根据《钢标》3.5.1条，$\sigma_{\max}=\frac{N}{A}+\frac{M_x}{I_x}y_1=\frac{425\times10^3}{1.33\times10^4}+\frac{135\times10^6}{6.31\times10^8}\times(\frac{500}{2}-16)=82.01\mathrm{N/mm^2}$。$\sigma_{\min}=\frac{N}{A}-\frac{M_x}{I_x}y_1=\frac{425\times10^3}{1.33\times10^4}-\frac{135\times10^6}{6.31\times10^8}\times(\frac{500}{2}-16)=-18.11\mathrm{N/mm^2}$。$\alpha_0=\frac{\sigma_{\max}-\sigma_{\min}}{\sigma_{\max}}=\frac{82.01-(-18.11)}{82.01}=1.22$。$\frac{h_0}{t_w}=\frac{500-2\times16}{8}=58.5$。S3级：$(40+18\alpha_0^{1.5})\varepsilon_k=(40+18\times1.22^{1.5})\times0.814=52.3$。S4级：$(45+25\alpha_0^{1.66})\varepsilon_k=(45+25\times1.22^{1.66})\times0.814=64.9$。腹板板件高厚比不满足S3，满足S4。选D。