A dynamic source model for the San Fernando earthquake

1978 ◽  
Vol 68 (6) ◽  
pp. 1555-1576
Author(s):  
Michel Bouchon
Keyword(s):  
Fault Plane ◽  
High Stress ◽  
Time History ◽  
High Strength ◽  
High Amplitude ◽  
Tectonic Stress ◽  
Source Model ◽  
Dynamic Crack ◽  
San Fernando ◽  
High Level

abstract We model the San Fernando earthquake as a propagating rupture in a half-space, using for the slip-time-history on the fault plane analytical expressions which approximate the slip functions of dynamic crack models obtained by Das and Aki (1977a, b). We synthesize the strong ground motions and accelerations at the Pacoima Dam site and compute the teleseismic signals for different models of cracks. Three major featuras of the data–the strong pulse associated with the beginning of the rupture, the high acceleration phase on the Pacoima Dam records, and the presence of ripples on the teleseismic seismograms–which are not compatible with a smooth rupture process, are well explained by a crack with barriers model where the rupture encounters, along the fault plane, barriers or obstacles of high strength materials which may remain unbroken after the passage of the rupture front. A high-stress drop (400 to 500 bars) is required in the hypocentral area to explain the high-amplitude short-duration first pulse of the teleseismic records. This indicates a high level of tectonic stress in the area. A study of the earthquake series following the main shock shows that the aftershocks which took place in the region where major slipping occurred during the earthquake may represent the release of some of the barriers.

Experimental Data on Seismic Response of Piping Components

1998 ◽  
Vol 120 (4) ◽  
pp. 449-455 ◽  
Author(s):  
G. C. Slagis
Keyword(s):  
Experimental Data ◽  
Seismic Performance ◽  
Low Frequency ◽  
Time History ◽  
High Amplitude ◽  
Dynamic Reliability ◽  
Performance Trends ◽  
Potential Failure ◽  
High Level ◽  
The Impact

Experimental data from the EPRI Piping and Fitting Dynamic Reliability Program are evaluated. High-amplitude, seismic time history loads were applied to 32 piping components in a cantilevered configuration. Components included elbows, tees, reducers, a reinforced fabricated tee, a nozzle, and lugs. The test levels were about 2 to 8 times Level D. The seismic capability of elbows is shown to be remarkable. The seismic performance of lugs is judged to be poor. The tests demonstrate that collapse is a potential failure mode, particularly in low-frequency systems. The tests also demonstrate that a fatigue failure in a single, high-level, seismic event is possible. Of the 15 nonelbow tests that failed by fatigue, six (40 percent) failed during the first high-level seismic test. Design and fabrication details are crucial to seismic performance. Trends in the data need to be assessed to determine appropriate Section III stress limits for seismic loads. In particular, the impact of component frequency on seismic capability has to be quantified.

RMS accelerations and spectral amplitudes of strong ground motion during the San Fernando, California earthquake

1980 ◽  
Vol 70 (5) ◽  
pp. 1907-1919
Author(s):  
Robin K. McGuire ◽  
Thomas C. Hanks
Keyword(s):  
Stress Drop ◽  
Free Field ◽  
Amplitude Spectrum ◽  
High Stress ◽  
Seismic Source ◽  
Source Model ◽  
Horizontal Shear ◽  
Initial Rupture ◽  
San Fernando ◽  
Source Excitation

abstract An estimate of the Fourier amplitude spectrum of horizontal shear-wave motion is obtained using the Brune seismic source model in the presence of anelastic attenuation, from which the root-mean-square acceleration (arms) can be calculated. Predicted spectral amplitudes and values of arms are compared to observations for 160 free-field or basement-level components of horizontal acceleration of the San Fernando earthquake. For a stress drop of 50 bars and a faulting duration of 10 sec, observed and predicted spectral amplitudes and values of arms are in reasonable agreement: the observations conform to the predicted attenuation with distance (which is frequency-dependent for spectral amplitudes and proportional to R−3/2 for arms), but exceed predicted values by an average factor of about 3. Some of this difference is attributable to azimuthal variation in source excitation and the highly nonuniform distribution of stations with azimuth; the remainder results from the high-stress drop associated with the initial rupture for this earthquake. Predictions made by the model are nonetheless in agreement, both in terms of attenuation and amplitude, with spectral amplitudes estimated by empirical models calibrated with records from a wide variety of earthquakes.

INLAND DURASPRING

Alloy Digest ◽  
1998 ◽  
Vol 47 (5) ◽  
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Tensile Properties ◽  
High Stress ◽  
High Strength ◽  
Spring Steel ◽  
Fatigue Properties ◽  
Light Truck ◽  
Suspension Systems ◽  
Spring Steels

Abstract Inland DuraSpring is a high-strength microalloyed spring steel for use in high stress coil springs for automobile and light truck suspension systems. This bar product offers significant improvements in tensile strength, fatigue properties, and fracture toughness compared to conventional spring steels. This datasheet provides information on composition, hardness, and tensile properties as well asfracture toughness and fatigue. Filing Code: SA-496. Producer or source: Ispat Inland Inc.

