• Title/Summary/Keyword: Push-out test

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COMPARISON OF BOND STRENGTH OF A FIBER POST CEMENTED WITH VARIOUS RESIN CEMENTS (다양한 레진시멘트로 합착한 섬유포스트의 결합강도 비교)

  • Lee, Hyun-A;Cho, Young-Gon
    • Restorative Dentistry and Endodontics
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    • v.33 no.6
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    • pp.499-506
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    • 2008
  • The purpose of this study was to compare the push-out strength of a fiber post cemented with various resin cements. Newly extracted 36 human mandibular premolars which had single root canal were selected and their crown portions were removed. The root canal was instrumented using $PROTAPER^{TM}$ system and obturated using continuous wave technique. In each root, a 9-mm deep post space was prepared. #2 translucent fiber post (DT Light post, Bisco Inc., Schaumburg, IL, U.S.A.) was cemented using injection technique with Uni-dose needle tip (Bisco) and six different resin cements. The tested resin cements were Duo-Link (Bisco Inc., Schaumburg, IL, U.S.A.), Variolink II (Ivoclar-Vivadent AG, Schann, Liechtenstein), Panavia F (Kuraray Medical Inc., Okayama, Japan), Multilink Automix (Ivoclar-Vivadent AG, Schann, Liechtenstein), RelyX Unicem (3M ESPE Dental Products, St. Paul, MN, U.S.A.), and Maxcem (Kerr Co., CA, U.S.A.). After storage in distilled water for 24 hours, each root was transversally sectioned into approximately 1-mm thick sections. This procedure resulted in 6 serial sections per root. Push-out test wasperformed using a universal testing machine (EZ Test, Shimadzu Co.) with a crosshead speed of 1 mm/min. The data were analyzed with one-way ANOVA and Tukey HSD (p=0.05). The push-out strength of the groups which cemented fiber post with Panavia F and Multilink Automix were lower than those of the other groups. But, there were no statistically significant difference among groups at a probability level of 0.05.

A Study on the Slip Test of Shear Connector in Fire (전단 연결재의 고온 성능 평가에 관한 연구)

  • Han, Sang-Hoon;Park, Won-Sup;Lee, Choul-Ho
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2008.04a
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    • pp.48-51
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    • 2008
  • Shear connector is the element which resist in the horizontal shear force between steel and concrete of composite members and the stud bolt is often used because of its constructional convenience and serviceability. Although the push-out test is the most common method to evaluate shear slip behaviour, it is suitable for only room temperature conditions. In this study, we investigated about shear force, temperature distribution and slip displacement of shear connector in high temperature through the modified push-out test with electronic furnace invented for steel part heating.

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Investigation of pipe shear connectors using push out test

  • Nasrollahi, Saeed;Maleki, Shervin;Shariati, Mahdi;Marto, Aminaton;Khorami, Majid
    • Steel and Composite Structures
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    • v.27 no.5
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    • pp.537-543
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    • 2018
  • Mechanical shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface in composite beams. Steel pipe as a new shear connector is proposed in this research and its performance to achieve composite strength is investigated. Experimental monotonic push-out tests were carried out for this connector. Then, a nonlinear finite element model of the push-out specimens is developed and verified against test results. Further, the finite element model is used to investigate the effects of pipe thickness, length and diameter on the shear strength of the connectors. The ultimate strengths of these connectors are reported and their respective failure modes are discussed. This paper comprises of the push-out tests of ten specimens on this shear connector in both the vertical and horizontal positions in different reinforced concretes. The results of experimental tests are given as load-deformation plots. It is concluded that the use of these connectors is very effective and economical in the medium shear demand range of 150-350 KN. The dominant failure modes observed were either failure of concrete block (crushing and splitting) or shear failure of pipe connector. It is shown that the horizontal pipe is not as effective as vertical pipe shear connector and is not recommended for practical use. It is shown that pipe connectors are more effective in transferring shear forces than channel and stud connectors. Moreover, based on the parametric study, a formula is presented to predict the pipe shear connectors' capacity.

