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Nonlinear Static Analysis (nonlinear + static_analysis)

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Engineering100%

Selected Abstracts

Identification of Modal Combinations for Nonlinear Static Analysis of Building Structures

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2004
Sashi K. Kunnath
An increasingly popular analytical method to establish these demand values is a "pushover" analysis in which a model of the building structure is subjected to an invariant distribution of lateral forces. Although such an approach takes into consideration the redistribution of forces following yielding of sections, it does not incorporate the effects of varying dynamic characteristics during the inelastic response. Simple modal combination schemes are investigated in this article to indirectly account for higher mode effects. Because the modes that contribute to deformations may be different from the modes that contribute to forces, it is necessary to identify unique modal combinations that provide reliable estimates of both force and deformation demands. The proposed procedure is applied to typical moment frame buildings to assess the effectiveness of the methodology. It is shown that the envelope of demands obtained from a series of nonlinear static analysis using the proposed modal-combination-based lateral load patterns results in better estimation of inter-story drift, a critical parameter in seismic evaluation and design. [source]

Collapse of Reinforced Concrete Column by Vehicle Impact

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2008
Hing-Ho Tsang
The column slenderness ratio can be in the order of 6,9. Some of these buildings are right next to busy streets and hence continuously exposed to the potential hazard of a vehicle impacting on a column in an accident. In the early part of this study, the ultimate energy absorption capacity of a reinforced concrete column is compared to the kinetic energy embodied in the moving vehicle. The energy-absorption capacity is calculated from the force-displacement curve of the column as determined from a nonlinear static (push-over) analysis. The ultimate displacement of the column is defined at the point when the column fails to continue carrying the full gravitational loading. Results obtained from the nonlinear static analysis have been evaluated by computer simulations of the dynamic behavior of the column following the impact. Limitations in the static analysis procedure have been demonstrated. The effects of strain rate have been discussed and the sensitivity of the result to changes in the velocity function and stiffness of the impacting vehicle has also been studied. [source]

Identification of Modal Combinations for Nonlinear Static Analysis of Building Structures

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2004
Sashi K. Kunnath
An increasingly popular analytical method to establish these demand values is a "pushover" analysis in which a model of the building structure is subjected to an invariant distribution of lateral forces. Although such an approach takes into consideration the redistribution of forces following yielding of sections, it does not incorporate the effects of varying dynamic characteristics during the inelastic response. Simple modal combination schemes are investigated in this article to indirectly account for higher mode effects. Because the modes that contribute to deformations may be different from the modes that contribute to forces, it is necessary to identify unique modal combinations that provide reliable estimates of both force and deformation demands. The proposed procedure is applied to typical moment frame buildings to assess the effectiveness of the methodology. It is shown that the envelope of demands obtained from a series of nonlinear static analysis using the proposed modal-combination-based lateral load patterns results in better estimation of inter-story drift, a critical parameter in seismic evaluation and design. [source]

On the evaluation of seismic response of structures by nonlinear static methods

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 13 2009
Melina Bosco
Abstract In the most recent seismic codes, the assessment of the seismic response of structures may be carried out by comparing the displacement capacity, provided by nonlinear static analysis, with the displacement demand. In many cases the code approach is based on the N2 method proposed by Fajfar, which evaluates the displacement demand by defining, as an intermediate step, a single degree-of-freedom (SDOF) system equivalent to the examined structure. Other codes suggest simpler approaches, which do not require equivalent SDOF systems, but they give slightly different estimation of the seismic displacement demand. The paper points out the differences between the methods and suggests an operative approach that provides the same accuracy as the N2 method without requiring the evaluation of an equivalent SDOF system. A wide parametric investigation allows an accurate comparison of the different methods and demonstrates the effectiveness of the proposed operative approach. Copyright © 2009 John Wiley & Sons, Ltd. [source]