Seismic Performance Evaluation of Steel Moment-Resisting Frames Designed According to 3rd and 4th Editions of 2800 Seism
- PDF / 2,059,133 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 75 Downloads / 195 Views
RESEARCH PAPER
Seismic Performance Evaluation of Steel Moment‑Resisting Frames Designed According to 3rd and 4th Editions of 2800 Seismic Code Mohsen Izadinia1 · Navid Amini1 Received: 3 June 2017 / Accepted: 15 June 2020 © Shiraz University 2020
Abstract Current design codes have prepared linear analysis methods instead of nonlinear ones in order to reduce time, cost and other factors such as less need of these methods for expert knowledge. In linear analysis method, elastic strength demand of structure is decreased by applying a response modification factor called behavior factor (R) and by considering the design code regulations, structure members will be permitted to experience nonlinear response (in the time of middle-to-severe earthquakes). Because of different assumptions for linear (force-based method that has deficiencies) and nonlinear methods and whereas seismic stability or instability is not merely related to the strength of structure, rather it depends largely on the capability of structure to resist drifts, seismic performance evaluation of structures designed by linear procedure appears to be necessary using standards for evaluation. In this research, seismic performance of steel moment frames once designed based on 3rd edition of 2800-Iranian seismic code and allowable stress design (ASD) method and another time based on new ones, the 4th edition of 2800 seismic code and load and resistance factor design (LRFD) method, are compared with each other through nonlinear pushover and time-history analyses according to ASCE/SEI 41–13. Results showed positive change of design codes procedure with respect to alteration of design method in both types of ductile design, intermediate and special. Since mean of overstrength values and mean of ductility values have increased a little, mean of behavior factor values has become closer to the recommended values of the new seismic code. Also, a small number of structures met total collapse during nonlinear time-history analyses. Keywords Intermediate and special moment-resisting frames · Nonlinear static analysis · Nonlinear time-history analysis · Seismic parameters · Structural performance levels
1 Introduction For steel structures two types of design method, allowable stress and limit state also called load and resistance factor method are presented in American and Iranian standards. The allowable stress method has been established based on yield criteria and limit state method is based on plastic criteria. In formulation of allowable stress method, internal forces of structural members are computed from linear elastic analysis method and based on serviceability loads (without factor). Allowable stresses are calculated based on both yield and stability criteria with safety factor for different actions of members (flexural, tensile, compression, etc.) * Mohsen Izadinia [email protected] 1
fa < Fa
(1)
fa and Fa are required and allowable stresses, respectively. It is worth noting that in this method when design load combinations contain emergency loads
Data Loading...
