Experimental study on shear behavior of I-girder with concrete-filled tubular flange and corrugated web

Y.B. Shao,Y.M. Wang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.22 No.6

Conventional plate I-girders are sensitive to local buckling of the web when they are subjected mainly to shear action because the slenderness of the web in out-of-plane direction is much bigger. The local buckling of the web can also cause the distorsion of the plate flange under compression as a thin-walled plate has very low torsional stiffness due to its open section. A new I-girder consisted of corrugated web, a concrete-filled rectangular tubular flange under compression and a plate flange under tension is presented to improve its resistance to local buckling of the web and distorsion of the flat plate flange under compression. Experimental tests on a conventional plate I-girder and a new presented I-girder are conducted to study the failure process and the failure mechanisms of the two specimens. Strain developments at some critical positions, load-lateral displacement curves, and load-deflection curves of the two specimens have all be measured and analyzed. Based on these results, the failure mechanisms of the two kinds of I-girders are discussed.

Hysteretic behaviour of circular tubular T-joints with local chord reinforcement

Y.B. Shao,Y.M. Wang,D.P. Yang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.5

When a welded circular hollow section (CHS) tubular joint is subjected to brace axial loading, failure position is located usually at the weld toe on the chord surface due to the weak flexural stiffness of the thin-walled chord. The failure mode is local yielding or buckling in most cases for a tubular joint subjected to axial load at the brace end. Especially when a cyclic axial load is applied, fracture failure at the weld toe may occur because both high stress concentration and welding residual stress along the brace/chord intersection cause the material in this region to become brittle. To improve the ductility as well as to increase the static strength, a tubular joint can be reinforced by increasing the chord thickness locally near the brace/chord intersection. Both experimental investigation and finite element analysis have been carried out to study the hysteretic behaviour of the reinforced tubular joint. In the experimental study, the hysteretic performance of two full-scale circular tubular T-joints subjected to cyclic load in the axial direction of the brace was investigated. The two specimens include a reinforced specimen by increasing the wall thickness of the chord locally at the brace/chord intersection and a corresponding un-reinforced specimen. The hysteretic loops are obtained from the measured load-displacement curves. Based on the hysteretic curves, it is found that the reinforced specimen is more ductile than the un-reinforced one because no fracture failure is observed after experiencing similar loading cycles. The area enclosed by the hysteretic curves of the reinforced specimen is much bigger, which shows that more energy can be dissipated by the reinforced specimen to indicate the advantage of the reinforcing method in resisting seismic action. Additionally, finite element analysis is carried out to study the effect of the thickness and the length of the reinforced chord segment on the hysteretic behaviour of CHS tubular T-joints. The optimized reinforcing method is recommended for design purposes.

Zoogloea caeni sp. nov., a floc-forming bacterium isolated from activated sludge

Shao, Y.,Chung, B. S.,Lee, S. S.,Park, W.,Lee, S.-S.,Jeon, C. O. Microbiology Society 2009 International journal of systematic and evolutiona Vol.59 No.3

<P>Two floc-forming, nitrogen-fixing bacteria, strains EMB43(T) and EMB61, obtained from activated sludge of a domestic wastewater treatment plant in Korea, were characterized. The two strains were very closely related, sharing 99.7 % 16S rRNA gene sequence similarity and showing a level of DNA-DNA relatedness of 93 %, which suggests that they represent members of a single species. Phylogenetic analysis based on 16S rRNA gene sequences showed that the two novel isolates formed a distinct phyletic lineage within the genus Zoogloea and were related most closely to Zoogloea resiniphila DhA-35(T) and Zoogloea oryzae A-7(T), with sequence similarities of 97.2 %. Levels of DNA-DNA relatedness between strain EMB43(T) and Z. resiniphila DhA-35(T) and Z. oryzae A-7(T) were 12.8 and 7.4 %, respectively. Cells of strains EMB43(T) and EMB61 were facultatively aerobic, rod-shaped, Gram-negative and motile by means of a polar flagellum. The strains grew at temperatures of 15-40 degrees C (optimum: 25-30 degrees C) and at pH 6.0-9.0 (optimum: pH 6.5-7.5). The predominant fatty acids were C(16 : 0), C(10 : 0) 3-OH and summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH), and the predominant polar lipid was phosphatidylethanolamine. The genomic DNA G+C content was 64.9-65.0 mol% and the major isoprenoid quinone was ubiquinone-8 (Q-8). On the basis of phenotypic, chemotaxonomic and molecular data, the isolates are considered to represent a novel species of the genus Zoogloea, for which the name Zoogloea caeni sp. nov. is proposed. The type strain is EMB43(T) (=KCTC 22084(T)=DSM 19389(T)).</P>

