Seismic Behavior Of Step Joints In Reinforced Concrete Frames

In recent years, with the rapid development of housing, comfortable indoor environment, reasonable space arrangement and beautiful living environment have become the object of pursuit, then the stucture of staggered floor arises at the historic moment. As the vertical space of staggered floor dwelling can be changed flexibly, which result most of the floor are not in the same horizontal plane, so that column joints to form a step joint. It is more complex than the normal nodes, which is affected by many factors, such as staggered height and axial force ratios. The current Code for Design Concrete Structures(GB50010-2002) isn't specified for the step joint, so it is urgent for related study. Currently the research on staggered floor node mechanism can not saticefied the actual project, therefore, this article makes a preliminary study on the staggered layer node design.In this paper, it is main study on reinforced concrete frame step joint.By collecting and analyzing the test results at home and abroad, the damage features,hysteretic energy and influencing factors are analyzed. Then the design method of staggered nodes is proposed. The main works of this paper are:1.Four non-regular nodes specimens datas of home and abroad are collected. The reinforced concrete staggered floor joints as the main research object, by introducing the experimental phenomina, the damage features and failure mode of staggered floor joint are analyzed. By contrast with normal node stress mechanism, based on the struss mechanism and diagonal strut mechanism, the stress mechanism applied tostaggered floor joint is proposed.2.The influence affects on mechanical characteristics of staggered floor joint are analyzed, such as different staggered height,axial force ratios and bond behavior and so on.3.Combining the test results and analysis results, based on the mechanical characteristics of staggered floor joint, the formula for calculating shear force,the shear strength formula and construction measure of joint core area are proposed.The researching result of this paper will help improving the stress machanism of staggered floor node. Meanwhile,some useful suggestions are proposed for the practical engineering of staggered floor node design in reinforced concrete frame.