scholarly journals Prediction of Mean Responses of RC Bridges Considering the Incident Angle of Ground Motions and Displacement Directions

2021 ◽  
Vol 11 (6) ◽  
pp. 2462
Author(s):  
Payam Tehrani ◽  
Denis Mitchell
Keyword(s):  
Incident Angle ◽  
Combination Rules ◽  
Maximum Displacement ◽  
Seismic Demands ◽  
Averaging Methods ◽  
Displacement Direction ◽  
The Mean ◽  
Ground Motion Records ◽  
Directivity Effects ◽  
2D And 3D

Inelastic dynamic analyses were carried out using 3D and 2D models to predict the mean seismic response of four-span reinforced concrete (RC) bridges considering directionality effects. Two averaging methods, including an advanced method considering displacement direction, were used for the prediction of the mean responses to account for different incident angles of ground motion records. A method was developed to predict the variability of the mean displacement predictions due to variability in the incident angles of the records for different averaging methods. When the concepts of averaging in different directions were used, significantly different predictions were obtained for the directionality effects. The accuracy of the results obtained using 2D and 3D analyses with and without the application of the combination rules for the prediction of the mean seismic demands considering the incident angle of the records was investigated. The predictions from different methods to account for the records incident angles were evaluated probabilistically. Recommendations were made for the use of the combination rules to account for the directivity effects of the records and to predict the actual maximum displacement, referred to as the maximum radial displacement.

Investigating the effects of combinations of irregularities on seismic ductility demands and mean response for four-span RC bridges considering displacement direction

2021 ◽  
Vol 16 (2-3) ◽  
pp. 105-117
Author(s):  
Mohsen Sajed ◽  
Payam Tehrani
Keyword(s):  
Time History ◽  
The Past ◽  
History Analysis ◽  
Different Types ◽  
Displacement Direction ◽  
The Mean ◽  
Support Conditions ◽  
Irregular Bridges ◽  
Ground Motion Records ◽  
The Impact

The effects of combinations of different types of irregularities have not been studied in details in the past and current seismic design codes do not address this issue appropriately. In this research, 76 regular and irregular bridges with irregularities in both superstructure and substructure were designed and evaluated to investigate the impact of combinations of irregularities on the seismic ductility demands. The irregularity parameters considered in this study include irregularities in span arrangement, different lengths of columns, different abutments support conditions and different stiffness of superstructure. The bridges were designed and checked according to AASHTO provisions. Inelastic time history analysis was conducted using OpenSees software and ductility demands in bridge columns for different bridge configurations were predicted. Predictions of ductility demands were based on the mean responses obtained using a number of ground motion records. Finally, the effect of considering displacement directions in predicting the mean bridge response (i.e., using different methods for predicting the mean response) for irregular and regular bridges was investigated. The results indicate that the combinations of irregularities can significantly increase the ductility demands in some cases compared to the case of regular bridges.

scholarly journals Investigating the Use of Natural and Artificial Records for Prediction of Seismic Response of Regular and Irregular RC Bridges Considering Displacement Directions

2021 ◽  
Vol 11 (3) ◽  
pp. 906
Author(s):  
Payam Tehrani ◽  
Denis Mitchell
Keyword(s):  
Seismic Response ◽  
Radial Displacement ◽  
Time History ◽  
Good Prediction ◽  
3D Analysis ◽  
Combination Rules ◽  
Principal Axes ◽  
Artificial Records ◽  
The Mean ◽  
Irregular Bridges

The seismic responses of continuous multi-span reinforced concrete (RC) bridges were predicted using inelastic time history analyses (ITHA) and incremental dynamic analysis (IDA). Some important issues in ITHA were studied in this research, including: the effects of using artificial and natural records on predictions of the mean seismic demands, effects of displacement directions on predictions of the mean seismic response, the use of 2D analysis with combination rules for prediction of the response obtained using 3D analysis, and prediction of the maximum radial displacement demands compared to the displacements obtained along the principal axes of the bridges. In addition, IDA was conducted and predictions were obtained at different damage states. These issues were investigated for the case of regular and irregular bridges using three different sets of natural and artificial records. The results indicated that the use of natural and artificial records typically resulted in similar predictions for the cases studied. The effect of displacement direction was important in predicting the mean seismic response. It was shown that 2D analyses with the combination rules resulted in good predictions of the radial displacement demands obtained from 3D analyses. The use of artificial records in IDA resulted in good prediction of the median collapse capacity.

scholarly journals Evaluation of three-dimensional acromiohumeral distance in the standing position and comparison with its conventional measuring methods

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Yuki Yoshida ◽  
Noboru Matsumura ◽  
Yoshitake Yamada ◽  
Minoru Yamada ◽  
Yoichi Yokoyama ◽  
...  
Keyword(s):  
Supine Position ◽  
Humeral Head ◽  
Three Dimensional ◽  
Standing Position ◽  
Ct Scanner ◽  
Mean Values ◽  
Measuring Methods ◽  
The Mean ◽  
Acromiohumeral Distance ◽  
2D And 3D

