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Questions and Answers
What should be considered when selecting a resistance factor for shafts in clays?
What should be considered when selecting a resistance factor for shafts in clays?
- The latest construction technology
- Local experience with geological formations (correct)
- Standard practices from other regions
- Cost implications of the projects
By what percentage should the resistance factor values in Table 10.5.5.2.4-1 be reduced for a single shaft supporting a bridge pier?
By what percentage should the resistance factor values in Table 10.5.5.2.4-1 be reduced for a single shaft supporting a bridge pier?
- 30 percent
- 50 percent
- 20 percent (correct)
- 10 percent
What factor should not be increased when the resistance factor is decreased?
What factor should not be increased when the resistance factor is decreased?
- The foundation redundancy factor (correct)
- The material strength factor
- The safety margin
- The load-bearing capacity
How is the number of static load tests determined to justify resistance factors?
How is the number of static load tests determined to justify resistance factors?
In the context of variability assessment, how is a site defined?
In the context of variability assessment, how is a site defined?
Flashcards
Resistance Factor
Resistance Factor
The factor applied to the calculated shaft resistance to account for uncertainties in design and construction. It reflects the confidence in the calculated resistance.
Shaft Resistance in Clay
Shaft Resistance in Clay
The resistance factor used for shafts in clay and easily disturbed formations should consider local geological conditions and construction practices.
Single Shaft Resistance Factor
Single Shaft Resistance Factor
For a single shaft supporting a bridge pier, the resistance factor from Table 10.5.5.2.4-1 should be reduced by 20 percent.
Static Load Tests
Static Load Tests
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Site Variability Assessment
Site Variability Assessment
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Study Notes
Resistance Factor Selection
- Resistance factors are chosen based on the method for determining nominal shaft resistance.
- For shafts in easily disturbed formations (like clay), local experience with geology and construction is crucial.
- If using resistance factors from Table 10.5.5.2.4-1 for a single shaft supporting a bridge pier, reduce the values by 20%.
- When reducing resistance factors, do not increase the R factor from Article 1.3.4 to account for a lack of foundation redundancy.
- The number of static load tests needed to justify resistance factors is decided by the variability in site properties and geology.
Defining a Site
- A site, for variability assessment, is a project site or portion of it.
- Subsurface conditions should be geologically similar regarding subsurface stratification (sequence, thickness, geologic history), engineering properties and groundwater conditions.
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Description
This quiz assesses your understanding of resistance factor selection for foundations in geotechnical engineering. Focus is placed on nominal shaft resistance methods, site variability assessment, and factors influencing resistance based on geological properties. Test your knowledge on the critical aspects of foundation support for structures like bridge piers.
