>>13645029> If the angle is ~45 degrees (extremely generous to your position), then central arch still only supports about 1/(1+sqrt(2)) = 41% of the total loaYou assume that the outer arches carry load. This is not obvious from the geometry, because not only geometry factors into it.
How will you move a massive force from the road into a into a connection consisting of a steel plate and bolts loaded in shear? Answer: you wouldn't, least of all for a timber bridge.
It makes no sense at all to transfer load by anything other than direct bearing, which is why the central arch exists and has a massive steel prop (think of it as a bar in compression, for simplicity) connected to the deck at regularly spaced intervals.
Those horizontal arches may be used to provide strength against minor torsion and stiffness against buckling and vibration, but other than that, the connection is not robust enough to warrant assuming that it transfers significant forces.
