2017 Competition Guide
Vertical Loading Systems
The vertical loading system is typically one of the most expensive pieces of equipment on the competition floor. Typically, bridges are loaded manually however we occasionally see 'automated' devices surfacing at the student competitions. Automated devices improve safety and can cycle through the loading sequence much faster than manual systems.
Whatever method is used must abide by the following principles:
The process must be:
The most common weight used consists of steel angles weighing approximately 20 lbs each. This is what is used at the national competition. Sandbags, concrete blocks, steel blocks, and more have also been used on occasion.
Teams have to take care not to disturb deflection and sway measurement devices during loading. Judges must monitor the loading carefully to ensure that safe procedures are used by the team members loading the bridge. Also, the load should be applied at a uniform rate (i.e. don't allow teams to stop the process to discuss loading strategy once the process starts).
'Automated' Loading Devices:
We have seen a few automated devices over the years. No two have been alike. Presented here is one such device used recently. If anyone has images/video/drawings for another system, please send them to firstname.lastname@example.org for inclusion here.
In 2011 the crew at the University of Alaska Anchorage hosted the ASCE Pacific Northwest Student conference and used a pneumatic device to load the bridges vertically. The system allowed the bridge to be tested quickly and without anyone being nearby. The video below shows the system. It took about 15 minutes to set up and test a bridge once the bugs were ironed out of the procedure. The biggest complaint was the lack of drama. It seems that competitors like the drama which is associated with hand loading of the bridges.
Advantages of this system include stationary weight (nothing to drop or damage the floor), consistent loading of the bridges (the load rate was identical for every bridge), the turn around time is very short. Also, they were able to borrow (instead of purchase) the weight as most fabrication shops have stock in 20 ft lengths.
Disadvantages of the system include it is sway inhibiting, requires a bit more equipment (pressure tanks, valves, tubing, rams, fabrication of crossheads, platforms, etc), and the lack of drama.
If you have trouble with the video below, check it out on Youtube. The URL is: http://youtu.be/n4qcvL8eMCY