What is Osterberg Cell?

What is Osterberg Cell?

The Osterberg Load Cell allows geotechnical engineers to determine the capacity of drilled shafts, piers, and driven piles. It is used to test for the bearing and skin friction forces that can be developed in the soil through which the shaft, pier, or pile is placed.

How does an Osterberg cell work?

The O-cell is a hydraulically driven, high capacity, sacrificial jacking device installed within the foundation unit. Working in two directions, upward against side-shear and downward against end-bearing, the O-cell automatically separates the resistance data.

What is one of the limitations of O-cell pile testing?

The O-cell method also has some limitations compared to conventional top load testing. These include: 5.1 Advance Installation Required: With bored piles and most driven piles, the O-cell must be installed prior to construction or driving.

What is O-cell test?

The O-cell test is a full scale static loading test, just two running simultaneously, which measure directly the upward upper skin friction and downward end bearing and lower frictional resistance.

How many piles should be tested?

The number of piles in the sampling test may not be less. than 2% of the total piles and should be no less than 5 piles in routine inspection. If there is any serious problem, the whole pile foundation engineering must be evaluated.

How is pile load capacity calculated?

Step 2: compute the ultimate end bearing capacity (acting as individual piles). Ultimate end bearing capacity in clay = Nc × C × pile tip area (Nc = 9). Ultimate end bearing capacity in soft clay = 9 × 120 × π × diameter2/4 = 848.2 lbs/per pile. Total ultimate bearing capacity per pile = 76,920 + 848.2 = 77,768 lbs.

What is safe load in pile?

The safe load shall be the least of the following: a) 2/3rd of the load at which the total displacement is 12 mm or the load corresponding to a specified permissible lift. b) Half of the load at which the load displacement curve shows a clear break. Read More on Pile Foundations.

What is PDA test for piling?

Technical Profiles. Dynamic load testing using Pile Driving Analyser (PDA) equipment is a high-strain non-destructive load test method which can be performed during or after pile installation using conventional pile driving equipment. This test can be applied to driven steel, driven timber and even concrete piles (eg.

How many piles are integrity tested?

If less than 100% of piles are initially tested, additional piles may be selected for testing at the discretion of the engineer if circumstances either during or after pile installation should make a piles’ integrity suspect, or if the initial tests reveal major defects.

How do you measure pile size?

Required Rnfield resistance is 150/0.5= 300 kips. Pile length is estimated as 57.5 ft from Figure 1 at the depth where Rnfield is equal to 300 kips. For the contract documents, include an estimated pile length of 60 ft and required Rndr of 300 kips to finalize this length during construction in the field.

What is structural capacity of pile?

Structural Capacity Based on CP4 For rock-socketed piles with full-length reinforcement, using a short column formula, CP4 states that the ultimate structural capacity is given by the sum of stress multiplied by area for both concrete and steel components: Pu = 0.4fcuAc + 0.75fyAs.

How calculate piles load capacity?

How many tests are there in pile?

There are essentially two main types of pile load tests: the preliminary pile test and the working pile test. A preliminary pile test is typically carried out before the piling works commence while the working pile test is carried out during piling or when substantial piling works are completed.

What is minimum footing size?

Minimum Thickness of Concrete Footing

Type of Footing Minimum Thickness
Masonry 250 mm; twice the maximum projection from the face of the wall
Plain concrete 200 mm, or twice the maximum offset in a stepped footing
Reinforced concrete (depth above bottom reinforcement) 150mm 300mm

How is pile capacity calculated?

What is Hiley formula?

Hiley’s formula R=E/(s+0.5c) is based on the principle of energy conservation in which the energy brought about by hammers during the action of hitting are transferred to piles in ground. When the hammer force and displacement is plotted, the energy absorbed by piles is the area under the curve.

Why PDA test is important?

High Strain Dynamic Load Tests, also called PDA tests, assess the capacity of several piles in a single day. Pile Driving Analyzer systems also evaluate shaft integrity, driving stresses, and hammer energy when monitoring installation.