Residual static strength of cracked concrete-filled circular steel tubular (CFCST) T-joint

M.J. Cui,Y.B. Shao 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4

Concrete-filled circular t steel tubular joints (CFSTJs) in practice are frequently subjected to fluctuated loadings caused by wind, earthquake and so on. As fatigue crack is sensitive to such cyclic loadings, assessment on performance of CFSTJs with crack-like defect attracts more concerns because both high stress concentration at the brace/chord intersection and welding residual stresses along weld toe cause the materials in the region around the intersection to be more brittle. Once crack initiates and propagates along the weld toe, tri-axial stresses in high gradient around the crack front exist, which may bring brittle fracture failure. Additionally, the stiffness and the load carrying capacity of the CFSTJs with crack may decrease due to the weakened connection at the intersection. To study the behaviour of CFSTJs with initial crack, experimental tests have been carried out on three full-scale CFCST T-joints with same configuration. The three specimens include one uncracked joint and two corresponding cracked joints. Load-displacement and load-deformation curves, failure mode and crack propagation are obtained from the experiment measurement. According to the experimental results, it can be found that he load carrying capacity of the cracked joints is decreased by more than 10% compared with the uncracked joint. The effect of crack depth on the load carrying capacity of CFCST T-joints seems to be slight. The failure mode of the cracked CFCST T-joints represents as plastic yielding rather than brittle fracture through experimental observation.

Quantitative recovery of high purity nanoporous silica from waste products of the phosphate fertilizer industry

Elineema, G.,Kim, J.K.,Hilonga, A.,Shao, G.N.,Kim, Y.N.,Quang, D.V.,Sarawade, P.B.,Kim, H.T. Korean Society of Industrial and Engineering Chemi 2013 Journal of industrial and engineering chemistry Vol.19 No.1

This study reports on the quantitative recovery of high purity nanoporous silica from wastes material (H<SUB>2</SUB>SiF<SUB>6</SUB>) of the phosphate fertilizer industry and Na<SUB>2</SUB>O.SiO<SUB>2</SUB>. The silica recovered from the wastes was compared with silica from the reaction of H<SUB>2</SUB>SO<SUB>4</SUB> and Na<SUB>2</SUB>O.SiO<SUB>2</SUB> because H<SUB>2</SUB>SO<SUB>4</SUB> is commonly used. The product recovered from the wastes material and H<SUB>2</SUB>SO<SUB>4</SUB> were 99.3% and 99.1% pure, respectively. The quantity recovered were 22.30g and 20.11g, respectively. The product had superior properties suitable for applications such as chromatography, reinforcing material for rubber and plastics. The process may significantly reduce the release of SiF<SUB>4</SUB> gas into the environment.

Fluorescent Realgar Quantum Dots: New Life for an Old Drug

J. Z. Wu,G. Chen,Y. B. Shao,J. Liu,Y. C. Sun,H. S. Lin,Paul C. Ho 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.1

"Quantum dots (QDs) possess unique properties that are expected for various applications. Herein, realgar (As4S4) QDs were synthesized via a wet chemical method in a coordinating solvent (e.g., ethanolamine (EA)) with assistance of an acid (e.g., citric acid (CA)). The asprepared realgar QDs using EA and CA have a narrow size distribution with a mean value of 5.48 nm and a relative standard deviation of 20%, and exhibit bright photoluminescence (PL) in a short wavelength window (< 480 nm) with high quantum yield up to 70%. Moreover, realgar QDs can retain their high PL after one-year storage, indicating their excellent stability. Bulk realgar is a commonly used traditional medicine, however, its water-insolubility limits its broad applications. Realgar QDs could be an alternative for the bulk realgar owing to their excellent water-solubility and efficient PL. In preliminary in vivo toxic and pharmaceutical experiments, the synthesized realgar QDs at a single oral dose of 10.0 mg realgar/kg body weight for 21 days showed tolerability in healthy mice and effective against tumor-bearing nude mice, respectively. In this study, assembly of realgar QDs into specific hollow nanospheres was first constructed by introducing an acid into their original colloidal solution. Simple dissolution of such assemblies in EA can partially return them into the fluorescent QDs. Such property is desired for a variety of media-responsive luminescence materials. In addition, a flexible inorganic/organic hybrid composite film was fabricated for the first time by incorporation of realgar QDs into polyvinyl alcohol matrix. The resulting film presents excellent PL, good transparency, intense mechanical strength and facile processibility, which meet the requirements for device integration. "