Variable vs. invariable elastic response spectrum shapes: impact on the mean annual frequency of exceedance of limit states

2020 ◽  
Vol 214 ◽  
pp. 110620 ◽  
Author(s):  
F. Barbagallo ◽  
M. Bosco ◽  
E.M. Marino ◽  
P.P. Rossi
Keyword(s):  
Response Spectrum ◽  
Elastic Response ◽  
Limit States ◽  
Annual Frequency ◽  
The Mean ◽  
Mean Annual Frequency

A Spectrum-to-Spectrum Method for Calculating Uniform Hazard Floor Response Spectra

2017 ◽  
Author(s):  
Andrea Lucchini ◽  
Paolo Franchin ◽  
Fabrizio Mollaioli
Keyword(s):  
Ground Motion ◽  
Response Spectra ◽  
Seismic Demand ◽  
Spectral Acceleration ◽  
Demand Model ◽  
Nonstructural Components ◽  
Floor Response Spectra ◽  
Annual Frequency ◽  
The Mean ◽  
Mean Annual Frequency

In codes’ provisions and design procedures for acceleration-sensitive nonstructural components, seismic demand is commonly defined by means of floor response spectra expressed in terms of pseudo-acceleration. Depending on the considered analysis method, floor response spectra may be derived from floors’ acceleration histories, based on structural response-history analysis, or calculated using a predictive equation from a given input ground motion spectrum. Methods for estimating floor response spectra that are based on the second alternative are commonly called spectrum-to-spectrum methods. The objective of this paper is to briefly review these methods, and to discuss the main assumptions they are based on. Both predictive equations from selected seismic codes and proposals from the literature are included in the review. A new probability-based method, recently developed by the Authors for generating uniform hazard floor response spectra, namely, floor response spectra whose ordinates are characterized by a given target value of the mean annual frequency of being exceeded, is also described. By using this method floor spectra are determined through closed-form equations, given the mean annual frequency of interest, the damping ratio of the spectra, the modal properties of the structure, and three uniform hazard ground spectra. The method is built on a proposal for a probabilistic seismic demand model that relates the ground spectral acceleration with the floor spectral acceleration, and is able to explicitly account for the ground motion variability of the nonstructural response. Results for a case study consisting of a service frame of a visbreaking unit in an oil refinery are presented to show the good predictive accuracy of the method with respect to exact uniform hazard floor response spectra obtained through a standard probabilistic analysis.

scholarly journals Long-Term Ground-Based Measurements of Aerosol Optical Depth over Kuwait City

2018 ◽  
Vol 10 (11) ◽  
pp. 1807 ◽  
Author(s):  
Panagiotis Kokkalis ◽  
Hala K. Al Jassar ◽  
Stavros Solomos ◽  
Panagiotis-Ioannis Raptis ◽  
Hamad Al Hendi ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Source Area ◽  
Simultaneous Increase ◽  
Storm Events ◽  
Back Trajectories ◽  
Annual Frequency ◽  
The Mean ◽  
Mean Annual Frequency

We analyze ten years (2008–2017) of ground-based observations of the Aerosol Optical Depth (AOD) in the atmosphere of Kuwait City, in Middle East. The measurements were conducted with a CIMEL sun-sky photometer, at various wavelengths. The daily average AOD at 500 nm (AOD500) is 0.45, while the mean Ångström coefficient (AE), calculated from the pair of wavelengths 440 and 870 nm, is 0.61. The observed high AOD500 values (0.75–2.91), are due to regional sand and dust storm events, which are affecting Kuwait with a mean annual frequency of almost 20 days/year. The long-term record analysis of AOD500 and AE, shows a downward and upward tendency respectively, something which could be attributed to the continuous expansion and industrialization of the main city of Kuwait, in combination with the simultaneous increase of soil moisture over the area. By utilizing back trajectories of air masses for up to 4 days, we assessed the influence of various regions to the aerosol load over Kuwait. The high aerosol loads during spring, are attributed to the dominance of coarse particles from Saudi Arabia (AOD500 0.56–0.74), a source area that contributes the 56% to the mean annual AOD500. Other dust sources affecting significantly Kuwait originated from the regions of Iraq and Iran with contribution of 21%.