Abstract Background Narrowing of the acromiohumeral distance (AHD) implies a rotator cuff tear. However, conventional AHD measurements using two-dimensional (2D) imaging or with the patient in the supine position might differ from that while standing during daily activity. This study aimed to evaluate the three-dimensional (3D) actual distance between the acromion and humeral head in the standing position and compare the AHD values with those obtained using conventional measuring methods. Methods Computed tomography (CT) images of 166 shoulders from 83 healthy volunteers (31 male and 52 female; mean age 40.1 ± 5.8 years; age range, 30–49 years) were prospectively acquired in the supine and standing positions using conventional and upright CT scanners, respectively. The minimum distance between the acromion and humeral head on the 3D surface models was considered as the 3D AHD. We measured the 2D AHD on anteroposterior digitally reconstructed radiographs. The AHD values were compared between the supine and standing positions and between the 2D and 3D measurements. Results The mean values of 2D AHD were 8.8 ± 1.3 mm (range, 5.9–15.4 mm) in the standing position and 8.1 ± 1.2 mm (range, 5.3–14.3 mm) in the supine position. The mean values of 3D AHD were 7.3 ± 1.4 mm (range, 4.7–14.0 mm) in the standing position and 6.6 ± 1.2 mm (range, 4.4–13.7 mm) in the supine position. The values of 3D AHD were significantly lower than those of 2D AHDs in both the standing and supine positions (P < 0.001). The values of 2D and 3D AHDs were significantly lower in the supine position than in the standing position (P < 0.001). Conclusions This study evaluated the 3D AHD of normal shoulders in the standing position using an upright CT scanner. The present results indicated that assessments in the supine position can underestimate the value of the AHD compared with those made in the standing position and that assessments using 2D analysis can overestimate the value.

scholarly journals 1180 2D and 3D assessment of the left ventricle volume and ejection fraction in a general population

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
F Ericsson ◽  
B Tayal ◽  
K Hay Kragholm ◽  
T Zaremba ◽  
N Holmark Andersen ◽  
...  
Keyword(s):  
General Population ◽  
Left Ventricle ◽  
Ejection Fraction ◽  
Large Population ◽  
Systolic Volume ◽  
End Diastolic Volume ◽  
Significant Difference ◽  
End Systolic Volume ◽  
The Mean ◽  
2D And 3D

Abstract Introduction In standard practice, LV volumes and EF are estimated by 2D technique. 3D echocardiographic assessment seems more reliable; however, this method has not yet been validated in the general population. Purpose To validate 3D echocardiography in a large population sample and investigate differences between 2D and 3D LVEF and volumes Methods In The Copenhagen City Heart Study, 4466 echocardiograms were available for analysis. The echocardiograms were obtained during four consecutive heartbeats in both 2D and 3D with GE Vivid E9. Offline analysis was performed on EchoPac v. 201. LVEF was calculated by the modified Simpsons Biplane Auto EF for 2D and by the 4LVQ method for 3D. Results The study included 2090 echocardiograms. The mean 2D LVEF was 57.3 ± 6.1% (IQR 54 - 61%) and 51.7 ± 7.9% (IQR 47 - 57%) by 3D. The mean end-diastolic volume (EDV) and end-systolic volume (ESV) by 2D and 3D techniques were: EDV 2D 106.1 ± 29.6 ml vs EDV 3D 128.2 ± 32.3 ml , ESV 2D 45.7 ± 15.6 ml vs. ESV 3D 45.7 ± 20.7 , p &lt; 0.05 among all variables. The average difference of means between 2D and 3D LVEF was 5.6 ± 11.2%, -22.1 ± 56.8 ml for EDV, and -16.9 ± 32.9 ml for ESV. The correlation coefficient for LVEF was 0.42, EDV 0.76 and for ESV 0.70. Conclusion In our study, we found a significant difference in both LVEF and ventricular volumes when comparing 2D echocardiograms with 3D. 3DE had, in general, lower LVEF, higher EDV and ESV compared to 2D. Table 1: Summary of results Table 1 - Summary of results n = 2090 Variable Min Max Mean IQR (25-75) p-value LVEF, 2D (%) 18 76 57.3 ± 6.1 54-61 &lt; 0.05 LVEF, 3d (%) 13 77 51.7 ± 7.9 47-57 &lt; 0.05 EDV, 2D (ml) 13 275 106.1 ± 29.6 85-123.8 &lt; 0.05 EDV, 3D (ml) 50 270 128.2 ± 32.3 106-148 &lt; 0.05 ESV, 2D (ml) 15 150 45.7 ± 15.6 35-54 &lt; 0.05 ESV, 3D (ml) 13 185 45.7 ± 20.7 48-74 &lt; 0.05 LVEF: left ventricle ejection fraction, EDV: end-diastolic volume, ESV: end systolic volume, IQR: Inter-quartile range Abstract 1180 Figure 1: Correlation and BA-plot

scholarly journals The 3D Tele Motion Tracking for the Orthodontic Facial Analysis

