ANSYS-based Elastic-plastic Time-history Analysis Of The Irregular Reinforced Concrete Frame Structures

Plenty of irregular structures come into exsitence because of several factors such as functions of the architectures, confination to the sites, etc. Earthquake field investigations repeatedly confirm that irregular structures suffered more damages than their regular counterparts,which could be attributed to unexpcted torsional motions that occurred in addition to the lateral motions.Based on great amounts of reading documentations, the paper pointed out that regularity of structures should include not only regularity in geometry, but aslo in dynamic regularity and the implementing approach was gived. Directed at the offsetting method presently uesd for designing such structures, the concepts of mass center, stiffness center as well as rigidity center were discussed and the formula for them as well as the condition for which three of them are the same were derived. The paper suggested that center of mass was supposed to contain spacial concept which would be vital to the vertical earthquake and that neither of the stiffness center nor the twist center were the same as rigidity center, which would be a non-trivial matter for further investigation.Aimed at the eccentric mass system, a caculating model with aspect ratio 1 and large areas loss forming plan-irregular was analyzed during the elastic-plastic stage in rare earthquake. Three different conditions of openings such as the same place while different sizes, the same size while different places and the same size the same place while different shapes were analyzed. Some conlusions about the main controlling internal forces, the controlling displacements and the disadvantageous torsion in the structure or the elements were made.