Evaluation of Recorded Earthquake Response of a Curved Highway Bridge

1997 ◽  
Vol 13 (3) ◽  
pp. 363-386 ◽  
Author(s):  
Reginald Desroches ◽  
Gregory L. Fenves
Keyword(s):  
Linear Models ◽  
Free Field ◽  
Three Dimensional ◽  
Strong Motion ◽  
Earthquake Response ◽  
Highway Bridge ◽  
Vibration Period ◽  
Support Points ◽  
Moderate Effect ◽  
Input Motion

The Landers and Big Bear earthquakes on June 18, 1992, triggered a strong motion instrumentation network on a curved highway bridge. System identification of the processed acceleration records show the vibration period of the fundamental mode lengthened from 1.56 sec to 1.75 sec between the two earthquakes. A three-dimensional, calibrated model of the bridge is used to investigate the effect of modeling assumptions on the earthquake response of the structure. Linear models, commonly used in design, adequately bound the earthquake response of the bridge. However, the linear models do not provide an upper bound on the forces in all the columns. Longitudinal hinge restrainers have minimal effect on the earthquake response. The non-uniform input motion recorded at four support points has a moderate effect on the response when compared with the assumption of uniform free-field motion.

Simulation-based site amplification model for shallow bedrock sites in Korea

2021 ◽  
pp. 875529302098198
Author(s):  
Muhammad Aaqib ◽  
Duhee Park ◽  
Muhammad Bilal Adeel ◽  
Youssef M A Hashash ◽  
Okan Ilhan
Keyword(s):  
Linear Models ◽  
Site Response ◽  
Site Amplification ◽  
One Dimensional ◽  
Nonlinear Component ◽  
Nonlinear Site Response ◽  
Simulation Based ◽  
Linear And Nonlinear ◽  
Input Motion ◽  
Nonlinear Components

A new simulation-based site amplification model for shallow sites with thickness less than 30 m in Korea is developed. The site amplification model consists of linear and nonlinear components that are developed from one-dimensional linear and nonlinear site response analyses. A suite of measured shear wave velocity profiles is used to develop corresponding randomized profiles. A VS30 scaled linear amplification model and a model dependent on both VS30 and site period are developed. The proposed linear models compare well with the amplification equations developed for the western United States (WUS) at short periods but show a distinct curved bump between 0.1 and 0.5 s that corresponds to the range of site natural periods of shallow sites. The response at periods longer than 0.5 s is demonstrated to be lower than those of the WUS models. The functional form widely used in both WUS and central and eastern North America (CENA), for the nonlinear component of the site amplification model, is employed in this study. The slope of the proposed nonlinear component with respect to the input motion intensity is demonstrated to be higher than those of both the WUS and CENA models, particularly for soft sites with VS30 < 300 m/s and at periods shorter than 0.2 s. The nonlinear component deviates from the models for generic sites even at low ground motion intensities. The comparisons highlight the uniqueness of the amplification characteristics of shallow sites that a generic site amplification model is unable to capture.

Experimental Study on the Continuous Type Three-Dimensional Control of the Cable-Stayed Bridge

2011 ◽  
Vol 71-78 ◽  
pp. 1933-1937
Author(s):  
Jia Yun Xu ◽  
Ji Chen ◽  
Xian Wei Qu ◽  
Wen Kai Gong
Keyword(s):  
Angular Displacement ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Highway Bridge ◽  
Changjiang River ◽  
Continuous Type ◽  
Torsional Response ◽  
Cable Stayed Bridge ◽  
Bridge Model ◽  
Wind Induced Vibration

This paper takes a Chinese Changjiang River highway bridge as engineering background, and a kind of continuous three-dimensional (vertical, lateral and torsion)controllers which can apply in the large span cable-stayed bridge is presented. The controllers can control vertical, lateral and torsional response of bridge wind-induced vibration at the same time. Through comparative wind tunnel test of the bridge model with and without controllers, some important conclusions are made as follows: when the continuous three-dimensional controllers are installed on the bridge model, its flutter critical wind speed increases significantly (mostly increases 33.36%); Meanwhile, there is a certain degree of reduction in its RMS values of vertical, lateral and torsional angular displacement response.

scholarly journals Comparison of multiphase models for computing shock-induced bubble collapse

2019 ◽  
Vol 30 (8) ◽  
pp. 3845-3877 ◽  
Author(s):  
Eric Goncalves Da Silva ◽  
Philippe Parnaudeau
Keyword(s):  
Blast Wave ◽  
Cavitation Erosion ◽  
Volume Fraction ◽  
Free Field ◽  
Three Dimensional ◽  
Strong Shock ◽  
Bubble Collapse ◽  
Multiphase Model ◽  
Content Type ◽  
Multiphase Models

