This study is conducted to estimate the effect of the gravity load on the inelastic behavior of the beams. Using layer model, the characteristic inelastic behavior of the beam with partly concentrated are investigated, and the effect of the gravity load is estimated. Also, layer model is verified and the effects of the gravity load are investigated through the quasi-static tests. From the results of inelastic analysis using layer model, it can be shown that the moment-inelastic rotation curve of a beam is gradually shifted to the positive moment direction. Finally plastic hinge model which can consider the shift of the moment-inelastic rotation curve is proposed.