Although steel girders have been u sed for many years, new gener ation of optimized steel girders is developed by the advances in structural and fabricat ion technology. Girders with corrugated webs are used in bridge s as an efficient alternative to conventional girders with flat stiffened webs, It was also found that, the vertically corrugat ed girders had a 10.6% reduction in weight when compared with the beam with flat web.[1] Advantages Economical design of steel girders normally requires thin webs. The use of corrugated webs is a possible wa y of achieving adequate out-of- plane stiffness without using stiffeners. Particularly in bri dge girders with corrugated webs (BGCWs), the corrugated webs are the main elements for bearing the shear forces. Instead of prismatic BGCWs, tapered BGCWs are currently used mainly due to their structural efficie ncy, providing at the same time aesthetical appearance. Available literature shows that tapered BGCWs may be classified into four typologies. Among these typologies, Case I and Case II are the most common cases appearing commonly near to the intermediate supports of continuous bridges. Accordingly, in this thesis, the finite element (FE) method is employed to investigate the inelastic behaviour of tapered BGCWs of Case I and Case II, fol lowing to the fundamental behaviour of such girders published recently by Hassanein et al [6]. The thesis seeks, firstly, considering initial imperfection amp litudes of 200 / 1 w h . Accordingly, with euro code 3 part 1-5, annex D [12], 1 w h is the height of the long vertical edge of the web panel, it investigates the effect of the aspect ratio of the we b panels, different flange inclination angles and different web thickness. Finally, the thesis checks previously proposed design model usi ng the results of the generated parametric studies. Overall, the outcomes of this study are exp ected to provide more insight into the behaviour of tapered BGCWs and enable accurate predict ion of the shear capacity of this special type of BGCWs.