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Stefano Mummolo ◽  
Alessandro Nota ◽  
Enrico Marchetti ◽  
Giuseppe Padricelli ◽  
Giuseppe Marzo
Keyword(s):  
Motion Tracking ◽  
Dynamic Testing ◽  
Three Dimensional ◽  
Cephalometric Analysis ◽  
Facial Analysis ◽  
The Face ◽  
The Mean ◽  
2D And 3D ◽  
Very High ◽  
Posterior Anterior

Aim. This study aimed to evaluate the reliability of 3D-TMT, previously used only for dynamic testing, in a static cephalometric evaluation. Material and Method. A group of 40 patients (20 males and 20 females; mean age 14.2±1.2 years; 12–18 years old) was included in the study. The measurements obtained by the 3D-TMT cephalometric analysis with a conventional frontal cephalometric analysis were compared for each subject. Nine passive markers reflectors were positioned on the face skin for the detection of the profile of the patient. Through the acquisition of these points, corresponding plans for three-dimensional posterior-anterior cephalometric analysis were found. Results. The cephalometric results carried out with 3D-TMT and with traditional posterior-anterior cephalometric analysis showed the 3D-TMT system values are slightly higher than the values measured on radiographs but statistically significant; nevertheless their correlation is very high. Conclusion. The recorded values obtained using the 3D-TMT analysis were correlated to cephalometric analysis, with small but statistically significant differences. The Dahlberg errors resulted to be always lower than the mean difference between the 2D and 3D measurements. A clinician should use, during the clinical monitoring of a patient, always the same method, to avoid comparing different millimeter magnitudes.

Wake Formation for an Oscillating Small-Incidence-Angle Cylinder Pair in Cross-Flow

2011 ◽  
Author(s):  
Mir M. Hayder
Keyword(s):  
Incidence Angle ◽  
Flow Direction ◽  
Incident Angle ◽  
Cross Flow ◽  
Wake Flow ◽  
Circular Cylinders ◽  
Mean Flow ◽  
Small Incidence ◽  
The Mean ◽  
Wake Formation

The wake region of a pair of equal-diameter staggered circular cylinders in cross-flow is investigated experimentally for Reynolds numbers, based on the mean flow velocity, U, and the cylinder diameter, D, within the range 540 ≤ Re ≤ 755. The centre-to-centre pitch ratio and stagger angle of the cylinders at their mean position are P/D = 2.0 and α = 16°, respectively. In an earlier study, wake formation of a small-incident-angle cylinder pair was investigated for forced oscillation (transverse to the flow direction) of the upstream cylinder only. The present study is aimed to reveal the modification of the wake when the oscillation is shifted from the upstream to downstream cylinder or vice versa. Results with cylinder excitation frequencies in the range 0.07 ≤ feD/U ≤ 1.10 are reported. It is observed that for both upstream and downstream cylinder oscillations with frequency feD/U ≤ 0.10 the wake flow patterns remain essentially the same as those of the corresponding static cases. However, for frequency feD/U &gt; 0.10 the wake undergoes considerable modification vis-a`-vis when the cylinders are stationary, and the flow pattern within the wake is strongly dependent on feD/U value. As also observed in the previous study, there are distinct regions of synchronization between the dominant wake periodicities and the cylinder oscillation over the whole range of feD/U. These synchronizations involve sub- and super-harmonics as well as fundamental synchronizations and are the result of the formation of two rows of vortices, one on either side of the combined wake of the cylinder pair. The manner in which the wake responds to the cylinder oscillation depends strongly on whether it is the upstream or downstream cylinder which is oscillating. Flow-visualization images suggests that the synchronizations on the mean-flow side of the downstream cylinder occur from the outer vortices shed by the downstream cylinder, and those on the mean-flow side of the upstream cylinder occur from the vortices formed by the interaction of the two gap shear layers and the outer shear layer separated from the upstream cylinder.

