scholarly journals Acoustic nondestructive testing and measurement of tension for steel reinforcing members

2021 ◽  
Author(s):  
Michael McInerney ◽  
Matthew Brenner ◽  
Sean Morefield ◽  
Robert Weber ◽  
John Carlyle
Keyword(s):  
Laboratory Tests ◽  
Quantitative Methods ◽  
Longitudinal Velocity ◽  
Measurement Techniques ◽  
Field Tests ◽  
Shear Velocity ◽  
Structural Members ◽  
Unstressed State ◽  
Testing And Measurement ◽  
Theory And Model

Many concrete structures contain internal post-tensioned steel structural members that are subject to fracturing and corrosion. The major problem with conventional tension measurement techniques is that they use indirect and non-quantitative methods to determine whether there has been a loss of tension. This work developed an acoustics-based technology and method for making quantitative tension measurements of an embedded, tensioned steel member. The theory and model were verified in the laboratory using a variety of steel rods as test specimens. Field tests of the method were conducted at three Corps of Engineers dams. Measurements of the longitudinal and shear velocity were done on rods up to 50 ft long. Not all rods of this length were able to be measured and the quality and consistency of the signal varied. There were fewer problems measuring the longitudinal velocity than shear velocity. While the tension predictions worked in the laboratory tests, the tension could not be accurately calculated for any of the field sites because researchers could not obtain the longitudinal or shear velocities in an unstressed state, or precise measurements of the longitudinal and shear velocities due to the unknown precise length of the rods in the tensioned state.

scholarly journals Point Load Test of Half-Cylinder Core Using the Numerical Model and Laboratory Tests: Size Suggestion and Correlation with Cylinder Core

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Fengyu Ren ◽  
Huan Liu ◽  
Rongxing He ◽  
Guanghui Li ◽  
Yang Liu
Keyword(s):  
Numerical Model ◽  
Laboratory Tests ◽  
Failure Load ◽  
Field Tests ◽  
Point Load ◽  
Diameter Ratio ◽  
Load Test ◽  
Index Test ◽  
Point Load Test ◽  
Calculation Procedures

The point load test (PLT) is intended as an index test for rock strength classification or estimations of other strength parameters because it is economical and simple to conduct in the laboratory and in field tests. In the literature, calculation procedures for cylinder cores, blocks, or irregular lumps can be found, but no study has researched such procedures for half-cylinder cores. This paper presents the numerical model and laboratory tests for half-cylinder and cylinder specimens. The results for half-cylinder and cylinder specimens are then presented, analysed, and discussed. A correlation of failure load between half-cylinder and cylinder specimens is established with a suitable size suggestion and correction factor. It is found that the failure load becomes stable when half-cylinder specimens have a length/diameter ratio higher than 0.9. In addition, the results show that the point load strength index (PLSI) of half-cylinder cores can be calculated using the calculation procedures for diametral testing on cylinder cores, and it is necessary to satisfy the conditions that the length/diameter ratio be higher than 0.9 and the failure load be multiplied by 0.8.

scholarly journals Comparison analysis of using micrometers and strain gauges for measuring deformations and loads in the method of monitoring the stress-strain state

2021 ◽  
Vol 18 (3) ◽  
pp. 71-75
Author(s):  
M. O. Lobovskiy ◽  
◽  
A. L. Tukkiya ◽  
P. A. Pyatkin ◽  
◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Strain Gauge ◽  
Laboratory Tests ◽  
Strain State ◽  
Field Tests ◽  
Strain Gauges ◽  
Construction Site ◽  
Comparison Analysis ◽  
Stress Strain ◽  
Stress Strain State

The micrometer method for measuring deformations and loads in bar elements has proved to be effective not only in laboratory tests, but also in field tests on a real construction site. Having carried out a comparative analysis of the method proposed by the authors for monitoring the stress-strain state (SSS) with the strain gauge method which is widely used at present, the authors have proved that the method for measuring deformations and loads using a micrometer is not inferior in accuracy to the strain gauge method, although it is much cheaper.

STATIC AND DYNAMIC PERFORMANCE EVALUATION OF A PRE-STRESSED CONCRETE BRIDGE THROUGH FIELD TESTING AND MONITORING

2009 ◽  
Vol 09 (04) ◽  
pp. 711-728 ◽  
Author(s):  
C. S. CAI ◽  
M. ARAUJO ◽  
A. NAIR ◽  
X. SHI
Keyword(s):  
Quantitative Methods ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Field Tests ◽  
Field Measurements ◽  
Field Testing ◽  
Concrete Bridge ◽  
Bridge Structures ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This paper presents field tests performed on a slab-on-girder pre-stressed concrete bridge. The bridge was tested under static loading, crawling loading, and dynamic loading. A full three-dimensional finite element prediction under both static and dynamic loadings was carried out and the results were compared with the field measurements. While acoustic emission (AE) monitoring of bridge structures is not a new vista, the method has not been fully exploited in bridge monitoring. Though numerous quantitative methods have been proposed, they have not yet developed to be useful for actual field tests of bridges. Therefore, in this study, an attempt was made to use the intensity analysis technique for damage quantification using the AE method.

Air speed effects during drying of harvested pasture material

1965 ◽  
Vol 16 (3) ◽  
pp. 385 ◽  
Author(s):  
W Shepherd
Keyword(s):  
Moisture Content ◽  
Laboratory Tests ◽  
External Surface ◽  
Field Tests ◽  
High Moisture Content ◽  
High Moisture ◽  
High Speeds ◽  
Field Investigations ◽  
Air Speed ◽  
Drying Rates

Laboratory and field investigations indicated effects of air speed on the drying rates of harvested clover and ryegrass. In laboratory tests, the drying rates of material of high moisture content increased with increasing air speed to 0.4 m sec-1 past single units or through bulked material, and to 4 m sec-1 over bulked material. These critical air speeds decreased as drying progressed. Critical through-speeds, initially unattainable even with high speeds over bulked material, could then be attained at moderate over-speeds. The effects were confirmed during field tests involving material bulked into swaths and windrows such as are employed in the field drying of mown pasture for conservation as hay. Effective external (surface) resistances of material in swaths and windrows were estimated to be 8–12 times those of plant units exposed singly. Evidence is presented that "turning" of material during field drying, to release entrapped water vapour, is necessary even on windy days in the early stages of drying, and on still days in the later stages. Under still but otherwise favourable conditions, turning appears necessary also as a substitute for the continuous supply of warm air to spaces within the bulk.

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