Scaling Procedure for Natural Accelerograms Based on a System of Spectrum Intensity Scales

1998 ◽  
Vol 14 (1) ◽  
pp. 135-152 ◽  
Author(s):  
Juan Enrique Martínez-Rueda
Keyword(s):  
Structural Parameters ◽  
Time History ◽  
Natural Period ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Scaling Procedure ◽  
Wide Range ◽  
Spectrum Intensity ◽  
Strength And Stiffness ◽  
Nonlinear Time History

A parametric study on the scaling of natural accelerograms using spectrum intensity scales is presented. A series of nonlinear time-history analyses for a SDOF system is conducted using an ensemble of world-wide damaging earthquake records for a wide range of seismic conditions. Structural parameters considered in the study include: yield seismic coefficient, yield natural period and postyield stiffness. The effectiveness of several spectrum intensity scales is evaluated in terms of their correlation with displacement ductility demand. Results indicate that there is not a unique scale with best performance over the entire range of strength and stiffness. An alternative combined criterion to define spectrum intensity is proposed in terms of a system of spectrum intensity scales. The system optimises the correlation between spectrum intensity and displacement ductility demand. This is achieved by defining regions in the space of structural parameters for which it is possible to identify a spectrum intensity scale of best performance.

scholarly journals Estimation of Cyclic Demand in Metallic Yielding Dampers Installed on Frame Structures

2020 ◽  
Vol 10 (12) ◽  
pp. 4364 ◽  
Author(s):  
Leandro Morillas ◽  
David Escolano-Margarit
Keyword(s):  
Structural Parameters ◽  
Time History ◽  
Dissipated Energy ◽  
Concrete Frames ◽  
Displacement Ductility ◽  
Design Values ◽  
Supplemental Dampers ◽  
Hysteretic Dampers ◽  
Nonlinear Time History ◽  
Cyclic Demand

The efficacy of hysteretic dampers can be formulated as the number or equivalent inelastic cycles, or the ratio of normalised dissipated energy to displacement ductility. This parameter is used in the design of framed structures with supplemental dampers and it is strongly influenced by the impulsive effects of earthquakes and other structural parameters. This paper presents an estimate of the cyclic demand of dampers installed in reinforced concrete frames, based on nonlinear time history analyses. Statistical analyses of the results are used to highlight relevant parameters and calibrate a predictive formula and upper-bound design values. The collapse pattern of the frames seems to have no effect on the efficacy of the dampers; thus, the seismological parameters that describe impulsivity should drive the design of hysteric dampers.

Blind Predictions of the Seismic Response of a Woodframe House: An International Benchmark Study

2004 ◽  
Vol 20 (3) ◽  
pp. 825-851 ◽  
Author(s):  
Bryan Folz ◽  
Andre Filiatrault
Keyword(s):  
Seismic Response ◽  
Numerical Models ◽  
Time History ◽  
Shake Table ◽  
Solution Strategies ◽  
Benchmark Study ◽  
Research Activities ◽  
Wide Range ◽  
Time History Response ◽  
Nonlinear Time History

As part of the CUREE-Caltech Woodframe Project, the international engineering community was invited to blind predict the dynamic characteristics and inelastic seismic response of a two-story woodframe house that had been extensively tested on a shake table. This research study provided a unique opportunity to assess the state of the art of numerical models in predicting the inelastic dynamic response of woodframe structures. Another objective of this study was to foster cooperation between the CUREE-Caltech Woodframe Project and other related research activities being conducted worldwide. Five international teams completed the benchmark exercise and provided blind predictions of the nonlinear time-history response of the shake-table test structure under varying levels of seismic input as well as its pushover response. The participating teams adopted a wide range of numerical models and solution strategies. This paper provides a summary of the activities conducted under the CUREE-Caltech Woodframe Project International Benchmark Study.

Analytical Models for the Seismic Performance of Gypsum Drywall Partitions

2006 ◽  
Vol 22 (2) ◽  
pp. 391-411 ◽  
Author(s):  
Amit M. Kanvinde ◽  
Gregory G. Deierlein
Keyword(s):  
Time History ◽  
Elastic Stiffness ◽  
Analytical Models ◽  
Published Data ◽  
Lateral Shear ◽  
Wall Boundary Conditions ◽  
Wall Panels ◽  
Lateral Strength ◽  
Strength And Stiffness ◽  
Nonlinear Time History

Gypsum drywall partitions may contribute significantly to the lateral strength and stiffness of woodframe structures, whether or not the walls are explicitly designed for that purpose. This paper proposes analytical models to determine the lateral shear strength and initial elastic stiffness of wood-framed gypsum wall panels, taking into account the effects of wall geometry, door and window openings, connector type and spacing, and wall boundary conditions. The strength and stiffness models are incorporated in a multilinear curve to describe the monotonic lateral shear versus deformation response of the walls. Additional parameters to calibrate the response of a peak-oriented hysteretic cyclic model are also proposed, thus making the models suitable for nonlinear time-history simulations of woodframe buildings. The models are developed and validated using published data from 16 shear tests of full-scale gypsum wall panels.

