• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.2
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• pp.76-82
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• 2006

The concrete shear strength of FRP Bar reinforced concrete beam according to the variation of flexural reinforcement ratio was investigated. A number of experimental result showed that the concrete shear strength was lower than that of RC beam, but it was increased according to the increasement of reinforcement ratio. Shear strength correction factors considering the kind and reinforcement ratio of FRP Bar was proposed using the proposed formula in the literature and regression analysis of the experimental result.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.4
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• pp.3-13
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• 2018

Load bearing capacity of dowel type fasteners loaded perpendicular to the shear plane is determined based on Johansen's yield theory (Johansen, 1949). In case of inclined screws whose axis is no longer perpendicular, the ultimate load of connection increases because of additional axial withdrawal capacity. To calculate load bearing capacity for inclined screws, KBC2016 and Eurocode5 provide design equations using the combination of two effects; axial and bending strength. Although their equations have been validated for a long time, there is still minimal information how to apply them for concrete-CLT joints. Since there are not many test data available, engineers have to make certain assumptions and thus results may look inconsistent in practice. In this paper, authors would like to describe the current approach and assumptions indicated by KBC2016 and Eurocode 5 and how they match the experimental results in terms of shear strength of CLT-concrete connections. To fulfill the objective, several push-out tests were performed on nine different test specimens. Each specimen has different penetration angles and depths. By analyzing load-displacement curves, the maximum shear strength, stiffness, and ductility were obtained. Shear strength values were compared with the current design codes and theoretical equations proposed in this paper. Observations on stiffness and ductility were briefly discussed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.1
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• pp.93-102
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• 2002

Steel fiber and polymer are used widely for reinforcement material of RC structures because of its excellences of the durability, serviceability as well as mechanical properties. The purpose of this study is to investigate the shear behavior of polymer cement high strength concrete beams mixed with steel fiber. The compressive strength of concrete was based on the 100$\times$200 mm cylinder specimens. The compressive strength of concrete are 320$kgf/cm^2$, 436 $kgf/cm^2$ and 520 $kgf/cm^2$ in the 28 days. The static test was carried out to measure the ultimate load, the initial load of flexural and diagonal cracking, crack patterns and fracture modes. Also, load-strain and load-deflection examined. During the test cracks were sketched against the load values according to the growth of crack. result are as follows; (1) The failure modes of the specimens are increased in rigidity and durability with mixing steel fiber and polymer. (2) The load of initial crack was similar a theory of shear-crack strength. (3) The deflection and strain at failure load of Polymer-steel fiber high strength concrete beams were increased, improving the brittleness of the high strength concrete.

• Journal of Ocean Engineering and Technology
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• v.11 no.4
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• pp.31-39
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• 1997

This research is to evaluate the effect of sunshine treatment on the strength in the Al 6061/AFRP hybrid composite(APAL). APAL specimens were processed by autoclave curing system under the constant condition of curing temperature, time and aluminum surface pertreatment. Aramid patched aluminum alloy can be widely used for the repair of the damage part of the aircraft. The tensile strength of the sunshine treated APAL 2P and 6P composite is 14%, 22% smaller than that of the non-treated material. The interlaminar shear strength of the APAL specimens for the adhesive length of 5mm is 24% higher than that of the APAL for the adhesive length of 10mm. In the case of APAL DS 1P material, interlaminar shear strength of the specimen which was sunshine treated for 200 hours is 21% smaller than that of the non-treated material while interlaminar shear strength of the specimen which was immersed in a 70.deg. C fresh water for 1200 hours decreases by 75.7%.

• Geomechanics and Engineering
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• v.10 no.3
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• pp.257-267
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• 2016

Charts are used extensively in slope practical application to meet the need of quick assessment of rock slope design. However, Charts for estimating the shear strength of the rock mass of a slope are considerably limited. In this paper, based on the Hoek-Brown (HB) criterion which is widely used in rock slope engineering, we present charts which can be used to estimate the Mohr-Coulomb (MC) parameters angle of friction ${\phi}$ and cohesion c for given slopes. In order to present the proposed charts, we firstly present the derivation of the theoretical relationships between the MC parameters and ${\sigma}_{ci}/({\gamma}H)$ which is termed the strength ratio (SR). It is found that the values of $c/{\sigma}_{ci}$ and ${\phi}$ of a slope depend only on the magnitude of SR, regardless of the magnitude of the individual parameters ${\sigma}_{ci}$(uniaxial compressive strength), ${\gamma}$(unit weight) and H (slope height). Based on the relationships between the MC parameters and SR, charts are plotted to show the relations between the MC parameters and HB parameters. Using the proposed charts can make a rapid estimation of shear strength of rock masses directly from the HB parameters, slope geometry and rock mass properties for a given slope.

