Steel beams with corrugated web are widely used because of their high load-carryingrncapacity and optimized configuration to resist lateral-torsional buckling (LTB). Thernpurpose of this thesis is to provide a comparative study of elastic buckling analysis andrnlinear FE analysis and nonlinear FE analysis as well as hand calculation. The authorrnfocuses on LTB of plate girders with trapezoidal corrugated and flat webs. Thisrncomparative study is performed through two groups of plate girders with corrugated andrnflat webs under consideration four types of steel classes. While in the numerical study, thernelastic-plastic material model, residual stress distribution, and geometrical imperfectionsrnfactors are considered for both flat and corrugated web. Thirty individual data types ofrndifferent sample dimensions were examined for two types of girders, one girder with flatrnwebs and an identical girder with the corrugated web. The samples are 15 flat web beamsrnwith three slenderness categories and 15 corrugated web beams with the same threernslenderness categories. For the sake of control, the expected outcome, initial random crosssectionrndimensions are generated concerning three values of non-dimensional slendernessrnratio ranges: 0.4, 0.6, and 1.2, corresponding to very stocky, intermediate, and veryrnslender slenderness properties respectively to draw a sample which represents a totalrnpopulation. Besides, the comparison considers one type of plate girder with flat and anrnidentical corrugated web within particular engineering parameters. To carry out arncomparative study into the behavior of trapezoidal corrugated steel and flat webs, anrnadvanced finite element analysis has been employed to understand buckling problems andrnto investigate the behavior of beams. FE-simulations are performed to represent thernconditions of reality as good as possible and empirical hand calculations are made to verifyrnthe results. The corrugated web has an increased load capacity and stiffness by (32-67%),rn(12-31.3%) and (0.058%-0.418%) for very slender, intermediate, and very stockyrnrespectively than flat web beams. A comparison study between flat web with webrnstiffeners and corrugated web I beam is suggested as a topic for future research.