scholarly journals Ductility demand for uni-directional and reversing plastic hinges in ductile moment resisting frames

1999 ◽  
Vol 32 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Richard Fenwick ◽  
Raad Dely ◽  
Barry Davidson
Keyword(s):  
Plastic Hinge ◽  
Time History ◽  
Simple Relationship ◽  
Plastic Hinges ◽  
Ductility Demand ◽  
Displacement Ductility ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Negative Moment ◽  
Unidirectional Plastic

In a major earthquake the beams in moment resisting frames may develop either reversing or unidirectional plastic hinges. The form of plastic hinge depends upon the ratio of the moments induced by the gravity loading to those induced by the seismic actions. Where this ratio is low the plastic hinges form at the ends of the beams and the sign of the inelastic rotation changes with the direction of sway. These are reversing plastic hinges, and the magnitude of the rotation that they sustained is closely related to the inter-storey displacement. However, when the moment ratio exceeds a certain critical value, unidirectional plastic hinges may form. In this case negative moment plastic hinges develop at the column faces and the positive moment plastic hinges form in the beam spans. As the earthquake progresses the positive and negative inelastic rotations accumulate in their respective zones so that peak values are always sustained at the end of the earthquake. With this type of plastic hinge no simple relationship exists between inter-storey drift and inelastic rotation. Several series of time history analyses have been made to assess the relative magnitudes of inelastic rotation that are imposed on the two forms of plastic hinge. It is found that with design level earthquakes typically the unidirectional plastic hinge is required to sustain 21/ 2 to 4 times the rotation imposed on reversing plastic hinges, with the curvature ductilities ranging up to 140. These values are appreciably in excess of the values measured in tests using standard details. This indicates that in structures where unidirectional plastic hinges may form, the design displacement ductility and or the allowable inter-storey drift should be reduced below the maximum values currently permitted in the New Zealand codes. The problems associated with the formation of unidirectional plastic hinges can be avoided by adding positive moment flexural reinforcement in the mid regions of the beams. By this means the potential positive moment plastic hinges can be restricted to the beam ends.

scholarly journals Comparison of Novel Seismic Protection Devices to Attenuate the Earthquake Induced Energy

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 73
Author(s):  
Osman Hansu ◽  
Esra Mete Güneyisi
Keyword(s):  
Lateral Displacement ◽  
Time History ◽  
Seismic Protection ◽  
Base Shear ◽  
Seismic Demands ◽  
Nonlinear Time History Analyses ◽  
History Of ◽  
Protection Devices ◽  
Nonlinear Time History ◽  
Better Than

This study addresses an alternative use of viscous dampers (VDs) associated with buckling restrained braces (BRBs) as innovative seismic protection devices. For this purpose, 4-, 8- and 12-story steel bare frames were designed with 6.5 m equal span length and 4 m story height. Thereafter, they were seismically improved by mounting the VDs and BRBs in three patterns, namely outer bays, inner bays, and all bays over the frame heights. The structures were modeled using SAP 2000 software and evaluated by the nonlinear time history analyses subjected to the six natural ground motions. The seismic responses of the structures were investigated for the lateral displacement, interstory drift, absolute acceleration, maximum base shear, and time history of roof displacement. The results clearly indicated that the VDs and BRBs reduced seismic demands significantly compared to the bare frame. Moreover, the all-bay pattern performed better than the others.

scholarly journals Importance of $${{d}}_{{{xy}}}$$ orbital and electron correlation in iron-based superconductors revealed by phase diagram for 1111-system

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tsuyoshi Kawashima ◽  
Shigeki Miyasaka ◽  
Hirokazu Tsuji ◽  
Takahiro Yamamoto ◽  
Masahiro Uekubo ◽  
...  
Keyword(s):  
Electron Correlation ◽  
Weak Coupling ◽  
Structural Parameters ◽  
Structural Flexibility ◽  
Superconducting Transition ◽  
Iron Based Superconductors ◽  
Wide Range ◽  
Band Filling ◽  
Iron Based ◽  
Correlation Strength

AbstractThe structural flexibility at three substitution sites in LaFeAsO enabled investigation of the relation between superconductivity and structural parameters over a wide range of crystal compositions. Substitutions of Nd for La, Sb or P for As, and F or H for O were performed. All these substitutions modify the local structural parameters, while the F/H-substitution also changes band filling. It was found that the superconducting transition temperature $$T_{\text{c}}$$ T c is strongly affected by the pnictogen height $$h_{Pn}$$ h Pn from the Fe-plane that controls the electron correlation strength and the size of the $$d_{xy}$$ d xy hole Fermi surface (FS). With increasing $$h_{Pn}$$ h Pn , weak coupling BCS superconductivity switches to the strong coupling non-BCS one where electron correlations and the $$d_{xy}$$ d xy hole FS may be important.

