Estimating static tip resistance of driven piles with bottom pile instrumentation

2012 ◽  
Vol 49 (4) ◽  
pp. 381-393 ◽  
Author(s):  
Khiem T. Tran ◽  
Michael McVay ◽  
Rodrigo Herrera ◽  
Peter Lai
Keyword(s):  
Static Load ◽  
Accelerometer Data ◽  
Driven Piles ◽  
Unknown Parameters ◽  
Single Degree Of Freedom ◽  
Tip Resistance ◽  
Load Tests ◽  
Energy Equilibrium ◽  
Static Resistance ◽  
Time Assessment

A technique is presented to estimate static tip resistance of a pile during driving from embedded strain and accelerometer data located one diameter (D) from the bottom of the pile. The approach uses a nonlinear single degree of freedom system to satisfy force and energy equilibrium with a global genetic inversion approach. By balancing force and energy from inertia, damping, and stiffness against the measured tip data, the unknown parameters (mass, damping, and nonlinear stiffness) are estimated. Requiring a few seconds for analysis for each blow, the algorithm ensures a real-time assessment of static tip resistance as a function of displacement, which is important when setting pile lengths. The proposed approach was applied to four test piles at two bridge sites (Florida and Louisiana). Mobilized static tip resistances ranging from 400 to 1500 kN as a function of displacement were predicted. The predicted static resistance versus displacements compared favorably with measured values from static load tests. Interestingly, the maximum recorded increase in tip resistance in silty to clayey sands was less than 20% when piles were re-struck at times ranging from 2 to 30 days after initial drive.

Interpreting Ultimate Capacity of Driven Piles with S-lgt Curve and Davisson Offset Limit

2011 ◽  
Vol 90-93 ◽  
pp. 121-127 ◽  
Author(s):  
Dong Yuan Wang ◽  
Jian Jun Zhao ◽  
Yu Ming Zhou ◽  
Li Qiang Lu
Keyword(s):  
Static Load ◽  
Soft Soil ◽  
Western World ◽  
Engineering Practice ◽  
Load Testing ◽  
Ultimate Capacity ◽  
Driven Piles ◽  
Concrete Pipe ◽  
Ground Conditions ◽  
Load Tests

This paper explores the methods used widely in China and western world interpreting the ultimate capacity of driven piles based on axial static load tests. A database consisting of 57 prestressed high- compression-capacity concrete pipe piles, which are widely used in soft soil ground conditions for building and transportation projects in China, is built. Two methods widely used in China and western world to interpret the ultimate capacity of driven piles based on axial static load testing data, S-lg(t) curve and Davisson Offset Limit, are applied to the database. Findings indicate that both methods work well and reach almost the same estimation. Conclusions suggest that both academia and industry of China and western world should take the advantages of the methods and apply them to engineering practice.

A Load-Testing Program on Large-Diameter (66-Inch) Open-Ended and PSC-Instrumented Test Piles to Evaluate Design Parameters and Pile Setup

2018 ◽  
Vol 2672 (52) ◽  
pp. 291-306 ◽  
Author(s):  
Md. Nafiul Haque ◽  
Murad Y. Abu-Farsakh ◽  
Chris Nickel ◽  
Ching Tsai ◽  
Jesse Rauser ◽  
...  
Keyword(s):  
Static Load ◽  
Large Diameter ◽  
Load Test ◽  
Design Parameters ◽  
Soil Conditions ◽  
Load Testing ◽  
Static Load Test ◽  
Testing Program ◽  
Tip Resistance ◽  
Load Tests

