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CONTENTS
Volume 13, Number 5, November 2012
 

Abstract
Recently, as the height of building is getting higher, the applications of CFST column for highrise buildings have been increased. In structural system of high-rise building, The RC core and exterior concrete-filled tubular (CFST) column-beam pinned connection is one of the structural systems that support lateral load. If this structural system is used, due to the minimal CFST column thickness compared to that of the CFST column width, the local moment occurred by the eccentric distance between the column flange surface from shear bolts joints degrades the shear strength of the CFST column-beam pinned connections. This study performed a finite element analysis to investigate the shear strength under eccentric moment of the CFST column-beam pinned connections. The column

Key Words
shear strength; concrete filled tubular column; pinned connections; width-thickness ratio; yield line method; fem analysis.

Address
Seong-Hui Lee : Automobile Examination Division, Korean Intellectual Property Office, Daejeon 302-701, Korea
2Sejin Patent & Law Office, Seoul 135-080, Korea
Young-Ho Kim : Sejin Patent & Law Office, Seoul 135-080, Korea
Sung-Mo Choi : Division of Architectural Engineering, School of Architecture and Architectural Engineering,
University of Seoul, Seoul 130-743, Korea

Abstract
In this study total of six buckling-restrained braces (BRBs) were manufactured using a square steel rod as a load-resisting core member and a hollow steel tube as restrainer to prevent global buckling of the core. The gap between the core and the tube was filled with steel rods as filler material. The performances of the proposed BRB from uniaxial and subassemblage tests were compared with those of the specimens filled with mortar. The test results showed that the performance of the BRB with discontinuous steel rods as filler material was not satisfactory, whereas the BRBs with continuous steel rods as filler material showed good performance when the external tubes were strong enough against buckling. It was observed that the buckling strength of the external tube of the BRBs filled with steel rods needs to be at least twice as high as that of the BRBs filled with mortar to ensure high cumulative plastic deformation of the BRB.

Key Words
buckling-restrained braces; seismic performance; uniaxial tests; subassembalge tests.

Address
Junhee Park : Korea Atomic Energy Research Institute, Daejeon, Republic of Korea
Junho Lee and Jinkoo Kim : Department of Architectural Engineering, Sungkyunkwan University, Suwon, Korea

Abstract
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.

Key Words
CFST; CCFT; shear capacity; shear span ratio; axial compression ratio; confinement index.

Address
China Academy of Building Research, No. 30 Beisanhuandonglu, Chaoyang District, Beijing, China

Abstract
Concrete filled steel tube (CFST) structures have been used widely in high-rise buildings and bridges due to the efficiency of structurally favourable interaction between the steel tube and the concrete core. In the current design codes only one loading condition in the column members is considered, i.e., the load is applied on the steel tube and concrete core at the same time. However, in engineering practice the tube structures may be subjected to various loading conditions such as loading on the concrete core only, preloading on the steel tube skeleton before filling of concrete core, and so on. In this research, a series of comparative experiments were carried out to study the structural performance of concrete filled circular steel tube columns subject to four concentric loading schemes. Then, a generalized prediction method is developed to evaluate the ultimate load capacity of CFST columns subject to various loading conditions. It is shown that the predictions by the proposed method agree well with test results.

Key Words
concrete filled steel tube column; confinement effect; comparative study; loading scheme; generalized method; nominal poisson

Address
School of Civil Engineering, Fuzhou University, China

Abstract
An experimental study was performed to investigate the seismic performance of steel reinforced concrete (SRC) special-shaped columns. For this purpose, 17 steel reinforced concrete special-shaped column specimens under low-cyclic reversed load were tested, load process and failure patterns of the specimens with different steel reinforcement were observed. The test results showed that the failure patterns of these columns include shear-diagonal compression failure, shear-bond failure, shear-flexure failure and flexural failure. The failure mechanisms and characteristics of SRC special-shaped columns were also analyzed. For different SRC special-shaped columns, based on the failure characteristics and mechanism observed from the test, formulas for calculating ultimate shear capacity in shear-diagonal compression failure and shear-bond failure under horizontal axis and oblique load were derived. The calculated results were compared with the test results. Both the theoretical analysis and the experimental results showed that, the shear capacity of T, L shaped columns under oblique load are larger than that under horizontal axis load, whereas the shear capacity of

Key Words
steel reinforced concrete (SRC); special-shaped columns; shear mechanism; bearing capacity.

Address
J.Y. Xue,H.T. Zhao, L. Gao and Z.Q. Liu : College of Civil Engineering, Xi

Abstract
Cold-formed steel profile sheets acting as decks have been popularly used in composite slab systems in steel structural works, since it acts as a working platform as well as formwork for concreting during construction stage and also as tension reinforcement for the concrete slab during service. In developing countries like India, this system of flooring is being increasingly used due to the innate advantage of these systems. Three modes of failure have been identified in composite slab such as flexural, vertical shear and longitudinal shear failure. Longitudinal shear failure is the one which is difficult to predict theoretically and therefore experimental methods suggested by Eurocode 4 (EC 4) of four point bending test is in practice throughout world. This paper presents such an experimental investigation on embossed profile sheet acting as a composite deck where in the longitudinal shear bond characteristics values are evaluated. Two stages, brittle and ductile phases were observed during the tests. The cyclic load appears to less effect on the ultimate shear strength of the composite slab.

Key Words
composite slab; embossed profile sheet; m-k value; longitudinal shear strength.

Address
Saravanan, M., Marimuthu, V., Prabha, P., Arul Jayachandran, S. : CSIR-Structural Engineering Research Centre, CSIR campus, Chennai-600113, India
Datta, D. : Institute for Steel Development And Growth (INSDAG), Ispat Niketan, 52/1A, Ballygunge Circular Road, Kolkata - 700 019, India


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