Author2022 TCNJ Steel Bridge Team |
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Construction Practice3/27/2022 The team was running around endlessly for the second half of March. This is no joke because let me tell you building a bridge is tiring. The team was up for the task though because we were able to get our construction time down to 23 minutes from the first time of 40 minutes.
For the steel bridge competition each team is required to build their bridge as fast as they can. This construction time is calculated into the final score. For our team we are opting to have 5 builders. This allowed us to get under the 30 minute mark. After 30 minutes there is a penalty that anything over counts as 180 minutes of construction time. After the 45 minute mark the bridge construction has to be stopped. Our team had to come up with the best way to construct the bridge to cut down as much time as possible. The Construction will start with two people on the West side of the highway and three people on the East side. The West Side will build the North stringer extended to east side of the highway, simultaneously the East side will build the South stringer extended to the west side of the highway. Once the East Side has finished the south stringer portion, they will build the North stringer from the east footing to the highway. The West side North stringer will be swung across the highway for the East side to connect the stringer’s entire back span between the two North footings. The West side will then construct the South stringer to connect with the already built and tightened East side of the back span. The East side constructs the cantilever portion of the stringers, while the West side begins placing lateral bracing. The diagonal lateral bracing is then placed and then all of the stringers and bracing is fully tightened. For the next two weeks the team will continue to practice building the bridge as well as painting it to make the bridge aesthetically pleasing.
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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. |