This paper presents the results from a pile load testing program for a bridge construction project at Chalmette, Louisiana. The load testing includes three 66-in. spun-cast post-tensioned open-ended cylinder piles and one 30-in. square prestressed concrete (PSC) pile driven at four different locations along the bridge site in clayey-dominant soil. Both cone penetration tests and soil borings/laboratory testing were used to characterize the subsurface soil conditions. All test piles (TP) were instrumented with strain gauges to measure the load distribution along the length of the TPs and to measure the side and tip resistances, separately. Dynamic load tests (DLT) were performed on all TPs at different waiting periods after pile installations to quantify the amount of setup (i.e., increase in pile resistance with time). Case Pile Wave Analysis Program (CAPWAP®) analyses were performed on the DLT data to calculate the resistance distributions along the TPs. A static load test was performed only on the PSC pile and statnamic load tests (SNLT) were conducted on both pile types. Design parameters such as the total stress adhesion factor, α, and the effective stress coefficient, β, were back-calculated. The α values ranged from 0.41 to 0.86, and the β values ranged from 0.13 to 0.29. The load test results showed that SNLT overestimated the tip resistance as compared with dynamic and static load tests. Moreover, the pile tip resistance was almost constant during the testing period, and setup was mainly attributed to increase in pile side resistance with time.

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.

scholarly journals Pressure Orientation-Dependent Recovery of 3D-Printed PLA Objects with Varying Infill Degree

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1275 ◽  
Author(s):  
Guido Ehrmann ◽  
Andrea Ehrmann
Keyword(s):  
Shape Memory ◽  
Fused Deposition Modeling ◽  
Static Load ◽  
Shape Memory Polymer ◽  
Applied Pressure ◽  
Poly Lactic Acid ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
Load Tests ◽  
3D Printed

Poly(lactic acid) is not only one of the most often used materials for 3D printing via fused deposition modeling (FDM), but also a shape-memory polymer. This means that objects printed from PLA can, to a certain extent, be deformed and regenerate their original shape automatically when they are heated to a moderate temperature of about 60–100 °C. It is important to note that pure PLA cannot restore broken bonds, so that it is necessary to find structures which can take up large forces by deformation without full breaks. Here we report on the continuation of previous tests on 3D-printed cubes with different infill patterns and degrees, now investigating the influence of the orientation of the applied pressure on the recovery properties. We find that for the applied gyroid pattern, indentation on the front parallel to the layers gives the worst recovery due to nearly full layer separation, while indentation on the front perpendicular to the layers or diagonal gives significantly better results. Pressing from the top, either diagonal or parallel to an edge, interestingly leads to a different residual strain than pressing from front, with indentation on top always firstly leading to an expansion towards the indenter after the first few quasi-static load tests. To quantitatively evaluate these results, new measures are suggested which could be adopted by other groups working on shape-memory polymers.

Investigation of Grouted Coupler Connection Details for Accelerated Bridge Construction

2021 ◽  
pp. 036119812199939
Author(s):  
Brent Phares ◽  
Yoon-Si Lee ◽  
Travis K. Hosteng ◽  
Jim Nelson
Keyword(s):  
Crack Width ◽  
High Performance ◽  
Static Load ◽  
High Performance Concrete ◽  
Precast Concrete ◽  
Chloride Penetration ◽  
Load Testing ◽  
Test And Evaluation ◽  
Load Tests ◽  
Precast Elements

This paper presents a laboratory investigation on the performance of grouted rebar couplers with the connection details similar to those utilized on the precast concrete elements of the Keg Creek Bridge on US 6 in Iowa. The testing program consisted of a series of static load tests, a fatigue test, and evaluation of the chloride penetration resistance of laboratory specimens. The goal of this testing was to evaluate the ability of the grouted rebar couplers to develop flexural capacity at the joint between the precast elements as well as the durability of the connection. For structural load testing, seven full-scale specimens, each with #14 epoxy-coated rebars spliced by epoxy-coated grouted couplers, were fabricated and tested in three different loading cases: four-point bending, axial tension plus bending, and a cyclic test of the system in bending. The static load testing demonstrated that the applied axial load had a minimal effect on the formation of cracks and overall performance of the connection. When ultra-high performance concrete was used as a bedding grout, the initiation of crack was slightly delayed but no considerable improvement was observed in the magnitude of the crack width during loading or the crack closure on unloading. The results of the seventh specimen, tested in fatigue to 1 million cycles, showed little global displacement and crack width throughout the test, neither of which expanded measurably. No evidence of moisture or chloride penetration was detected at the grouted joint during the 6-month monitoring.

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