Distortional and local buckling of steel-concrete composite box-beam

Lizhong Jiang,Jingjing Qi,Andrew Scanlon,Linlin Sun 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.14 No.3

Distortional and local buckling are important factors that influences the bearing capacity of steel-concrete composite box-beam. Through theoretical analysis of distortional buckling forms, a stability analysis calculation model of composite box beam considering rotation of steel beam top flange is resented. The critical bending moment calculation formula of distortional buckling is established. In addition, mechanical behaviors of a steel beam web in the negative moment zone subjected separately to bending stress, shear stress and combined stress are investigated. Elastic buckling factors of steel web under different stress conditions are calculated. On the basis of local buckling analysis results, a limiting value for height-to thickness ratio of a steel web in the elastic stage is proposed. Numerical examples are presented to verify the proposed models.

Flexural behavior of concrete beams reinforced with aramid fiber reinforced polymer (AFRP) bars

김민숙,이영학,김희철,Andrew Scanlon,이준복 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.4

Due to the low elastic modulus of FRP, concrete members reinforced with FRP rebars show greater deflections than members reinforced with steel rebars. Deflection is one of the important factors to consider the serviceability of horizontal members. In this study flexural test of AFRP reinforced concrete beams was performed considering reinforcement ratio and compressive strength as parameters. The test results indicated that flexural capacity and stiffness increase in proportion to the reinforcement ratio. The test results were compared with existing proposed equations for the effective moment of inertia including ACI 440. The most of the proposed equations were found to over-estimate the effective moment of inertia while the equation proposed by Bischoff and Scanlon (2007) most accurately predicted the values obtained through actual testing.

Ductility-based seismic design of precast concrete large panel buildings

Astarlioglu, Serdar,Memari, Ali M.,Scanlon, Andrew Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.10 No.4

Two approximate methods based on mechanism analysis suitable for seismic assessment/design of structural concrete are reviewed. The methods involve use of equal energy concept or equal displacement concept along with appropriate patterns of inelastic deformations to relate structure's maximum lateral displacement to member and plastic deformations. One of these methods (Clough's method), defined here as a ductility-based approach, is examined in detail and a modification for its improvement is suggested. The modification is based on estimation of maximum inelastic displacement using inelastic design response spectra (IDRS) as an alternative to using equal energy concept. The IDRS for demand displacement ductilities are developed for a single degree of freedom model subjected to several accelerograms as functions of response modification factor (R), damping ratios, and strain hardening. The suggested revised methodology involves estimation of R as the ratio of elastic strength demand to code level demand, and determination of design base shear using $R_{design}{\leq}R$ and maximum displacement, determination of plastic displacement using IDRS and subsequent local plastic deformations. The methodology is demonstrated for the case of a 10-story precast wall panel building.

Polymorph Engineering of TiO₂: Demonstrating How Absolute Reference Potentials Are Determined by Local Coordination

Buckeridge, John,Butler, Keith T.,Catlow, C. Richard A.,Logsdail, Andrew J.,Scanlon, David O.,Shevlin, Stephen A.,Woodley, Scott M.,Sokol, Alexey A.,Walsh, Aron American Chemical Society 2015 Chemistry of materials Vol.27 No.11

<P>We report that the valence and conduction band energies of TiO<SUB>2</SUB> can be tuned over a 4 eV range by varying the local coordination environments of Ti and O. We examine the electronic structure of eight known polymorphs and align their ionization potential and electron affinity relative to an absolute energy reference, using an accurate multiscale quantum-chemical approach. For applications in photocatalysis, we identify the optimal combination of phases to enhance activity in the visible spectrum. The results provide a coherent explanation for a wide range of phenomena, including the performance of TiO<SUB>2</SUB> as an anode material for Li-ion batteries, allow us to pinpoint hollandite TiO<SUB>2</SUB> as a new candidate transparent conducting oxide, and serve as a guide to improving the efficiency of photo-electrochemical water splitting through polymorph engineering of TiO<SUB>2</SUB>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-11/acs.chemmater.5b00230/production/images/medium/cm-2015-00230v_0006.gif'></P>

Comparison of minimum thickness provisions for concrete beams in building codes and standards

Lee, Young Hak,Kim, Min Sook,Lee, Junbok,Scanlon, Andrew Canadian Science Publishing 2013 Canadian journal of civil engineering. Revue canad Vol.40 No.7

<P> Building codes and standards generally include provisions for deflection control of beams and slabs. These provisions usually include prescriptive methods for computing deflection as well as minimum thickness or span-depth limitations. In this paper, results of a study comparing minimum thickness provisions in several codes and standards including the Canadian (CSA A23.3) and American (ACI 318) provisions are presented. These results are in turn compared with results obtained based on a minimum thickness equation proposed by the authors. The results show that the CSA and ACI provisions have limited application and the proposed equation is recommended for adoption. </P>

Flexural behavior of concrete beams reinforced with aramid fiber reinforced polymer (AFRP) bars

Kim, Min Sook,Lee, Young Hak,Kim, Heecheul,Scanlon, Andrew,Lee, Junbok Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.38 No.4

Due to the low elastic modulus of FRP, concrete members reinforced with FRP rebars show greater deflections than members reinforced with steel rebars. Deflection is one of the important factors to consider the serviceability of horizontal members. In this study flexural test of AFRP reinforced concrete beams was performed considering reinforcement ratio and compressive strength as parameters. The test results indicated that flexural capacity and stiffness increase in proportion to the reinforcement ratio. The test results were compared with existing proposed equations for the effective moment of inertia including ACI 440. The most of the proposed equations were found to over-estimate the effective moment of inertia while the equation proposed by Bischoff and Scanlon (2007) most accurately predicted the values obtained through actual testing.

Concrete Beams with Fiber-Reinforced Polymer Shear Reinforcement

Kim, Dae-Jin,Kim, Min Sook,Choi, Jonghoon,Kim, Heecheul,Scanlon, Andrew,Lee, Young Hak American Concrete Institute 2014 ACI structural journal Vol.111 No.4

<p>A new type of fiber-reinforced polymer (FRP) shear reinforcement is proposed for reinforced concrete beams. The new FRP shear reinforcement consists of FRP plate material with openings. The performance of the proposed shear reinforcement was investigated by performing tests on nine concrete beam specimens with a shear span-depth ratio of 2.4. Test parameters include the type of FRP, shape of FRP shear reinforcement, and the amount of the FRP reinforcement. The effects of these parameters on the shear strength of the FRP plate shear reinforced concrete beam were examined. A shear strength equation for concrete beams with the proposed FRP shear reinforcement is proposed based on modifying the existing shear strength equation for concrete beams with steel stirrups in ACI 318-11. The comparison between the test results and the estimations by the proposed equation generally shows good agreement, and the test results indicate that the proposed system is a promising candidate for shear reinforcement in FRP reinforced concrete beams.</p>