Application of Normalized Spectral Acceleration-Displacement (NSAD) Format on Performance-Based Seismic Design of Bridge Structures

2007 ◽  
Vol 23 (2) ◽  
pp. 87-94
Author(s):  
Y.-C. Sung ◽  
S.-Y. Chang ◽  
M.-C. Lai ◽  
T.-W. Lin ◽  
I.-C. Tsai
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Time History ◽  
Wave Form ◽  
Spectral Acceleration ◽  
Ground Acceleration ◽  
Seismic Demands ◽  
Sdof System ◽  
Bridge Structures ◽  
Performance Based Seismic Design

AbstractFor a bi-linear SDOF system subjected to a specific wave form of the ground acceleration, the unique yielding pseudo spectral acceleration and spectral displacement (Say, Sdy) together with various inelastic responses (Sai, Sdi) can be obtained via nonlinear time history analyses, respectively, by tuning the different levels of peak ground acceleration as various input ground motions. Meanwhile, the corresponding elastic responses (Sae, Sde) of a linear SDOF system with the identical mass, viscous damping and elastic stiffness as those of the bi-linear one can also be determined through linear time history analyses under the same excitations. The proposed NSAD format shown on the diagram of the elastic force ratio, Ω=Sae/Say I Say, versus the ductility ratio, (μ= (Sdi/Sdy), is a dimensionless plot of the seismic demands suitable to the engineers who are familiar with the conventional force-based design using linear structural analysis. In this paper, more than two hundred ground motions recorded in the Chi-Chi earthquake, Taiwan (1999) were chosen as the seismic inputs for the establishment of the NSAD format. The characteristics and applications of the NSAD format on the performance-based seismic design of the bridge structures were discussed, and realistic procedures for the methodology were proposed.The results obtained shows that the NSAD format can help the engineers evaluate the multiple-level seismic demands not only with a well precision but also with a great convenience.

Probabilistic Peak Displacement Analysis of Bridge Structures with P-Δ Effect

2013 ◽  
Vol 405-408 ◽  
pp. 1674-1677
Author(s):  
Bo Yu ◽  
Di Liu ◽  
Lu Feng Yang
Keyword(s):  
Time History ◽  
Dynamic Responses ◽  
Nonlinear Time History Analysis ◽  
Bridge Structure ◽  
Vibration Period ◽  
Peak Displacement ◽  
Sdof System ◽  
Bridge Structures ◽  
Performance Based Seismic Design ◽  
Nonlinear Time History

Peak displacement is one of the most important parameters for the performance based seismic design of bridge structure, while the peak displacement is often significantly impacted by the P-Δ effect. In this study, the influence of the P-Δ effect on the statistics of peak displacement of bridge structure was quantificationally investigated based on a series of nonlinear time-history analysis. The bridge structure was idealized as the single degree of freedom (SDOF) system and the hysteretic behaviour was represented by the improved Bouc-Wen model. The statistic analysis was implemented based on the inelastic dynamic responses of the SDOF system under 69 selected earthquake records. The results show that the P-Δ effect has significant impact on the mean and dispersion of peak displacement of bridge structures, especially if the normalized yield strength and the natural vibration period are small.

Influence of Earthquake Attack Angle on Seismic Demands for Structures under Bi-Directional Ground Motions

2011 ◽  
Vol 255-260 ◽  
pp. 2330-2334 ◽  
Author(s):  
Yu Zhang ◽  
Quan Wang Li ◽  
Jian Sheng Fan
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Time History ◽  
Earthquake Excitation ◽  
Seismic Demands ◽  
3 Dimensional ◽  
Nonlinear Time History Analyses ◽  
Modification Factor ◽  
Structural Responses ◽  
Nonlinear Time History

The earthquake may attack the structural building from any angle, but in current seismic design codes, this type of uncertainty is seldom accounted. The uncertainty associated with the direction of earthquake excitation was considered in this paper, and its effect on structural responses was investigated. For this purpose, a simple 3-dimensional model with symmetric plan was established, which had fundamental periods ranged from 0.1s to 5.0s, and was subjected to a set of 30 ground motion pairs for which both linear and nonlinear time history analyses were performed. Analyzing results showed that, on average, the elastic roof acceleration is 32% underestimated, and the inelastic roof displacement is 18% underestimated if the variation of earthquake excitation direction is not consider. Recognizing this, a modification factor for the seismic demand was proposed thorough a statistical analysis, which guarantees a probability of 95% design safety

scholarly journals Improvement of the Performance-Based Seismic Design Method of Cable Supported Bridges with the Resilient-Friction Base Isolation Systems

2020 ◽  
Vol 10 (11) ◽  
pp. 3942 ◽  
Author(s):  
Heungbae Gil ◽  
Kyoungbong Han ◽  
Junho Gong ◽  
Dooyong Cho
Keyword(s):  
Seismic Design ◽  
Design Method ◽  
Response Spectrum ◽  
Design Procedure ◽  
Time History ◽  
Modal Shape ◽  
Ground Acceleration ◽  
Performance Based Seismic Design ◽  
Seismic Design Method ◽  
Shape Analyses

