scholarly journals Static and Dynamic Load Tests of Shaft and Base Grouted Concrete Piles

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Jialin Zhou ◽  
Xin Zhang ◽  
Hongsheng Jiang ◽  
Chunhao Lyu ◽  
Erwin Oh
Keyword(s):  
Dynamic Load ◽  
Static Load ◽  
Test Results ◽  
Pile Capacity ◽  
Friction Resistance ◽  
Concrete Piles ◽  
Double Tangent ◽  
Load Tests ◽  
Bored Piles ◽  
Comparison Of The Results

This paper examines shaft and base grouted concrete piles by conducting vertical static load tests (SLTs) and dynamic load tests. Three concrete piles with shaft and base grouting, with base grouting only, and without grouting techniques were selected, and compressive SLTs were conducted. Two piles with grouting were also assessed with dynamic load tests. Another two uplift SLTs were conducted to one shaft and base grouted pile and one pile without grouting. Traditional presentations were provided to check whether the bored piles reached the design requirement. Interpretations of test results were also provided to determine the ultimate pile capacity. Results from these 5 SLT programs indicated that double-tangent and DeBeer's methods are close to each other, and Chin's method overestimates the pile capacity. Comparison of the results from the SLTs and dynamic load tests shows that the results from Chin's method are close to dynamic results, and Mazurkiewicz's method overestimates for friction resistance. The results also demonstrate that base and shaft grouted pile and base grouted pile increase by 9.82% and 2.89% in compressive capacity, respectively, and compared to the uplift SLTs; there is a 15.7% increment in pile capacity after using base and shaft grouting technology.

Research on Static Load Tests of Damaged Bridge Strengthened with Pre-Stressed HFRP

2014 ◽  
Vol 1079-1080 ◽  
pp. 258-265
Author(s):  
Chen Ning Cai ◽  
Shan He ◽  
Li Na Liu ◽  
Shi Kun Ou
Keyword(s):  
Static Load ◽  
Flexural Rigidity ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Structural Members ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Load Tests

Thispaper presents an experimental study to strengthen an existing bridge usingpre-stressed carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer(GFRP) materials. The method using pre-stressed hybrid fiber reinforced polymer(HFRP) to strengthened structural members is an emerging pre-stressed strengtheningtechnology. In this study, experimental data selected from result of staticloading test conducted to hollow slabs with CFRP/GFRP has been compared with specimenswithout strengthening. Test results showed that the strengthening methoddeveloped in this study could effectively reduce the stress in hollow slab,improving the flexural rigidity and inhibiting the concrete from fracture.

Driven cast-in-situ pile capacity: insights from dynamic and static load testing

2021 ◽  
Author(s):  
Kevin N. Flynn ◽  
Bryan A. McCabe
Keyword(s):  
Dynamic Load ◽  
Shear Stresses ◽  
Load Testing ◽  
Pile Capacity ◽  
Compression Load ◽  
Shaft Resistance ◽  
Pile Installation ◽  
Cast Concrete ◽  
Load Tests

Driven cast-in-situ (DCIS) piles are classified as large displacement piles. However, the use of an oversized driving shoe introduces additional complexities influencing shaft resistance mobilisation, over and above those applicable to preformed displacement piles. Therefore, several design codes restrict the magnitude of shaft resistance in DCIS pile design. In this paper, a series of dynamic load tests was performed on the temporary steel driving tubes during DCIS pile installation at three UK sites. The instrumented piles were subsequently subjected to maintained compression load tests to failure. The mobilised shear stresses inferred from the dynamic tests during driving were two to five times smaller than those on the as-constructed piles during maintained load testing. This was attributed to soil loosening along the tube shaft arising from the oversized base shoe. Nevertheless, the radial stress reductions appear to be reversible by the freshly-cast concrete fluid pressures which provide lower-bound estimates of radial total stress inferred from the measured shear stresses during static loading. This recovery in shaft resistance is not recognised in some European design practices, resulting in conservative design lengths. Whilst the shaft resistance of DCIS piles was underpredicted by the dynamic load tests, reasonable estimates of base resistance were obtained.

Helical Pile Capacity-to-Torque Correlation: A More Reliable Capacity-to-Torque Factor Based on Full Scale Load Tests

2020 ◽  
Vol 14 (2) ◽  
Author(s):  
Moncef Souissi
Keyword(s):  
Axial Load ◽  
Static Load ◽  
Full Scale ◽  
Load Direction ◽  
Pile Capacity ◽  
Helical Piles ◽  
Load Tests ◽  
High Torque ◽  
Low Torque ◽  
The One

The capacity-to-torque ratio, Kt, has been used in the design of helical piles and anchors for over half a century. Numerous research efforts have been conducted to accurately predict this capaci-ty-to-torque ratio. However, almost of all these Kt factors are based on shaft geometry alone. The ca-pacity-to-torque ratio described herein was found to depend on the shaft diameter, shaft geometry, helix configuration, axial load direction, and installation torque. In this study, 799 full scale static load tests in compression and tension were conducted on helical piles of varying shaft diameters, shaft geometry, and helix configurations in different soil types (sand, clay, and weathered bedrock). The collected data were used to study the effect of these variables on the capacity-to-torque ratio and resulted in developing a more reliable capacity-to-torque ratio, Km, that considers the effect of the variables mentioned above. The study shows that the published Kt values in AC358 (ICC-ES Acceptance Criteria for Helical Piles Systems and Devices) underestimate the pile capacity at low torque and overestimate it at high torque. In addition, and based on probability analysis, the predicted capacity using the modified Km results in a higher degree of accuracy than the one based on the published Kt values in AC358.

