Observation Platform

In order to study the natural wildlife, a small elevated observation platform was constructed with just a single center post. There is a small hinged door on the floor to access the platform. Only one person is on the platform at one time.

What is known:

• Maximum weight of the observer is 300 lb.
• The center supporting post is a 6x8 wood timber (check Structure Shapes appendix for exact cross section size).
• The platform overall dimensions are 6 feet by 7 feet.
• The observer can move around the platform, but the furthest location from the center is 3 feet and 2.5 feet as shown in the diagram (6 inches from either railing)..

What is the maximum stress in the center wood post due to a 300 lb person standing on the platform at one of the corners?

• The observers weight will cause unsymmetrical bending.
• Find the moment around both axes that define the plane of the platform.
• Find the moment of inertia for both materials around both axes.
• Use the unsymmetric beam bending stress equation
  
       
  
• Check the compression stress due to the axial load of the observer on the center post.