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Muneyoshi Fujita,Hirotaka Kawano,Tomoaki Kitagawa,Hiroki Iwai,Yuichi Takano,Hirohiko Inanami,Hisashi Koga 대한척추신경외과학회 2019 Neurospine Vol.16 No.1
Objective: Full-endoscopic spine surgery (FESS) is a relatively less invasive treatment for lumbar disc herniation (LDH). This study investigated the optimal operative route of the posterolateral approach (PLA) of FESS for the treatment of L5/S1 LDH. Methods: Between June 2016 and November 2018, a total of 21 patients with leg pain due to L5/S1 LDH underwent PLA of FESS. According to the partial removal of the superior articular process (SAP) of the L5/S1 facet joint (FJ), we categorized these patients into 2 groups. LDH type, anatomical configurations (FJ, sacral ala [SA], and iliac crest [IC]), the presence or absence of spondylolysis, operation time, and operative outcome were compared between these 2 groups. Results: Although the anatomical configuration of the FJ was the most important factor for the necessity of SAP removal, the configuration of the SA and IC did not restrict endoscope insertion and subsequent LDH removal. Even in intracanal LDH, the removal of SAP was not absolutely required depending on the FJ configuration. Furthermore, the presence of spondylolysis was a factor associated with the unnecessity of SAP removal. Conclusion: Detailed radiological examination of the FJ configuration is an important preoperative investigation to determine the optimal operative route for PLA of FESS.
Effect of Compression Overload on Fatigue Strength Improved by ICR Treatment
Toshiyuki Ishikawa,Masaru Shimizu,Hajime Tomo,Hirotaka Kawano,Kentaro Yamada 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.1
ICR (Impact Crack-closure Retrofit) treatment was developed for extending fatigue life of cracked steel structures by closing the fatigue crack opening. By applying the ICR treatment to as-welded condition, compressive stress remains at weld toe. Therefore, ICR treatment can be used for the improvement of fatigue strength of welded joint at the same level of the other fatigue strength improved techniques. If a compression overload is subjected after ICR treatment, however, the residual compressive stress at weld toe will shift the tensile stress region. Accordingly, improved fatigue strength of welded joints by ICR treatment will be reduced after the compression overloaded. In order to investigate the effect of the compression overload on fatigue strength improved by ICR treatment, fatigue tests of out-of-plane gusset specimens were carried out. As the results,fatigue strength improved by ICR treatment was hardly reduced under the compression overload condition of nominal stress of −190 MPa.
Extending Fatigue Life of Out-of-plane Gusset Joint by Bonding CFRP Plates Under Bending Moment
Risa Matsumoto,Toshiyuki Ishikawa,Manabu Takemura,Yoshisato Hiratsuka,Hirotaka Kawano 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4
Carbon fiber reinforced plastic, CFRP, plates bonding method is one of the new repair methods for fatigue cracks. In this method, propagation of fatigue crack will be delay because of the suppression of crack opening by crack bridging and stress reduction by composite effect of bonding CFRP plates. In this study, to clarify the effect of bonding CFRP plates on fatigue life extension, bending fatigue tests were carried out. First, fatigue tests on the specimens in as-welded condition were conducted until fatigue crack propagated to 10mm away from the weld toe. Then, fatigue crack was covered by CFRP plates and the specimens were re-tested until fatigue crack penetrated through the base plate. As the results of bending fatigue tests, the fatigue test data of the specimens repaired by bonding CFRP plates showed much longer fatigue life compared with that in as-welded condition, under stress ratio, R=0 and -infinity.
Experimental Study on Ultimate Strength of Concrete Filled Double Tubular Steel with Shear Connector
Masaru Shimizu,Fumihito Tatsumi,Toshiyuki Ishikawa,Atsushi Hattori,Hirotaka Kawano 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.1
Concrete Filled Tubular steel (CFT) member, which represents a superb deformability due to well-known confined effectbetween steel tube and concrete, has been used mainly as bridge pier. As a progressive composite member, Concrete FilledDouble tubular steel (CFDT), which is consist of double skin steel tubes and filled concrete between them, has been proposed. Although a lot of reports on mechanical characteristics of the CFDT member are presently published, the necessity of shearconnector for the CFDT member has not been addressed. In this research, the shear connector was installed at the interfacebetween tubes and concrete in the CFDT member. To investigate the effect of the shear connector on the bending characteristics,the four points bending test were carried out. The results show that integrating the steel tubes and concrete enhances its bearingcapacity. Furthermore, the strains of outer and inner tubes were also discussed in this paper.
Prediction of Bending Fatigue Life of Cracked Out-of-Plane Gusset Joint Repaired by CFRP Plates
Risa Matsumoto,Takafumi Komoto,Toshiyuki Ishikawa,Atsushi Hattori,Hirotaka Kawano 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.4
Carbon fi ber reinforced polymer (CFRP), plates bonding repair method is one of the simple repair methods for cracked steel structures. In this study, the infl uence of width of CFRP plates on bending fatigue life of out-of-plane gusset joint strengthened with CFRP plates was investigated from the experimental and numerical point of view. In the bending fatigue test of cracked out-of-plane gusset joint strengthened with CFRP plates, the eff ect of width of CFRP plates on crack growth life was clarifi ed experimentally. Namely, it was revealed that the crack growth life becomes larger with increasing the width of CFRP plates. In the numerical approach, the stress intensity factor ( SIF ) at the surface point of a semi-elliptical surface crack was estimated based on the linear fracture mechanics. Furthermore, the extended fatigue life of cracked out-of-plane gusset joint strengthened with CFRP plates was evaluated by using the estimated SIF at the surface point and the empirical formula of the aspect ratio of semi-elliptical crack. As the results of numerical analysis, the estimated fatigue life of the specimen strengthened with CFRP plates showed the good agreement with the test results.