scholarly journals Effects of Structural and Seismic Factors on the Constant-Strength Ductility Spectra Based on NGA-West2 Database

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jinjun Hu ◽  
Qinghui Lai ◽  
Xuan Liu ◽  
Lili Xie
Keyword(s):  
Seismic Design ◽  
Demand Curve ◽  
Structural Parameters ◽  
Response Spectrum ◽  
Structural Factors ◽  
Ductility Demand ◽  
Constant Strength ◽  
Performance Based Seismic Design ◽  
The Mean ◽  
Ground Motion Records

The constant-strength ductility spectrum is a nonlinear response spectrum that is commonly used to establish the demand curve of the seismic response during performance-based seismic design. It is affected by many factors. In this paper, to evaluate the effect of the major influencing factors, including the structural parameters and seismic factors, the constant-strength ductility spectrum is calculated under different conditions based on 5535 ground motion records. Conclusions are drawn based on the mean constant-strength ductility spectra. (1) With respect to the effects of structural factors, the variation trend of the ductility spectra is highly consistent with increasing T, and the ductility spectra are usually larger for larger ζ and smaller Cy and k2. (2) With respect to the seismic factors, the ductility spectra show obvious differences in different periods; however, some parameters, such as PGA, have no influence on the ductility spectra. The results of this study can provide a theoretical basis for the calculation of ductility demand in the seismic design of structures.

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.

A Comparative Study of Seismic Performance Defined by Chinese Code and Eurocode8 on Seismic Design of Bridges

2011 ◽  
Vol 90-93 ◽  
pp. 3108-3116
Author(s):  
Ben Yan Lu ◽  
Gang Wang
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Highway Bridges ◽  
Lessons Learned ◽  
Performance Criteria ◽  
Existing Problems ◽  
Performance Based Seismic Design ◽  
Earthquake Action ◽  
Ground Types ◽  
Current Code

Earthquake codes have been revised and updated in recent years. The issue and implementation of the guidelines for seismic design of bridges have attracted interests and attentions of many researchs at home and abroad. The most important aspect of the code rests on its main approach incorporating “performance-based seismic design”. The main purpose of this study is to investigate the differences caused by the use of guidelines for seismic design of highway bridges and Eurocode8 for bridges in performance criteria, seismic design categories, ground types, response spectrum, earthquake action and detailing of ductile piers. The differences in expressions and some important points for performance criteria, seismic design categories, ground types, response spectrum, earthquake action and detailing of ductile piers by codes are briefly illustrated in tables and figures. Based on the lessons learned from significant earthquakes in the last few years, the existing problems of the current code are pointed, and the trends of future study are discussed.

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.

Research Progress of Structural Seismic Design Thought

2012 ◽  
Vol 457-458 ◽  
pp. 1420-1423
Author(s):  
Ting Yue Hao
Keyword(s):  
Seismic Design ◽  
Design Theory ◽  
Design Method ◽  
Response Spectrum ◽  
Theoretical Research ◽  
Research Progress ◽  
Analysis Theory ◽  
Performance Based Seismic Design ◽  
Seismic Design Method ◽  
Design Ideas

Research progress of structural seismic design theory is analyzed and collated in this paper, including static analysis theory, theory of response spectrum, dynamic theory. The three theoretical research and design methods are analyzed and described in the paper one by one. At last, modern seismic design method which is called performance-based seismic design theory is compared and analyzed with the traditional anti-seismic design theory. Its advanced characteristics and advantages are obtained, which will be the core and development of seismic design ideas.

scholarly journals A sectionalized-dual-band method for the selection of ground motion record sets

2021 ◽  
Vol 9 (3A) ◽  
Author(s):  
Hongmei Hou ◽  
Keyword(s):  
Dynamic Analysis ◽  
Ground Motion ◽  
Seismic Design ◽  
Response Spectrum ◽  
Time History ◽  
Spectral Shape ◽  
Dual Band ◽  
Base Shear ◽  
Period Range ◽  
Ground Motion Records

