Seismic Resilience of Large-Span Lattice Structures

Abstract eng:
Reasonable quantitative performance indicators are extremely important for the assessment and classification of performance levels of structures that experienced strong earthquakes. Seismic resilience is introduced to offer a direct assessment mean for quantifying the ability of highly redundant large-span lattice structures with some degree of damage due to earthquakes to restore or retain their original seismic capacity. A macroscopic global seismic damage model proposed previously with the consideration of multiple vibration modes for lattice structures is adopted to quantify the level of initial damage and to act as a collapse judge criterion. The so-called seismic resilience index is then defined as the ratio of the seismic capacity of an initially intact lattice structure to that of a damaged one. The incremental dynamic analysis is carried out to evaluate the seismic capacity of intact and damaged lattice structures. Lattice structures can be classified as different grades of seismic resilience according to the complete relationship curve between resilience index and global damage index. Five types of single-layer lattice structures are used to study the influence of some factors on seismic resilience. Computational results indicate that failure mode has significant impact on resilience level of a damaged lattice structure. Structurally global instability can lead to substantial loss of seismic resilience. Structures with any level of damage can still have the ability to withstand earthquakes with certain degree if strength failure eventually takes place. Compared with other response-based or damage-based performance indexes, seismic resilience index is advantageous to provide a complete scanned photo of reservation in seismic resistance of structures with certain damage. A parametric study is conducted to investigate the effects of some factors, e.g. structural system, rise-span-ratio, and initial imperfection, etc. on seismic resilience. Seismic resilience has a strong correlation with robustness and integrity of structures. Thus, seismic resilience index can also be regarded as a useful tool more reasonably to quantify the degree of robustness or integrity.

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