We present a high fidelity numerical simulation technique to analyze the nonlinear behavior of a composite beam under cyclic loading. The analysis is performed by using the in-house software called E-Simulator. A constitutive model for concrete; extended Drucker-Prager model considering the compressive failure and the tensile crack has been employed and the parameters are identified so that compressive and tensile behavior of concrete can be reproduced. The relation between the bending moment and deflection angle of a composite beam has been analyzed and compared with experimental results. Damage propagation and stiffness degradation results of concrete slab are demonstrated.