Structure-Specific Scalar Intensity Measures for Near-Source and Ordinary Earthquake Ground Motions

2007 ◽  
Vol 23 (2) ◽  
pp. 357-392 ◽  
Author(s):  
Nicolas Luco ◽  
C. Allin Cornell
Keyword(s):  
Ground Motions ◽  
Linear Regression Analysis ◽  
Structural Performance ◽  
Intensity Measures ◽  
Earthquake Ground Motions ◽  
Long Period ◽  
Earthquake Records ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses ◽  
A Site

Introduced in this paper are several alternative ground-motion intensity measures ( IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the “efficiency” and “sufficiency” of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions.

An evaluation ofP-Δ amplification factors in multistorey steel moment resisting frames

1999 ◽  
Vol 26 (5) ◽  
pp. 535-548 ◽  
Author(s):  
R Tremblay ◽  
B Côté ◽  
P Léger
Keyword(s):  
Amplification Factor ◽  
Ground Motions ◽  
Beam Model ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frame ◽  
Dynamic Analyses ◽  
Moment Resisting ◽  
Shear Beam ◽  
Nonlinear Dynamic Analyses ◽  
Shear Beam Model

Three different amplification factors that have been proposed to account for P-Δ effects in the seismic design of multistorey building structures are described and compared. Nonlinear dynamic analyses of a typical 20-storey steel moment resisting frame are carried out under earthquake ground motions typical of eastern and western Canada to evaluate the gravity load effects and to assess the effectiveness of each type of amplification factor in accounting for these effects. All three approaches maintain the ductility demand within the level computed without P-Δ effects, but lateral deformations are generally larger than those obtained neglecting the gravity loads. Nonlinear dynamic analyses are also performed on a shear-beam (stick) model of the same building to examine the possibility of using such simple models for studying the dynamic stability of buildings subjected to ground motions. The shear-beam model does not predict adequately the seismic behaviour of steel moment resisting frames for which P-Δ effects are significant.Key words: ductility, earthquake, ground motion, lateral deformation, moment resisting frame, P-Δ effects, push-over analysis, seismic, shear-beam model, stability coefficient, amplification factor.

Comparative Study of the Inelastic Seismic Demand of Eastern and Western Canadian Sites

2001 ◽  
Vol 17 (2) ◽  
pp. 333-358 ◽  
Author(s):  
Robert Tremblay ◽  
Gail M. Atkinson
Keyword(s):  
Current Practice ◽  
Ground Motions ◽  
Seismic Demand ◽  
Uniform Hazard Spectra ◽  
Damage Potential ◽  
Single Degree Of Freedom ◽  
Dynamic Analyses ◽  
Damage Law ◽  
Nonlinear Dynamic Analyses ◽  
R Factors

The damage potential of earthquake ground motions compatible with site-specific 2% in 50 year uniform hazard spectra is compared at two North American sites in areas of moderate seismic hazard: Montreal, in the east, and Vancouver, along the west coast. For Vancouver, crustal, subcrustal and Cascadia subduction ground motion earthquake ensembles are considered. Nonlinear dynamic analyses of bi-linear single-degree-of-freedom oscillators exhibiting various ductility levels and damage laws were performed to determine R factors required to prevent structural collapse for each site and each system. Then, inelastic response parameters were computed for the general design case, wherein a prescribed R factor is used for a given system irrespective of tectonic region or structural period. The results show that the R factors vary with the ductility level, the damage law, the structural period, and the tectonic region. Neglecting the latter two dependencies in design, as is current practice, may lead to significant discrepancies in the level of protection achieved for different structures in different regions.

