bearing walls. Wall loadings are anticipated to be 4000 pounds per lineal foot.

Conversion of N values to qc values

Use of qc values to estimate Es values

You can use an equation like Janbu's equation that uses soil modulus of elasticity, Es; or you can use Schmertmann's method.  In one case (Janbu Method) you need Es, and in the case of the Schmertmann Method you need qc (cone penetration tip bearing) and then Schmertmann gives you a conversion to Es.

1. To convert N values to qc values, you first have to convert N values to N70.

2. Using N70 values you multiply them by the qc/N70 ratio to get qc (you need to know the soil type to determine the appropriate ratio).

3. See Chart below. The qc values you get have units of tons per square foot or kg per centimeter squared.

1. For square footings Es = 2.5 qc, and for long footings (L > 5 B) Es = 3.5 qc (conversion from qc to Es from John H. Schmertmann’s Cone Penetration Testing Manual, FHWA-TS-78-209)