Week 2 Civil Engineering
Overview:
This week our team was tasked with both modeling and testing a bridge (through simulations). We needed to design a bridge which met the required specifications while keeping the cost down. While we learned about how the bridges work structurally, we also learned about how forces act on the structure. Through learning about how compression, tension and gravity work on a bridge we were able to design a bridge that could stay stable while sustaining the force of cars/weight moving across it.
Civil Engineering:
Civil engineering is an engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports, sewerage systems, pipelines, structural components of buildings, and railways.Civil engineering is arguably the oldest engineering discipline. It deals with the built environment and can be dated to the first time someone placed a roof over his or her head or laid a tree trunk across a river to make it easier to get across.
Bridges:
Bridges are generally thought of as static structures. The truth is that they actually act more like dynamic, living beings. They constantly change, responding to different loads, weather patterns, and other types of stress in order to function.The most profound force affecting bridges is gravity, which is constantly pulling at them, trying to drag them down to earth. The complicating factor is that compression and tension on a bridge are constantly shifting.The towers (piers) of a suspension bridge are in compression and the deck hangs from cables that are in tension. The deck itself is in both tension and compression.
Design Plan:
Our plan in the beginning with bridge designer was to first get a bridge that worked and then change it to fit all of the requirements. Once we got a bridge that held the weight of the car, we looked at the graph given to us for tension and compression and the number of hollow bridges needed. Since we needed 15 percent of the bridge to be hollow tubes, we changed this first. We looked at the chart that listed the values of tensions and compression and changed the bars to tubes that had low values. Once the tubes and bars were in place, we had to work on the values of the tension and compression. Since tension had to be less than .45 and compression had to be less than .40, every bar that had values over these had to be changed. To help lower the value we first tried change the size of the bars or tube bigger. The bigger the bars or tubes, the lower the tension and compression values got. Once we were satisfied with our values we worked on the price. The price decreased when the sizes went down. For the bars and tubes that had low values for tension and compression, we lowered the sizes of the bars until we were happy with the price.
Our plan in the beginning for the model we wanted to make a bridge that was 4 ft long to fit the requirement. next we divided the bridge into eight groups. The design was a howe truss bridge. We added all of the joins in and made x's along the sides. Next we copied the joints over to make the half of the bridge. We then connected the two sides of the bridge. To reenforce our bridge we added members along the bridge in areas that were weak. Once we were happy with the design we tested the bridge. After we saw the areas that needed help, we added portal frames which add support to those areas. To maximize total load, we increased the size of the bridge members to 1/2 inch.
Conclusion:
What we learned:
Forces applied on Bridges
How materials affect cost and stability
The complexity of designing bridges
How forces such as G's, compression and tension work
What we would change:
Do a better job of understanding the concepts in the textbook before answering the questions.
Find a way to make the bridge less expensive while still meeting the constraints