Adaptive Spectra-Based Pushover Procedure for Seismic Evaluation of Structures

2000 ◽  
Vol 16 (2) ◽  
pp. 367-391 ◽  
Author(s):  
Balram Gupta ◽  
Sashi K. Kunnath
Keyword(s):  
Response Spectrum ◽  
Pushover Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Time History ◽  
Northridge Earthquake ◽  
Seismic Evaluation ◽  
Seismic Demands ◽  
Ground Shaking ◽  
Motion Characteristics ◽  
Nonlinear Time History

The estimation of inelastic seismic demands using nonlinear static procedures, or pushover analyses, are inevitably going to be favored by practicing engineers over nonlinear time-history methods. While there has been some concern over the reliability of static procedures to predict inelastic seismic demands, improved procedures overcoming these drawbacks are still forthcoming. In this paper, the potential limitations of static procedures, such as those recommended in FEMA 273, are highlighted through an evaluation of the response of instrumented buildings that experienced strong ground shaking in the 1994 Northridge earthquake. A new enhanced adaptive “modal” site-specific spectra-based pushover analysis is proposed, which accounts for the effect of higher modes and overcomes the shortcomings of the FEMA procedure. Features of the proposed procedure include its similarity to traditional response spectrum-based analysis and the explicit consideration of ground motion characteristics during the analysis. It is demonstrated that the proposed procedure is able to reasonably capture important response attributes, such as interstory drift and failure mechanisms, even for structures with discontinuities in strength and/or stiffness that only a detailed nonlinear dynamic analysis could predict.

scholarly journals A simple method for determining seismic demands on gravity load frames

2017 ◽  
Vol 44 (8) ◽  
pp. 661-673 ◽  
Author(s):  
J. Beauchamp ◽  
P. Paultre ◽  
P. Léger
Keyword(s):  
Response Spectrum ◽  
Time History ◽  
Bending Moment ◽  
New Method ◽  
Simple Method ◽  
Seismic Demands ◽  
Gravity Load ◽  
Comparison Results ◽  
Seismic Force ◽  
Nonlinear Time History

This paper presents a simple method based on modal response spectrum analysis to compute internal forces in structural elements belonging to gravity framing not part of the seismic force resisting system (SFRS). It is required that demands on these gravity load resisting system (GLRS) be determined according to the design displacement profile of the SFRS. The proposed new method uses the fact that if the linear stiffness properties of the GLRS not part of the SFRS have negligible values compared to those of the SFRS, only the latter will provide lateral resistance. Displacements of the GLRS then correspond to those of the SFRS alone. The new method is illustrated by computing the seismic responses of a symmetric and an asymmetric multi-storey reinforced concrete building. These results are compared to those obtained from the application of the simplified analysis method proposed in the Canadian standard for the design of concrete structures. Nonlinear time history analyses are also performed to provide a benchmark for comparison. Results show that the new method can predict shear and bending moment in all members at once with ease. Therefore, this new simplified method can effectively be used to predict seismic forces in elements not considered part of the SFRS.

Modal Superposition Technique to Predict the Seismic-Pushover Load for Jacket-Type Structures

2002 ◽  
Author(s):  
Kanthi Srirengan ◽  
Partha Chakrabarti ◽  
Rupak Ghosh
Keyword(s):  
Response Spectrum ◽  
Pushover Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Elastic Response ◽  
Preliminary Evaluation ◽  
Inelastic Behavior ◽  
Linear Superposition ◽  
Linear Elastic ◽  
Nonlinear Time History

Two novel methods namely the Dominant Modes method and the All Modes method to predict the seismic-pushover load for the jacket-type structures are presented. Both of these methods are based on the linear superposition of the modal reactions. As a preliminary evaluation, the linear elastic response of a jacket structure subjected to seismic-pushover loads is compared with that obtained from the response spectrum analysis. Furthermore, the nonlinear inelastic behavior obtained from the seismic-pushover analysis is compared with that obtained from the nonlinear time-history analysis, for a portal frame subjected to El Centro earthquake motion. When more than one mode is dominant in an excitation direction, both the linear elastic and the nonlinear inelastic responses obtained using the loads generated from the All Modes method are representative of the reference solutions.

