A grade 60 bar has a minimum yield strength of what?

The designation of a grade 60 bar in reinforced concrete refers to its minimum yield strength, which is specified in units of psi (pounds per square inch). For grade 60 steel, the "60" indicates that the minimum yield strength is 60,000 psi. This is a critical value used in engineering and design calculations, as it establishes the stress level at which the steel will begin to deform permanently under load.

Knowing the yield strength is essential for structural engineers and builders when designing concrete structures that can safely carry the intended loads while adhering to safety standards and building codes. In this case, recognizing that "grade 60" corresponds directly to a yield strength of 60,000 psi clarifies why this option is the correct answer. Other yield strengths listed in the choices do not define a grade 60 bar and represent different grades of steel, which underline the importance of recognizing material specifications accurately.