BETHSTAR 60

Alloy Digest ◽  
1986 ◽  
Vol 35 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Yield Strength ◽  
Steel Plate ◽  
High Stress ◽  
High Strength ◽  
Heat Treating ◽  
Low Carbon ◽  
Bethlehem Steel Corporation ◽  
Low Sulfur ◽  
Minimum Yield

Abstract BethStar 60 steel plate is a high-strength product with a 60,000 psi minimum yield strength. It contains low carbon and low sulfur and has outstanding toughness, weldability and formability. It provides the design engineer with a an economical high-strength low-alloy (HSLA) grade that can be fabricated readily. Applications include weight-sensitive components subject to high stress such as frames for large off-highway haulers. This datasheet provides information on composition, physical properties, microstructure, elasticity, and tensile properties as well as fracture toughness. It also includes information on forming, heat treating, and joining. Filing Code: SA-421. Producer or source: Bethlehem Steel Corporation.

scholarly journals Evaluation of the Most Stressful Dental Treatment Procedures of Conservative Dentistry among Polish Dental Students

2021 ◽  
Vol 18 (9) ◽  
pp. 4448
Author(s):  
Katarzyna Mocny-Pachońska ◽  
Rafał J. Doniec ◽  
Sylwia Wójcik ◽  
Szymon Sieciński ◽  
Natalia J. Piaseczna ◽  
...  
Keyword(s):  
Dental Treatment ◽  
High Stress ◽  
Dental Students ◽  
Endodontic Treatment ◽  
Stressful Environment ◽  
Caries Treatment ◽  
Dental Procedures ◽  
Conservative Dentistry ◽  
High Level ◽  
Treatment Procedures

Background: Dental schools are considered to be a very stressful environment; the stress levels of dental students are higher than those of the general population. The aim of this study was to assess the level of stress among dental students while performing specific dental procedures. Methods: A survey was conducted among 257 participants. We used an original questionnaire, which consisted of 14 questions assigned to three categories: I—Diagnosis, II—Caries Treatment, and III—Endodontic Treatment. Each participant marked their perceived level of stress during the performed dental treatment procedures. The scale included values of 0–6, where 0 indicates no stress, while 6 indicates high stress. Results: Third- (p=0.006) and fourth-year (p=0.009) women were characterized by a higher level of perceived stress during dental procedures related to caries treatment. Caries treatment procedures were the most stressful for 18.3% of third-year students, 4.3% of fourth-year students, and 3.2% of fifth-year students. Furthermore, 63.4% of third-year students, 47.3% of fourth-year students, and 17.2% of fifth-year students indicated that they felt a high level of stress when performing endodontic procedures. Conclusion: Third- and fourth-year female students are characterized by a higher level of stress during caries and endodontic treatment procedures. The most stressful treatments for participants were endodontic treatment procedures.

Dynamic Response Analysis of Butt Joint of HTS-A Steel Considering Welding Residual Stresses

2013 ◽  
Vol 423-426 ◽  
pp. 944-950
Author(s):  
Wei Shen ◽  
Ren Jun Yan ◽  
Lin Xu ◽  
Kai Qin ◽  
Xin Yu Zhang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Dynamic Response ◽  
Hot Spot ◽  
Time History ◽  
High Strength ◽  
Simulation Method ◽  
Butt Joint ◽  
Welding Residual Stress ◽  
Response Analysis ◽  
Hull Structure

This paper uses both numerical simulation method and experimental research method to study on welding residual stress of high-strength steel of the cone-cylinder hull. Welding is often accompanied by a larger welding residual stress, which directly affects the safety and service life of the hull structure. In order to obtain the distribution of the welding residual stress, the welding procedure was developed by its parameter language by using FE analysis software in this paper. Then the welding residual stress of hot spot region was measured through X-ray nondestructive testing method, and compared it with simulation results. Finally, considering the residual stress as the initial stress, this paper analyzed dynamic response process of the welding structure under combined actions of the welding residual stress and multiaxial loads, which could more accurately determine the stress of welding structure and the location of fatigue risk point. According to the amplitude of damage parameters and strain time-history curve, we can estimate the fatigue life of structure by selecting the corresponding damage models.

