Author2022 TCNJ Steel Bridge Team |
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Load Testing3/15/2022 During the first half of March the finishing touches were completed. The final stages of fabrication included making the diagonal lateral bracing and welding the bolts to the angles for the lateral bracing. Clearances were also checked to make sure the bridge would pass all the measurement specifications from the guidelines.
Load testing was also performed for the bridge. The two tests were for sway and deflection based on the competition guidelines. For the sway test it was recorded at two positions, the midway point on the north side back span and 1 inch from the end of the cantilever on the south side. A 50 pound pulling force was applied at both positions. The sway was recorded by utilizing a level laser and ruler. The sway was recorded to be ¼ inch for the back span and ½ inch for the cantilever, which both meet the requirement of ¾inch for the competition. For the deflection test the team loaded the bridge using 30 gallon drums and 5 gallon buckets filled with water to obtain the necessary 2500 pounds of weight that will be administered during competition. Before loading was performed, the bridge height was measured at the back span and cantilever to be 26 1/2 inch and 26 3/8 inch respectively. The bridge was then loaded based on the worst case scenario dimensions and the deflection was measured. At the center of the 3 foot load at the back span and cantilever, the height of the bridge was 26 3/8 inch and 26 inch. The difference in height is the deflection that the bridge experienced, which was found to be 1/8 inch and 3/8 inch for a total aggregate deflection of 1/2 inch. The maximum aggregate deflection allowed is 2 ½ inches. The bridge passed the deflection test with flying colors. After the loading test was completed all the drums and buckets of water were removed. The bridge was remeasured to see if there was any permanent deformation. The bridge held up very well and the only thing we had to do was bend a connection plate to make it fit within the clearance template smoothly. The load testing was a success for both sway and deflection. The next step is now practicing building the bridge for competition.
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