It is of great importance to select appropriate ground motion records for time-history dynamic analysis of structures. The consistency between record response spectral shape and seismic design response spectral shape is the basic principle for records selection. A sectionalized-dual-band (SDB) method considering influence of higher modes was proposed to select ground motion records according to the seismic fortification intensity requirements and the site characteristic. Furthermore, the newly proposed method has been employed to construct record sets within the whole response spectrum period. As compared with other traditional methods, the records obtained from the SDB method are more effective in predicting base shear derived from time-history dynamic analysis. When the period of a structure is determined, the records in the matched period range of the records set can be directly used to conduct time-history dynamic analysis. This method can avoid tedious work for reselecting ground motion records for different structures in the same seismic design intensity and site conditions.

Assessment of ductility demand and reliability of bilinear single-degree-of-freedom systems under earthquake loading

2007 ◽  
Vol 34 (12) ◽  
pp. 1606-1615 ◽  
Author(s):  
H. P. Hong ◽  
P. Hong
Keyword(s):  
Coefficient Of Variation ◽  
Degree Of Freedom ◽  
Initial Stiffness ◽  
Single Degree Of Freedom ◽  
Ductility Demand ◽  
Single Degree ◽  
Code Calibration ◽  
Probabilistic Characterization ◽  
The Mean ◽  
Ground Motion Records

Probabilistic assessments of the ductility demand and reliability analysis were carried out for hysteretic bilinear single-degree-of-freedom (SDOF) systems. The assessment considered a set of strong ground motion records, and focused on evaluating the mean and coefficient of variation of the ductility demand for a given normalized yield strength. Results indicated that the ductility demand could be modeled as a Frechet (extreme value type II) variate. Based on the obtained results, empirical equations were provided to predict the mean ductility demand for hysteretic bilinear SDOF systems considering different natural vibration periods, damping ratios, and post-yield stiffness to initial stiffness ratios. Numerical results showed that the coefficient of variation of the ductility demand can go as high as one, depending on the characteristics of the structure. Also, a simple approach was given to estimate the probabilities of incipient damage and incipient collapse using the developed probabilistic characterization of the ductility demand. This approach, which could be suitable for design code calibration analysis, is illustrated numerically in this study.

Seismic Performance Spectra

2010 ◽  
Vol 163-167 ◽  
pp. 443-453
Author(s):  
Wen Feng Liu ◽  
Xing Pan Fu
Keyword(s):  
Seismic Performance ◽  
Seismic Design ◽  
Response Spectra ◽  
Seismic Demand ◽  
Three Dimension ◽  
Seismic Demands ◽  
Performance Objective ◽  
Objective Performance ◽  
Performance Based Seismic Design ◽  
Ground Motion Records

The seismic performance spectrum is a new kind of the response spectra which is formed according to the designated performance objectives. The performance objectives are changed according to the performance objective level and period of structure, and are different in the acceleration sensitive, velocity sensitive and displacement sensitive range in the seismic performance spectrum. The seismic performance spectrum formulas are derived, which demonstrate the mathematic relationship between the seismic demands of the different performance objective levels and the period of structure. The fitted formulas of the seismic performance spectra for seismic design are obtained due to statistical result of 1085 ground motion records. The new seismic performance spectra are shown in visual three-dimension figures which can represent the seismic demand, performance objective and period of structure in this paper. The philosophy of the seismic performance spectrum is analyzed which reveals the rules for estimating seismic demand of structure at the different performance objective levels. So the multi-objective performance-based seismic design is also proposed using the seismic performance spectrum.

Inter-Story Capacity Spectrum for the Performance Based Seismic Design of Vertically Irregular RC Frame Structures I: Method

2012 ◽  
Vol 517 ◽  
pp. 745-748
Author(s):  
Jin Jie Men ◽  
Qing Xuan Shi ◽  
Qi Zhou
Keyword(s):  
Seismic Design ◽  
Demand Curve ◽  
Frame Structure ◽  
Frame Structures ◽  
Dynamical Characteristic ◽  
Displacement Curve ◽  
Inelastic Behavior ◽  
Capacity Spectrum ◽  
Demand Curves ◽  
Performance Based Seismic Design

