The Planar Truss System Steel Truss Bridge - Assignment Example

After consultations, my team and I decided to look at the freight train bridge as the planar truss system to analyze. We finally chose the one to analyze a specific freight train bridge; the on that runs over Marybyrnong River which is found in Napier saint, south of Dynon Road located in Footscray. Below are some pictures of the set up. Enough and relevant information concerning our analysis was gathered by our team which included the truss system’s measurements. We decided to use to utilize one side of the system, which made it two-dimensional. Therefore, the total weights established will be split into two in order to evaluate measurements of one side of the truss system. In accordance to our findings, the measurements were as follows: Length at 49 metres 001*9-p The width at 10 metres The height at 7 metres In order to estimate the dead weight of the bridge truss system, the steel chamber’s weight had to be evaluated per every unit length and the entire length of the truss (Mikhelson 2004). Concrete and gravel makes a major component of the bridge and it is mathematically critical to include their weights in the calculations. The total weight of the concrete used in the bridge was 24 Newtons per Cubic metre according to table A1,AS/NZS1170.1;2002. The steel of the bridged were assumed to be 310UB which was 453 Newtons per metre or 42.6 kilograms per metre (from One Steel Catalogue). The following are the individual measurements obtained from the structure per every material used that included steel, concrete, and further explores the dead weight and live weight of the bridge truss system. Steel The whole length of the beam that constitutes the bottom length, top length vertical beams were as follows. Bottom length = 49 meters Top length = 35 metres Plus 6*7 metres (vertical beams) + 7*9.9 metres. Therefore, the total length added up to 195.3 metres. Mathematically, The Total mass of the truss bridge is 195.3 metres*46.2 kilograms = 9022.86 kilograms To obtain the weight of the truss beams, which must be presented in Newtons, we had to multiply the whole mass by the Newton’s constant, which is 9.8. Therefore, the total weight of the truss bridge beams is, 9022.86*9.81 = 8851.26N This magnitude concluded in kilonewtons becomes 88514.26/1000 = 88.51 kN Concrete To evaluate the total weight of the concrete used in the construction of the bridge, we had to first estimate the thickness of the bridge (Mikhelson 2004). In our approximation, we established that the thickness of the truss bridge system is 30 metres. This measurement was strictly taken on the concrete. Because we were covering the measurements in two dimensions, we divided the width by 2, which gave us 5. By converting the concrete thickness into kilometers, 30/1000 = 0.3 m The length is constant at 49m Therefore, to estimate the volume of the calculation, we used the fomula V = widnth x length x height = 0.3*49*5 = 73.5 cubic metres. The Total weight therefore translated to, 24kN x 73.5m3 = 1764 kN. Dead Load To get the dead load of the truss system, both the load of the steel and concrete had to be brought together by addition. The load of the concrete is 1764kN and that of steel is 1852.51kN. Therefore, the Dead load of the system is, 1764kN + 88.51kN = 1852.51kN Live Load In order to get the live load, both the weights of the bridge and that of the freight train had to be combined (Mikhelson 2004). There are two railway tracks constructed on the bridge alongside other features. The freight engines that are found in Melbourne are the NR; an abbreviation for the national Rail Class. They have an aggregate mass of about 132 tons. They also have lengths of 22meters. The freight cars found in the same place are of 30 tons when empty and 140 tons when loaded. We had to make the worst-case scenario of an assumption of 140 ton loaded mass which can be approximated at 25 metres long. This assumption leads us to a conclusion that there will be one car and one engine on the bridge per every given time. Therefore, the total train weight would be (140t + 132t) x 9.81 = 2668.32kN. Total Dead and Live Load would therefore be = 1852.51 + 2668.32 = 4520.83kN This weight however is distributed to the lowest joints that exist in a total of six vertical bars. Mathematically, it means that to get the total weight per node of the truss system bottoms, the total beams have to be divided by 6, which are placed on the right points along the truss. This calculation would give us 753.47 kN/ node as estimated through the bottom of the truss. Beam – Concrete Pedestrian Bridge In this analysis, the chosen beam was the pedestrian walkway made of concrete and next to the trust system that was analyzed in part 1 of this paper. The pedestrian walkway however was essentially made of a concrete slab, but we analyzed it as a beam; with half of its weight as the two main support it had in a two dimensional view. Note The beam experiences the forces that are commonly experienced by other beams regardless of the materials of make. It experienced both the compression and tensile forces when subjected to the loads. It is therefore proper to note that the beam experienced both the bending forces (compressive) along the top and the bending forces (tensile) along the bottom. Bibliography Mikhelson, I. 2004. Structural engineering formulas: compression, tension, bending, torsion, impact, beams, frames, arches, trusses, plates, foundations, retaining walls, pipes and tunnels. New York: McGraw-Hill. Read More