In areas of civil engineering, the resilient friction base isolator (R-FBI) system has been used due to its enhanced isolation performance under seismic excitations. However, because nonlinear behavior of the R-FBI should be reflected in seismic design, effective stiffness (Keff) of the R-FBI is uniformly applied at both peak ground acceleration (PGA) of 0.08 g and 0.154 g which use a multimodal response spectrum (RS) method analysis. For rational seismic design of bridges, it should be required to evaluate the dynamics of the R-FBI from in-field tests and to improve the seismic design procedure based on the performance level of the bridges. The objective of this study is to evaluate the dynamics of the R-FBI and to suggest the performance-based seismic design method for cable-supported bridges with the R-FBI. From the comparison between the experiments’ results and modal shape analyses, the modal shape analyses using primary (Ku) or infinite stiffness (fixed end) showed a great agreement with the experimental results compared to the application of Keff in the shape analysis. Additionally, the RS or nonlinear time history method analyses by the PGA levels should be applied by reflecting the dynamic characteristics of the R-FBI for the reasonable and efficient seismic design.

scholarly journals Effectiveness of earthquake selection and scaling method in New Zealand

2007 ◽  
Vol 40 (3) ◽  
pp. 160-171 ◽  
Author(s):  
Rajesh P. Dhakal ◽  
Sandip Singh ◽  
John B. Mander
Keyword(s):  
New Zealand ◽  
Ground Motion ◽  
Ground Motions ◽  
Time History ◽  
Seismic Demand ◽  
Scaling Method ◽  
Ground Acceleration ◽  
Seismic Demands ◽  
Least Squares Fit ◽  
Ground Motion Records

In New Zealand, time history analysis is either the required or preferred method of assessing seismic demands for torsionally sensitive and other important structures, but the criteria adopted for the selection of ground motion records and their scaling to generate the seismic demand remains a contentious and debatable issue. In this paper, the scaling method based on the least squares fit of response spectra between 0.4-1.3 times the structure’s first mode period as stipulated in the New Zealand Standard for Structural Design Actions: Earthquake Actions (NZS1170.5) [1] is compared with the scaling methods in which ground motion records are scaled to match the peak ground acceleration (PGA) and spectral acceleration response at the natural period of the structure corresponding to the first mode with 5% of critical damping; i.e. Sa(T1, 5%). Incremental dynamic analysis (IDA) is used to measure the record-to-record randomness of structural response, which is also a measure of the efficiency of the intensity measure (IM) used. Comparison of the dispersions of IDA curves with the three different IMs; namely PGA, Sa(T1, 5%) and NZS1170.5 based IM, shows that the NZS1170.5 scaling method is the most effective for a large suite of ground motions. Nevertheless, the use of only three randomly chosen ground motions as presently permitted by NZS1170.5 is found to give significantly low confidence in the predicted seismic demand. It is thus demonstrated that more records should be used to provide a robust estimate of likely seismic demands.

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.

Duration of nuclear explosion ground motion

1978 ◽  
Vol 68 (4) ◽  
pp. 1133-1145
Author(s):  
Walter W. Hays ◽  
Kenneth W. King ◽  
Robert B. Park
Keyword(s):  
Epicentral Distance ◽  
Ground Motions ◽  
Broad Band ◽  
Time History ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Distance Range ◽  
Nuclear Explosions ◽  
Dependent Site ◽  
Strong Ground

abstract This paper evaluates the duration of strong ground shaking that results from nuclear explosions and identifies some of the problems associated with its determination. Knowledge of the duration of horizontal ground shaking is important out to epicentral distances of about 44 km and 135 km, the approximate distances at which the ground shaking level falls to 0.01 g for nuclear explosions having yields of about 100 kt and 1,000 kt, respectively. Evaluation of the strong ground motions recorded from the event STRAIT (ML = 5.6) on a linear array of five, broad-band velocity seismographs deployed in the distance range 3.2 to 19.5 km provides information about the characteristics of the duration of ground shaking. The STRAIT data show that: (1) the definition that is used for defining duration is very important; (2) the duration of ground acceleration, as defined in terms of 90 per cent of the integral of the squared time history (Trifunac and Brady, 1975), increased from about 4 to 26 sec over the approximately 20-km distance range; and (3) the duration of ground velocity and displacement were slightly greater because of the effect of the alluvium layer on the propagating surface waves. Data from other events (e.g., MILROW, CANNIKIN, HANDLEY, PURSE) augment the STRAIT data and show that: (1) duration of shaking is increased by frequency-dependent site effects and (2) duration of shaking, as defined by the integral of the squared time history, does not increase as rapidly with increase in yield as is indicated by other definitions of duration that are stated in terms of an amplitude threshold (e.g., bracketed duration, response envelopes). The available data suggest that the duration of ground acceleration, based on the integral definition, varies from about 4 to 40 sec for a 100-kt range explosion and from about 4 to 105 sec for a megaton range explosion in the epicentral distance range of 0 to 44 km and 0 to 135 km, respectively.

