单项选择题

对于T型截面正截面承载力计算时,属于第一类(中和轴在翼缘内)的判别式是()。

A、M<a1fcbf'hf'(ho-hf'/2)或fyAs≤a1fcbf'hft    
B、M>a1fcbf'hf'(ho-hf'/2)或fyAs≤a1fcbf'hft    
C、M≤a1fcbf'hf'(ho-hf'/2)或fyAs=a1fcbf'hft