Purpose The purpose of this paper is to quantify the relative importance of the multiphase model for the simulation of a gas bubble impacted by a normal shock wave in water. Both the free-field case and the collapse near a wall are investigated. Simulations are performed on both two- and three-dimensional configurations. The main phenomena involved in the bubble collapse are illustrated. A focus on the maximum pressure reached during the collapse is proposed. Design/methodology/approach Simulations are performed using an inviscid compressible homogeneous solver based on different systems of equations. It consists in solving different mixture or phasic conservation laws and a transport-equation for the gas volume fraction. Three-dimensional configurations are considered for which an efficient massively parallel strategy was developed. The code is based on a finite volume discretization for which numerical fluxes are computed with a Harten, Lax, Van Leer, Contact (HLLC) scheme. Findings The comparison of three multiphase models is proposed. It is shown that a simple four-equation model is well-suited to simulate such strong shock-bubble interaction. The three-dimensional collapse near a wall is investigated. It is shown that the intensity of pressure peaks on the wall is drastically increased (more than 200 per cent) in comparison with the cylindrical case. Research limitations/implications The study of bubble collapse is a key point to understand the physical mechanism involved in cavitation erosion. The bubble collapse close to the wall has been addressed as the fundamental mechanism producing damage. Its general behavior is characterized by the formation of a water jet that penetrates through the bubble and the generation of a blast wave during the induced collapse. Both the jet and the blast wave are possible damaging mechanisms. However, the high-speed dynamics, the small spatio-temporal scales and the complicated physics involved in these processes make any theoretical and experimental approach a challenge. Practical implications Cavitation erosion is a major problem for hydraulic and marine applications. It is a limiting point for the conception and design of such components. Originality/value Such a comparison of multiphase models in the case of a strong shock-induced bubble collapse is clearly original. Usually models are tested separately leading to a large dispersion of results. Moreover, simulations of a three-dimensional bubble collapse are scarce in the literature using such fine grids.

Seismic Design and Construction Practices for RC Structural Wall Buildings

2012 ◽  
Vol 28 (1_suppl1) ◽  
pp. 245-256 ◽  
Author(s):  
Leonardo M. Massone ◽  
Patricio Bonelli ◽  
René Lagos ◽  
Carl Lüders ◽  
Jack Moehle ◽  
...  
Keyword(s):  
Linear Models ◽  
Principal Direction ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Load Resistance ◽  
Floor Plan ◽  
Structural Walls ◽  
Cross Sectional ◽  
Structural Wall ◽  
Wall Area

Reinforced concrete buildings utilizing structural walls for lateral load resistance are the predominant form of construction in Chile for buildings over four stories. Typical buildings include a large number of walls, with ratios of wall cross-sectional area to floor plan area of roughly 3% in each principal direction. Based on the good performance of RC buildings in the March 1985 earthquake, requirements for closely spaced transverse reinforcement at wall boundaries were excluded when Chile adopted a new concrete code in 1996 based on ACI 318-95. In recent years, use of three-dimensional linear models along with modal response spectrum analysis has become common. Since 1985, nearly 10,000 new buildings have been permitted. Although the newer buildings have similar wall area to floor plan areas as older buildings, newer walls are thinner and buildings are taller, leading to significantly higher wall axial load ratios.

scholarly journals Variations between Foundation-Level and Free-Field Earthquake Ground Motions

2000 ◽  
Vol 16 (2) ◽  
pp. 511-532 ◽  
Author(s):  
Jonathan P. Stewart
Keyword(s):  
Free Field ◽  
Low Frequency ◽  
Strong Motion ◽  
Dimensionless Frequency ◽  
Spectral Acceleration ◽  
Ground Acceleration ◽  
Attenuation Relations ◽  
Ground Motion Selection ◽  
Motion Data ◽  
Embedded Foundations

Strong motion data from sites having both an instrumented structure and free-field accelerograph are compiled to evaluate the conditions for which foundation recordings provide a reasonably unbiased estimate of free-field motion with minimal uncertainty. Variations between foundation and free-field spectral acceleration are found to correlate well with dimensionless parameters that strongly influence kinematic and inertial soil-structure interaction phenomena such as embedement ratio, dimensionless frequency (i.e., product of radial frequency and foundation radius normalized by soil shear wave velocity), and ratio of structure-to-soil stiffness. Low frequency components of spectral acceleration recorded on shallowly embedded foundations are found to provide good estimates of free-field motion. In contrast, foundation-level peak ground acceleration (both horizontal and vertical) and maximum horizontal velocity, are found to be de-amplified. Implications for ground motion selection procedures employed in attenuation relations are discussed, and specific recommendations are made as to how these procedures could be improved.