Considering the dynamical characteristic of structure under different earthquake hazard level, inelastic demand curves, namely, inter-story shear versus inter-story displacement curve are established by using mode spectrum method. Based on the relation of structure performance object and displacement ductibility, the relation of structure performance object and inter-story demand curve is established. And the inter-story demand curves take into account the inelastic behavior of structure under earthquake action adequately. Then considering the seismic respond characteristic and the capacity curve of the frame structure a new method named inter-story capacity spectrum (ISCS) is put forward for the performance based seismic design of vertically irregular frame structures. Examples are presented to demonstrate the applicability and utility of the proposed method. In part , the procedure to establish the ISCS method is mainly explained. And the examples will be introduced in part .

scholarly journals Probabilistic seismic response analysis of coastal highway bridges under scour and liquefaction conditions: does the hydrodynamic effect matter?

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiaowei Wang ◽  
Yutao Pang ◽  
Aijun Ye
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Highway Bridges ◽  
Element Model ◽  
Response Analysis ◽  
Hydrodynamic Effect ◽  
Strong Earthquakes ◽  
Influence Of Water ◽  
Scour Hazard ◽  
Ground Motion Records

AbstractCoastal highway bridges are usually supported by pile foundations that are submerged in water and embedded into saturated soils. Such sites have been reported susceptible to scour hazard and probably liquefied under strong earthquakes. Existing studies on seismic response analyses of such bridges often ignore the influence of water-induced hydrodynamic effect. This study assesses quantitative impacts of the hydrodynamic effect on seismic responses of coastal highway bridges under scour and liquefaction potential in a probabilistic manner. A coupled soil-bridge finite element model that represents typical coastal highway bridges is excited by two sets of ground motion records that represent two seismic design levels (i.e., low versus high in terms of 10%-50 years versus 2%-50 years). Modeled by the added mass method, the hydrodynamic effect on responses of bridge key components including the bearing deformation, column curvature, and pile curvature is systematically quantified for scenarios with and without liquefaction across different scour depths. It is found that the influence of hydrodynamic effect becomes more noticeable with the increase of scour depths. Nevertheless, it has minor influence on the bearing deformation and column curvature (i.e., percentage changes of the responses are within 5%), regardless of the liquefiable or nonliquefiable scenario under the low or high seismic design level. As for the pile curvature, the hydrodynamic effect under the low seismic design level may remarkably increase the response by as large as 15%–20%, whereas under the high seismic design level, it has ignorable influence on the pile curvature.

scholarly journals Brain capillary structures of schizophrenia cases and controls show a correlation with their neuron structures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rino Saiga ◽  
Masayuki Uesugi ◽  
Akihisa Takeuchi ◽  
Kentaro Uesugi ◽  
Yoshio Suzuki ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Superior Temporal Gyrus ◽  
Anterior Cingulate ◽  
Dimensional Structure ◽  
Constant Diameter ◽  
The Mean ◽  
Cartesian Coordinate ◽  
Micrometer Scale

AbstractBrain blood vessels constitute a micrometer-scale vascular network responsible for supply of oxygen and nutrition. In this study, we analyzed cerebral tissues of the anterior cingulate cortex and superior temporal gyrus of schizophrenia cases and age/gender-matched controls by using synchrotron radiation microtomography or micro-CT in order to examine the three-dimensional structure of cerebral vessels. Over 1 m of cerebral blood vessels was traced to build Cartesian-coordinate models, which were then used for calculating structural parameters including the diameter and curvature of the vessels. The distribution of vessel outer diameters showed a peak at 7–9 μm, corresponding to the diameter of the capillaries. Mean curvatures of the capillary vessels showed a significant correlation to the mean curvatures of neurites, while the mean capillary diameter was almost constant, independent of the cases. Our previous studies indicated that the neurites of schizophrenia cases are thin and tortuous compared to controls. The curved capillaries with a constant diameter should occupy a nearly constant volume, while neurons suffering from neurite thinning should have reduced volumes, resulting in a volumetric imbalance between the neurons and the vessels. We suggest that the observed structural correlation between neurons and blood vessels is related to neurovascular abnormalities in schizophrenia.

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