In this work, experimental and finite element (FE) analysis of L-shape cross-ply fiber-reinforced composite beams are carried out to investigate the effect of out-of-plane wrinkles on the interlaminar strength and competing damage mechanisms. L-shape laminates are fabricated with manufacturing and geometrical variabilities, cured in a temperature and pressure-controlled autoclave process, and mechanically tested under four-point-bending tests. An in-situ high-fidelity FE models are constructed based on in-plane micrograph images of beam cross sections. Explicit FE failure simulations are performed to study the effect of wrinkles and to differentiate among different failure modes. Simulation results show a reasonable agreement with the test data in terms of delamination onsets, matrix cracking and through thick strength. Combined delamination, matrix cracking and kinking pattern is significant in the specimens with visible out-of-plane wrinkle. While, in the specimen with no noticeable wrinkle, a major single delamination is observable leading to final failure. The competing damage mechanisms is highly dependent on the assumed fracture properties and in-situ-condition of finite element model, regardless of good agreement between simulated global mechanical response and test data.