I'm reading here on buckling resistance of members according to Eurocode.
Non-dimensional slenderness is defined as:
$$\bar{\lambda}=\frac{\lambda}{\lambda_1}$$
where
$$\lambda_1=\pi \sqrt{\frac{E}{f_y}}$$ $$\lambda = \frac{L_{cr}}{i}$$
The plain $\lambda$ is by definition the slenderness of the column, the ratio of its effective length to its radius of gyration. But what is the meaning of $\lambda_1$? No explanation besides its definition is given in the text. It is some factor by which we can divide the plain lambda or slenderness to make it "non-dimensional", but why does it take the form it does? What meaning does the square root of the ratio of elastic modulus to yield stress multiplied by pi have?