$($Caalculate manually$)$ an engineer is asked to carry out a simple analysis of girder connections if an axle is passed through with the load distribution assumed to be parabolic in the longitudinal direction of the bridge and evenly shaped in the transverse direction of the bridge.

The girder connections are designed using a simplified asphalt plug joint in the shape of a triangle. The asphalt material uses the AC$-20$ type with a Young's modulus of $1454$MPa and a Poisson ratio of $0\mathrm{.}3.$

The analysis carried out is checking the stress at the lowest base position of the asphalt and checking the maximum displacement.

Explain in detail, complete with arguments, how the engineer carried out FEA analysis using only CST elements, complete with calculations and steps.

Asphalt length $=120mm$

Height of asphalt $58mm$

Force $17$ KN