Seismic evaluation of concrete moment frames in existing government buildings

2009 ◽  
Vol 36 (5) ◽  
pp. 813-825
Author(s):  
G. Akhras ◽  
W. Li
Keyword(s):  
Response Spectrum ◽  
Shear Walls ◽  
Linear Segment ◽  
Seismic Evaluation ◽  
Moment Frames ◽  
Limit States ◽  
Frame Element ◽  
Weak Beam ◽  
Detailed Evaluation ◽  
Column Joint

Many government departments have hundreds of buildings located in active seismic regions. Most of these buildings were built decades ago according to old design codes, and could be vulnerable to strong or even moderate earthquakes. To evaluate the seismic performance of concrete moment frames or moment frames with shear walls in these buildings, the static, vibration and modal response spectrum analyses are carried out according to the 2005 National building code of Canda NBCC. The analysis uses 2-D finite element models consisting of frame elements and inplane elements. The frame element has a built-in rigid linear segment at each end for modeling the portion within the beam–column joint, whereas the inplane element may have openings for modeling doors and windows in shear walls. The stiffness of both elements is adjusted to include effects of shear deformation in beams and bending deformation in wall piers. The results are further adjusted to incorporate effects of torsion and accidental torsion. Then, CSA-A23.3-04 is followed for detailed evaluation on safety in limit states, “strong column – weak beam” concept and shear strength requirements. Based on this approach, a new computer program is developed to perform this evaluation with minimum input data. Important issues in each step are discussed in detail. Examples are presented, and results are compared with available existing data.

On the Combined Effect of Mean Flow and Acoustic Excitation on Structural Response and Radiation

1997 ◽  
Vol 119 (3) ◽  
pp. 448-456 ◽  
Author(s):  
A. Frendi ◽  
L. Maestrello
Keyword(s):  
Mach Number ◽  
Response Spectrum ◽  
Structural Response ◽  
Harmonic Excitation ◽  
Two Dimensions ◽  
Physical Problem ◽  
Acoustic Excitation ◽  
Mean Flow ◽  
Power Spectral ◽  
The Mean

Numerical experiments in two dimensions are carried out in order to investigate the response of a typical aircraft structure to a mean flow and an acoustic excitation. Two physical problems are considered; one in which the acoustic excitation is applied on one side of the flexible structure and the mean flow is on the other side while in the second problem both the mean flow and acoustic excitation are on the same side. Subsonic and supersonic mean flows are considered together with a random and harmonic acoustic excitation. In the first physical problem and using a random acoustic excitation, the results show that at low excitation levels the response is unaffected by the mean flow Mach number. However, at high excitation levels the structural response is significantly reduced by increasing the Mach number. In particular, both the shift in the frequency response spectrum and the broadening of the peaks are reduced. In the second physical problem, the results show that the response spectrum is dominated by the lower modes (1 and 3) for the subsonic mean flow case and by the higher modes (5 and 7) in the supersonic case. When a harmonic excitation is used, it is found that in the subsonic case the power spectral density of the structural response shows a subharmonic (f/4) while in the supersonic case no subharmonic is obtained.

Stiffness Design for Specified Nonexceedance Probability of Seismic Response

1998 ◽  
Vol 14 (1) ◽  
pp. 165-188 ◽  
Author(s):  
Yutaka Nakamura ◽  
Tsuneyoshi Nakamura
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Seismic Response ◽  
Amplification Factor ◽  
Design Method ◽  
Response Spectrum ◽  
Time History ◽  
Stiffness Design ◽  
The Mean ◽  
Shear Building

A direct procedure is presented for generating a response spectrum for an arbitrary nonexceedance probability from a prescribed design mean response spectrum. An amplification factor is derived to estimate the maximum response values of an MDOF system for a nonexceedance probability from the mean maximum ones. An efficient stiffness design method for a shear building is developed with the use of its fundamental frequency and translational eigenvector as parameters for adjusting the nonexceedance probability of the seismic drifts to the specified value. The validity and accuracy of the proposed method are demonstrated by a Monte Carlo simulation together with time-history analyses.

