In this study, a nonlinear model of micro-arch beams under the action of electrostatic loadings with an initial air gap is presented. Based on the well-developed 3D beam theory proposed by Yang and Kuo [1], the arch beam is modelled as a series of uniform straight beam elements and the pull-in magnetic force is simulated as an electric-induced force by an electrode lying. Then the nonlinear structural analysis of snap-through and pull-in stability for a simply supported shallow arch subjected to a concentrated electrostatic loading will be investigated. To tackle the path-dependent features of electric forces due to presence of air gaps and nonlinear deformations, this study regards the electric forces as pseudo-forces acting at the arch-beam and solves the structure equations using an incremental-iterative procedure. From the numerical results, the present approach demonstrates that the micro-arch beam has the capacity to withstand further electrostatic loading after the snap-through jump
