NSSBC Host Equipment

The following is a list of equipment that the host must supply for each of the stations in the competition. Note that the exact nature of the equipment often varies from competition to competition but it must be sufficient to verify that all provisions of the rules are met.

The stations listed here are the same as those used at the national competition. Hosts may decide to use the same station for more than one activity. Regardless of the number of stations, the equipment listed here will be needed to operate the competition.

Note that equipment that is needed for more than one area may be shared between areas if necessary.

Click on the links below to see images of the equipment.

GENERAL EQUIPMENT

It is useful to provide the judges with clipboards, pencils, and judging sheets at all stations. Also make sure that a copy of the rules and the latest official rules clarifications from the web are available for reference by the judges and participants at all stages of the competition.

AESTHETICS JUDGING / TEAM CAPTAIN'S MEETING

Tape Measure or Ruler: A measuring device is used to verify that lettering meets the requirements of Rule 7.1.2 and that the poster is within the limits of Rule 7.1.3.

Die : A die (i.e. half of a pair of dice) is needed to determine the load pattern. (Rule 8.4)

THE ERECTION AREA

Prior to actual erection of the bridge, the judges must check the components of the bridge for compliance with section 10 of the rules.

Scale: The scale must be able to verify no member weighs more than 20 lbs. (Rule 10.1.1)

Magnet: The magnet is used to verify compliance with Rule 10.2.1.

Tape Measure: The tape measure is used to verify compliance with the member size requirements in Rule 10.2.4. A Member sizing box (see below) may also be used.

Tape: Tape is used to mark pieces that need to be checked at later stages of the competition. (see Rules 10.2.5, 10.2.6, and 10.2.10)

Suggested Template:

Member Size Box: A box constructed to the specified dimensions may be used to check the sizes of bridge members. (Rule 10.2.4)

During the erection of the bridge:

Stop Watch: Used for timing the erection sequence. The stop watch must be capable of being stop and restarted without being reset.

After construction, the bridge must be checked for compliance with the functionality, safety, and usability requirements of section 9 of the rules.

Tape Measure: Used to verify compliance with the sections 9.1 and 9.2 of the rules.

Plumb Bob or 4 ft level: Used to verify that no part of the bridge extends beyond the decking supports. (Rule 9.2.3)

String: Used to verify the flatness of the site and/or to provide a reference for measuring clearances when there is doubt about the flatness of the floor. The string can be stretched between supports to provide a reference line for measuring. The string is also used to establish the nominal centerline of the bridge using the holes provided by the team in accordance with Rule 9.4.

Suggested Templates: Templates may be used to facilitate checking of clearances.

Decking Template: May be a straight piece of wood or any other linear object (for example a 4 ft level) that is at least 4 ft long. This template is slid the full length of the bridge to verify compliance with with Rules 9.2.8 and 9.2.10.

River, Floodway, & Passageway Clearance Templates: A template that can be slid under the length of the bridge over the river and floodways to verify compliance with Rules 9.2.11 and 9.2.12.

THE LOAD STATION

There is a wide variety of devices used in the load station. This section endeavors to show some common method for accomplishing the judging tasks in the load station.

Coin: A coin is flipped to determine the "A" and "B" sides of the bridge. (Rule 12.3) Other equally random methods may be used.

Tape Measure: The tape measure is used to locate measurement targets. (Rules 12.4 and 12.5)

Targets: To assure accuracy, deflections should be measured to precise points, termed targets. A target can be as simple as masking tape scribed (+) with a sharp pencil or ballpoint pen.

Targets for vertical deflection measurements should be at the level of the bottom of the decking where it is supported by the bridge, and may be installed on either the bottom of the decking or on the decking support as close to the top as possible. If targets are installed on the decking, clamps will be needed to assure tight contact of the decking with the decking support.

Decking: The decking is steel bar grating identified as W-19-4 (1 x 1/8). The dimensions of a piece of grating are 3'6” x 3’0” x 1”. Three pieces are needed for each load testing area but it is advisable to have a spare piece since damage is possible. Alternative decking material, such as wood planks or panels, is acceptable if it provides adequate strength. Decking should not deviate from the 3'6" width and should not provide significant bending stiffness in the longitudinal direction of the bridge.

Safety Support: Safety support is intended to prevent injury if a bridge collapses. The safety supports should be stable, have a capacity of at least 6000 pounds, and be adjustable in height and width to fit a variety of bridge styles. The safety supports must extend for at least the full length of the load on all sections of loaded decking. The height of the safety supports must be adjusted for each bridge so that the load will not fall more than six inches if the bridge collapses. Safety supports can be steel, plastic buckets, timber, sand bags or masonry units.

It is important to emphasize a couple of safety rules that relate to safety supports:

NO LOAD SHALL BE PLACED ON A BRIDGE WITHOUT SAFETY SUPPORT IN PLACE .

NO ONE IS ALLOWED TO CRAWL, REACH OR STEP UNDER A LOADED BRIDGE.

Lateral Loading Device: This device must be capable of applying a lateral load of 75 lbs to the bridge at the decking level in compliance with Rule 12.4. One common approach is to use a 75 lb weight on a rope that passes over a pulley or wheel that can be placed vertically so that the rope is horizontal when attached to the bridge. Another simple approach is to use a spring scale that is pulled until the specified lateral load is reached.

Sway Measurement Devices: Sway (horizontal translation) may be measured with reference to a mark on the ground using a plumb bob suspended from the bridge. Sway measurements may be made with a scale. Alternatively, dial gauges mounted on stands may be used.

Load: 2,500 lbs of reasonably handled weight should be made available. At the national competition steel angles weighing 25 lbs each are used. At regional competitions steel billets, sandbags, concrete weights, and more have been used. The main criteria are that the weights can be safely handled and the weights are accurately determined. Some regions have, in the past, developed "automated" loading devices that make the load testing quick and safe.

Vertical Deflection Measurement Devices: Ideally, vertical deflections should be measured accurately to a precision of 0.01 inch. The measurement devices must be able to read both upward and downward deflection with a range of 2" either way (i.e. 4" total). A variety of devices have been used over the years. Linearly variable differential transducers (LVDTs) or dial gages may be used; spares are needed in case some are damaged when a bridge collapses. If LVDTs or gages cannot be procured, deflections may be measured with a level (optical or laser). In recent years a number of ingenious devices have been created for the competitions. Whatever devices are used need to be able to be mounted and read quickly and efficiently. Some dial gauge setups have been extremely slow to install and zero which has led to very long competitions. Design the measurement system so that it will not be necessary to reach under a loaded bridge.

Floor Protection: The bearing points of bridges may damage finished floors, particularly during load testing. It is advisable to protect floors with steel plates.

WEIGH STATION

Scales: A scale is needed to check weights of the bridge and/or its members. Bridge weight may be determined before construction or by scales placed under the piers of the bridge after construction. Bathroom scales are commonly used. Bridge weight at the national competition is determined to the nearest pound.

DATA ENTRY STATION

Computer with MS Excel: Use the spreadsheet available on this web site. A reminder: No invitations to nationals will be extended until the official final scoresheet is submitted to aftbq@uaa.alaska.edu.
Printer: The printer is used to print out the scoring summary sheets for each team. Don't forget to have enough paper and ink/toner for the printer!
Calculator: The team captains should be able to use the calculator to verify the calculations.

IMAGES

Click on thumbnail images to see full size.

Misc. Equipment Templates 2009 Template Safety Supports Lateral Load & Sway

Deflection Load Scales Die