scholarly journals A field study on the load sharing behavior of a micropiled-raft underpinned by a waveform micropile

2021 ◽  
Author(s):  
Chengcan Wang ◽  
Jin-Tae Han ◽  
Seokjung Kim
Keyword(s):  
Load Transfer ◽  
Compressive Loading ◽  
Load Sharing ◽  
Single Pile ◽  
Long Term Effects ◽  
Loading Test ◽  
Total Load ◽  
Shear Keys ◽  
Loading Tests ◽  
Sharing Behavior

A waveform microiple(WMP) uses jet grouting method to generate shear keys along the pile shaft for improving the shaft resistance and cost efficiency. In this study,field loading tests were performed in this study to characterize the load sharing behavior upon inclusion of a waveform micropile (WMP) in a group of four micropiled-raft. First, single-pile compressive loading tests were conducted on three WMPs and five Type A micropiles (MP). Subsequently, a group-pile loading test was performed on a piled raft comprising 2 × 2 MPs and a central WMP. The load–settlements, axial stiffnesses, and load transfer mechanisms of individual MPs were analyzed during the tests, including the short- and long-term effects of the axial stiffnesses of the MPs on the load sharing ratio of the micropiled-raft. The single-pile loading test results revealed that the shear keys along the WMPs caused its bearing capacities and axial stiffnesses to be 1.5 times and 2–5 times higher than those of MPs, respectively. In the micropiled-raft loading test, the load sharing ratios of the MPs increased with their axial stiffnesses, and the highest load sharing capacity was exhibited by the WMP, which constituted 30% of the total load and 2–3 times that of MPs. Moreover, the influence of raft on the load-sharing capacity should be considered as well.

Cyclic Behavior of Concrete Confined by Active and Passive Jackets

2010 ◽  
Author(s):  
Eunsoo Choi ◽  
Yeon-Wook Kim ◽  
Young-Soo Chung ◽  
Hong-Taek Kim ◽  
Baik-Soon Cho
Keyword(s):  
Shape Memory ◽  
Compressive Loading ◽  
Volumetric Strain ◽  
Confined Concrete ◽  
Cyclic Behavior ◽  
Temperature Hysteresis ◽  
Plastic Strains ◽  
Carbon Fiber Reinforce Polymer ◽  
Concrete Cylinders ◽  
Loading Tests

Shape memory alloy (SMA) wire jackets for concrete are distinct from the conventional jackets of steel or FRP since they provide active confinement that can be easily archived due to the shape memory effect of SMAs. This study uses NiTiNb SMA wires of 1.0 mm diameter to confine concrete cylinder with the dimension of 300 mm × 150 mm (L × D). The NiTiNb SMAs have a relative wider temperature hysteresis than NiTi SMAs and, thus, are more applicable for severe temperature-variation environment which civil structures are exposed to. Steel jackets of passive confinement are also prepared to compare the cyclic behavior of active and passive confined concrete cylinders. For this purpose, monotonic and cyclic compressive loading tests are conducted to obtain axial and circumferential strain. The both of strains are used to estimate volumetric strains of concrete cylinders. Also, plastic strains from cyclic behavior are also estimated. For the NiTiNb SMA jacketed cylinders, the monotonic axial behavior differs from the envelope of cyclic behavior; this should be studied in future. The plastic strains of the active confined concrete show a similar trend to those of the passive confinement. The trend of plastic strain of this study does not match with that of CFRP (Carbon Fiber Reinforce Polymer) jackets. For the volumetric strain, the active jackets of the NiTiNb SMA wires provide more energy dissipation than the passive jacket of steel.

