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A modified continuum model of electro-statically actuated micro-beam is presented based on the modified couple stress theory. The new model contains a material length scale parameter and can capture the size effect, unlike the classical Bernoulli-Euler beam theory. The governing equation of the micro-beam is derived based on the Hamilton’s principle, which accounts for the effects of the moderately large deflection, the residual stress and the fringing electrostatic field. The numerical analysis of mechanical characterization is performed by the Analog Equation Method (AEM). The effects of the couple stress on the static and dynamic responses, pull-in voltage and pull-in time are discussed.

Pier concrete is vulnerable to cracking when using concrete rapid construction after long off period. In order to solve this problem, crack mechanism and effects of several temperature control measures of thin-walled structure concrete is analyzed. Through analyzing the temperature and stress time-space variation using 3D finite element method, it can be found that stress is more sensitive to controlling concrete placing temperature than other measures. It also shows that under the condition of taking other proper temperature control measures, low placing temperature can not be spared.