An Experimental Study of Cavity Nucleation During Superplastic Deformation

1990 ◽  
Vol 196 ◽  
Author(s):  
Jiang Xinggang ◽  
Cui Jianzhong ◽  
Ma Longxiang
Keyword(s):  
Grain Boundary ◽  
Superplastic Deformation ◽  
Thermomechanical Processing ◽  
High Stress ◽  
High Strength ◽  
Optical Microscope ◽  
Grain Boundary Sliding ◽  
Cavity Nucleation ◽  
High Stress Concentration ◽  
Voltage Electron

ABSTRACTCavity nucleation during superplastic deformation of a high strength aluminium alloy has been studied using a high voltage electron microscope and an optical microscope. The results show that cavities nucleation is due only to superplastic deformation and not to pre-existing microvoids which may be introduced during thermomechanical processing. The main reason for cavity nucleation is the high stress concentration at discontinuties in the plane of the grain boundary due to grain boundary sliding.

High Strength Combined Support Technology in Deep High Stress Soft Rock Roadway

2012 ◽  
Vol 524-527 ◽  
pp. 598-603
Author(s):  
Nian Jie Ma ◽  
Zhi Qiang Zhao ◽  
Hua Zhao ◽  
Li Shuai Jiang
Keyword(s):  
High Stress ◽  
Soft Rock ◽  
High Strength ◽  
Parameter Determination ◽  
Test Results ◽  
Actual Measurement ◽  
Computer Numerical Simulation ◽  
Soft Rock Roadway ◽  
Rock Roadway

In order to solve the serious damage and repeat revision problem of high stress soft rock roadway in deep -950 level of Tangshan coal mine, based on the theory of the maximum stress level, together with the actual measurement of geostress and the laboratory mechanical parameters of rock-core and computer numerical simulation, the high strength combined support technology and supporting parameters are determined and the engineering test has been done. The engineering test results show that the parameter determination of high strength combined support technology, which based on the actual measurement of geostress, can effective solve the support issue of high stress soft rock roadway and provide useful experience for similar engineering problems.

Microearthquakes in the Tihamat-Asir region of Saudi Arabia

1980 ◽  
Vol 70 (6) ◽  
pp. 2291-2293
Author(s):  
H. M. Merghelani ◽  
S. K. Gallanthine
Keyword(s):  
Saudi Arabia ◽  
Continental Crust ◽  
Red Sea ◽  
Fault Plane ◽  
Seismic Refraction ◽  
Earthquake Hazard ◽  
Tectonic Activity ◽  
Fault Plane Solutions ◽  
High Level ◽  
Asir Region

abstract During the course of a seismic refraction investigation in Saudi Arabia, an unexpected high level of microearthquake activity was detected near the border of the Red Sea and near the transition from oceanic to continental crust. The data is not adequate to determine fault plane solutions nor to relate the earthquakes to specific structures, but the existence of microearthquakes at this location suggest that there is a significant level of tectonic activity at a point 200 km from an axial trough of the Red Sea. These data, combined with other recent geological observations, may be an important clue to the understanding of continental rifting. The data suggest the need for a more thorough investigation of the earthquake hazard along the shores of the Red Sea.

scholarly journals Burnout, resilience, and perception of mindfulness programmes among GP trainees: a mixed-methods study

BJGP Open ◽  
2020 ◽  
Vol 4 (3) ◽  
pp. bjgpopen20X101058
Author(s):  
Petra Hanson ◽  
Amy Clarke ◽  
Manuel Villarreal ◽  
Majid Khan ◽  
Jeremy Dale
Keyword(s):  
Mixed Methods ◽  
Focus Groups ◽  
Help Seeking ◽  
High Stress ◽  
Mixed Methods Study ◽  
Mindfulness Practice ◽  
Negative Effects ◽  
High Prevalence ◽  
High Level ◽  
And Coping

BackgroundTrainee GPs are at risk of developing burnout as a result of high stress levels. Improving resilience may prevent the negative effects of stress on wellbeing, morale, and patient care, thereby supporting recruitment to general practice.AimTo explore experiences of stress and burnout among GP trainees, and their level of interest in undertaking a mindfulness programme.Design & settingA qualitative study was performed with a cohort of GP trainees in Coventry and Warwickshire.MethodThis mixed-methods study utilised a survey with validated measures to investigate the prevalence of burnout, state of wellbeing, and resilience in GP trainees. Focus groups were also used to explore experiences of stress and burnout, and perceptions of mindfulness practice.ResultsIn total, 47 (response rate 39%) trainees completed the survey and 14 participated in focus groups. There was a high prevalence of disengagement (n = 36; 80%) and emotional exhaustion (n = 35; 77%), with 29 (64%) scoring above the cut-off value for both. While 16 (34%) reported already practising mindfulness, 39 (83%) described interest in engaging in mindfulness practice. The focus groups identified a range of issues relating to how trainees recognise stress and burnout, their help-seeking and coping strategies, the perceived barriers to practising self-care, and motivations for participating in mindfulness training.ConclusionThis study confirms the degree of stress and burnout that GP trainees experience, and their desire for greater wellbeing and resilience support. It identified a high level of interest in attending a mindfulness programme, but also barriers to engagement. Results of this research shaped the Mindful Practice Curriculum programme, which was later provided to this cohort of trainees.

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