Experimental studies of headed stud shear connectors in UHPC Steel composite slabs

  • Gao, Xiao-Long;Wang, Jun-Yan;Yan, Jia-Bao
    • Structural Engineering and Mechanics
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    • v.74 no.5
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    • pp.657-670
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    • 2020
  • Due to the high compressive and tensile strength of ultra-high performance concrete (UHPC), UHPC used in steel concrete composite structures provided thinner concrete layer compared to ordinary concrete. This leaded to the headed stud shear connectors embedded in UHPC had a low aspect ratio. In order to systematic investigate the effect of headed stud with low aspect ratio on the structural behaviors of steel UHPC composite structure s this paper firstly carried out a test program consisted of twelve push out specimens. The effects of stud height, aspect ratio and reinforcement bars in UHPC on the structural behaviors of headed studs were investigated. The push out test results shows that the increasing of stud height did not obviously influence the structural behaviors of headed studs and the aspect ratio of 2.16 was proved enough to take full advantage of the headed stud strength. Based on the test results, the equation considering the contribution of weld collar was modified to predict the shear strength of headed stud embedded in UHPC. The modified equation could accurately predict the shear strength of headed stud by comparing with the experimental results. On the basis of push out test results, bending tests consisted of three steel UHPC composite slabs were conducted to investigate the effect of shear connection degree on the structural behaviors of composite slabs. The bending test results revealed that the shear connection degree had a significantly influence on the failure modes and ultimate resistance of composite slabs and composite slab with connection degree of 96% in s hear span exhibited a ductile failure accompanied by the tensile yield of steel plate and crushing of UHPC. Finally, analytical model based on the failure mode of composite slabs was proposed to predict the ultimate resistance of steel UHPC composite slabs with different shear connection degrees at the interface.

Effect of different adhesive systems and post surface treatments on the push-out bond strengths of fiber-reinforced post (다양한 접착 시스템 및 포스트의 표면 처리가 섬유 강화 포스트의 접착 강도에 미치는 영향)

  • Kim, Min-Woo;Ahn, Jin-Hee;Kim, Lee-Kyoung;Shim, Hye-Won
    • The Journal of Korean Academy of Prosthodontics
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    • v.54 no.3
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    • pp.218-225
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    • 2016
  • Purpose: The purpose of this study was to evaluate the push-out bond strength of glass-fiber post cemented with different adhesive systems and surface treatments. Materials and methods: 160 tooth samples made from 48 human maxillary single-rooted teeth with similar root length were divided into 4 groups according to the adhesive system (no adhesive, Adper Single Bond 2, Clearfil SE Bond, Clearfil S3). Each group had 4 subgroups according to the post surface treatment methods (no treatment, sandblast, silane, sandblast and silane). Posts (Parapost Fiber White) were cemented with Rely X Unicem. The teeth were sectioned perpendicular to their long axis into 1-mm thick sections. The push-out tests was performed at a speed of 0.5 mm/min. The results were evaluated by 2-way ANOVA, 1-way ANOVA and multiple comparison procedures (Tukey test) (${\alpha}=0.05$). Results: Tukey test showed that the adhesive system significantly influenced the push-out strength. The Clearfil SE Bond group showed the highest value. Post surface treatments showed no significant effect. Conclusion: Bond strength of glass-fiber post cemented with self-adhesive resin cement using Clearfil SE Bond showed significantly higher values compared to other adhesive systems.

Evaluation of Shear Strength of Perfobond Rib in Ultra High Performance Concrete (초고성능 콘크리트에 대한 Perfobond Rib 전단연결재 거동 평가)

  • Kang, Jae-Yoon;Jung, Woo-Tai
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.7
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    • pp.5015-5020
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    • 2015
  • Push-out test is performed on perfobond shear connectors applying ultra high performance concretes with compressive strength higher than 80 MPa to evaluate their shear resistance. The test variables are chosen to be the diameter and number of dowel holes and, the change in the shear strength of the perfobond rib connector is examined with respect to the strength of two types of UHPC: steel fiber-reinforced concrete with compressive strength of 180 MPa and concrete without steel fiber with compressive strength of 80 MPa. The test results reveal that higher concrete strength and larger number of holes increased the shear strength, and that higher increase rate in the shear strength was achieved by the dowel action.

