• Title/Summary/Keyword: Push-out test

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Push out tests on various shear connectors used for cold-formed steel composite beam

  • Rajendran, Senthilkumar;Perumalsamya, Jayabalan;Mohanraj, Divya
    • Steel and Composite Structures
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    • v.42 no.3
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    • pp.315-323
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    • 2022
  • Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self-tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

Deterioration in strength of studs based on two-parameter fatigue failure criterion

  • Wang, Bing;Huang, Qiao;Liu, Xiaoling
    • Steel and Composite Structures
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    • v.23 no.2
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    • pp.239-250
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    • 2017
  • In the concept of two-parameter fatigue failure criterion, the material fatigue failure is determined by the damage degree and the current stress level. Based on this viewpoint, a residual strength degradation model for stud shear connectors under fatigue loads is proposed in this study. First, existing residual strength degradation models and test data are summarized. Next, three series of 11 push-out specimen tests according to the standard push-out test method in Eurocode-4 are performed: the static strength test, the fatigue endurance test and the residual strength test. By introducing the "two-parameter fatigue failure criterion," a residual strength calculation model after cyclic loading is derived, considering the nonlinear fatigue damage and the current stress condition. The parameters are achieved by fitting the data from this study and some literature data. Finally, through verification using several literature reports, the results show that the model can better describe the strength degradation law of stud connectors.

A Newly Designed Miniplate Staple for High Tibial Osteotomy (근위골절술을 위한 Staple 설계)

  • Mun, Mu-Seong;Bae, Dae-Kyung
    • Proceedings of the KOSOMBE Conference
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    • v.1995 no.05
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    • pp.19-22
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    • 1995
  • A biomechanical study was made to demonstrate the superior mechanical performance of the newly designed Miniplate staple to the conventional Coventry staple in high tibial osteotomy(HTO). Using twenty fresh porcine tibiae, the fixational strengh of the two different types of staple in HTO was compared. To minimize the error due to the specimen-to-specimen individuality, the bone mineral density of the tibiae was measured with a bone densitometry (Dual photon absorptionometer, Luner, USA) and those with $0.8\;{\sim}\;1.2\;gm/cm^2$ at the proximal tibia was used in the biomechanical test. Testing was performed on a material testing system (Autogram ET-5, Shimatzu, Japan) with aid of a commercial data processor (IBM 80386/ ASYST). Using two differant loading modes, 'pull-out' and 'push-out', the maximum resistant force required to release the staple from the substrate bone was recorded. In the pull-out test, ten non-osteotomized specimens were used and the staple was pullout by subjecting an axial tension on the head of the staple inserted. While in the pull-out test where ten tibiae osteotomized in the usual way of HTO were used, the staple was not directly loaded. In this testing, as a mimic condition of the natural knee, the distal part of the specimen tibia was pushed horizontally in order for the staple to be pulled out while the proximal tibia was fixed. The pull-out strength of Coventry staple and miniplate staple were found to be $27.88\;{\pm}\;5.12\;kgf$ and $182.47\;{\pm}\;32.75\;kgf$, respectively. The push-out strength of Coventry staple and miniplate staple were $18.40\;{\pm}\;4.47\;kgf$ and $119.95\;{\pm}\;19.06\;kgf$, respectively. The result revealed that miniplate staple had the pull-out/ push-out strength at least fivetimes higher than Coventry staple. Based on the measured data, it was believed that the newly designed miniplate staple could provide much better postoperative fixation in HTO. The postoerative application of long leg casting may not be needed after HTO surgery.

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Interfacial shear resistance of angle shear connectors welded to concrete filled U-shaped CFS beam

  • Oh, Hyoung Seok;Shin, Hyeongyeop;Ju, Youngkyu;Kang, Thomas H.K.
    • Steel and Composite Structures
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    • v.43 no.3
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    • pp.311-325
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    • 2022
  • For multi-story structural systems, Korean steel industry has fostered development of a steel-concrete composite beam. Configuration of the composite beam is characterized by steel angle shear connectors welded to a U-shaped cold formed-steel beam. Effects of shear connector orientation and spacing were studied to evaluate current application of the angle shear connector design equation in AC495. For the study, interfacial shear resistance behavior was investigated by conducting 24 push-out tests and attuned using unreinforced push-out specimens. Interfacial shear to horizontal slip response was reported along with corresponding failure patterns. Pure shear connector strength was also evaluated by excluding concrete shear contribution, which was estimated in relation to steel beam-slab interface separation or interfacial crack width.

Shear Stiffness of Shear connections in Full-Depth Precast Concrete Deck Bridge (프리캐스트 바닥판 교량 전단연결부의 전단강성)

  • Shim, Chang Su;Chung, Chul Hun;Kim, Chul Young;Chang, Sung Pil
    • Journal of Korean Society of Steel Construction
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    • v.10 no.4 s.37
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    • pp.749-758
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    • 1998
  • The evaluation of shear stiffness of shear connection in composite bridges with CIP concrete deck is analysed. Shear stiffness of shear connection in full-depth precast concrete deck bridges is obtained from experiments. 3-dimensional finite element analyses of push-out specimen are carried out to investigate the effects of characteristics of filling material strength in shear connection on shear stiffness and local stress distribution. The load-slip relations obtained from the analyses are compared with those of experiments. The equation of initial shear stiffness of shear connection in precast concrete deck bridge is proposed. Linear analyses are performed to evaluate the effects of the shank diameter of shear connector and the strength of mortar on the characteristics of deterioration and failure load obtained by the failure criterions of each material. The failure loads are estimated and compared with test results.