scholarly journals Field Static Load Tests of Post-Grouted Piles under Various Failure Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Jialin Zhou ◽  
Jianwei Zhang ◽  
Yuzhuo Wang ◽  
Erwin Oh
Keyword(s):  
Static Load ◽  
Concrete Strength ◽  
Soil System ◽  
Failure Characteristics ◽  
Concrete Piles ◽  
Load Tests ◽  
Field Static ◽  
Failure Conditions ◽  
Set Up ◽  
Punching Failure

In practice, inappropriate test set-up and design will result in pile eccentricity, reducing pile bearing capacity. Also, inappropriate piling will reduce the strength of the upper part of concrete. These pile elements under inappropriate design and construction are easy to be overlooked since they are invisible. Because the research focuses on the pile failure behaviour under different conditions, this paper aims to determine the outcomes of pile foundation under eccentric loading, pile with inadequate concrete strength, and pile with punching failure. Four concrete piles were cast, and compressive static load tests (SLTs) were performed. The top part of the first pile was cast with inadequate concrete strength. The other two piles were cast with achieved concrete strength; however, one of these applied with eccentric loading. The third pile was the standard pile, and the fourth pile was tested until punching failure occurred. For the fourth pile, the T-Z method was used for determining the failure characteristics. It is discovered that, for the pile with inadequate concrete strength, the cracks occurred at the pile head, and the concrete crushed at 0.9–1.2 m below the ground; for the pile suffering eccentricity, the partial concrete crushed, and the concrete from the opposite side suffered tension fracture; for the pile suffering punching failure, the crack on the soil extends up to 50 mm. Traditional result presentations and interpretations were also provided. Furthermore, it was found that, for the pile suffering punching failure, the shaft resistance increased as the loads increased, and after the loading achieved the maximum resistance, the loading transferred to the pile tip and finally led to the destruction of the pile-soil system.

scholarly journals Bi-Directional Static Load Tests of Pile Models

2020 ◽  
Vol 10 (16) ◽  
pp. 5492
Author(s):  
Michał Baca ◽  
Włodzimierz Brząkała ◽  
Jarosław Rybak
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Load Testing ◽  
Pile Capacity ◽  
Pile Shaft ◽  
Load Tests ◽  
S Curve ◽  
Definition Of ◽  
Standard Tests ◽  
Static Load Testing

This work examined a new method of bi-directional static load testing for piles, referencing the Osterberg test. Measurements were taken, on a laboratory scale, using six models of piles driven into a box filled with sand. This method allowed for separate measurements of pile base and pile shaft bearing capacities. Based on the results, the total pile bearing capacity and equivalent Q–s diagrams were estimated. The results obtained show that the structure of the equivalent curve according to Osterberg is a good approximation of the standard Q–s curve obtained from load tests, except for loads close to the limit of bearing capacity (those estimates are also complicated by the inapplicability and ambiguity of a definition of the notion of limit bearing capacity); the equivalent pile capacity in the Osterberg method represents, on average, about 80% of the capacity from standard tests.

Study on the Crack in Concrete Flange of Outer-Plated Steel-Concrete Continuous Composite Beams

2012 ◽  
Vol 166-169 ◽  
pp. 1023-1028 ◽  
Author(s):  
Li Hua Chen ◽  
Qi Liang Jin ◽  
Haiyu Si
Keyword(s):  
Crack Width ◽  
Static Load ◽  
Bending Moment ◽  
Structural Features ◽  
Composite Beams ◽  
Test Results ◽  
Load Tests ◽  
Reversed Loading ◽  
Negative Bending ◽  
Stress Block

Static load tests were conducted on two reversed-loading simply supported and two continuous outer-plated steel-concrete composite beams to study the formation and development of cracks in such beams under negative bending moment. The test results show that based on the plane section assumption, it is an effective and economical method to calculate the cracking moment of the composite beams assuming a rectangular stress block for concrete in tension zone. Considering the structural features of outer-plated steel-concrete composite beams, the formula for calculating crack width of concrete flange of outer-plated steel-concrete composite beams is discussed and presented, and the calculated values of crack width agree well with the experimental results.

Identification of residual force in static load tests on instrumented screw displacement piles

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Adam Krasiński ◽  
Mateusz Wiszniewski
Keyword(s):  
Static Load ◽  
External Factors ◽  
Load Test ◽  
Necessary Condition ◽  
Measuring Instruments ◽  
Test Results ◽  
Pile Shaft ◽  
Load Tests ◽  
Residual Force ◽  
Proper Interpretation

Abstract Occurrence of the so-called residual force of an unknown value significantly disturbs interpretation of static load tests performed on piles equipped with additional measuring instruments. Screw displacement piles are the piling technology in which the residual force phenomenon is very common. Its formation mechanism is closely related to the installation method of this type of piles, which initiates generation of negative pile skin friction without any additional external factors. Knowledge of the value and distribution of a residual force (trapped in a pile shaft before starting the load test) is a necessary condition for the proper interpretation of instrumented pile test results. In this article, a clear and easy-to-use method of residual force identification, based on the analysis of shaft deformations recorded during pile unloading is presented. The method was successfully verified on two pile examples and proved to be effective and practical.

Static load tests of driven concrete piles under CFRP confinement

2019 ◽  
Vol 15 (3) ◽  
pp. 159-171
Author(s):  
Jialin Zhou ◽  
Xin Zhang ◽  
Lin Zhang ◽  
Fang Dong ◽  
Erwin Oh
Keyword(s):  
Static Load ◽  
Concrete Piles ◽  
Load Tests ◽  
Cfrp Confinement
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