Hello everyone. I am trying to calculate the stiffness coefficient in all directions by using displacement-load data. As we know, stiffness is the force per unit displacement in a particular degree of freedom, and another degree of freedom will be fixed. So I consider a beam element, apply a load, obtain displacement, and get the stiffness coefficient in that direction. This result matches the analytical result( code written in Matlab). Now I follow the same procedure to obtain the stiffness coefficient in the shell element for a node in one DOF. Then the results of the shell element do not match with Matlab. I am attaching one image for the clarification. Please help me out; what is wrong I am doing? Is there a conceptual error for calculating the stiffness coefficient for a node in one direction?

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