Analysis of Strain-gage Records from a Static Loading Test on a CFA Pile

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Bengt Fellenius
Keyword(s):  
Strain Gage ◽  
Axial Stiffness ◽  
Loading Test ◽  
Static Test ◽  
Load Distributions ◽  
Effective Stress Analysis ◽  
Static Loading Test ◽  
Load Movement ◽  
Lacustrine Clay ◽  
Test Pile

A static test was performed on a 610-mm diameter, 10 m long CFA pile installed through 3 m of clay and sand and into a thick deposit of lacustrine clay. The loading procedure included prolonged load-holding and an unloading-reloading event, which adversely affected the interpretations of the strain records and demonstrated the inadvisability of not performing a test with equal load-increments and equal load-holding durations and avoiding all unloading-reloading sequences. The pile was strain-gage instrumented at three levels and the recorded strains were used to calculate the pile axial stiffness and determine the load distributions for the applied load. Back-calculations using effective stress analysis were fitted to strain-gage determined load distributions and were then used in simulating the measured pile-head load-movement of the test pile.

Prediction, Testing, and Analysis of a 50 m Long Pile in Soft Marine Clay

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Bengt Fellenius
Keyword(s):  
Peak Load ◽  
Pile Head ◽  
Marine Clay ◽  
Loading Test ◽  
Head Displacement ◽  
Floating Pile ◽  
Peak Loads ◽  
Static Loading Test ◽  
Beta Coefficient ◽  
Load Movement

On April 4, 2018, 209 days after driving, a static loading test was performed on a 50 m long, strain-gage instrumented, square 275-mm diameter, precast, shaft-bearing (“floating”) pile in Göteborg, Sweden. The soil profile consisted of a 90 m thick, soft, postglacial, marine clay. The groundwater table was at about 1.0 m depth. The undrained shear strength was about 20 kPa at 10 m depth and increased linearly to about 80 kPa at 55m depth. The load-distribution at the peak load correlated to an average effective stress beta-coefficient of 0.19 along the pile or, alternatively, a unit shaft shear resistance of 15 kPa at 10 m depth increasing to about 65 kPa at 50 m depth, indicating an α-coefficient of about 0.80. Prior to the test, geotechnical engineers around the world were invited to predict the load-movement curve to be established in the test—22 predictions from 10 countries were received. The predictions of pile stiffness, and pile head displacement showed considerable scatter, however. Predicted peak loads ranged from 65% to 200% of the actual 1,800-kN peak-load, and 35% to 300% of the load at 22-mm movement.

Probabilistic Simulation of the Mechanical Response of a Pre-Stressed Railway Sleeper: Initiation and Propagation of Cracks during Static Test

2014 ◽  
Vol 969 ◽  
pp. 298-301 ◽  
Author(s):  
Ladislav Řoutil ◽  
Václav Veselý ◽  
Zbyněk Keršner
Keyword(s):  
Static Loading ◽  
Mechanical Response ◽  
Numerical Models ◽  
Specific Load ◽  
Loading Test ◽  
Static Test ◽  
Probabilistic Simulation ◽  
Initiation And Propagation ◽  
Static Loading Test ◽  
Railway Sleeper

The paper deals with the mechanical response of a pre-stressed railway sleeper during a standardized static loading test estimations of the variability of the sleepers response and especially the probabilities of the occurrence of cracks of specific widths at specific load levels (as a consequence of random concrete parameters) based on the results of (3D) numerical models are presented. The paper follows on from and extends previous results obtained by the authors research team in cooperation with specialists from the sleeper manufacturing company ZPSV a. s.

Distribution of residual load and true shaft resistance for a driven instrumented test pile

2011 ◽  
Vol 48 (4) ◽  
pp. 583-598 ◽  
Author(s):  
Sung-Ryul Kim ◽  
Sung-Gyo Chung ◽  
Bengt H. Fellenius
Keyword(s):  
River Estuary ◽  
Field Tests ◽  
Wait Time ◽  
Loading Test ◽  
Dense Sand ◽  
Shaft Resistance ◽  
Heating And Cooling ◽  
Static Loading Test ◽  
The Nakdong River ◽  
Test Pile

Foundation conditions are studied for a series of apartment buildings in a shore area reclaimed from the Nakdong River estuary delta west of Busan, South Korea, in full-scale field tests on two 600 mm, post-driving grouted, concrete cylinder piles instrumented with strain gages, driven through compressible layers and a short distance into underlying dense sand at depths of 56 m (Shinho) and 35 m (Myeongji). One test pile was provided with an O-cell so that after an initial O-cell test, a subsequent head-down test only affected pile shaft resistance. The purpose was to evaluate drivability of the piles, magnitude of the drag load due to consolidating soils, and potential settlement (downdrag) of the piled foundations. Early in the study, it became apparent that the internal process of heating and cooling of the grout during the hydration process and swelling from absorption of water affected the strain records and the assessment of residual load in the test piles during the wait time before the static loading test. The paper reports the measurements, analyses, and method for determining residual load, strain-dependent modulus of test piles, and actual load distribution in the test piles. The results are correlated to cone penetration test (CPTU) sounding data and effective stress analysis.