Direct Displacement Procedure for Performance-Based Seismic Design of Mid-Rise Wood-Framed Structures

2009 ◽  
Vol 25 (3) ◽  
pp. 583-605 ◽  
Author(s):  
Wei Chiang Pang ◽  
David V. Rosowsky
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Design Procedure ◽  
Time History ◽  
Time History Analysis ◽  
Nonlinear Time History Analysis ◽  
Framed Structures ◽  
History Analysis ◽  
Performance Based Seismic Design ◽  
Nonlinear Time History

This paper presents a direct displacement design (DDD) procedure that can be used for seismic design of multistory wood-framed structures. The proposed procedure is applicable to any pure shear deforming system. The design procedure is a promising design tool for performance-based seismic design since it allows consideration of multiple performance objectives (e.g., damage limitation, safety requirements) without requiring the engineer to perform a complex finite element or nonlinear time-history analysis of the complete structure. A simple procedure based on normalized modal analysis is used to convert the code-specified acceleration response spectrum into a set of interstory drift spectra. These spectra can be used to determine the minimum stiffness required for each floor based on the drift limit requirements. Specific shear walls can then be directly selected from a database of backbone curves. The procedure is illustrated on the design of two three-story ATC-63 archetype buildings, and the results are validated using nonlinear time-history analysis.

scholarly journals Effect of Flexible Soil in Seismic Hazard Assessment for Structural Design in Kuala Lumpur

2019 ◽  
Vol 10 (1) ◽  
pp. 30-42
Author(s):  
Abu Bakar Nabilah ◽  
Chan Ghee Koh ◽  
Nor Azizi Safiee ◽  
Nik Norsyahariati Nik Daud
Keyword(s):  
Seismic Design ◽  
Hazard Assessment ◽  
Structural Design ◽  
Time History ◽  
Seismic Hazard Assessment ◽  
Eurocode 8 ◽  
Kuala Lumpur ◽  
Long Distance ◽  
Ground Acceleration ◽  
Building Safety

Kuala Lumpur, Malaysia, is considered to be safe against an earthquake threat. However, tremors felt by occupants due to long distance earthquakes from Sumatra has raised concern on building safety in this region. Consequently, Malaysia will adopt the Eurocode 8 for seismic design. The suitability of this code must be studied especially on the threat from far field earthquakes. Thus, site specific hazard assessment has been conducted on seven flexible soil sites in Kuala Lumpur, based on modified time history. The peak ground acceleration (PGA) falls in the category of very low seismicity, however, the amplifications are much higher than recommended by Eurocode 8. The period limits for maximum accelerations are also much higher compared to the value in the code, especially for flexible soils. Adoption of Eurocode 8 for seismic design in this region should be studied to include the effects of high period motions in flexible soils, especially on the amplification factors and its corner periods.

Study on Performance Index for Reinforced Concrete Bridge Structures

2012 ◽  
Vol 193-194 ◽  
pp. 1079-1085
Author(s):  
Ben Yan Lu ◽  
Zhong Bin Cai ◽  
Zhong Qin Ye ◽  
Ya Jun Chen
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Bridge Columns ◽  
Concrete Bridge ◽  
Performance Levels ◽  
Reinforced Concrete Bridge ◽  
Flexural Failure ◽  
Operational Life ◽  
Bridge Structures ◽  
Performance Based Seismic Design

According to the failure characteristics of reinforced concrete bridge columns and the need of performance based seismic design in bridge, reinforced concrete bridge column performance levels, which are categorized into fully operational, temporarily operational, reparably operational, life safe and near collapse levels are established. To relate bridge damage to socio-economic descriptions at the five designated performance levels, qualitative indices are established. Considering field investigations following a seismic event, quantitative indices for the same five designated performance levels are proposed. Based on the statistical data of 154 seismic performance tests of RC bridge columns with circular section subjected to flexural failure, drift ratio limit for the same five designated performance levels are put forward. It can be used to determine displacement of pier top in performance based seismic design.

A PERFORMANCE-BASED SEISMIC DESIGN METHODOLOGY FOR STEEL BRIDGE SYSTEMS

2009 ◽  
Vol 03 (03) ◽  
pp. 175-193 ◽  
Author(s):  
TSUTOMU USAMI ◽  
HANBIN GE
Keyword(s):  
Seismic Design ◽  
Design Methodology ◽  
Evaluation Method ◽  
Ultimate Strain ◽  
Steel Bridge ◽  
Performance Matrix ◽  
Bridge Structures ◽  
Performance Based Seismic Design ◽  
Displacement Based ◽  
A Performance

This paper outlines a performance-based seismic design methodology for steel bridge systems. Two kinds of menus are proposed. The first is the displacement-based evaluation method which compares the response displacement with the ultimate displacement, and the second is the strain-based evaluation method which compares the response strain and the ultimate strain. Moreover, the seismic required performance matrix for bridge structures and soundness matrix for members are presented and discussed.

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