This paper approximately analyzes the dynamic response mode of building materials under impact load according to the Lagrange equation. We use the redundant constraint force of the statically indeterminate structure to list its strain energy expression. At the same time, the paper introduces the Lagrange multiplier and combines the static equilibrium equation to obtain the internal force of the statically indeterminate structure. The calculation results show that the load duration and peak value are important factors determining structural members’ failure mode. This study lays the foundation for the research on the structural building material’s dynamic control and mechanism performance. At the same time, our research results also provide methods and ideas for the rigid body dynamics modeling of other structural redundant parallel mechanisms.