• Title/Summary/Keyword: Shear key

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Horizontal Shear Behavior of Precast Concrete Slab Track on Bridge (교량구간 프리캐스트 콘크리트 슬래브궤도의 수평전단 거동)

  • Jang, Seung-Yup;Na, Sung-Hoon;Kim, Yu-Bong;Ahn, Ki-Hong
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.998-1001
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    • 2011
  • The concrete track on bridge should be designed to effectively cope with the behavior of the bridge superstructure. For this purpose, in general, shear keys are designed to be installed at a certain intervals on the bridge deck, and the track slab is cast on these shear keys to transfer the load induced by the relative displacement between track and bridge. In this study, to apply the precast concrete slab track on bridge, a shear key structure and its effective installation method are presented. Also, the structural behavior of this shear key has been evaluated by the laboratory mock-up test.

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Shear lag prediction in symmetrical laminated composite box beams using artificial neural network

  • Chandak, Rajeev;Upadhyay, Akhil;Bhargava, Pradeep
    • Structural Engineering and Mechanics
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    • v.29 no.1
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    • pp.77-89
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    • 2008
  • Presence of high degree of orthotropy enhances shear lag phenomenon in laminated composite box-beams and it persists till failure. In this paper three key parameters governing shear lag behavior of laminated composite box beams are identified and defined by simple expressions. Uniqueness of the identified key parameters is proved with the help of finite element method (FEM) based studies. In addition to this, for the sake of generalization of prediction of shear lag effect in symmetrical laminated composite box beams a feed forward back propagation neural network (BPNN) model is developed. The network is trained and tested using the data base generated by extensive FEM studies carried out for various b/D, b/tF, tF/tW and laminate configurations. An optimum network architecture has been established which can effectively learn the pattern. Computational efficiency of the developed ANN makes it suitable for use in optimum design of laminated composite box-beams.

Shear failure and mechanical behavior of flawed specimens containing opening and joints

  • Zhang, Yuanchao;Jiang, Yujing;Shi, Xinshuai;Yin, Qian;Chen, Miao
    • Geomechanics and Engineering
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    • v.23 no.6
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    • pp.587-600
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    • 2020
  • Shear-induced instability of jointed rock mass has greatly threatened the safety of underground openings. To better understand the failure mechanism of surrounding rock mass under shear, the flawed specimens containing a circular opening and two open joints are prepared and used to conduct direct shear tests. Both experimental and numerical results show that joint inclination (β) has a significant effect on the shear strength, dilation, cracking behavior and stress distribution around flaws. The maximum shear strength, occurring at β=30°, usually corresponds to a unifrom stress state around joint and an intense energy release. However, a larger joint inclination, such as β=90°~150°, will cause a more uneven stress distribution and a stronger stress concentration, thus a lower shear strength. The stress distribution around opening changes little with joint inclination, while the magnitude varys much. Both compression and tension around opening will be greatly enhanced by the 30°-joints. In addition, a higher normal stress tends to enhance the compression and suppress the tension around flaws, resulting in an earlier generation and a larger proportion of shear cracks.

Effects of Reinforcing Method Influnced to the Shear Strength of Vertical and Horizontal Joints in Precast Concrete Large Panel Structures -Focused on the Vertical Joints and Slab-Slab Type Horizontal Joints- (대형판조립식 구조 수직.수평접합부의 전단강도에 미치는 보강방법의 영향-수직접합부 및 슬래브-슬래브 수평접합부를 중심으로-)

  • Chung, Lan;Park, Hyun-Soo;Cho, Seung-Ho
    • Magazine of the Korea Concrete Institute
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    • v.8 no.4
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    • pp.171-179
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    • 1996
  • A proposal of the basic fbrm on the design of joint parts that can increase the shear strength by the useful joint shapes of each member is intended. The vertical joint parameters are the number of' shear key and a variety of' reinfbrcement details and the horizontal joint paramctcrs arc t,hc number of shear key and the direction of' shear f'orcc. 10 PC panel vortical joint arid 12 PC panel horizontal joint specimens were tested to investigate the effects of these parameters. Test results show that : 1. The ductility of the test specimen that has the horizontal reinforcing steels is larger than that does not have. 2. The maximum resisting force of round bar specimen is similar to that of strand wire specimen under the condition of fixed horizontal displacement.

Shear strength analyses of internal diaphragm connections to CFT columns

  • Kang, Liping;Leon, Roberto T.;Lu, Xilin
    • Steel and Composite Structures
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    • v.18 no.5
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    • pp.1083-1101
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    • 2015
  • Previous theoretical equations for the shear capacity of steel beam to concrete filled steel tube (CFT) column connections vary in the assumptions for the shear deformation mechanisms and adopt different equations for calculating shear strength of each component (steel tube webs, steel tube flanges, diaphragms, and concrete etc.); thus result in different equations for calculating shear strength of the joint. Besides, shear force-deformation relations of the joint, needed for estimating building drift, are not well developed at the present. This paper compares previously proposed equations for joint shear capacity, discusses the shear deformation mechanism of the joint, and suggests recommendations for obtaining more accurate predictions. Finite element analyses of internal diaphragm connections to CFT columns were carried out in ABAQUS. ABAQUS results and theoretical estimations of the shear capacities were then used to calibrate rotational springs in joint elements in OpenSEES simulating the shear deformation behavior of the joint. The ABAQUS and OpenSEES results were validated with experimental results available. Results show that: (1) shear deformation of the steel tube dominates the deformation of the joint; while the thickness of the diaphragms has a negligible effect; (2) in OpenSEES simulation, the joint behavior is highly dependent on the yielding strength given to the rotational spring; and (3) axial force ratio has a significant effect on the joint deformation of the specimen analyzed. Finally, modified joint shear force-deformation relations are proposed based on previous theory.