Prediction, Testing, and Analysis of a 50 m Long Pile in Soft Marine Clay

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Bengt Fellenius
Keyword(s):  
Peak Load ◽  
Pile Head ◽  
Marine Clay ◽  
Loading Test ◽  
Head Displacement ◽  
Floating Pile ◽  
Peak Loads ◽  
Static Loading Test ◽  
Beta Coefficient ◽  
Load Movement

On April 4, 2018, 209 days after driving, a static loading test was performed on a 50 m long, strain-gage instrumented, square 275-mm diameter, precast, shaft-bearing (“floating”) pile in Göteborg,Sweden. The soil profile consisted of a 90 m thick, soft, postglacial, marine clay. The groundwater table was at about 1.0 m depth. The undrained shear strength was about 20 kPa at 10 m depth and increased linearly to about 80 kPa at 55m depth. The load-distribution at the peak load correlated to an average effective stress beta-coefficient of 0.19 along the pile or, alternatively, a unit shaft shear resistance of 15 kPa at 10 m depth increasing to about 65 kPa at 50 m depth, indicating an α-coefficient of about 0.80. Prior to the test, geotechnical engineers around the world were invited to predict the load-movement curve to be established in the test—22 predictions from 10 countries were received. The predictions of pile stiffness, and pile head displacement showed considerable scatter, however. Predicted peak loads ranged from 65% to 200% of the actual 1,800-kN peak-load, and 35% to 300% of the load at 22-mm movement.

Axial load transfer for piles in sand. I. Tests on an instrumented precast pile

1992 ◽  
Vol 29 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Ameir Altaee ◽  
Bengt H. Fellenius ◽  
Erman Evgin
Keyword(s):  
Static Loading ◽  
Load Transfer ◽  
Precast Concrete ◽  
Critical Depth ◽  
Compression Tests ◽  
Loading Test ◽  
Shaft Resistance ◽  
Load Distributions ◽  
Concrete Pile ◽  
Static Loading Test

A precast concrete pile was driven 11.0 m into a sand deposit and subjected to three compression and one tension static loading tests. By means of strain-gage instrumentation, the loads imposed in the pile during the tests were determined. The observed load distributions appeared to suggest the existence of a critical depth. However, when the load data were supplemented with the residual load acting before the start of the tests, the appearance of critical depth disappeared. Instead, the analysis of the tests showed that the load distribution was a function of the effective overburden stresses in the soil over the full pile length, with β-ratios ranging from 0.40 through 0.65 and a toe bearing coefficient of 30. The shaft resistance degraded slightly from test to test. The shaft resistance in tension was about equal with the shaft resistance in compression. The β-ratios and the toe bearing coefficient derived from the test were applied unchanged to the results of compression tests on a second test pile, a 15 m long identical pile, and the calculated capacity agreed with the capacity found in the static loading test. Key words : instrumented pile, sand, loading test, residual load, load transfer.

scholarly journals Research and development of thick rubber bearing for SFR (Design formulas for thick rubber bearing based on static loading test utilized scale model)

2017 ◽  
Vol 83 (852) ◽  
pp. 17-00050-17-00050 ◽  
Author(s):  
Tsuyoshi FUKASAWA ◽  
Shigeki OKAMURA ◽  
Tomohiko YAMAMOTO ◽  
Nobuchika KAWASAKI ◽  
Satoru INABA ◽  
...  
Keyword(s):  
Research And Development ◽  
Static Loading ◽  
Scale Model ◽  
Loading Test ◽  
Rubber Bearing ◽  
Static Loading Test

Analysis and Test on Mechanical Properties of a Flexible Suspension Bridge

2013 ◽  
Vol 405-408 ◽  
pp. 1616-1622
Author(s):  
Guo Hui Cao ◽  
Jia Xing Hu ◽  
Kai Zhang ◽  
Min He
Keyword(s):  
Mechanical Properties ◽  
Suspension Bridge ◽  
Experimental Results ◽  
Suspension Bridges ◽  
Loading Test ◽  
Main Cable ◽  
Element Simulation ◽  
Static Loading Test ◽  
Geometric Nonlinear Analysis ◽  
Test Process

In order to research on mechanical properties of flexible suspension bridges, a geometric nonlinear analysis method was used to simulate on the experimental results, and carried on static loading test finally. In the loading test process, the deformations were measured in critical section of the suspension bridge, and displacement values of measured are compared with simulation values of the finite element simulation. Meanwhile the deformations of the main cable sag are observed under classification loading, the results show that the main cable sag increment is basically linear relationship with the increment of mid-span loading and tension from 3L/8 and 5L/8 to L/2 section, the main cable that increasing unit sag required mid-span loads and tension are gradually reduce in near L/4 and 3L/4 sections and gradually increase in near L/8 and 7L/8 sections and almost equal in near L/2, 3L/8 and 5L/8 sections. From the experimental results, the flexible suspension bridge possess good mechanical properties.

scholarly journals Experimental Analysis of Perimeter Shear Strength of Composite Sandwich Structures

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 12
Author(s):  
Łukasz Święch ◽  
Radosław Kołodziejczyk ◽  
Natalia Stącel
Keyword(s):  
Experimental Analysis ◽  
Sandwich Structures ◽  
Maximum Load ◽  
Core Material ◽  
Foam Core ◽  
Honeycomb Core ◽  
Loading Test ◽  
Composite Sandwich ◽  
Destruction Mechanism ◽  
Static Loading Test

The work concerns the experimental analysis of the process of destruction of sandwich structures as a result of circumferential shearing. The aim of the research was to determine the differences that occur in the destruction mechanism of such structures depending on the thickness and material of the core used. Specimens with a Rohacell foam core and a honeycomb core were made for the purposes of the research. The specimen destruction process was carried out in a static loading test with the use of a system introducing circumferential shear stress. The analysis of the tests results was made based on the load-displacement curves, the maximum load, and the energy absorbed by individual specimens. The tests indicated significant differences in the destruction mechanism of specimens with varied core material. The specimen with the honeycomb core was characterized by greater stiffness, which caused the damage to occur locally in the area subjected to the pressure of the punch. In specimens with the foam core, due to the lower stiffness of that core, the skins of the structure were bent, which additionally transfers compressive and tensile loads. This led to a higher maximum force that the specimens obtained at the time of destruction and greater energy absorption.

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