What is the general required strength of concrete for columns and walls in a building?

The typical required strength of concrete for structural elements such as columns and walls in a building is indeed within the range of 3000 to 5000 psi (pounds per square inch). This range is considered standard for most non-specialty concrete applications, as it provides a good balance between strength, workability, and durability.

Concrete with a strength of 3000 psi is generally sufficient for residential buildings, while concrete at the higher end of the range (up to 5000 psi) is often used in commercial or industrial applications, where greater structural integrity and load-bearing capacity are necessary. This strength also allows for the concrete to withstand various loads, environmental factors, and potential stresses encountered over the lifespan of the structure.

Using concrete with a strength below this recommended range may not meet the structural demands of columns and walls, resulting in possible safety risks. On the other hand, strengths significantly above this range, such as 6000 psi or more, can be overly expensive and unnecessary for typical construction purposes unless specific structural requirements dictate its use.