Our common goal is achieved by applying science
and engineering to foundation design as directed by the Post
Tensioning Institute
| - Collect Soil Samples |
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- Classify Soil (USCS) Record Layer Depths, and Determine Soil Characteristics
Pertinent to Foundation Design (LL, PL, PI, Allowable Bearing Pressure,
Depth to Constant Suction)
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| - Foundation Design |
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- Use the Information from the Soil Analysis (VolFlo) to Determine
the PTI Design values for Edge Lift and Center Lift Configurations
(Ym=Diff. Soil Movement, Em=Edge Moisture Distance)
- Perform a Static Load Analysis Based on the Applied Loads for all
Edge Lift and Center Lift Configurations
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| Soil Sample Collection |
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- Continuous (Macro Core) Sample |
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- Easy to determine layer locations and thickness
- Abundant sample qty
- 1-1/2” Dia x 4’ deep clear collection tubes
- Qty 5 – 4’ samples for each hole
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- Sample Frequency |
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- 1 sample acceptable for small additions
- 2 samples min for new structures
- 3 samples for structures > 5K ft²
- 200 ft centers across a sub-division
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| Soil Analysis |
- Determine Layer Location & Thickness
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- Visual Inspection of Continuous
Samples |
- Determining Soil Characteristics
for the Purpose of Foundation Design
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- Field Testing per ASTM 2488
- Engineering Judgment
- Laboratory Testing |
- Soil Classification per Unified Soil Classification System (USCS)
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- Based on soil characteristics (Grain Size and Plasticity) |
- Allowable Bearing Pressure
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- Dynamic Penotrometer
- Pocket Penotrometer
- Unconfined Compression |
| Foundation Design |
- Determine Edge Lift & Center Lift Design Parameters (Em & Ym)
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- VolFlo Software |
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- Stream lines the calculation process
- Creates accurate results in
a fraction of the time
- Results in report format
- Detailed graphs of Em & Ym for both Shrink and Swell conditions
- Simplifies Cut & Fill recommendations to achieve a PVR of 1” or
less
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- Input Soil Analysis Results
into PTI Equations
|
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- Design Foundation per PTI Procedure |
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- Design Variables
- Em & Ym Values
- Applied Loads
- Structural Characteristics of Reinforced Concrete
>> Applicable
to both Post Tension and Conventional reinforced designs
|
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- Perform Static Structural Analysis
- Rib & Beam Spacing, Depth, Width
- Steel or Tendon Qty. & Spacing
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| Deep Foundations |
- Structural Slab with Piers (Isolated Floor System)
|
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- Piers located below moisture active zone
(constant suction)
- Void Form Slab
- Suited for extreme differential movement
- Sub-grade Preparation Not Required
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- Expansive soils
- Tree Removal
|
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- Slab-On-Fill Foundation Supported on Piers
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- Piers located below moisture active zone
(constant suction)
- Can be supported on spread footings in the absence of expansive soil
- Suitable for expansive soils
- Fill used to reduce PVR
- Requires Proper Drainage & Vegetation control |
- Floating (Stiffened)
Slab Supported on Piers
|
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- Piers located below moisture active zone
(constant suction)
- Suitable for expansive soils
- Conventionally reinforced or Post-Tensioned Slab
- Piers are not connected to grade beams with steel
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- Slab may move up in the presence of expansive soil (Floating
Slab)
- Slab can not move down because of piers
|
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| Shallow
Foundations |
- Floating Super-Structural
Slab
|
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- No Piers
- Suitable for expansive soils
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- Must Be Significantly Stiffened to minimize effects of
diff. movement
- Properly Compacted Fill under grade beams (not slab)
- Slab fill must be firm enough to support floor @ construction
- May require cut & fill to reduce PVR
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- Bearing is only on grade beams
- Structural slab spans between grade beams
- Requires Proper Drainage & Vegetation control
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- Very important for shallow foundations
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- Common in Texas for lightly loaded structures
- Conventionally reinforced or Post-Tensioned Slab |
|
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- No Piers
- Suitable for expansive soils
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- Must Be Significantly Stiffened to minimize effects of
diff. movement
- Properly Compacted Fill under entire slab
- May require cut & fill to reduce PVR
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- Bearing is on beams and slab
- Slab is not designed to span between grade beams
- Requires Proper Drainage & Vegetation control
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- Very important for shallow foundations
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- Common in Texas for lightly loaded structures
- Conventionally reinforced or Post-Tensioned Slab |
| Conclusions |
- Do not compromise
the most important building block of your structure.
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- Common Goal
Stable Foundation at a reasonable cost
-Achieve Our Goal
Professional Engineered Foundation
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| Contact the Professionals
at Dynamic Engineering for all your Geotechnical and Foundation Design
Needs. |
