Analysis Process

This week in class we were introduced to the "Method of Joints". It allowed us to perform an analysis of a simple Knex truss bridge. Using the calculations of this method, the forces acting upon the bridge and the force of each of the members were found, and also the tension and compression of each member.  

I believe this method of analysis is insufficient because it disregards the outside forces acting on the bridge such as the weather, deterioration, and the weight on the bridge. Also, the force being taken into account is the vertical force. Forces come in all directions, such as wind would be a horizontal force. I would like to learn more about the impact that adding a new member would have on the bridge, and the strength that each member has, so that we know which member is unstable and causing the bridge to collapse.