A deflection theory of earth-anchored suspension bridges having the fabrication camber is presented considering tower effects and large deflection effects of main cables. And the Unstrained Length Method (ULM), which keeps unstrained lengths of both cable and frame elements constant in the iteration process, is extendedly applied to nonlinear FE analyses of suspension bridges under live load combinations. Finally, one cable without the suspended girder and two earth-anchored suspension bridge models are analytically and numerically solved. And the numerical results are compared to demonstrate accuracy and validity of both the deflection theory and ULM. In particulars, it is emphasized that the load effects of suspension bridges under live loads can be effectively evaluated by applying the semi-linearized theory without relying on nonlinear FE analyses.