Uplift behaviour of tapered piles established from model tests

2000 ◽  
Vol 37 (1) ◽  
pp. 56-74 ◽  
Author(s):  
M Hesham El Naggar ◽  
Jin Qi Wei
Keyword(s):  
Load Transfer ◽  
Compressive Loading ◽  
Compressive Load ◽  
Tensile Load ◽  
Confining Pressure ◽  
Cohesionless Soil ◽  
Uplift Capacity ◽  
Experimental Modelling ◽  
Confining Pressures ◽  
Load Tests

Tapered piles have a substantial advantage with regard to their load-carrying capacity in the downward frictional mode. The uplift performance of tapered piles, however, has not been fully understood. This paper describes the results of an experimental investigation into the characteristics of the uplift performance of tapered piles. Three instrumented steel piles with different degrees of taper were installed in cohesionless soil and subjected to compressive and tensile load tests. The soil was contained in a steel soil chamber and pressurized using an air bladder to facilitate modelling the confining pressures pertinent to larger embedment depths. The results of this study indicated that the pile axial uplift capacity increased with an increase in the confining pressure for all piles examined in this study. The ratios of uplift to compressive load for tapered piles were less than those for straight piles of the same length and average embedded diameter. The uplift capacity of tapered piles was found to be comparable to that of straight-sided wall piles at higher confining pressure values, suggesting that the performance of actual tapered piles (with greater length) would be comparable to that of straight-sided wall piles. Also, the results indicated that residual stresses developed during the compressive loading phase and their effect were more significant on the initial uplift capacity of piles, and this effect was more pronounced for tapered piles in medium-dense sand.Key words: tapered piles, uplift, axial response, load transfer, experimental modelling.

scholarly journals Analisis Pondasi Tiang Pancang Berdasarkan Hasil Perhitungan dan Loadding Test

2020 ◽  
Vol 2 (2) ◽  
pp. 48
Author(s):  
Nusa Setiani Triastuti ◽  
Indriasari Indriasari
Keyword(s):  
Carrying Capacity ◽  
Pile Foundation ◽  
Secondary Data ◽  
Linear Structure ◽  
Primary Data ◽  
Loading Test ◽  
High Rise ◽  
Pile Cap ◽  
Calculation Results ◽  
Loading Tests

<p><em>Pile foundation is one of the solutions of high-rise buildings not in the area of restrict area. When the pile foundation reached until the hard ground reaches, a small settlement is expected and  different  setlement  are  not occur. The objective: analyze the results of loading tests compared carryng capacity calculations, pile cap thick required secure.</em></p><p><em>The research method used in this research is the case study of pile foundation  twelve floors building in Batam island. The reaction on the pile is analyzed using software program of non-linear structure version 9.5 which is supported by primary data, namely loading test and secondary data of soil investigation and the largest column force taken on the pole 1.618,854 ton, Mx -7,936 ton meter, My -75,531 ton meter.</em></p><p><em>Carrying capacity analysis is based on friction and end bearing and calculated pole efficiency. The axial load of the plan is supported by 16 (sixteen) piles, based on the loading test (P) the ultimate pile foundation reaches 200% (two hundred percent) in the amount of 411.52 tons. </em><em>Single pile carrying capacity is 205.76 tons .Settlement in the loading test results 10mm is smaller than from the setlement in calculation results. The stress acting on the pile cap of 12.453 kg/cm<sup>2</sup> is smaller than the permit strees of 13 kg/cm<sup>2</sup>.</em></p>

Mechanical Behaviour of Steel-Concrete Twin I-Girder Bridges

2018 ◽  
Author(s):  
Weiwei Lin ◽  
Heang Lam ◽  
Teruhiko Yoda
Keyword(s):  
Load Transfer ◽  
Mechanical Performance ◽  
Experimental Studies ◽  
Test Results ◽  
Loading Test ◽  
Girder Bridges ◽  
Bridge Model ◽  
Symmetrical Loading ◽  
Unsymmetrical Loading ◽  
Girder Bridge