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Estimation of Shear Strength of RC Shear Connection for the Steel-Concrete Composite Girder (강합성 거더용 철근콘크리트 전단연결체의 전단강도 평가)

  • Shin, Hyun Seop;You, Young Jun;Jeong, Youn Ju;Eom, In Su
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.3A
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    • pp.229-239
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    • 2010
  • For the purpose of improvement of the load carrying capacity and constructibility of the conventional steel-concrete composite girder through a effective appliance of the construction materials and optimization of the girder section, a new type section of composite girder and RC shear connection were proposed. In this study shear strength of the RC shear connection is estimated, and the characteristics of shear load-slip behaviour is analyzed. Push-out tests on shear specimens and FEM analysis with various design parameters are carried out, and results are analyzed. The results of test and FEM analysis showed that shear strength of RC shear connection is underestimated by the design provisions of the current design code. By regression analysis a empirical equation for the estimation of shear strength of RC shear connection is proposed.

Experimental investigation of shear connector behaviour in composite beams with metal decking

  • Qureshi, Jawed;Lam, Dennis
    • Steel and Composite Structures
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    • v.35 no.4
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    • pp.475-494
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    • 2020
  • Presented are experimental results from 24 full-scale push test specimens to study the behaviour of composite beams with trapezoidal profiled sheeting laid transverse to the beam axis. The tests use a single-sided horizontal push test setup and are divided into two series. First series contained shear loading only and the second had normal load besides shear load. Four parameters are studied: the effect of wire mesh position and number of its layers, placing a reinforcing bar at the bottom flange of the deck, normal load and its position, and shear stud layout. The results indicate that positioning mesh on top of the deck flange or 30 mm from top of the concrete slab does not affect the stud's strength and ductility. Thus, existing industry practice of locating the mesh at a nominal cover from top of the concrete slab and Eurocode 4 requirement of placing mesh 30 mm below the stud's head are both acceptable. Double mesh layer resulted in 17% increase in stud strength for push tests with single stud per rib. Placing a T16 bar at the bottom of the deck rib did not affect shear stud behaviour. The normal load resulted in 40% and 23% increase in stud strength for single and double studs per rib. Use of studs only in the middle three ribs out of five increased the strength by 23% compared to the layout with studs in first four ribs. Eurocode 4 and Johnson and Yuan equations predicted well the stud strength for single stud/rib tests without normal load, with estimations within 10% of the characteristic experimental load. These equations highly under-estimated the stud capacity, by about 40-50%, for tests with normal load. AISC 360-16 generally over-estimated the stud capacity, except for single stud/rib push tests with normal load. Nellinger equations precisely predicted the stud resistance for push tests with normal load, with ratio of experimental over predicted load as 0.99 and coefficient of variation of about 8%. But, Nellinger method over-estimated the stud capacity by about 20% in push tests with single studs without normal load.

Study on Fire Performance of Stud Connectors (스터드커넥터의 내화성능에 관한 연구)

  • Kim, Sung-Bae;Han, Sang-Hoon;Choi, Seng-Kwan
    • Fire Science and Engineering
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    • v.23 no.4
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    • pp.59-66
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    • 2009
  • This research aims to conduct a pilot study for the in-fire performance of headed studs, commonly used in composite structures over the world. The robustness of the shear studs in fire appears to be a key element to govern the composite behaviour after a sudden local instability developed in structures such as trusses and cellular beams. In order to experimentally evaluate the residual strength of studs in fire, the standard push-out test was modified for a half of the original set-up to be equipped with a furnace. The adjustments allow the steel section to have a 3-sided exposure against fire. Under the Standard ISO fire, the modified push-out tests under loading were conducted to identify the failure mechanism of the studs in relation to temperature developments.

Push-out Performance Test of Composite Steel Truss Deck using Light Weight Concrete (경량콘크리트를 사용한 합성 철선트러스 데크의 푸쉬 아웃 성능 실험)

  • Choi, Byong Jeong;Moon, Hyo Jin;Han, Hong Soo;Han, Kweon Gyu
    • Journal of Korean Society of Steel Construction
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    • v.21 no.1
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    • pp.15-26
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    • 2009
  • Push-out tests were performed to evaluate the shear capacity of a composite steel truss deck slab system, called an automatic prefabrication bar-mesh system, using lightweight concrete. The six specimens were classified into three groups: DP, NDP, and Solid, according to the variations between the bar mesh and the zinc plate automatic prefabrications. This paper focused on the failure behaviors, load-displacement characteristics, and a performance comparison based on design codes.

Experimental shear strength evaluation of perfobond shear connector with various hole shapes

  • Zheng, Shuangjie;Zhao, Chen;Liu, Yuqing
    • Structural Engineering and Mechanics
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    • v.67 no.2
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    • pp.131-142
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    • 2018
  • The perfobond connector, composed of a steel plate with a number of holes, serves as a certain type of shear connector in steel and concrete composite structures. Depending on limits in hole distances and rib heights, various hole shapes including circular-hole and long-hole are alternatives for perfobond connectors. This study presented the results of tests performed on 72 push-out specimens with perfobond connectors. The purpose was to evaluate the shear strength of perfobond connectors with circular-hole and long-hole. The effects of various parameters were investigated, including the hole diameter, the hole length, the hole height, the concrete strength, the existence, diameter and strength of rebar in the hole, the thickness, height and distance of perfobond ribs, and the thickness of concrete slabs. On the basis of 132 push-out test results in references and in this study, an analytical model was proposed by regression analysis to predict the shear strength of perfobond connectors. The proposed equation agreed reasonably well with the experimental results of perfobond connectors with different hole shapes.