The current theoretical calculation formula of effective flange width of RC frame considering slab rein- forcement participation is too complicated and inconvenient for practical application.In order to solve these prob- lems,by taking into account two main factors influencing effective flange width,namely,axial compression ratio and joint type,RC frames with different axial compression ratios are designed and a numerical regression analysis on the distribution of the effective flange width with different joint types is conducted.Thus,a simplified formula of effective flange width is obtained,which is convenient for practical application.Then,some issues for improving designs are suggested for the purpose of No Collapsing in the Strong Earthquake,and the suggestions and the sim- plified formulas are verified by an example.The results show that (1) the simplified formula is simple and easy to handle,so it is feasible in actual designs; and (2) the suggestions help to realize the purpose of No Collapsing in the Strong Earthquake better.