Exact’’ ThreeDimensional Linear and Nonlinear （的u201C三维线性和非线性）.pdfVIP

‘‘Exact’’ Three-Dimensional Linear and Nonlinear Seismic Analysis of Structures with Two-Dimensional Models Michael Mehrain,a) M.EERI, and Farzad Naeim,b) M.EERI This paper presents a modeling technique by which a complete three- dimensional (3-D) structural analysis of a structure can be performed using two-dimensional (2-D) models, and hence 2-D software. The approach in- cludes the effect of torsion, walls perpendicular and inclined to the direction of motion as well as walls with L, T, and H shapes in plan. Diaphragm dis- placements are easily modeled. The method can be used with linear and non- linear analysis. Nonlinearity in the diaphragms can also be modeled with relative ease. Furthermore, unlike the conventional analysis that requires two 2-D models, one in each direction of motion, to model the 3-D structure, this approach requires only a single model. [DOI: 10.1193/1.1623498] INTRODUCTION In a traditional two-dimensional (2-D) structural analysis of a three-dimensional (3-D) structure, the seismic resisting elements such as walls and frames in the direction of motion are lined up in a 2-D plane and slaved at the roof and each floor. For ground motion in the perpendicular direction, a completely new 2-D model that includes walls and frames in that direction is required. Since all seismic resisting elements in a conventional 2-D model undergo equal dis- placements at each level, the 2-D model represents a 3-D structure in which torsional displacements are locked. This can cause substantial inaccuracies in structures with sig- nificant torsion. Standards and guidelines for design and retrofit of structures typically restrict the use of 2-D analysis when substantial torsion exists. FEMA-356 (ASCE 2000), for example, defines parameter , representing torsion, as the