The method to control the width of crack at bottom of reinforced concrete slabs by adjusting plastic moment ratio of slab bottom is proposed, and the plastic-moment-ratio formula is established to enhance the character of anti-crack at bottom of reinforced concrete slabs based on Navier’s thin slab theory.

Through the expression,the influence factor of coordination coefficient under different end moment ratios is discussed,and some useful conclusions are also drawn.

In addition,we present the relation curves of bending moment ratio .

The optimized adoption methods of plastic bending moment ratio are derived to make the anti-crack capability best and the mount of steel least separately for reinforced concrete slab bottom based on Navier solution and steel optimization of the thin-slab theory.

In order to analyze the mechanical behavior of out-plane beam-wall joint,especially the reason of \'pulling-out\' damage,the moment transfer factor of joint should be defined firstly.

The problem of designating the sign of bending moment in the curvature-bending moment equation;

A study of axial force and bending moment in tube numerical control bending based on finite element method;

Study of predicting theory of cutting bending moment in orthogonal cutting;

Some important mechanical phenomena are analyzed,such as the strain in the transverse direction,longitudinal direction and direction of fiber,flexural torque and longitudinal curvature during the bending process.