• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.897-902
• /
• 2001

The purpose of this experimental study is to investigate the shear behavior of high-strength concrete deep beam and to grasp the conservatism of ACI Building Code. Experimental results on 12 deep beams under two equal symmetrically placed point loads are reported. Main variables are vertical and horizontal web reinforcement and shear span-to-overall depth ratio. Test results indicated that web reinforcement dose not affect on formation of inclined cracks but shear span-to-overall depth ratio affect on inclined shear cracks and ultimate shear strength. Addition of vertical web reinforcement improves ultimate shear strength of H.S.C. deep beams that shear span-to-overall depth ratio is 1.0. Considerable increase in ultimate shear strength of H.S.C. deep beams with increasing horizontal web reinforcement that shear span-to-overall depth ratio is 0.5. Especially with increasing concrete strength($f_{ck}$) the ACI code is conservative in estamating the ultimate shear strength of deep beams.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.240-243
• /
• 2004

A new shear connection for the application of precast decks to PSC girders was proposed and push-off tests were conducted to evaluate the horizontal shear strength of the shear connection. Major parameters of the tests were connector type, shank area, vertical load, surface condition and bedding height. Judging from the test results, shear strength of the suggested shear connection was proportional to the shank area and yield strength of the connectors and was in inverse proportion to the bedding height. Shear connection with shear key at the surface showed better performance. An empirical equation for the evaluation of the shear strength of the shear connection without considering bond strength was proposed and it showed good correlation with the test results.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.256-259
• /
• 2004

The objective of this experimental study is to understand the effects of horizontal and vertical shear reinforcement on the shear strength of concrete deep beams. Main variables were the horizontal shear reinforcement ratio $(P_{sh})$, vertical shear reinforcement ratio$(P_{sv})$ and shear span-to-overall depth ratio(a/h). Test results revealed that the effectiveness of shear resistance of shear reinforcement was greatly related to the a/h. For the beams with $a/h\geq1.0$, the vertical shear reinforcement was more effective than horizontal shear reinforcement.

• Korea-Australia Rheology Journal
• /
• v.12 no.3_4
• /
• pp.143-149
• /
• 2000

In this article, we considered shear-induced microstructure and rheological behavior of micellar solutions of cationic surfactant, cetylpyridinium chloride (CPC) in the presence of a structure-forming additive, sodium salicylate (NaSal). Shear viscosity, shear moduli and flow birefringence were measured as functions of the surfactant and additive concentrations. In the presence of NaSal, the micellar solution exhibited the non-linear rheological behavior due to the formation of supramolecular structures when the molar ratio of NaSal to CPC exceeded a certain threshold value. Flow birefringence probed the change in micelle alignment under shear flow. At low shear rates, the flow birefringence increased as the shear rate increased. On the other hand, fluctuation of flow birefringence appeared from the shear rate near the onset of shear thickening, which was caused by shear-induced coagulation or aggregation. These results were confirmed by the SEM images of in situ gelified micelle structure through sol-gel route.

• Steel and Composite Structures
• /
• v.13 no.5
• /
• pp.437-449
• /
• 2012

Concrete filled steel tube (CFST) structures have recently seen wide use in China, but studies of the shear problem of CFST are inadequate. This paper presents an experimental study on the shear capacity of circular concrete filled steel tube (CCFT) specimens with and without axial compression force. Shear capacity, ductility, and damage modes of CCFTs were investigated and compared. Test results revealed the following: 1) CCFTs with a small shear span ratio may fail in shear in a ductile manner; 2) Several factors including section size, material properties, shear span ratio, axial compression ratio, and confinement index affect the shear capacity of CCFTs. Based on test results and analysis, this paper proposes a design formula for the shear capacity of CCFTs.

• Steel and Composite Structures
• /
• v.28 no.4
• /
• pp.449-460
• /
• 2018

This paper reports the experimental results of three through bolt beam-column connections under pure shear forces using modified push-out tests. The investigated specimens include extended end-plates and six through-bolts connecting square concrete-filled steel tubular column (S-CFST) to steel beams. The main goal of this study is to investigate if and how the mechanical shear connectors, such as steel angles and stud bolts, contribute to the shear transfer mechanisms in the steel-concrete interface of the composite column. The contribution of shear studs and steel angles to improve the shear resistance of steel-concrete interface in through-bolt connections was investigated using tests. The results showed that their contribution is not significant when the beam-column connection is included in the push-out tests. The specimens failed by pure shear of the long bolts, and the ultimate load can be predicted using the shear resistance of the bolts under shear forces. The predicted values of load allowed obtaining a good agreement with the tests results.

• The Korean Journal of Rheology
• /
• v.8 no.3_4
• /
• pp.226-231
• /
• 1996

침강제에 의해 형성된 E. coli floc들의 강도를 측정하기 위해 floc 의 shear index를 측정하였다. 형성된 E. coli floc은 10/sec 같이 낮은 shear rate에서도 분쇄되거나 변형되었 다. 측정된 shear index의 감소에서 보듯이 E. coli floc의 강도는 염의 농도가 증가함에 EK 라 감소하였다. E. coli floc의 shear index는 NaCl의 농도가 0에서 100 mM로 증가함에 따 라 0.47에서 0.09로 줄었다. 발효배지의 조성에서 형성된 E. coli floc들은(shear index=0.18-0.24 with BPA-1000. 0.13-0.22 with BPA-1050 and 0.37-0.42 with BPA-5020) 염이 없을 때 형성된 floc에(shear index=0.47 with BPA-1000 and 0.46 with BPA-1050) 비 해 약하였다. 따라서 발효배지에서 형성된 floc은 생물공정 중 쉽게 shear에 의해 분쇄되거 나 변형될것이다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.158-161
• /
• 2006

The numerical analysis and the experiment was performed to investigate the influences of shear connector on shear resistance capability. The numerical analysis's results should that the H/B ratio of shear key is more effective than angle of shear key against shear strength and shear behavior, and it is more desirable to use a half of the H/B ratio of shear key. The specimen was made with same condition as AASHTO recommended. There model tests were performed under various form of shear key, number, arrangement reinforcement and condition using epoxy. As a result of the experiment, there is little difference(or there is no difference) between the case of using epoxy on shear connector and the unused case.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.587-590
• /
• 2003

In flat-plate floors, slab-column connections are broken down with a brittle shear failure. And it can cause the collapse of the whole structures. Thus, the proper method of shear reinforcement in flat plate-column connections must be required. The objective of this study is to compare shear reinforcement specimens using lattice bars to no shear reinforcement specimens in view of shear strength and ductility of the flat plate-column connections. The test results have shown that shear reinforcement specimens varying $\rho$, $b_0$/d and $C_1$/$C_2$ increase in shear strength by 36.85% and in ductility by 9.16 for no shear reinforcement specimens on the average. This results confirm the effectiveness of this type of shear reinforcement in improving shear strength and ductility.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.223-228
• /
• 2003

Results of 61 framed reinforced concrete shear walls with openings were reviewed to evaluate the current design provisions for nominal shear strength. Provisions for ACI 318-02 and AIJ Code pertaining to shear design of shear walls evaluated the applicability of shear walls with openings subjected to lateral and vertical loads. Evaluation of test results indicates that the nominal unit shear strength($\Psi$=1.0) calculated using the provisions of ACI and AIJ does not represent the observed shear strength well. Based on the limited database considered in this study, A reasonable lower bound to the shear strength of high-strength concrete shear walls is found to be $1.09\sqrt{f_{cu}}$ kgf/$\textrm{cm}^2$.