How to solve a coupled problem (bvp) with 2 different mesh?

I have to solve a system of differential equations coupling vertical deformation of an arch with vertical deformation of a beam throught a steel element.

Initially, I solved only the system of equations that describes the deformation of an arch with bvp4c, then the beam one and both were right. But, when I want to couple them, I don't know how to run a mesh for the arch and another one for the deck.

The system is the following

The BC are u1,v1,phi1,etha1,etha2 = 0 at both extremes.

Thank you