Performance of Structures with Passive Energy Dissipators

2002 ◽  
Vol 18 (1) ◽  
pp. 105-119 ◽  
Author(s):  
H. Kit Miyamoto ◽  
J. P. Singh
Keyword(s):  
High Intensity ◽  
Linear Time ◽  
Response Spectrum ◽  
Time History ◽  
Seismic Intensity ◽  
Ground Shaking ◽  
Blue Book ◽  
Earthquake Performance ◽  
Energy Dissipators ◽  
Nonlinear Time History

The purpose of this paper is to evaluate the earthquake performance of structures with passive energy dissipators. This paper addresses the following issues: (1) evaluation of seismic intensity levels at which frames incorporating the energy dissipating system (EDS) remain elastic; (2) performance evaluation of frames incorporating an EDS for high-intensity ground shaking; and (3) evaluation of SEAOC Blue Book provisions. Linear time-history analyses indicate that frames with an EDS generally remain elastic during earthquake events that do not greatly exceed the UBC Zone 4 response spectrum. Nonlinear time-history analyses indicate the following: (1) the frames with an EDS can provide “immediate occupancy performance” for high-intensity earthquakes; (2) the performance level of the frames with an EDS exceeds that of frames without an EDS; and (3) the performance of the frame with an EDS, which was designed per Blue Book provisions, can exceed life safety performance.

scholarly journals Effectiveness of modified pushover analysis procedure for the estimation of seismic demands of buildings subjected to near-fault ground motions having fling step

2013 ◽  
Vol 13 (6) ◽  
pp. 1579-1593 ◽  
Author(s):  
A. Mortezaei ◽  
H. R. Ronagh
Keyword(s):  
Ground Motions ◽  
Pushover Analysis ◽  
Time History ◽  
Building Structures ◽  
Seismic Demands ◽  
Near Fault ◽  
Load Pattern ◽  
Dynamic Time ◽  
Near Fault Earthquakes ◽  
Nonlinear Time History

Abstract. Near-fault ground motions with long-period pulses have been identified as being critical in the design of structures. These motions, which have caused severe damage in recent disastrous earthquakes, are characterized by a short-duration impulsive motion that transmits large amounts of energy into the structures at the beginning of the earthquake. In nearly all of the past near-fault earthquakes, significant higher mode contributions have been evident in building structures near the fault rupture, resulting in the migration of dynamic demands (i.e. drifts) from the lower to the upper stories. Due to this, the static nonlinear pushover analysis (which utilizes a load pattern proportional to the shape of the fundamental mode of vibration) may not produce accurate results when used in the analysis of structures subjected to near-fault ground motions. The objective of this paper is to improve the accuracy of the pushover method in these situations by introducing a new load pattern into the common pushover procedure. Several pushover analyses are performed for six existing reinforced concrete buildings that possess a variety of natural periods. Then, a comparison is made between the pushover analyses' results (with four new load patterns) and those of FEMA (Federal Emergency Management Agency)-356 with reference to nonlinear dynamic time-history analyses. The comparison shows that, generally, the proposed pushover method yields better results than all FEMA-356 pushover analysis procedures for all investigated response quantities and is a closer match to the nonlinear time-history responses. In general, the method is able to reproduce the essential response features providing a reasonable measure of the likely contribution of higher modes in all phases of the response.

Seismic Evaluation of the Santa Catalina’s Church of Valencia (Spain) Applying a Scalar Damage Model

2017 ◽  
Vol 747 ◽  
pp. 638-645
Author(s):  
Jésica Moreno-Puchalt ◽  
Adolfo Alonso-Durá ◽  
Verónica Llopis-Pulido ◽  
Ana Almerich-Chulia
Keyword(s):  
Pushover Analysis ◽  
Damage Model ◽  
Nonlinear Dynamic Analysis ◽  
Time History ◽  
Element Model ◽  
Structural System ◽  
Seismic Evaluation ◽  
Seismic Effects ◽  
Good Correspondence ◽  
Gothic Architecture

