The criteria for the bridge were to have the compression force/strength ratio not exceed .40 (+/-.01), tension force/strength ratio not exceed .45 (+/-.01), have 15% of bridge of members hollow tubes (+/- 1%), and have the lowest possible cost. By carefully tweaking the value of each member to stay within the requirements, we were able to get the cost of the bridge to under 300,000 dollars. For example, of the compression force is 0.30, I could change the size of the bar, to be smaller, so that the compression force is closer to 0.40 and would also be cheaper. A major setback during this bridge designer software project was that when we went for lunch, the computers turned off and didn't save our progress, therefore forcing us to restart.Â
On the top of the paper is a key for the joints and members used for the calculations.