Abstract 12605: Defining the Reference Range for Left Ventricular Strain by Echocardiography in Healthy Subjects: A Novel Meta-analysis Strategy

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Tom Kai Ming Wang ◽  
Milind Y Desai ◽  
Patrick H Collier ◽  
Richard A Grimm ◽  
Brian Griffin ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Confidence Intervals ◽  
Healthy Subjects ◽  
Meta Analysis ◽  
Left Ventricular ◽  
Reference Ranges ◽  
Global Strain ◽  
Echocardiographic Parameters ◽  
The Mean ◽  
2D And 3D

Background: Left ventricular global longitudinal strain (LVGLS), circumferential strain (LVGCS) and radial strain (LVGRS) are established echocardiographic parameters of systolic function with wide clinical applicability and prognostic implications. Despite this, the reference ranges of left ventricular (LV) strain, particularly the lower limit of normal (LLN), are not well established. This meta-analysis aims to determine the mean and LLN of two- (2D) and three-dimensional (3D) LV strain in healthy subjects and factors that may influence strain measurements. Methods: We searched Pubmed, Embase and Cochrane databases until 30 November 2019 for studies reporting left ventricular (LV) global strain in at least 50 healthy subjects. We pooled the mean and LLN of 2D and 3D LV strain using random-effects models, and performed subgroup and meta-regression analysis for 2D-LVGLS. Results: Forty-four studies were eligible totaling 8747 subjects. The pooled means and LLNs (95% confidence intervals) were -20.0% (-20.6%, -19.5%) and -15.6% (-16.2%, -15.0%) respectively for 2D-LVGLS; -22.1% (-23.7%, -20.5%) and -15.7% (-17.3%, -14.1%) respectively for 2D-LVGCS; and 48.0% (43.8%, 52.1%) and 23.2% (20.9%, 25.5%) respectively for 2D-LVGRS; all listed in Table 1. Significant heterogeneity was observed for almost all pooled LV strain analyses. The only factors associated with significant differences in both pooled mean and LLN of 2D-LVGLS were systolic blood pressure and vendor software. Conclusion: Pooled means and LLNs of 2D- and 3D- LV global strain parameters in healthy subjects were reported. Based on the pooled LLNs and their confidence intervals, the thresholds for abnormal, borderline and normal LV strains can be defined. Systolic blood pressure and vendor software were the most important parameters influencing 2D-LVGLS mean and LLN. Our novel methodology can also be applied to the meta-analysis of other echocardiographic parameters to define reference ranges.

Seismic performance criteria based on response history analysis

2014 ◽  
Vol 47 (3) ◽  
pp. 224-228 ◽  
Author(s):  
Brendon A. Bradley
Keyword(s):  
Seismic Performance ◽  
Performance Metrics ◽  
Performance Criteria ◽  
Art Practice ◽  
Seismic Demands ◽  
Codes Of Practice ◽  
History Analysis ◽  
Response History Analysis ◽  
The Mean

This paper provides a comparison of four different seismic performance metrics which relate to the determination of design seismic demands from seismic response history analyses. The considered metrics include those implemented in New Zealand and international codes of practice, as well as emerging metrics which are well established in related research and state-of-the-art practice, but have yet to find their way into conventional guidelines. The metrics are directly compared and contrasted based on a central example. It is illustrated that the use of the “maximum demand” metric in the NZ loadings standard, and the “mean demand” in international codes of practice are notably conservative and unconservative, respectively. Either of the two emerging metrics provide a significant improvement, and given that they require the same information from an analyst’s perspective, are recommended as replacements.

INHOMOGENEITY INDUCED CONDUCTIVITY FLUCTUATION IN YBa2Cu3O7-δ/BaTiO3–CoFe2O4 COMPOSITE

2013 ◽  
Vol 27 (20) ◽  
pp. 1350099 ◽  
Author(s):  
MOUSUMIBALA SAHOO ◽  
DHRUBANANDA BEHERA
Keyword(s):  
Model Fitting ◽  
Mean Field ◽  
Xrd Analysis ◽  
Fluctuation Analysis ◽  
Superconducting Transition ◽  
Solid State Route ◽  
Zero Resistance ◽  
The Mean ◽  
2D And 3D ◽  
Conductivity Fluctuation

Polycrystalline (1-x) YBa 2 Cu 3 O 7-y + x BaTiO 3– CoFe 2 O 4(x = 0.0, 0.2, 0.4, 0.6 wt. %) superconductors were prepared by solid state route. XRD analysis reveals no significant change in "b" parameter and increase in "a" and "c" parameters. SEM micrographs show no change in grain size of the samples. With the increase of BaTiO 3– CoFe 2 O 4 (BTO–CFO) addition it has been analyzed that the superconducting transition temperatures (Tc) determined from standard four-probe method was decreased and dropped sharply with higher wt.% addition. Excess conductivity fluctuation analysis using Aslamazov–Larkin model fitting reveals transition of two dominant regions (2D and 3D) above Tc. The decrease in 2D–3D crossover temperature T LD (Lawerence–Doniach temperature) in the mean field region has been observed as a consequent dominance of 3D region to increase in wt.% in the composite. The increasing value of ρwl and ρ0 and the decreasing trend in the value of zero-resistance critical temperature (Tc0) indicates that the connectivity between grains decreases gradually with the addition of magneto–electric composite BTO–CFO.

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