From Pile Buck Magazine:
A practical example: follow the stresses
Imagine a large powerboat moored to a floating concrete dock during a storm. The boat’s considerable windage, the currents in the marina, and the wave forces against the boat are all transmitted through fenders and mooring lines to the dock. These forces are transmitted through the dock and are felt as shear forces at the module connections.
Figure A. Hinged Connection System
In this example, shear force at the connection points between two adjacent floats is 10,000 pounds. Under actual circumstances this number will vary, but 10,000 lbs. provides a round number to work with.
Figure B. Waler Connection System
A dock system with walers and a typical complement of 10 through rods receives the same 10,000 pound load. Unlike the hinged system, where loads are concentrated at the corners, the shear load is transmitted along the walers and distributed among all the through-rod entry/exit points. Each of the through rods in a module must contend with 1,000 lbs. of shear force. The waler system, with its distributed-load design, has reduced the shear load on the concrete structure by 80%.
Inspection of Walers and Through Rods
Walers: Look for damage and deterioration.
Through Rods: Look for missing, damaged, or corroded rods, nuts and washers.