外文翻译---静力弹塑性分析法在侧向荷载分布方式下的评估研究(编辑修改稿)

外文翻译---静力弹塑性分析法在侧向荷载分布方式下的评估研究(编辑修改稿)内容摘要：

tural period of the 3story frame structure is puted s. The crosssection of all beams in this frame is rectangularshapes with 25cm width and 50cm height. The crosssection of all columns is 30cmx30cm. The first natural period of 5story frame structure is s and the crosssection of beams is 25cm width and 50cm height similar to 3story frame. Crosssection of columns at the first three stories is 40cmx40cm and at the last two stories, it is 30cmx30cm. The eightstory and 15story frame structures have natural period of s and s. The cross section of beams for both frame structures is 25cmx55cm. The 8story frame structure has 50cmx50cm columns for the first five stories and 40cmx40cm for the last three stories. The cross section of columns for first eight stories in the 15story frame structures is 80cmx80cm and at the last seven stories, it is 60cmx60cm. NONLINEAR STATIC PUSHOVER ANALYSIS OF FRAME STRUCTURES For low performance levels, to estimate the demands, it is required to consider inelastic behavior of the structure. Pushover analysis is used to identify the seismic hazards, selection of the performance levels and design performance objectives. In Pushover analysis, applying lateral loads in patterns that represent approximately the relative inertial forces generated at each floor level and pushing the structure under lateral loads to displacements that are larger than the maximum displacements expected in design earthquakes (Li, ., 1996). The pushover analysis provides a shear vs. displacement relationship and indicates the inelastic limit as well as lateral load capacity of the structure. The changes in slope of this curve give an indication of yielding of various structural elements. The main aim of the pushover analysis is to determine member forces and global and local deformation capacity of a structure. The information can be used to assess the integrity of the structure. After designing and detailing the reinforced concrete frame structures, a nonlinear pushover analysis is carried out for evaluating the structural seismic response. For this purpose the puter program Drain 2D has been used. Three simplified loading patterns。 triangular, (IBC, k=1), (IBC, k=2) and rectangular, where k is an exponent related to the structure period to define vertical distribution factor, are used in the nonlinear static pushover analysis of 3, 5, 8 and 15story R\C frame structures. Load criteria are based on the distribution of inertial forces of design parameters. The simplified loading patterns as uniform distribution, triangular distribution and IBC distribution, these loading patterns are the most mon loading parameters. Vertical Distribution of Seismic Forces: VCF vxx  （ 1） VXCni kiikxxhwhw1 （ 2） where: Cvx = Vertical distribution factor V = Total design lateral force or shear at the base of structure wi and wx = The portion of the total gravity load of the structure hi and hx = The height from the base k = An exponent related to the structure period In addition these lateral loadings, frames are subjected live loads and dead weights. P△ effects have been taken into the account during the pushover analyses. The lateral force is increased for 3, 5 and 8story frames until the roof displacement reached 50 cm and 100cm for15story frame. Beam and column elements are used to analyze the frames. The beams are assumed to be rigid in the horizontal plane. Inelastic effects are assigned to plastic hinges at member ends. Strainhardening is neglected in all elements. Bilinear momentrotation relationship is assumed for both beam and column members. Axial loadMoment, PM, interaction relation, suggested by ACI 31889, is used as yielding surface of column elements. Inertial moment of cracked section, Icr, is used for both column and beam members during analyses. Icr is puted as half of the gross moment of inertia, Ig. The results of the pushover analyses are presented in Figures 2 to 5. The pushover curves are shown for three distributions, and for each frame structures. The curves represent base shearweight ratio versus story level displacements for uniform, triangular and IBC load distribution. Shear V was calculated by summing all applied lateral loads above the ground level, and the weight of the building W is the summation of the weights of all floors. Beside these, these curves represent the lost of lateral load resisting capacity and shear failures of a column at the displacement level. The changes in slope of these curves give an indication of yielding of various structural elements, first yielding of beam, first yielding of column and shear failure in the members. By the increase in the height of the frame structures, first yielding and shear failure of the columns is experienced at a larger roof displacements (Figures 25.) and rectangular distribution always give the higher base shearweight ratio paring to other load distributions for the corresponding story displacement (horizontal displacement). NONLINEAR DYNAMIC TIME HISTORY ANALYSIS OF FRAME STRUCTURES After performing pushover analyses, nonlinear dynamic time history analyses have been emp。