Integrated seismic assessment and design of plan-irregular structures

Moon, Do Soo

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Description

Title

Integrated seismic assessment and design of plan-irregular structures

Author(s)

Moon, Do Soo

Issue Date

2013-02-03T19:29:46Z

Director of Research (if dissertation) or Advisor (if thesis)

Elnashai, Amr S.

Doctoral Committee Chair(s)

Elnashai, Amr S.

Committee Member(s)

• Spencer, Billie F., Jr.
• Popovics, John S.
• Song, Junho

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Plan-irregular Structure
• Kinematic Eccentricity
• Torsional Response
• Integrated Framework
• Seismic Design and Assessment
• Inelastic Seismic Response

Abstract

Structures that have non-coincident centers of mass and stiffness are referred to as plan-irregular structures. Such structures could be highly vulnerable to earthquake damage due to torsional response. Thus, the structural design of plan-irregular structures requires advanced seismic assessment and design guidelines which address torsional effects. This study aims to provide advanced and improved seismic assessment and design guidelines for plan-irregular structures. Furthermore, this study aims to develop an integrated seismic assessment and design framework by which reliable and effective seismic designs for plan-irregular structures can be created. In order to develop advanced seismic assessment guidelines, this study extensively investigates the inelastic torsional response of reinforced concrete structures, both regular and irregular in plan. The concept of “kinematic eccentricity” is introduced, which is the eccentricity that arises from inelastic deformations even when the original structure is perfectly symmetric. In contrast to previous research, this study evaluates seismic torsional response through temporal eccentricity variation. In order to obtain the instantaneous location of the center of resistance in the inelastic range, an inelastic stiffness evaluation method for lateral load-resisting members is proposed. By utilizing this method, it is observed that the maximum eccentricities occur when one or a few of the lateral load-resisting members yield. Also, the observed maxima of the temporally-varying distances between the centers of mass and stiffness are shown to be higher than the design accidental eccentricities in current seismic codes. The latter observation supports the notion that the current provisions considerably underestimate the seismic torsional response of plan-regular and -irregular structures. Accordingly, it is recommended to utilize a percentage increase in eccentricity due to inelastic response even when structures have a regular plan. Based on the cumulative knowledge from the inelastic analyses presented, improved seismic design guidelines for irregular structures are proposed. Whereas design eccentricities adopted by current seismic design codes only use initial stiffness eccentricity in their calculation, which is adequate only for the elastic response range defined when the lateral load-resisting members remain intact, this study proposes to utilize transient eccentricities. The latter is defined when one or a few of the lateral load-resisting members yield. To validate the proposed method, inelastic dynamic response-history analyses, equivalent lateral force analyses with code-defined eccentricities, and proposed static analyses with transient eccentricities are conducted. A comparison of the results proves the validity and superiority of the proposed method. Lastly, an integrated seismic assessment and design framework for plan-irregular structures is proposed and developed. To achieve a seamless interaction between analysis and design, an advanced bi-directional link interface is developed between Revit Structure from Autodesk, one of the innovative Building Informational Modeling (BIM) software packages, and ZEUS-NL from Mid-America Earthquake (MAE) Center, one of the most advanced structural analysis packages. This interface is referred to as “advanced” since it provides the functionality of exporting and updating, with various options, non-structural as well as structural components. Also, a torsional response prediction tool, which provides guidance for assessment and design that addresses damaging torsional effects, is developed. Finally, the feasibility of the proposed framework is demonstrated via a pilot implementation.

Graduation Semester

2012-12

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http://hdl.handle.net/2142/42267

Copyright and License Information

Copyright 2012 Do Soo Moon

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