Seismic Analysis Of Specially-shaped Column In Rainforced Concrete Frame Structures

With rapid development of urban construction and various design requirements ofarchitects, different types of structural design of constructions have taken into shapenowadays. The original brick structure has now developed into structures such asframe structure, frame-shear wall structure, wall structure, framed tube structure, andtube-in-tube structure. Among these structures, frame structure develops rapidlybecause it is simple and easy to follow the rules and also can meet demands for largerspace. However, customers need more than fundamental housing function from thebuilding since people’s living standards improve greatly. They need their houses to beas perfect as possible in terms of aesthetic. So frame structure with specially-shapedcolumns blooms, especially for villa and multi-level buildings. This kind of structuresatisfies spatial requirements of corners and intersection of the wall, as well asintersection of corners and intersections, so that no obvious edges or prominent columnwould appear in the buildings and thus expands the actual usable floor area and morefurniture can be placed into the buildings. That’s why seismic analysis underearthquake for frame structure with specially-shaped columns is of practicalsignificance in engineering.Based on a villa project--Shan shui Lin jian in Yongchuan District, Chongqing,the paper transfers the cross-section of specially-shaped column into rectangularcolumn with the same area. The interior moment of a specially-shaped column is largerthan that of a rectangular column, which leads to the increase of overall anti-swaystiffness of specially-shaped column. But the structure cycle decreases as its structuralstiffness increases. both bending moment and shear force under earthquakes increasewhen part structures apply specially-shaped columns. The object of the paper was tocarry out analysis and comparison of reinforced concrete columns with both specialshape and rectangular shape with the same area and to testify that under equal-areaconversion, whether the increase of anti-sway stiffness is larger than the increase ofearthquakes. The paper also proved that the overall anti-sway stiffness ofspecially-shaped column is better than that of a rectangular column, and thus provedthe rationality for the project to apply specially-shaped column. Whether the structure needs to be more rigid or more flexible under an earthquake has also been analyzed inthe paper.Seismic analysis was carried out on the basis of kinetic theory, comparison aboutoverall anti-sway stiffness between specially-shaped column and rectangular columnwas carried out in the form of elastic time-history and elastic-plastic time-history.Finite element analysis software was used for data processing, PMCAD in PKPM wasused for the modeling of elastic time-history analysis under earthquakes with lowermagnitude, and EPDA was used for elastic-plastic time-history analysis underearthquakes with much higher magnitude. Finally seismic performance ofspecially-shaped column is proved to be better than that of a rectangular column.