• Title, Summary, Keyword: shear design

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High-strength concrete deep beams with web openings strengthened by carbon fiber reinforced plastics

  • Lu, Wen-Yao;Yu, Hsin-Wan;Chen, Chun-Liang;Liu, Shen-Lung;Chen, Ting-Chou
    • Computers and Concrete
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    • v.15 no.1
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    • pp.21-35
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    • 2015
  • The objective of this study is to examine the effect of carbon fiber reinforced polymer (CFRP) on the shear strengths of deep beams with web openings. A total of 18 high-strength concrete deep beams with web openings were tested. Twelve were externally wrapped with four layers of CFRP, six of them strengthened in the horizontal direction and the others in the vertical direction. The parameters of the configuration of CFRP, the sizes of the openings and the locations of the openings were covered in this study. The test results indicates the shear strengths of deep beams with openings sized $60{\times}40mm$ were about 16% higher than that with openings sized $68{\times}68mm$. For deep beams with openings sized $60{\times}40mm$, the lower the locations of openings the higher the shear strengths were. The test results also indicate the shear strengths of deep beams with web openings strengthened by CFRP wrapped in the vertical direction can be enhanced by about 10%. However, the shear strengths of deep beams with web openings strengthened by CFRP wrapped in the horizontal direction can only be enhanced by about 6%. The shear strengths of deep beam, with different size and location of web openings and strengthened by different configuration of CFRP can be reasonably predicted by the empirical formulas of Kong and Sharp.

Shear Experiments on Concrete Filled PHC Pile with Composite Shear Connectors with Rebar Holes (보강 철근 정착 홀을 갖는 합성 전단연결재를 적용한 콘크리트 충전 PHC말뚝의 전단성능 평가)

  • Kim, Jeong-Hoi;Park, Young-Shik;Min, Chang-Shik
    • Journal of the Korea Concrete Institute
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    • v.29 no.3
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    • pp.259-266
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    • 2017
  • The purpose of this study was to contribute to the field application cost effectively and reasonably by developing the functional piles that reinforces shear force. CFP pile (Concrete Filled Pretensioned Spun High Strength Concrete Pile with Ring type Composite shear connectors) developed in this study increases the shear stress by placing composite shear connector and filling the concrete into hollow part of the pile. By placing the reinforcement (H13-8ea) and the reinforcement (H19-8ea) into hollow section inside of PHC piles, it also improves the shear strength due to increasing steel ratio. It reinforces shear strength effectively by dowel force that is generated by putting reinforcement (H13-8) into the holes of composite shear connectors for the composite behavior of filled concrete and PHC pile. The study was reviewed and compared the calculated result of the shear strength by limit state design method highway bridge design standards (2012) and experiment result of the shear strength by KS F 4306. We can design the shear strength reasonably as the safety ratio of 2.20, 2.15, 2.05 is shown comparing to design shear strength, according to design shear strength on each cross sections and the experiment results of the CFP pile.

Shear Strength of Hybrid Beams Combining Precast Concrete and Cast-In-Place Concrete (프리캐스트 콘크리트와 현장타설 콘크리트 복합 보의 전단강도)

  • Kim, Chul-Goo;Park, Hong-Gun;Hong, Geon-Ho;Kang, Su-Min
    • Journal of the Korea Concrete Institute
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    • v.25 no.2
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    • pp.175-185
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    • 2013
  • Currently in precast concrete construction, precast concrete and cast-in-place concrete with different concrete strengths are used. However, current design codes do not provide shear design methods for PC-CIP hybrid members using dual concrete strengths. In the present study, the shear strengths of beams using dual concrete compressive strengths (24 MPa, 60 MPa) were tested. The test variables were the area ratio of the two concretes, longitudinal bar ratio, and shear span-to-depth ratio. The shear strengths of test specimens were evaluated by current design methods, using an effective concrete strength (considering the area ratio of the two concrete strengths). The test result showed that when 60 MPa concrete was used in the compressive zone and the longitudinal bar ratio was low, the shear strengths of the test specimens were less than the predictions. On the basis of the results, design recommendations were provided for the shear design of the PC-CIP hybrid beams.

Fatigue Behavior of Large Stud Shear Connectors (대직경 스터드 전단연결재의 피로거동)

  • Shim, Chang Su;Lee, Pil Goo;Kim, Hyun Ho;Yoon, Tae Yang
    • Journal of Korean Society of Steel Construction
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    • v.15 no.6
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    • pp.621-628
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    • 2003
  • Stud shear connectors are the most commonly used shear connectors: up to 22mm studs are usually used in steel-concrete composite structures. To expand the current design codes for stud connectors, large studs with a diameter of more than 25mm should be investigated. Through push-out tests on large stud shear connectors that transcend the limitation of current design codes, fatigue behavior was investigated and comparisons with design equations performed. The shear stiffness of the connectors in elastic range was evaluated through shear tests on 25mm, 27mm, and 30mm studs and compared with those from static tests. The fatigue behavior of large studs was discussed in terms of residual slip and load-slip curves. The initiation of fatigue cracks in the welding part could be detected through the history of displacement range. Test results showed that the design fatigue endurance of S-N curves in current design codes could be applied to large stud shear connector.

