Pseudo-static Experimental Research On RC Fully Staggered Joint And Nonlinear Finite Element Analysis On RC Staggered Joint

During recent years, the researches of staggered floor structure have been paid close attention to by academic and engineering circles as the structure itself is increasingly applied in the civil industry. The key of the problem focuses on staggered joint. The intricate natures of the staggered joint cause the research more arduous than those on common joint. Therefore, only a few researches on the mechanisms of shear transfer and seismic resistant behaviors about staggered joint for empirical needs have been accomplished so far.In this paper as it is, trying to fill the gap of the lack of sufficient researches and the strong desire of the industry on the usage of the structure. This paper does research and investigation on the variation law of ductility, stiffness, load capacity, energy dissipation of beam-column assembly and the influence of staggered height axial load ratio in column on the seismic resistant behaviors of the staggered joints via testing three nearly full-sized specimens of reinforced concrete beam-column assembly under reverse cyclic loading. Further, the reinforced concrete nonlinear finite element analysis is thoroughly discussed under the variances of the mechanisms of shear forces transfer for different loading direction, staggered height and axial force ratios.After the test and nonlinear finite analysis on the staggered joint, the conclusion are drawn as following:1.The anchor behaviors of beam reinforcement in staggered joint are better than common interior joint, which is the main reason that makes the energy dissipation of staggered joint superior to common joint.2.The better quality of anchor behaviors is beneficial to the seismic behavior of the staggered joint, making the beam reinforcement overstength. Corresponding to the over strength, the anti-shear capacity of the beam becomes comparatively absent; and the shear forces in staggered joint does enhanced rather falling because of the sliding of the anaphase. The anti-shear capacity of the beam and the amount of stirrup in staggered joint are two crucial factors of affecting seismic resistant behavior of the staggered joint thereupon.3. The recommendation about the reinforcement in staggered joint:For the staggered full beam height, the design shear could use the design shear of end joint;For the staggered part beam height, the design shear should use the design shear ofcommon interior joint. And the anti-shear capacity of beam should be enhanced.4.The different loading direction will form different shear transfer mechanisms. The directions of the diagonal compression struts and whether there is horizontal centralized principal tensile stress are the major differences.5.With the staggered height from full beam height to part beam height, the behavior of the staggered joint is from end joint to interior joint.6.Because the constrain from axial force ratio, and the expansion of concrete crack, the stress in stirrup under moderate axial force ratio is lower than that if under low axial force ratio, the behavior of staggered joint under moderate axial force ratio is better than that if under low axial force ratio.