Structural Global Performance Assessment Versus Individual Element-Oriented Performance-Based Assessment
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RESEARCH PAPER
Structural Global Performance Assessment Versus Individual Element‑Oriented Performance‑Based Assessment Ebrahim Fadaei1 · Hamzeh Shakib1 · Alireza Azarbakht2,3 Received: 10 April 2018 / Accepted: 6 June 2019 © Shiraz University 2020
Abstract In this paper, three new performance indices are proposed which can be used in order to determine the global performance of a given structure. The ASCE41-13 standard and the FEMA350 guidelines are used as representatives of, respectively, an element-oriented and a system-oriented performance-based assessment algorithm. Two ten-storeyed special steel moment frames, consisting of a regular and an irregular structure, are designed and assessed using these two algorithms. The results show that the element-oriented assessment algorithm significantly underestimates the seismic demand and capacity, especially in the case of the immediate occupancy and collapse prevention limit states. This underestimation can cause a significant drop in the estimated confidence levels. Keywords Performance-based assessment · FEMA350 · ASCE41-13 · Confidence level
1 Introduction Performance-based engineering (PBE) is a significant improvement in seismic design and assessment of buildings which has become increasingly used in recent decades. It aims to provide stakeholders with an interpretation of structural performance corresponding to a given hazard level (Bozorgnia and Bertero 2004). FEMA356 was developed for the seismic rehabilitation of existing buildings. Four limit states have been introduced in FEMA356 (FEMA 2000a) which could be evaluated at different hazard levels by employing linear or nonlinear procedures. These limit states are: Immediate Occupancy (IO), Operational (O), Life Safety (LS), and Collapse Prevention (CP). FEMA356 later turned into ASCE41-06 (ASCE 2007) and ASCE41-13, which are mandatory regulations in the US. There is a shortcoming, however, which is that these regulations do not explicitly take into account either * Hamzeh Shakib [email protected] 1
School of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran
2
Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, UK
3
Department of Civil Engineering, Faculty of Engineering, Arak University, P.O. Box 38156‐88359, Arak, Iran
different uncertainties or acceptance criteria which are based on system-oriented behaviour. In the other word, exceeding a limit state in just one structural element is interpreted as the whole structure has exceeded the prescribed global performance level. The various structural limit states have mainly the same definitions in different regulations. For example, in ASCE41-13, IO corresponds to minor damage in which the structural system keeps its stiffness and strength without any residual drift. At the LS level, moderate damage occurs, but stiffness and strength change slightly. A residual drift will occur, and the structure needs to be repaired. At the CP level, the stiffness and strength change signific
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