A simply supported, uniformly loaded, two-way slab panel is torsionally unrestrained. The effective span lengths along the short span $\text{(x)}$ and long span $\text{(y)}$ directions of the panel are $l_{\mathrm{x}}$ and $l_{\mathrm{y}}$, respectively. The design moments for the reinforcements along the $\mathrm{x}$ and $\mathrm{y}$ directions are $\mathrm{M}_{\mathrm{ux}}$ and $\mathrm{M}_{\mathrm{uy}}$, respectively. By using Rankine-Grashoff method, the ratio $\text{M}_{u x} / \text{M}_{u y}$ is proportional to
- $l_{\mathrm{x}} / l_{\mathrm{y}}$
- $l_{\mathrm{y}} / l_{\mathrm{x}}$
- $\left(l_{\mathrm{x}} / l_{\mathrm{y}}\right)^{2}$
- $\left(l_{\mathrm{y}} / l_{\mathrm{x}}\right)^{2}$