INFLUENCE OF ADDED VISCOUS DAMPERS ON THE PROBABILISTIC SEISMIC PERFORMANCE EVALUATION OF RC FRAMES

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Luca Landi ◽  
Cristina Vorabbi ◽  
Pier Paolo Diotallevi
Keyword(s):  
Nonlinear Dynamic ◽  
Ground Motions ◽  
Frame Structures ◽  
Rc Frame ◽  
Viscous Dampers ◽  
Fluid Viscous Dampers ◽  
Hazard Curve ◽  
Dynamic Analyses ◽  
Nonlinear Dynamic Analyses ◽  
Rc Frame Structures

This paper deals with the parameters which influence the probability of reaching the near collapse limit state of RC frame structures equipped with nonlinear fluid viscous dampers. The study can be divided into two steps. The first aims to assess how the median and the dispersion of seismic demand can vary in the RC frame structures with and without dampers, considering a wide set of ground motions. The second step evaluates the expression in closed form, given by 2000 SAC/FEMA method, to assess the annual probability of failure of RC structures. This probability has been estimated considering a wide set of ground motions and different methods to approximate the hazard curve. The evaluations have been made on the basis of the results of a large number of nonlinear dynamic analyses; in particular, 180 nonlinear dynamic analyses have been made for the case studies with and without dampers. In conclusion, it has been noticed that the probabilistic assessment depends on the number of records considered and that the simplified formula provided by the 2000 SAC-FEMA method is strongly sensitive to the variation of the hazard curve and the dispersion.

scholarly journals Adaptive base isolation system to achieve structural resiliency under both short- and long-period earthquake ground motions

2018 ◽  
Vol 30 (1) ◽  
pp. 16-31 ◽  
Author(s):  
Ramin Rabiee ◽  
Yunbyeong Chae
Keyword(s):  
Base Isolation ◽  
Ground Motions ◽  
Resonance Effect ◽  
Design Procedure ◽  
Isolation System ◽  
Nonstructural Components ◽  
Earthquake Ground Motions ◽  
Long Period ◽  
Short Period ◽  
Base Isolation System

Base isolation system is widely used to protect important and essential buildings from seismic hazards. The use of high damping is effective in reducing the resonance effect under long-period earthquake ground motions. However, high damping increases the acceleration demand under short-period ground motions, leading to a higher risk of damage of nonstructural components. Actually, low damping is beneficial to reduce the acceleration demand under short-period ground motions, suggesting the use of adaptive damping control, that is, high damping under long-period motions and low damping under short-period motions. In order to implement this concept, a semi-actively controlled base isolation system is provided in this article along with a new control law based on the transmissibility theory. Unlike existing studies, the proposed method enables a systematic design procedure for base isolated structures with semi-active dampers, which is called the simplified design procedure in this article. The performance of the proposed system is evaluated with numerical simulations for a base isolated three-story building with magneto-rheological dampers. It was shown that the proposed system achieves a high level of performance under long-period ground motions, while maintaining the exceptional performance of a conventional base isolation system with low damping under short-period ground motions.

Seismic Performance of RC Structures Using an Improved Inelastic Analysis Method

2006 ◽  
Vol 324-325 ◽  
pp. 1021-1026
Author(s):  
Jin Ho Kim ◽  
Sin Chu Yang
Keyword(s):  
Ground Motions ◽  
Earthquake Hazard ◽  
Structural Performance ◽  
Analysis Method ◽  
Diagram Method ◽  
Rc Structures ◽  
Earthquake Ground Motions ◽  
Inelastic Analysis ◽  
First Approximation ◽  
Hazard Level

Inelastic analysis procedures may be useful as a first approximation for the seismic response of a structure. The Capacity Diagram Method procedure, which is based on R--T (Reduction-ductility-Period) relationships, is investigated to compare with the modified CDM procedure. The CDM procedure is applied to the example model, which is moment resistant RC frame. Two seismic hazard categories having exceedance probabilities of 2% in 50 years and 10% in 50 years earthquake ground motions have been selected for evaluating the performance of the example model. The performance objective of the example model is represented by the combination of a structural performance level and an earthquake hazard level.

Sign in / Sign up

Export Citation Format

Share Document