Seismic resistance and mechanical behaviour of exterior beam-column joints with crossed inclined bars

  • Bakir, P.G.
    • Structural Engineering and Mechanics
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    • v.16 no.4
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    • pp.493-517
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    • 2003
  • Attempts at improving beam-column joint performance has resulted in non-conventional ways of reinforcement such as the use of the crossed inclined bars in the joint area. Despite the wide accumulation of test data, the influence of the crossed inclined bars on the shear strength of the cyclically loaded exterior beam-column joints has not yet been quantified and incorporated into code recommendations. In this study, the investigation of joints has been pursued on two different fronts. In the first approach, the parameters that influence the behaviour of the cyclically loaded beam-column joints are investigated. Several parametric studies are carried out to explore the shear resisting mechanisms of cyclically loaded beam-column joints using an experimental database consisting of a large number of joint tests. In the second approach, the mechanical behaviour of joints is investigated and the equations for the principal tensile strain and the average shear stress are derived from joint mechanics. It is apparent that the predictions of these two approaches agree well with each other. A design equation that predicts the shear strength of the cyclically loaded exterior beam-column joints is proposed. The design equation proposed has three major differences from the previously suggested design equations. First, the influence of the bond conditions on the joint shear strength is considered. Second, the equation takes the influence of the shear transfer mechanisms of the crossed inclined bars into account and, third, the equation is applicable on joints with high concrete cylinder strength. The proposed equation is compared with the predictions of the other design equations. It is apparent that the proposed design equation predicts the joint shear strength accurately and is an improvement on the existing code recommendations.

Modified FHWA Design Method Considering Bending Stiffness of Soil Nail (휨강성을 고려한 수정 FHWA 쏘일네일 설계법 제안)

  • Kim, Nak-Kyung;Jung, Jung-Hee;Ju, Yong-Sun;Kim, Sung-Kyu
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1406-1416
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    • 2008
  • Soil nailing is used as a method of slope stabilization and excavation support. The design method of soil nail are based on experience or assumption of interaction between soil and reinforcement. Most design methods simply considers the tension of reinforcement for analysis of slope stabilization. Soil nails interact with soils under combined loading of shear and tension. Jewell & Pedley(1990) suggested a design equation of shear force with bending stiffness and discussed that the magnitude of the maximum shear force is small in comparison with the maximum axal force. However, they have used a very conservative limiting bearing stress on nails. This paper discusses that the shear strength of soil nails should not be disregarded with proper bearing stresses on nails. The modified FHWA design method was proposed by considering shear forces on nails with bending stiffness.

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An Evaluation of ACI 349 Code for Shear Design of CIP Anchor (직매형 앵커기초의 전단설계를 위한 ACI 349 Code의 평가)

  • Jang Jung-Bum;Hwang Kyeong-Min;Suh Yong-Pyo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.464-470
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    • 2005
  • The numerical analysis is carried out to identify the influence of design factors to shear capacity of cast-in-place (CIP) anchor in ACI 349 Code that is available for the design of fastening system at Nuclear Power Plant (NPP) in this study. The MASA program is used to develop the numerical analysis model and the developed numerical analysis model is verified on a basis of the various test data of CIP anchor. Both $l/d_o$ and $c_1/l$ we considered as design factors. As a result, the variation of $l/d_o$ has no influence on the shear capacity of CIP anchor but $c_1/l$ has a large influence on the shear capacity of CIP anchor, Therefore, it is proved that ACI 349 Code may give a non-conservative results compared with real shear capacity of CIP anchor according to $c_1/l$.

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Block Shear Failure : State of the Arts (블록전단파괴 : State of the Arts)

  • Jang, Sun-Jae;Lee, Woo-Chul;Lim, Nam-Hyoung;Lee, Chin-Ok
    • 한국방재학회:학술대회논문집
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    • pp.75-78
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    • 2008
  • Limit states of a tension member are the yielding of gross section, fracture of net section, and block shear failure. Block shear failure is very complicated than other limit state because of interaction of tension and shear failure. Block shear failure is studied continuously since the 1970s. However, failure model to estimate the strength of block shear failure provided in current design specifications is not reflective of the failure mode observed in the various experimental studies. Comparisons between the experimental results and design rules in various specifications about the block shear failure were conducted in this study. Also, the need for further studies of block shear failure were proposed.

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Shear strength of reinforced concrete dapped-end beams

  • Lin, Ing-Jaung;Hwang, Shyh-Jiann;Lu, Wen-Yao;Tsai, Jiunn-Tyng
    • Structural Engineering and Mechanics
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    • v.16 no.3
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    • pp.275-294
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    • 2003
  • In this study, 24 high-strength concrete dapped-end beams were tested to study the effects of the amount of main dapped-end reinforcement, the nominal shear span-to-depth ratio, and the concrete strength on the shear strength of dapped-end beams. Test results indicate that the shear strength of dapped ends increases with the increase in the amount of main dapped-end reinforcement and the concrete strength. The shear strength of dapped-end beam increases with the decrease of nominal shear span-to-depth ratio. A simplified method for determining the shear strength of reinforced concrete dapped ends is also proposed in this paper. The shear strengths predicted by the proposed method and the approach of PCI Design Handbook are compared with test results. The comparison shows that the proposed method can more accurately predict the shear strength of reinforced concrete dapped-end beams than the approach of PCI Design Handbook.

Shear bond failure in composite slabs - a detailed experimental study

  • Chen, Shiming;Shi, Xiaoyu;Qiu, Zihao
    • Steel and Composite Structures
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    • v.11 no.3
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    • pp.233-250
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    • 2011
  • An experimental study has been carried out to reveal the shear-bond failure mechanism of composite deck slabs. Thirteen full scale simply supported composite slabs are studied experimentally, with the influence parameters like span length, slab depth, shear span length and end anchorage provided by steel headed studs. A dozen of strain gauges and LVDTs are monitored to capture the strain distribution and variation of the composite slabs. Before the onset of shear-bond slip, the longitudinal shear forces along the span are deduced and found to be proportional to the vertical shear force in terms of the shear-bond strength in the m-k method. The test results are appraised using the current design procedures. Based on the partial shear-bond connection at the ultimate state, an improved method is proposed by introducing two reduction factors to assess the moment resistance of a composite deck slab. The new method has been validated and the results predicted by the revised method agree well with the test results.