Residential Building Inspector B1Building Planning and Life SafetyMedium
A residential building inspector is reviewing the plans for a new dwelling. The plans indicate that the dwelling will be constructed in a seismic design category D2. What is the minimum required strength of concrete for the foundation walls in this category, assuming standard residential construction?
- A3,000 psi
- B2,500 psi
- C2,000 psi
- D3,500 psi
Show answer & explanationAnswer & explanation
Correct answer: B. 2,500 psi
According to the 2021 IRC, Section R402.2 (Concrete), for concrete foundation walls in seismic design categories C, D0, D1, or D2, the minimum specified compressive strength (f'c) of concrete shall be 2,500 psi (17.2 MPa) at 28 days.
Why the other options are wrong
- A. 3,000 psi is often used but is not the minimum required for this seismic category.
- C. 2,000 psi is generally for non-structural applications or lower seismic categories.
- D. 3,500 psi exceeds the minimum requirement for this seismic category.
Concrete Compressive Strength (Foundation)
The minimum specified compressive strength of concrete used in foundation walls, critical for structural integrity, especially in seismic areas.
- Measured in pounds per square inch (psi).
- Requirements vary with seismic design category and specific application.
- Specified in IRC Section R402.2.
Memory trick: Concrete strength, 2500 psi, for shaky grounds, keeps houses high.