Study on push-out test and bond stress-slip relationship of circular concrete filled steel tube

  • Yin, Xiaowei;Lu, Xilin
    • Steel and Composite Structures
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    • v.10 no.4
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    • pp.317-329
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    • 2010
  • According to the results of 9 circular concrete filled steel tube (CFT) push-out tests, a new theoretical model for average bond stress versus free end slip curve is proposed. The relationship between verage bond stress and free end slip is obtained considering some varying influential parameters such as slenderness ratio and diameter-to-thickness ratio. Based on measured steel tube strain and relative slip at different longitudinal positions, the distribution of bond stress and relative slip along the length of steel tube is obtained. An equation for predicting the varying bond-slip relationship along longitudinal length and a position function reflecting the variation are proposed. The presented method can be used in the application of finite element method to analyze the behavior of CFT structures.

Fatigue strength of stud shear connector considering bedding layer thickness in precast deck composite bridges (프리캐스트 바닥판 합성형 교량에서의 베딩층의 두께를 고려한 전단연결재의 피로강도)

  • Ryu, Hyung Keun;Shim, Chang Su;Chung, Chul Hun;Chang, Sung Pil
    • Journal of Korean Society of Steel Construction
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    • v.14 no.1
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    • pp.113-120
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    • 2002
  • A shear connection in composite bridges with precast decks has considerable characteristics different from cast-in-place deck bridges such as shear pocket and bedding layer. Thus, it is necessary to build design basis of the shear connector in precast decks through the experiments. In order to estimate fatigue life of shear connector in precast deck bridges, push-out fatigue tests were conducted with parameter, bedding layer thickness. As a result of the tests, failure modes of shear connector were observed. Consequently, empirical S-N curve equations of stud shear connector in precast deck bridges were proposed in this paper.

The effect of individualization of fiberglass posts using bulk-fill resin-based composites on cementation: an in vitro study

  • Lins, Rodrigo Barros Esteves;Cordeiro, Jairo Matozinho;Rangel, Carolina Perez;Antunes, Thiago Bessa Marconato;Martins, Luis Roberto Marcondes
    • Restorative Dentistry and Endodontics
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    • v.44 no.4
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    • pp.37.1-37.10
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    • 2019
  • Objectives: This study evaluated the bond strength of various fiberglass post cementation techniques using different resin-based composites. Materials and Methods: The roots from a total of 100 bovine incisors were randomly assigned to 5 treatment groups: G1, post + Scotchbond Multi-Purpose (SBMP) + RelyX ARC luting agent; G2, relined post (Filtek Z250) + SBMP + RelyX ARC; G3, individualized post (Filtek Z250) + SBMP; G4, individualized post (Filtek Bulk-Fill) + SBMP; G5, individualized post (Filtek Bulk-Fill Flow) + SBMP. The samples were subjected to the push-out (n = 10) and pull-out (n = 10) bond strength tests. Data from the push-out bond strength test were analyzed using 2-way analysis of variance (ANOVA) with the Bonferroni post hoc test, and data from the pull-out bond strength test were analyzed using 1-way ANOVA. Results: The data for push-out bond strength presented higher values for G2 and G5, mainly in the cervical and middle thirds, and the data from the apical third showed a lower mean push-out bond strength in all groups. No significant difference was noted for pull-out bond strength among all groups. The most frequent failure modes observed were adhesive failure between dentine and resin and mixed failure. Conclusions: Fiberglass post cementation using restorative and flowable bulk-fill composites with the individualization technique may be a promising alternative to existing methods of post cementation.

Shear capacity equation for channel shear connectors in steel-concrete composite beams

  • Paknahad, Masoud;Shariati, Mahdi;Sedghi, Yadollah;Bazzaz, Mohammad;Khorami, Majid
    • Steel and Composite Structures
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    • v.28 no.4
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    • pp.483-494
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    • 2018
  • In this research the effect of high strength concrete (HSC) on shear capability of the channel shear connectors (CSC) in the steel concrete composite floor system was estimated experimentally and analytically. The push-out test was carried out for assessing the accurateness of the proposed model (nonlinear and finite element model) for the test specimens. A parametric analysis was conducted for predicting the shear capacity of the connectors (CSC) in the HSC. Eight push-out specimens of different sizes with different strength levels were tested under the monotonic loading system. The aim of this study was to evaluate the efficacy of the National Building Code of Canada (NBC) of Canada for analysing the loading abilities of the CSC in the HSC. Using the experimental tests results and verifying the finite element results with them, it was then confirmed by the extended parametric studies that the Canadian Design Code was less efficient for predicting the capacity of the CSC in the HSC. Hence, an alternative equation was formulated for predicting the shear capacity of these connectors during the inclusion of HSC for designing the codes.