On repairable earthquake resisting archetypes with a view to resiliency objectives and assisted self‐centering

Abstract

Performance-based seismic design, as an alternative to conventional methods of approach, has served engineers and the public rather well during the last two decades.Neither approach guaranties catastrophic collapse prevention nor post-earthquake realignment and repairs (PERR) due to major seismic events. As a result, most codecompliant buildings can be regarded as relatively safe but practically disposable. The paper presents a new philosophy that leads to sustainable design of new structures and the upgrading of existing earthquake resisting moment frames. Repairabilitybased design (RBD) relies on softening and control rather than strength and resistance to elevate seismic performance to economically viable, physical collapse prevention, damage control, and post-earthquake realignment and repairs. The new approach was inspired by design led analysis (DLA), performance control (PC), and recent developments in rocking core-moment frame design. DLA is a displacement based method of analysis with built-in results. PC is the ability to design a structure in such a way as to expect predetermined modes of response at certain stages of loading, extents of damage, and drift ratios. This paper advocates higher performance objectives than current codes of practice do. Several demonstrative examples have been provided.

Sustainable seismic design and health monitoring

“…Base isolation, (b) tuned mass damping, (c) post-tensioned RRC 14 (cables not shown), (d) the stiff column, 15 (e) solid RRC, 12 (f) tendon stabilized RRC, 16 (g) the strong back, 17 (h) linked RRCs, (i) stepping rigid core, with or without stabilizing central tendons 18 F I G U R E 2 (a) Proposed articulated beam-column joint, (b) proposed pinned-base column support, (c) proposed rocking-base column support, partial fixity provided by the grade beams frames and horizontal diaphragms that do not interact with non-structural elements. 25,26 This is a conservative assertion that tends to improve the global resistance of the structure but hinders the PERR process. 18,27 There are several code directives that are meant to improve the seismic behavior of conventional ERS but impede the recentering effort, for example, the strong column-weak beam requirement that prevents damage to beam-column joints but renders the structure practically unrepairable due to formation of plastic hinges at column supports or the simple beam-column connections that are supposed to carry zero moments but accumulate considerable residual strains due to large rotations.…”

“…Gravity loads include the self‐weight of all items enclosed within the building envelope. Although the complete building system, including architectural and non‐structural items, acts integrally to resist lateral loads, building codes construe ERSs as being composed of vertical frames and horizontal diaphragms that do not interact with non‐structural elements 25,26 . This is a conservative assertion that tends to improve the global resistance of the structure but hinders the PERR process 18,27 .…”

On the analysis of multilevel rocking cores—A bioinspired analogy

“…Drift control and prevention of soft story failure can be addressed either theoretically 35 or, by purpose, specific physical arrangements, leading to sustainable earthquake resisting systems. [36][37][38][39][40][41] Relatively rigid rocking cores tend to impose straight-line drift profiles upon the parent structures and absorb the entire lateral force at failure. The scope of the current article is limited to the study of the behavior of some of the most common MLRCs under different loading profiles and boundary support conditions.…”

“…Note that in order to relate the axial component of the deformation function to the mid-height of the modules, the integer (x) must be replaced with (x − 1 ∕ 2 ). In practical terms, Y a (x) for uniformly distributed, inverted triangular, and concentrated nodal forces can be computed by substituting (x − 1 ∕ 2 ) for x in Equations (37), (41), and (35)-(36), respectively.…”

“…Soft story failure and DS in multistory buildings are influenced by many factors. Drift control and prevention of soft story failure can be addressed either theoretically or, by purpose, specific physical arrangements, leading to sustainable earthquake resisting systems . Relatively rigid rocking cores tend to impose straight‐line drift profiles upon the parent structures and absorb the entire lateral force at failure.…”