A Numerical Study on the Two-Phase Natural Circulation Flow in Reactor Cavity under External Vessel Cooling (원자로 외벽냉각시 원자로공동에서의 자연순환 이상유동에 대한 수치적 연구)

  • Kim, Hong-Min;Seo, Jun-Woo;Kim, Kwang-Yong;Park, Rae-Joon;Ha, Kwang-Soon;Kim, Sang-Baik
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.781-785
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    • 2003
  • This work presents a numerical analysis of two-phase natural circulation flow in reactor cavity under external vessel cooling. Steady, incompressible, three-dimensional Reynolds-averaged Navier-Stokes equations for multiphase flows with zero equation turbulence model are solved to predict the shear key effect on the circulation rate of cooling water and the distribution of void fraction according to the different mass flow of inlet air. Results show that shear key has a positive effect on the circulation rate of cooling water and induce a local increase of void fraction below the shear key, but not remarkably.

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Behavior of Segments in Precast Prestressed Concrete Hollow Slab Bridges (프리캐스트 프리스트레스트 콘크리트 중공슬래브 교량의 분절거동)

  • Lee Ho Jun;Byun Kun Joo;Song Ha-Won;Kim Ho Jin;Kim Yun Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.43-46
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    • 2005
  • Precast prestressed concrete hollow slab bridge is one of segmented bridge which can be long span, so that the structural behavior of joints of adjacent segment should be evaluated by the analysis as well as experiment. In this study, small scaled beam tests were carried out to determine joint shear key shape and restraint stress by prestressing. From the tests and the analysis, it was found that the joint key shape and the restraint stress affect the behavior of segments and the segments which has the height to the width of shear key as 1/3 possess maximum shear resistance.

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Shear strength of match-cast-free dry joint in precast girders

  • Jiang, Haibo;Feng, Jiahui;Xiao, Jie;Chen, Mingzhu;Liang, Weibin
    • Computers and Concrete
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    • v.26 no.2
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    • pp.161-173
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    • 2020
  • Shear keys in precast concrete segmental bridges (PCSBs) are usually match-casting which is very labour intensive. In this research, an innovative match-casting-free construction was proposed by leaving small gap between the convex and the concave castellated shear keys in the joints of PCSBs. Specimen experiment, shear strength analysis and numerical simulation were conducted, investigating the loading performance of this new type of dry joints, the gap dry joints. Compared with match-casting joint specimens, it has been found from experiment that shear capacity of gap joint specimens significantly decreased ranging from 17.75% to 42.43% due to only partially constrained and contacted in case of gap dry joints. Through numerical simulation, the effects of bottom contacting location, the heights of the gap and the shear key base were analyzed to investigate strength reduction and methods to enhance shear capacity of gap joint specimens. Numerical results proved that shear capacity of gap dry joints under full contact condition was higher than that under partial contact. In addition, left contact destroyed the integrity of shear keys, resulting in significant strength reduction. Larger shear key base remarkably increased shear capacity of the gap joint. Experimental tests indicated that AASHTO provision underestimated shear capacity of the match-casting dry joint specimens, while the numerical results for the gap dry joint showed that AASHTO provision underestimated shear capacity of full contact specimens, but overestimated that of left contact specimens.

Estimation of the load-deformation responses of flanged reinforced concrete shear walls

  • Wang, Bin;Shi, Qing-Xuan;Cai, Wen-Zhe;Peng, YI-Gong
    • Structural Engineering and Mechanics
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    • v.73 no.5
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    • pp.529-542
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    • 2020
  • As limited well-documented experimental data are available for assessing the attributes of different deformation components of flanged walls, few appropriate models have been established for predicting the inelastic responses of flanged walls, especially those of asymmetrical flanged walls. This study presents the experimental results for three large-scale T-shaped reinforced concrete walls and examines the variations in the flexural, shear, and sliding components of deformation with the total deformation over the entire loading process. Based on the observed deformation behavior, a simple model based on moment-curvature analysis is established to estimate flexural deformations, in which the changes in plastic hinge length are considered and the deformations due to strain penetration are modeled individually. Based on the similar gross shapes of the curvature and shear strain distributions over the wall height, a proportional relationship is established between shear displacement and flexural rotation. By integrating the deformations due to flexure, shear, and strain penetration, a new load-deformation analytical model is proposed for flexure-dominant flanged walls. The proposed model provides engineers with a simple, accurate modeling tool appropriate for routine design work that can be applied to flexural walls with arbitrary sections and is capable of determining displacements at any position over the wall height. By further simplifying the analytical model, a simple procedure for estimating the ultimate displacement capacity of flanged walls is proposed, which will be valuable for performance-based seismic designs and seismic capacity evaluations.

Key factors affecting the shear behaviour of exterior RC beam-column joints

  • Ricardo, Costa;Paulo, Providencia
    • Structural Engineering and Mechanics
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    • v.85 no.3
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    • pp.353-367
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    • 2023
  • An extended parametric study based on nonlinear finite element analyses is performed to assess the key factors affecting the shear behaviour of exterior beam-column joints of unbraced reinforced concrete frames. Extensive results are presented, the major conclusion being that the few shear behaviour models for exterior reinforced concrete beam-column joints available in the literature do not properly account for some of the most influential factors. The present results are also compared with recently published results for interior joints, showing that while some factors have a similar influence on interior and exterior joints others are relevant for only one of these types of joints. This also confirms, numerically, that some resisting mechanisms of exterior joints differ from those of interior joints.