|M.Sc Student||Mashrikov Anton|
|Subject||Evaluation of Quantitative Demands for Performance-Based|
Design of Moment-Resisting Frames
|Department||Department of Civil and Environmental Engineering||Supervisor||Mr. Dimitry Val|
|Full Thesis text - in Hebrew|
Performance-based design is a design philosophy in which the design criteria are expressed in terms of achieving stated performance objectives when a structure is subjected to stated levels of seismic hazard. The performance targets may be a level of stress or displacement not to be exceeded, or a target damage state. When defining the performance of a structure, in terms of states of damage, strains or deformations are better indicators of damage than stresses. In effect, performance based-design is a powerful new approach that includes traditional methods of seismic design with significant upgrades. The aim of the present research is to compare the efficiency of different pushover analysis methods for predicting seismic demands (displacements and internal forces) for performance-based design of steel moment-resisting frames. In the thesis accuracy of the pushover procedure described in FEMA-273 with two different force distribution (uniform and first mode), and also of adaptive and modal pushover procedures is compared. These procedures are checked against nonlinear time-history analysis, which is treated as a benchmark. The comparison is carried out for a range of generic steel moment-resisting frames for an ensemble of earthquake ground motion records. The frames are designed according to the strong-columns weak-beams concept and include: (1) fifty vertically "regular" frames of six different heights: 3, 6,9,12 and 15 stories; and (2) three "irregular" frames (with stiffness irregularity), all 15 stories high. The frames are made of wide-flange sections and have dynamic characteristics similar to those used by other researchers. The ensemble of ground motions used in the study is LA10/50 (includes 10 records from the Los Angeles area) from the SAC project. The comparison is based on values of inter-story drifts and axial forces in columns calculated using the four pushover procedures and nonlinear time history analysis. Pushover analysis and nonlinear time-history analysis are performed with the help of SeismoStruct - a finite element program for nonlinear static and dynamic analysis of frame structures.