Research On3D Strip Method Of RC Beams And Slabs

In order to further explore and optimize the design method of reinforced concrete beam slab work together, this paper, based on a series of research in literature [44-47], using nonlinear finite element analysis of numerical simulation(ANSYS), made the necessary adjustment, correction and unified of the membrane effect coefficients and amplitude modulation coefficients of the "3D Strip Method" proposed by literature [46], and also analyzed the influence factors of the coefficients. Analysis results show that the bearing negative bending moment of slab should be3-12times of positive bending moment, rather than1.5～2.5times which was considered in traditional design methods.Calculation model is a two-way column from3×3span RC frame beam-slab structure (within secondary beams, full scale model). Comparative analysis of various possibilities of the secondary beam and corresponding strip dividing method were carried on; Results showed that the strip division number, which was not suitable for too much or too little either, for slabs along the direction of the slab without secondary beam was3-4advisable, and for slabs along the direction within secondary beam,1-2was advisable, adjacent strips could be disconnected or continuous, engineering design could be flexible according to specific situation; The middle beam (with slabs on both side) needs not take the effect of coordination of torsional torque. According to the nonlinear finite element analysis results, there is almost no negative bending moment on slab in the position of secondary beam, inflection point and its changing rules under the vertical load has been analyzed, on the basis of this, it is put forward that the truncation location should be determined by the frame column grid size, which is quite different from the traditional method. Further analysis shows that this is also one of the main causes of slab crack in engineering at present.A large number of nonlinear numerical simulation analysis shows that3D Strip Design Method is a relatively ideal and practical design method that the cooperative work of beams and slabs has been considered, it can be used for slab-column system, the floor without secondary beams, and also the floor within secondary beams.