Qingjun Chen

Axial Compressive Behavior of Through-Beam Connections between Concrete-Filled Steel Tubular Columns and Reinforced Concrete Beams

AbstractThis paper investigates the axial compressive behavior of a through-beam connection between concrete-filled steel tubular (CFST) columns and reinforced concrete (RC) beams. In this connection system, the steel tube is completely curtailed at the corresponding beam location, with the longitudinal steel reinforcing bars for the beam remaining continuous through the connection region. A strengthening ring beam is used to enlarge the connection zone in order to compensate for the possible decrease of the axial load-carrying capacity as a result of the discontinuity of the steel tube that encases the column. Two series of axial compressive tests on 32 beam-column specimens are reported. The first series of tests, including 5 full-scale connection specimens with CFST columns, show that with proper design, the axial load-carrying capacity of the connection can be higher than that of the CFST column. The feasibility of this type of connection is verified. The second series of tests, including 27 specimens...

Calculation Methods for Inter-Story Drifts of Building Structures

The current methods for calculating the inter-story harmful drift are evaluated, and new concepts of the inter-story average shear drift and the inter-story average rotation are proposed in this paper. The definitions and contents of the inter-story harmful and harmless drift are introduced. Four existing methods for calculating the harmful and harmless drift, including the secant method, tangent method, fixing floor method, and generalized shear deformation of region method are revisited, and the advantages as well as shortcomings of these methods are compared. Meanwhile, the misunderstanding in calculating the floor rotation is clarified. The inter-story average shear drift and the inter-story average rotation are proposed. In addition, the relationships among these proposed drifts and the harmful drift are derived, and are examined by the static and dynamic analysis of a simplified structural model. It demonstrates that the proposed drifts are effective in both static as well as dynamic analysis, and can be used for providing more specific information in the structural deformation analysis.

Modification of Ductility Reduction Factor for Strength Eccentric Structures Subjected to Pulse-Like Ground Motions

This article investigates the ductility reduction factors for RC eccentric frame structures subjected to pulse-like ground motions. The structural models are with the strength eccentricities which are much disadvantageous than the stiffness eccentricities during the inelastic response range. A method to determine the ductility reduction factors of the strength eccentric structures is suggested by modifying those of reference symmetric structures through an eccentricity modification factor. The four factors of strength eccentricity ratio, ductility ratio, story number and velocity pulse of ground motions, are investigated to gain insight into this modification factor. It shows that the ductility reduction factors of the eccentric structures are clearly smaller than those of the symmetric structures. The eccentricity modification factor is mainly affected by the strength eccentricity and the ductility ratio, decreasing with the increment of the eccentricity or the decrement of the ductility ratio in a medium eccentricity range. The earthquake pulse-like effect and the eccentricity have coupling influence on the modification factor, while the effect of story number is not apparent. Based on the results of a comprehensive statistical study a simplified expression is suggested, which can estimate the eccentricity modification factors for both pulse-like and nonpulse-like ground motion cases.