scholarly journals Seismic Performance of a Green Roof Structure

2021 ◽  
Vol 13 (8) ◽  
pp. 4278
Author(s):  
Svetlana Tam ◽  
Jenna Wong
Keyword(s):  
Green Roof ◽  
Time History ◽  
Green Roofs ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Roof Structure ◽  
Nonlinear Time History Analyses ◽  
Vegetated Roofs ◽  
Nonlinear Time History ◽  
The Impact

Sustainability addresses the need to reduce the structure’s impact on the environment but does not reduce the environment’s impact on the structure. To explore this relationship, this study focuses on quantifying the impact of green roofs or vegetated roofs on seismic responses such as story displacements, interstory drifts, and floor level accelerations. Using an archetype three-story steel moment frame, nonlinear time history analyses are conducted in OpenSees for a shallow and deep green roof using a suite of ground motions from various distances from the fault to identify key trends and sensitivities in response.

Seismic response analysis of steel–concrete hybrid wind turbine tower

2021 ◽  
pp. 107754632110075
Author(s):  
Junling Chen ◽  
Jinwei Li ◽  
Dawei Wang ◽  
Youquan Feng
Keyword(s):  
Wind Turbine ◽  
Response Spectrum ◽  
Ground Motions ◽  
Time History ◽  
Seismic Action ◽  
Response Spectrum Method ◽  
Spectrum Method ◽  
Wind Turbine Tower ◽  
Ground Types ◽  
Nonlinear Time History

The steel–concrete hybrid wind turbine tower is characterized by the concrete tubular segment at the lower part and the traditional steel tubular segment at the upper part. Because of the great change of mass and stiffness along the height of the tower at the connection of steel segment and concrete segment, its dynamic responses under seismic ground motions are significantly different from those of the traditional steel tubular wind turbine tower. Two detailed finite element models of a full steel tubular tower and a steel–concrete hybrid tower for 2.0 MW wind turbine built in the same wind farm are, respectively, developed by using the finite element software ABAQUS. The response spectrum method is applied to analyze the seismic action effects of these two towers under three different ground types. Three groups of ground motions corresponding to three ground types are used to analyze the dynamic response of the steel–concrete hybrid tower by the nonlinear time history method. The numerical results show that the seismic action effect by the response spectrum method is lower than those by the nonlinear time history method. And then it can be concluded that the response spectrum method is not suitable for calculating the seismic action effects of the steel–concrete hybrid tower directly and the time history analyses should be a necessary supplement for its seismic design. The first three modes have obvious contributions on the dynamic response of the steel–concrete hybrid tower.

scholarly journals Nonlinear time-history earthquake analysis for steel frames

Heliyon ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. e06832
Author(s):  
Phu-Cuong Nguyen ◽  
Thanh-Tuan Tran ◽  
Trong Nghia-Nguyen
Keyword(s):  
Steel Frames ◽  
Time History ◽  
Nonlinear Time History

scholarly journals Displacement Demand for Nonlinear Static Analyses of Masonry Structures: Critical Review and Improved Formulations

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 118
Author(s):  
Gabriele Guerrini ◽  
Stylianos Kallioras ◽  
Stefano Bracchi ◽  
Francesco Graziotti ◽  
Andrea Penna
Keyword(s):  
Time History ◽  
Nonlinear Static Analysis ◽  
Equivalent Linearization ◽  
Eurocode 8 ◽  
Masonry Structures ◽  
Equivalent Viscous Damping ◽  
Inelastic Displacement ◽  
N2 Method ◽  
Nonlinear Static ◽  
Nonlinear Time History

This paper discusses different formulations for calculating earthquake-induced displacement demands to be associated with nonlinear static analysis procedures for the assessment of masonry structures. Focus is placed on systems with fundamental periods between 0.1 and 0.5 s, for which the inelastic displacement amplification is usually more pronounced. The accuracy of the predictive equations is assessed based on the results from nonlinear time-history analyses, carried out on single-degree-of-freedom oscillators with hysteretic force–displacement relationships representative of masonry structures. First, the study demonstrates some limitations of two established approaches based on the equivalent linearization concept: the capacity spectrum method of the Dutch guidelines NPR 9998-18, and its version outlined in FEMA 440, both of which overpredict maximum displacements. Two codified formulations relying on inelastic displacement spectra are also evaluated, namely the N2 method of Eurocode 8 and the displacement coefficient method of ASCE 41-17: the former proves to be significantly unconservative, while the latter is affected by excessive dispersion. A non-iterative procedure, using an equivalent linear system with calibrated optimal stiffness and equivalent viscous damping, is then proposed to overcome some of the problems identified earlier. A recently developed modified N2 formulation is shown to improve accuracy while limiting the dispersion of the predictions.

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