Incremental dynamic analysis (IDA) is a parametric analysis method that has recently emerged in several different forms to estimate more thoroughly structural performance under seismic loads. It involves subjecting a structural model to one (or more) ground motion record(s), each scaled to multiple levels of intensity, thus producing one (or more) curve(s) of response parameterized versus intensity level. To establish a common frame of reference, the fundamental concepts are analysed, a unified terminology is proposed, suitable algorithms are presented, and properties of the IDA curve are looked into for both single-degree-of-freedom and multi-degree-of-freedom structures. In addition, summarization techniques for multi-record IDA studies and the association of the IDA study with the conventional static pushover analysis and the yield reduction R-factor are discussed. Finally, in the framework of performance-based earthquake engineering, the assessment of demand and capacity is viewed through the lens of an IDA study. Copyright © 2001 John Wiley & Sons, Ltd.

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Incremental dynamic analysis

(1991). Applied Linear Regression Models. Journal of Quality Technology: Vol. 23, No. 1, pp. 76-77.

Applied Linear Regression Models

Minimum Design Loads for Buildings and Other Structures provides requirements for general structural design and includes means for determining dead, live, soil, flood, wind, snow, rain, atmospheric ice, and earthquake loads, as well as their combinations, which are suitable for inclusion in building codes and other documents. This Standard, a revision of ASCE/SEI 7-05, offers a complete update and reorganization of the wind load provisions, expanding them from one chapter into six. The Standard contains new ultimate event wind maps with corresponding reductions in load factors, so that the loads are not affected, and updates the seismic loads with new risk-targeted seismic maps. The snow, live, and atmospheric icing provisions are updated as well. In addition, the Standard includes a detailed Commentary with explanatory and supplementary information designed to assist building code committees and regulatory authorities. Standard ASCE/SEI 7 is an integral part of building codes in the United States. Many of the load provisions are substantially adopted by reference in the International Building Code and the NFPA 5000 Building Construction and Safety Code. Structural engineers, architects, and those engaged in preparing and administering local building codes will find this Standard an essential reference in their practice. Note: New orders are fulfilled from the second printing, which incorporates the errata to the first printing.

Minimum Design Loads for Buildings and Other Structures

Estimation of fragility functions using dynamic structural analysis is an important step in a number of seismic assessment procedures. This paper discusses the applicability of statistical inferenc...

Efficient analytical fragility function fitting using dynamic structural analysis

Introduced in this paper are several alternative ground-motion intensity measures (IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the “efficiency” and “sufficiency” of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions.

Structure-specific scalar intensity measures for near source and ordinary earthquake ground motions

Computational Fluid Dynamics at the Nanoscale Narayana R. Aluru Simulation in Natural Hazards Engineering and the SimCenter

Nonlinear simulations of seismically enhanced light-frame systems

The downtown business districts of San Francisco, Los Angeles and other cities in the western United States have significant inventories of older (pre-2000) tall steel buildings that have elevated risk, compared to new code-conforming buildings, of damage and collapse from strong earthquakes. Many of these buildings have welded connections of the type that experienced sudden brittle fractures during the 1994 Northridge earthquake, and they were designed under building codes with less stringent requirements on seismic drifts, minimum column strengths, and seismic base shears. Compounding these deficiencies are new seismic hazard models which indicate that long-period spectral accelerations and durations of earthquake ground motions are larger than considered in older design codes. This study applies newly developed models to assess the response of older steel buildings from the onset of damage up to collapse. The analysis results are used to examine issues associated with post-earthquake inspection and safety, which have implications on building reoccupancy and recovery. The study considers the implication of structural damage on recovery of both the tall building itself, as well as implications of safety cordons around the tall building on the re-occupancy and recovery of neighboring buildings. A method is proposed for quantifying the post-earthquake safety of damaged tall buildings to inform criteria for establishing safety cordons. The building-specific performance-based assessment method of FEMA P58 is extended and applied to quantify the post-earthquake recovery time for neighboring buildings. In addition to providing more comprehensive estimates of community downtime, this framework can include metrics for whether certain buildings are likely to induce inordinately long downtimes in surrounding buildings or how a cordoning strategy will affect a community. This type of downtime assessment can inform a range of policy and planning decisions, such as requiring seismic retrofit of vulnerable tall buildings, evaluating emergency response strategies, and developing postearthquake recovery plans.

Gregory G. Deierlein

Papers

Computational Fluid Dynamics at the Nanoscale Narayana R. Aluru Simulation in Natural Hazards Engineering and the SimCenter

Nonlinear simulations of seismically enhanced light-frame systems

Safety of Tall Pre-Northridge Steel Frame Buildings and Implications on Cordoning and Recovery