scholarly journals Effect of Spatial Variability of the Elastic Modulus in Composite Ground on the Structural Performance of Large-diameter Tunnels

2021 ◽  
Vol 861 (7) ◽  
pp. 072010
Author(s):  
D M Zhang ◽  
W Chu ◽  
Z K Huang ◽  
B J Li ◽  
L Zhang ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Spatial Variability ◽  
Large Diameter ◽  
Structural Performance ◽  
Composite Ground

scholarly journals Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1015
Author(s):  
Antonio Bulum ◽  
Gordana Ivanac ◽  
Eugen Divjak ◽  
Iva Biondić Špoljar ◽  
Martina Džoić Dominković ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Large Diameter ◽  
Small Diameter ◽  
Shear Wave Elastography ◽  
Lesion Size ◽  
Ultrasound Elastography ◽  
Breast Lesions ◽  
Malignant Breast ◽  
The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

Pipeline Response to Directionally and Spatially Correlated Seismic Ground Motions

1993 ◽  
Vol 115 (1) ◽  
pp. 53-58 ◽  
Author(s):  
A. Zerva
Keyword(s):  
Spatial Variability ◽  
Exponential Decay ◽  
Random Vibration ◽  
Ground Motions ◽  
Large Diameter ◽  
Axis Orientation ◽  
Spatially Correlated ◽  
Stochastic Characteristics

This study analyzes the response of continuous, straight, large diameter pipelines subjected to spatially and directionally correlated seismic ground motions. The stochastic characteristics of the seismic motions of Event 5 recorded at the SMART-1 array in Lotung, Taiwan, are used as input motions in random vibration analyses of the structures. The results indicate that the pipeline response is sensitive to the structure’s axis orientation relative to the directions of the recorded seismic motions and to the degree of exponential decay of the spatial variability.

scholarly journals Dynamic Compressive Characteristics of Sandstone under Confining Pressure and Radial Gradient Stress with the SHPB Test

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Shiming Wang ◽  
Yunsi Liu ◽  
Jian Zhou ◽  
Qiuhong Wu ◽  
Shuyi Ma ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Large Diameter ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Peak Strain ◽  
Hopkinson Pressure Bar ◽  
Radial Gradient ◽  
The Impact

Research on the dynamic compressive characteristics of sandstone under radial gradient stress and confining pressure is conducive to understanding the characteristics of the surrounding rock, especially in an excavation operation for an underground mine roadway and tunnel. The present work aimed at studying the effects of radial gradient stress and confining pressure on the impact of compression of sandstone using a large-diameter split Hopkinson pressure bar. The results showed that the dynamic strength of sandstone under radial gradient stress increased with strain rate following a power function, and the dynamic strength of the sandstone under radial gradient stress was lower and more sensitive to strain rate. The increase in strain at peak stress (peak strain) was linearly correlated with the strain rate under different confining pressures. The sensitivity of the peak strain to confining pressure was lower for the sandstone with a hole, while the values of the elastic modulus were decreased. However, further increasing the stain rate would lead to an increase in the elastic modulus. Also, the ductility of the sandstone with a hole tested in this study was found to improve more significantly. Finally, with an increase in the incident energy, the absorbed energy per unit volume would increase, but would not be affected obviously by the radial gradient stress.

Verification of an Elastic Procedure to Estimate Elastic Follow-Up

1986 ◽  
Vol 108 (4) ◽  
pp. 461-469 ◽  
Author(s):  
A. K. Dhalla
Keyword(s):  
Thermal Expansion ◽  
Elastic Modulus ◽  
Numerical Estimate ◽  
Large Diameter ◽  
Piping System ◽  
Fast Breeder Reactor ◽  
Creep Analysis ◽  
Simplified Method ◽  
Thin Walled

This paper presents a simplified elastic procedure to estimate the amount of elastic follow-up due to thermal expansion stress experienced by a large diameter (greater than 200 mm) thin-walled (d/t greater than 30) piping system. The simplified method utilizes the concept of reduced elastic modulus which was successfully applied to classify clamp-induced pipe stresses into primary and secondary categories. The conservatism of the simplified method in quantifying elastic follow-up is illustrated in this paper by comparing the numerical estimate of elastic follow-up with that obtained from a detailed creep analysis of a Liquid Metal Fast Breeder Reactor piping system.

Numerical Simulation Analysis of Bearing Performance of Extra-Long and Large-Diameter Single Pile

2014 ◽  
Vol 1065-1069 ◽  
pp. 943-948
Author(s):  
Zhi Meng Zhao ◽  
Jin Yi Chai ◽  
Cai Xia Fan
Keyword(s):  
Numerical Simulation ◽  
Elastic Modulus ◽  
Bearing Capacity ◽  
Simulation Analysis ◽  
Large Diameter ◽  
Ultimate Bearing Capacity ◽  
Single Pile ◽  
Pile Shaft ◽  
Settlement Ratio ◽  
Pile Length

The effects of pile diameter, the property of pile end bearing stratum, the material parameters of pile shaft and the changes of pile length on the bearing performance of extra-long and large-diameter single pile were examined with the finite element software ABAQUS to make the numerical simulation analysis, by establishing the overall axial symmetry model, which was based on the data of static load test of single pile at the Yellow River Bridge site. The results show that the ultimate bearing capacity of single pile, the stiffness and the end resistance ratio would increase gradually, whereas the compression settlement ratio decreases slowly; the pile end grouting can significantly increase the ultimate loads, and therefore, improve the bearing performance of piles, but it has little effect on the stiffness of pile when loading was smaller; the elastic modulus of pile shaft has no effect on the ultimate bearing capacity of friction piles, little on the end resistance ratio, while the pile compression settlement ratio would gradually decrease and the stiffness would increased with the increase of the elastic modulus of pile shaft, and this increase of stiffness would slow down with the increase of elastic modulus of pile shaft; it is unreasonable to improve the ultimate bearing capacity of extra-long single pile only by means of increasing the pile length.

Structural Performance of Exterior Beam-Column Joints with Large Diameter Headed Bars

2017 ◽  
Vol 754 ◽  
pp. 337-340
Author(s):  
Hyung Suk Jung ◽  
Hyun Ki Choi ◽  
Chang Sik Choi ◽  
Joo Hong Chung
Keyword(s):  
Reinforced Concrete ◽  
Large Diameter ◽  
Structural Performance ◽  
Transverse Reinforcement ◽  
Test Results ◽  
Reinforced Concrete Structure ◽  
Current Design ◽  
Cover Thickness ◽  
Concrete Placement ◽  
Better Than

Generally, a conventional standard hook is used for the reinforcement's anchorage. However, this results in steel congestion, and it makes fabrication and construction difficult. Using a headed bar offers a potential solution for these problems and may also ease fabrication, construction and concrete placement. But, in current design code of the headed bar, it had limitation about the yield strength and the diameter of rebar etc. It hard to use the large diameter headed bar in the reinforced concrete structure. This paper presents the cyclic responses of four reinforced concrete exterior beam-column joints, which are anchored with large diameter headed bars or hooked bars. To evaluate the anchorage capacity of large diameter headed bars, specimen variables were set with anchorage detail, side cover thickness of concrete, and transverse reinforcement. Also, structural performance of beam-column joints is evaluated and compared with each other. The behavior of joints with headed bars are as good as, or better than those companion joints with 90-degree hooked bars. Test results show that the large diameter headed bar has enough anchorage capacity in exterior beam-column joints. Test results show side cover of concrete improved the anchorage capacity of the bars and transverse reinforcement enhanced the anchorage capacity and ductility of joints.

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