• Steel and Composite Structures
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• v.20 no.6
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• pp.1275-1303
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• 2016

Steel plates and carbon-fiber-reinforced polymer (CFRP) laminates or plates bonded to concrete substrates have been widely used for concrete strengthening. However, this technique cause plate debonding, which makes the strengthening system inefficient. The main objective of this study is to enhance the bond strength of externally bonded steel plates and CFRP laminates to the concrete surface by proposing new embedded adhesive and steel connectors. The effects of these new embedded connectors were investigated through the tests on 36 prism specimens. Parameters such as interfacial shear stress, fracture energy and the maximum strains in plates were also determined in this study and compared with the maximum value of debonding stresses using a relevant failure criterion by means of pullout test. The study indicates that the interfacial bond strength between the externally bonded plates and concrete can be increased remarkably by using these connectors. The investigation verifies that steel connectors increase the shear bond strength by 48% compared to 38% for the adhesive connectors. Thus, steel connectors are more effective than adhesive connectors in increasing shear bond strength. Results also show that the use of double connectors significantly increases interfacial shear stress and decrease debonding failure. Finally, a new proposed formula is modified to predict the maximum bond strength of steel plates and CFRP laminates adhesively glued to concrete in the presence of the embedded connectors.

• Steel and Composite Structures
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• v.32 no.2
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• pp.199-212
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• 2019

This paper presents an investigation on seismic behavior of out-of-code Q690 circular high-strength concrete-filled thin-walled steel tubular (HCFTST) columns made up of high-strength (HS) steel tubes (yield strength $f_y{\geq}690MPa$). Eight Q690 circular HCFTST columns with various diameter-to-thickness (D/t) ratios, concrete cylinder compressive strengths ($f_c$) and axial compression ratios (n) were tested under the constant axial loading and reversed cyclic lateral loading. The obtained lateral load-displacement hysteretic curves, energy dissipation, skeleton curves and ductility, and stiffness degradation were analyzed in detail to reflect the influences of tested parameters. Subsequently, a simplified shear strength model was derived and validated by the test results. Finally, a finite element analysis (FEA) model incorporating a stress triaxiality dependent fracture criterion was established to simulate the seismic behavior. The systematic investigation indicates the following: compared to the D/t ratio and axial compression ratio, improving the concrete compressive strength (e.g., the HS thin-walled steel tube filled with HS concrete) had a slight influence on the ductility but an obvious enhancement of energy dissipation and peak load; the simplified shear strength model based on truss mechanism accurately predicted the shear-resisting capacity; and the established FEA model incorporating steel fracture criterion simulated well the seismic behavior (e.g., hysteretic curve, local buckling and fracture), which can be applied to the seismic analysis and design of Q690 circular HCFTST columns.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.437-444
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• 2009

The purpose of this study was to evaluate the physical properties of different automixing resin cements and the shear bond strength on dentin. For this study, two self-adhesive automixing resin cement(Rely-X Unicem(3M ESPE, St. Paul, USA), Embrace resin cement(Pulpdent, Oakland, USA)) and one chemical polymerizing resin cement(Resiment Ready-Mix(J.L.Blosser Inc., Liberty Missouri, USA)) were used. To evaluate the physical properties, compressive strength, diametral tensile strength and flexural strength were measured. The specimens were fabricated using Teflon mould according to manufacturers' instructions and stored for 24 hours in an atmosphere of 100% humidity. To evaluate the shear bond strength on dentin, each cements were adhered to buccal dentinal surface of extracted human lower molars in 2mm diameter. Physical properties and shear bond strengths were measured using universal testing machine(Z010, Zwick GmbH, Ulm, Germany) at a crosshead speed of 0.5mm/min. The physical properties and shear bond strength of different automixing resin cements were statistically analyzed and compared between groups using One-way ANOVA test and Schffe post-hoc test at the 95% level of confidence. The result shows that chemical polymerizing automixing resin cement represents the relatively higher physical properties and shear bond strength than self-adhesive automixing resin cements.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.86-88
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• 2003

The characteristic of induction heating solder bump(solder ball: Sn-37Pb, Sn-3.5Ag, Sn-3.0Ag-0.5Cu) has analyzed in this paper. The initial condition of induction heating depends on the time and current. The shape of lead-free solder bump is better than lead solder. The shear strength of lead solder bump has decreased with aging time. The average of shear strength of solder bump is about 10N, 11N, and 11N respectively. The lead-free solder bump's shear strength is better than lead solder and varies irregularly with aging time.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.58-60
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• 2003

This study was conducted to optimize adhesive joining procedure for epoxy resin composite materials through investigations on correlation of curing condition with shear adhesive strength, curing mechanism analysis and fracture position observation. It was found that shear adhesive strength ranged 4 to 6MPa and could be improved 50 to 70% by increasing curing temperature from 20 to 140$^{\circ}C$. Based on FT-IR spectra analysis, formation of ether group(-$\bigcirc$-) as an evidence of curing was remarkable at the heated curing condition.