The Case for Using Mean Seismic Hazard

2005 ◽  
Vol 21 (3) ◽  
pp. 879-886 ◽  
Author(s):  
Robin K. McGuire ◽  
C. Allin Cornell ◽  
Gabriel R. Toro
Keyword(s):  
Decision Making ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Probabilistic Seismic Hazard ◽  
Benefit Analysis ◽  
Annual Frequency ◽  
The Mean ◽  
Motion Amplitude

Complete probabilistic seismic hazard analyses incorporate epistemic uncertainties in assumptions, models, and parameters, and lead to a distribution of annual frequency of exceedance versus ground motion amplitude (the “seismic hazard”). For decision making, if a single representation of the seismic hazard is required, it is always preferable to use the mean of this distribution, rather than some other representation, such as a particular fractile. Use of the mean is consistent with modern interpretations of probability and with precedents of safety goals and cost-benefit analysis.

Seismical Protection Properties of High Damping Rubber Bearing and Lead Rubber Bearing Base Isolation Systems for Multi-Storey RC Buildings

2012 ◽  
Vol 234 ◽  
pp. 90-95 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis
Keyword(s):  
Base Isolation ◽  
Response Spectrum ◽  
Limit State ◽  
Three Dimensional ◽  
Elastic Response ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
High Damping Rubber Bearing ◽  
High Damping Rubber ◽  
Isolation Systems

In the present paper two different base isolation systems, designed and verified according to the european seismic code (EC2 and EC8), are compared for evaluating the behaviour of a base isolated building, highly irregular in plan, in presence of a seismic excitation. The devices adopted for realizing the different base isolation systems are the High Damping Rubber Bearing (HDRB) and the Lead Rubber Bearing (LRB) both of them actuated in parallel with a Friction Slider (FS). A dynamic nonlinear analysis for a three-dimensional base isolated structure has been performed. Recorded accelerograms for bi-directional ground motions, compatible with the reference elastic response spectrum for each limit state have been used for a more realistic evaluation of the seismic response of the structure and a more realistic comparative analysis between the base isolated structure with the different considered base isolation systems and the traditional fixed base structure.

scholarly journals The Influence of Dowel-Pin Connections on the Seismic Fragility Assessment of RC Precast Industrial Buildings

2017 ◽  
Vol 11 (1) ◽  
pp. 1138-1157 ◽  
Author(s):  
Pardo Antonio Mezzapelle ◽  
Agnese Scalbi ◽  
Francesco Clementi ◽  
Stefano Lenci
Keyword(s):  
Seismic Vulnerability ◽  
Structural Safety ◽  
Seismic Fragility ◽  
Load Carrying Capacity ◽  
Structural Elements ◽  
The Past ◽  
Industrial Buildings ◽  
Load Carrying ◽  
Annual Frequency ◽  
The Mean

Background:Recent major earthquakes in the centre of the Italy, between August and October 2016, have reaffirmed the seismic vulnerability of precast industrial buildings with a lot of collapse recorded. This is typical due to the past Italian building practices, where structural deficiencies are mainly related to the capacity to transfer horizontal forces between primary structural elements.Objectives and Methods:In these types of structures, a key role is played by the dowel pin connections which allow to transfer lateral horizontal forces from the beam to the column, without losing load carrying capacity. For this reason, in this work, the assessment of the seismic fragility of single-story reinforced concrete precast building located not far from the epicentres of the two aforementioned earthquakes was done.Results and Conclusion:The seismic risk was evaluated in terms of annual frequency of exceedance for three performance levels provided by the European and Italian seismic codes, considering the mean hazard curves for the site. The comparison between the fragility of different structural models shows the importance in the choice of the column-beam connection modelling to obtain reliable results on the structural safety assessment.

scholarly journals ACCELEROMETRIC NETWORK AND ELASTIC RESPONSE SPECTRUM FOR GROUND TYPE A IN THE REPUBLIC OF SRPSKA

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Snježana Cvijić Amulić ◽  
Sanja Tucikešić
Keyword(s):  
Response Spectrum ◽  
Type A ◽  
Elastic Response ◽  
Eurocode 8 ◽  
Hazard Map ◽  
Ground Acceleration ◽  
Preparation Phase ◽  
The Republic ◽  
Accelerometric Network

This paper presents the content of an analysis of available relevant accelerometric data, which aimsat identifying a group of nationally determined parameters in the field of seismological activity thatwas used in the preparation phase of the B&H national annex for Eurocode 8. Seismological dataanalysis related to parameters that are in Eurocode 8 open to national choice, refer to the: soilclassification, horizontal elastic response spectrum and reference ground acceleration, respectivelyseismic hazard map.

Sign in / Sign up

Export Citation Format

Share Document