of which boxing weld toes were smoothly finished by burr grinding, were testedand analyzed in order to know the fatigue strength and the local stress behavior of the joint. Test and analysis resultsdemonstrated that the benefit of grinding on fatigue strength improvement is relatively small when shear stress is largely appliedto the cope hole detail.

Effect of UHPFRC Overlay on Fatigue Cracks Propagating from U-rib Welds of Orthotropic Steel Decks

Masafumi Hattori,Kazuo Tateishi,Takeshi Hanji,Masaru Shimizu 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.6

Over the last decade, fatigue cracks have been observed at welded joints between U-ribs and deck plates in many orthotropic steel deck bridges in Japan. This paper focuses on fatigue cracks that initiate from a weld root of rib-to-deck welded joints and propagate to a deck plate. This study examines the eff ect of a countermeasure that uses overlaying Ultra-High Performance Fiber Reinforced cement-based Composites (UHPFRCs) on steel decks with cracks from U-rib welds, and confi rms the fatigue durability of this method. Specifi cally, the retardation of crack propagation and the fatigue durability of the UHPFRC itself as well as the interface between the UHPFRC and the deck plate were confi rmed by a wheel running test and fi nite element analysis. Based on the results, it was clarifi ed that this countermeasure has a positive eff ect on retarding further crack propagation compared with the method of overlaying steel fi ber reinforced concrete, which is generally adopted. In addition, it was revealed that the studied countermeasure has suffi cient fatigue durability.

Study on Fatigue Crack Propagation of a Through-thickness Crack Subjected to Out-of-plane Bending

Xiaochen Ju,Kazuo Tateishi 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.1

In Japan, fatigue through-thickness cracks have been reported in some steel bridges. Some of the cracks originate due to the effects of out-of-plane bending. In order to perform more efficient maintenance to prevent fatigue damages, it is essential to identify the crack propagation behavior of through-thickness cracks due to stress resulting from out-of-plane bending. The stress intensity factor for through-thickness cracks resulting from bending is an important factor for the assessment crack propagation behavior and has previously been determined by making the assumption that the crack front shape is straight in the thickness direction. However, the actual crack front is curved under the stresses of out-of-plane bending. In this paper, in order to identify the propagation behavior of through-thickness cracking due to out-of-plane bending, a fatigue test on through-thickness cracked plate was carried out. Furthermore, the stress intensity factor along curved crack front was investigated via finite element analysis on a test specimen.

Slip Coeffi cient and Ultimate Strength of High-Strength Bolted Friction Joints with Compact Bolt Spacing and Edge Distance

Shogo Kiyokawa,Kazuo Tateishi,Takeshi Hanji,Masaru Shimizu 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.4

In current design codes, the minimum bolt spacing and edge distance for high-strength bolted friction joints are specifi ed based on the bolt diameter, regardless of the plate thickness or steel strength. However, the mechanical performance of joints with a more compact bolt spacing than that given in the current design specifi cations has been little examined. In this study, the slip and ultimate strength of high-strength bolted joints with a compact bolt spacing and edge distance were investigated. Tensile tests were conducted on friction-type joints with various bolt arrangements. The use of a compact bolt arrangement was not observed to have a negative infl uence on the slip strength in these tests. The estimated strengths corresponding to the experimentally observed failure modes were found to agree fairly well with the experimental results within a 10% error. A parametric fi nite element analysis was also conducted to investigate the infl uence of the bolt arrangement on the slip coeffi cient. It was concluded that the bolt spacing and edge distance have little infl uence on the slip coeffi cient.

CIVA-Lattice Boltzmann Method for Sallow Water Flow Based on Unstructured Grid

Yuji Ishikawa,Junya Tateishi,Kazuo Kashiyama 한국전산유체공학회 2006 한국전산유체공학회 학술대회논문집 Vol.2006 No.5

Local Strain-Based Low-Cycle Fatigue Assessment of Joint Structure in Steel Truss Bridges During Earthquakes

Chao Jiang,Takeshi Hanji,Kazuo Tateishi,Masaru Shimizu 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5

During the 2011 Tohoku Earthquake, a truss bridge joint structure was cracked due to large cyclic deformation, making us recognize the importance of assessing the seismic performance of joint structures in truss bridges from the viewpoint of low-cycle fatigue. In this study, seismic response analysis of an actual deck truss bridge was performed under diff erent seismic waves, and local strain behavior generated at welded joints around a joint structure was clarifi ed using a zooming analysis technique. The results revealed the possibility that welded joints for a lateral gusset-plate in a joint structure can be cracking sites during earthquakes. In addition, it was indicated that seismic isolation bearings can signifi cantly reduce the local strain at the joint structure and improve its low-cycle fatigue performance. Moreover, as a simple countermeasure, weld toe treatment by grinding is also eff ective to decrease the possibility of low-cycle fatigue cracking at the joint structure.

Failure Probability for Fatigue Crack in Web Plate of Bridge Girder

Cut Atika Putri,Kazuo Tateishi,Masaru Shimizu,Takeshi Hanji 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

Out-of-plane gusset joints are commonly used in welded assembly structures such as bridges. The studies regarding outof- plane gusset joint often defi ne fatigue life of this joint as the condition when the crack has fully penetrated through the web plate. However, the time frame from crack initiation until reaching complete structural failure is unclear. In this study, extended fatigue crack propagation analysis of out-of-plane gusset joint is performed. The variation of infl uential parameters such as fl ank angle, weld toe radius, material constant, and the threshold value of stress intensity factor range was considered. The crack propagation analysis was done until the crack reaches 80% of the lower fl ange plate of the bridge girder. Since the crack propagation life is highly infl uenced by traffi c conditions, the probability distribution of the number of cycles and the crack width (2 b ) is presented in regards to the fatigue life ratio. In estimating the failure probability of the joint, the infl uence of human error to detect cracks during the inspection is considered. Five cases of the probability of crack detection are assumed to represent the capability of the inspector. It was found that bridge inspection and reparation of cracks are important in controlling the failure probability.

Fatigue Crack Growth Characteristics of Several Kinds of Structural Steels Under Low-Cycle Fatigue Loading

Chao Jiang,Takeshi Hanji,Kazuo Tateishi,Masaru Shimizu 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.1

Because low-cycle fatigue is one of the failure modes in steel structures during earthquakes, crack growth prediction in the low-cycle fatigue region has become an important factor in the evaluation of the seismic performance of steel structures. This study conducted fatigue crack growth tests with several kinds of structural steels to clarify their crack growth behaviour in the low-cycle fatigue region. These tests employed an elastic compliance technique usually used in the high-cycle fatigue region to determine crack size. Before applying the elastic compliance method to a low-cycle fatigue crack growth test, a correlation between specimen load-line crack-opening elastic compliance and crack size was analytically derived. The test results indicated that crack sizes obtained by the elastic compliance method agree relatively well with those actually measured from images. Moreover, it was revealed that the crack growth rate can be correlated with the cyclic J-integral range calculated by finite element analysis, and that the relationships between the crack growth rate and the cyclic J-integral range are similar regardless of the steel type.