<p>Steel-concrete composite twin I-girder bridges have been built a lot in both Europe and Japan, but the lack of redundancy has always been a concern in U.S. and many other countries. In addition, few experimental studies have been performed on the mechanical performance of such bridges, particularly for the intact bridges. On this background, a steel-concrete composite twin I-Girder bridge model was designed according to the current highway bridge design specification in Japan and tested in the laboratory. The static loading tests were performed, and two loading conditions including both symmetrical loading and unsymmetrical loading were applied. Load versus deflection relationships were measured in the loading test, and the failure mode of the test specimen was discussed. The flexural strain development on bottom flanges of two main girders was also reported in this paper to confirm the load transfer between two main girders. In addition, the theoretical results on the basis of the classic theory were also provided to compare with the test results. The comparison indicates that the theoretical analyses can predict the behaviour of the twin I-girder bridges very well in the elastic stage by considering the effective width of the slab. The load transfer paths in such bridges were also discussed on the basis of the test results under un-symmetrical loading.</p>

scholarly journals A Full-Scale Experimental Study of the Vertical Dynamic and Static Behavior of the Pier-Cap-Pile System

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianlei Liu ◽  
Meng Ma ◽  
Flavio Stochino
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Dynamic Stiffness ◽  
Soil Layer ◽  
Low Frequency ◽  
Full Scale ◽  
Single Pile ◽  
Static Stiffness ◽  
Loading Test ◽  
Test Technique

The bearing capacity evaluation of bridge substructures is difficult as the static loading test (SLT) cannot be employed for the bridges in services. As a type of dynamic nondestructive test technique, the dynamic transient response method (TRM) could be employed to estimate the vertical bearing capacity when the relationship between static stiffness and dynamic stiffness is known. The TRM is usually employed to evaluate single piles. For the pier-cap-pile system, its applicability should be investigated. In the present study, a novel full-scale experimental study, including both TRM test and SLT, was performed on an abandoned bridge pier with grouped pile foundation. The test included three steps: firstly, testing the intact pier-cap-pile system; then, cutting off the pier and testing the cap-pile system; finally, cutting off the cap and testing the single pile. The TRM test was repeatedly performed in the above three steps, whereas the SLT was only performed on the cap-pile system. Based on the experimental results, the ratio of dynamic and static stiffness of the cap-pile system was obtained. The results show that (1) in the low-frequency range (between 10 and 30 Hz in this study), the dynamic stiffness of the whole system is approximately four times of that of a single pile; (2) the ratio of dynamic and static stiffness of the cap-pile system tested in the study is approximately 1.74, which was similar to other tested values of a single pile; (3) to evaluate the capacity of similar cap-pile system and with similar soil layer conditions by TRM, the value of Kd/Ks tested in the study can be used as a reference.

Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles

2016 ◽  
Vol 53 (4) ◽  
pp. 696-707 ◽  
Author(s):  
Hai-lei Kou ◽  
Jian Chu ◽  
Wei Guo ◽  
Ming-yi Zhang
Keyword(s):  
Static Loading ◽  
High Strength Concrete ◽  
Large Scale ◽  
Load Transfer ◽  
High Strength ◽  
Neutral Plane ◽  
Shaft Resistance ◽  
Strength Concrete ◽  
Loading Tests ◽  
Residual Force

A large-scale field testing program for the study of residual forces in pre-stressed high-strength concrete (PHC) pipe piles is presented in this paper. Five open-ended PHC pipe piles with 13 or 18 m in embedded length were installed and used for static loading tests at a building site in Hangzhou, China. All the piles were instrumented with fiber Bragg grating (FBG) strain gauges. The residual forces in these piles were recorded during and after installation. The measured load transfer data along a pile during the static loading tests are reported. The effect of the residual force on the interpretation of the load transfer behavior is discussed. The field data show that residual force along the installed pile increases approximately exponentially to the neutral plane and then reduces towards the toe. The residual force decreases with time to a stable value after pile jacking due to the secondary interaction between the pile and the disturbed soil around the pile and other factors. The large residual forces along the PHC pipe piles significantly affect the evaluation of the pile load distributions, and thus the shaft and toe resistances. The conventional bearing capacity theory tends to overestimate the shaft resistance at positions above the neutral plane and underestimate the shaft resistance at positions below the neutral plane, and the toe resistance for an open-ended PHC pipe piles founded in stratified soils.

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