\(\mathbb{B}_{I}^{u}=\begin{bmatrix}N_{I,x}&0\\ 0&N_{I,y}\\ 0&0\\ N_{I,y}&N_{I,x}\\ \end{bmatrix}\) , \(\mathbb{B}_{I}^{\varphi}=\begin{bmatrix}N_{I,x}\\ N_{I,y}\\ \end{bmatrix}\) ,