The structural system in Gothic architecture of Central Europe is characterized by the vaults supported on pillars and the dematerialization of walls to introduce into the Temple the maximum light possible. However the “Mediterranean Gothic” structure of the churches is formed by two sets of diaphragm walls breaking with the traditional gothic canons. The study carried out explains the reasons for these differences from an exhaustive structural analysis of Santa Catalina’s church of Valencia under seismic effects. Two methods for analyzing have been used for simulating the seismic effects: the pushover analysis and the nonlinear dynamic analysis in time-history. The non-linear damage model method with its evolution under static and dynamic loads was applied in both cases. The study has been extended up to five different simulations of the same Finite Element model, depending on the constructive elements that made up the wall structural system and two return periods of 475 and 950 years. The methods used gave a good correspondence in their results which make them two complementary methods according to the proposed objectives. The results show that the Santa Catalina’s church offers an optimal seismic response as a consequence of its structural system stiffness.

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.

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 Evaluation of p-delta effect in structural seismic response

2018 ◽  
Vol 162 ◽  
pp. 04019 ◽  
Author(s):  
Sardasht Sardar ◽  
Ako Hama
Keyword(s):  
Seismic Response ◽  
Pushover Analysis ◽  
Nonlinear Dynamic Analysis ◽  
Time History ◽  
Steel Structure ◽  
Nonlinear Static Analysis ◽  
Structural Behavior ◽  
Finite Element Software ◽  
History Analysis ◽  
Nonlinear Static

Numerous recent studies have assessed the effect of P-Delta on the structures. This paper investigates the effect of P-Delta in seismic response of structures with different heights. For indicating the effect of P-Delta, nonlinear static analysis (pushover analysis) and nonlinear dynamic analysis (Time history analysis) were conducted by using finite element software. The results showing that the P-Delta has a significant impact on the structural behavior mainly on the peak amplitude of building when the height of the structures increased. In addition, comparison has been made between concrete and steel structure.

Applicability of Modal Pushover Analysis on Bridges

2011 ◽  
Vol 255-260 ◽  
pp. 806-810
Author(s):  
Biao Wei ◽  
Qing Yuan Zeng ◽  
Wei An Liu
Keyword(s):  
Seismic Analysis ◽  
Pushover Analysis ◽  
Time History ◽  
Seismic Demand ◽  
Seismic Demands ◽  
Modal Pushover Analysis ◽  
History Analysis ◽  
Bridge Structures ◽  
Scope Of Application ◽  
Modal Pushover

Taking one irregular continuous bridge as an example, modal pushover analysis (MPA) has been conducted to judge whether it would be applicable for seismic analysis of irregular bridge structures. The bridge’s seismic demand in the transverse direction has been determined through two different methods, inelastic time history analysis (ITHA) and MPA respectively. The comparison between those two results indicates that MPA would be suitable only for bridges under elastic or slightly damaged state. Finally, some modifications are used to improve the MPA’s scope of application, and the results illustrate that the adapted MPA will be able to estimate bridges’ seismic demands to some extent.

Predictive Equations to Quantify the Impact of Spectral Matching on Ground Motion Characteristics

2016 ◽  
Vol 32 (1) ◽  
pp. 125-142 ◽  
Author(s):  
Clinton Carlson ◽  
Dimitrios Zekkos ◽  
Adda Athanasopoulos-Zekkos
Keyword(s):  
Ground Motion ◽  
Response Spectrum ◽  
Time History ◽  
Peak Ground Velocity ◽  
Spectral Matching ◽  
Predictive Equations ◽  
Earthquake Scenarios ◽  
Cumulative Absolute Velocity ◽  
Motion Characteristics ◽  
The Impact

Spectral matching, the process of modifying a seed acceleration time history in intensity and frequency content until its acceleration response spectrum matches a target spectrum, is used extensively in practice. Predictive equations that quantify the impact of spectral matching on the peak ground velocity, peak ground displacement, Arias intensity, and cumulative absolute velocity of a scaled seed time history have been developed and validated on the basis of thousands of matched motions, three different earthquake scenarios, and numerous target spectra. It is found that spectral mismatch is the most critical factor affecting the changes in ground motion characteristics. The technique used for modification (e.g., time domain or frequency domain) is in many cases not critical. Based on the results, recommendations in order to minimize the impact of matching on the ground motion characteristics are provided.

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