Evaluation of Intracranial Pressure Response in Rats Exposed to Complex Shock Waves

2012 ◽  
Author(s):  
Alessandra Dal Cengio Leonardi ◽  
Nickolas Keane ◽  
Cynthia Bir ◽  
Pamela VandeVord
Keyword(s):  
Intracranial Pressure ◽  
Shock Waves ◽  
Blast Wave ◽  
Preliminary Investigation ◽  
Free Field ◽  
Three Dimensional ◽  
Head Orientation ◽  
Reflected Shock ◽  
Complex Wave ◽  
The Individual

Studies on blast neurotrauma have focused on investigating the effects of exposure to free-field blast representing the simplest form of blast threat scenario without considering any reflecting surfaces. However, in reality personnel are often located within enclosures or nearby reflecting walls causing a complex blast environment, that is, involving shock reflections and/or compound waves from different directions. In fact, when a blast wave interacts with nearby structures, reflected shock waves are generated and complex three-dimensional shock waves are formed. Complex shock wave overpressure-time traces are significantly different from free-field profiles because reflections can cause super-positioning of shock waves resulting in increased pressure magnitudes and multiple pressure peaks. Very importantly, the shocks arrive from different directions which would invoke a different biomechanical response than a one-dimensional exposure. It has been reported that in complex wave environments, the extent of the injuries becomes a function of the location related to the surrounding structures rather than a function of the distance from the center of the explosion, as it is for free-field conditions (Yelverton et al. 1993; Mayorga 1997; Stuhmiller 1997). Furthermore, the resulting injuries when the individual is in confined spaces are noted to be more severe (Yelverton et al. 1993; Leibovici et al. 1996). The purpose of this study was to design a complex wave testing system and perform a preliminary investigation of the intracranial pressure (ICP) response of rats exposed to a complex blast wave environment. Furthermore, we explored the effects of head orientation in the same environment.

scholarly journals Shifting fish distributions in warming sub-Arctic oceans

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Steven E. Campana ◽  
Ragnhildur B. Stefánsdóttir ◽  
Klara Jakobsdóttir ◽  
Jón Sólmundsson
Keyword(s):  
Fish Species ◽  
Climate Warming ◽  
Large Scale ◽  
Linear Models ◽  
Three Dimensional ◽  
Species Abundance ◽  
Time Frame ◽  
Thermal Limits ◽  
Dimensional Distribution ◽  
Distribution Shifts

Abstract The distributional response of marine fishes to climate warming would be expected to be very different than that of homeothermic birds and mammals, due both to more direct thermal effects on poikilothermic fish physiology and on reduced habitat fragmentation. In this study, we use a combination of linear models and graphical tools to quantify three-dimensional distribution shifts in 82 fish species caught in 5390 standardized groundfish survey tows over a 22-year time frame in the highly-productive sub-Arctic waters around Iceland. Over a 1 °C range, temperature significantly modified the distributional centroids of 72% of all fish species, but had relatively little effect on diversity. Most of the geographic shifts were to the northwest, and there was no overall tendency to move to deeper waters. A doubling of species abundance significantly influenced the distribution of 62% of species, but lacked the poleward orientation observed with temperature increases. Stenothermal species, those near their upper or lower thermal limits, and those with restricted spatial ranges were most likely to shift their distribution in response to climate warming, while deepwater species were not. A 2–3 °C warming of marine waters seems likely to produce large-scale changes in the location of many sub-Arctic fisheries.

Soil-Foundation-Structure Behavior at the Oakland Outer Harbor Wharf

1996 ◽  
Vol 1546 (1) ◽  
pp. 100-111
Author(s):  
G. Norris ◽  
R. Siddharthan ◽  
Z. Zafir ◽  
S. Abdel-Ghaffar ◽  
P. Gowda
Keyword(s):  
Pile Foundation ◽  
Free Field ◽  
Strong Motion ◽  
Structural Failure ◽  
Loma Prieta ◽  
Soil Foundation ◽  
Batter Piles ◽  
Foundation Structure

The California Strong Motion Instrumentation Program's Loma Prieta records at Oakland Outer Harbor Wharf maybe used to study the free-field motions, the possible softening of soils surrounding the piles supporting the instrumented wharf, the determination of the motion on the instrumented wharf using free-field motion input and deflection-compatible lateral and vertical pile foundation stiffnesses, and conditions under which a soil-foundation interaction failure or structural failure of the batter piles might have developed.

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