Truss Report

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  • Topic: Force, Volt, Data acquisition
  • Pages : 5 (908 words )
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  • Published : May 11, 2011
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FORCES IN STATICALLY DETERMINATE TRUSS SYSTEM

1.Objective

1. To measure the forces in members of a statically determinate truss.

2. To perform theoretical calculation of a statically determinate truss.

3. To compare the theoretical calculation and experimental measurements.

2.Equipment

1. A plane cantilever truss with six members, 1 pinned and 1 roller support

2. A screw jack for applying load to the truss

3. A seven-channel data acquisition system.

3. Theory

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Figure 1

In this experiment, we are going to use the truss system shown Figure 1. The load W is adjustable using a screw jack. From the theory of equilibrium, we are able to calculate the support reaction at point A and E in terms of W. Finally, from the support reaction at A and E, we are also able to calculate the force at each member using method of joint and method of section. Experimentally, every member is connected to a data acquisition system that can change its voltage if a load is applied to it. The voltage sent to a module that is connected to a computer will show the reading in terms of volts, where every 1 mili Volt of voltage is proportional to 100 Newton of force (1V is proportional to 100 kN). After obtaining the experimental results, we are able to compare the results with the theoretical results in Model Calculation.

4.Experimental Procedure

1. Ensure that the pinned support is properly secured to the frame. 2. Attach the screw jack to the joint to be loaded.
3. Loosen the screw jack so that the truss is free from applied load. 4. Connect the wire from the load cell to the data acquisition module, each load cell occupying one channel of the module.

5. Run the Winview CP Plus software.
6. Select the ‘setting’ option to set the channels to be acquired and the conversion factor to convert mV output from the load cell to the measured units.
7. When the setting is complete, return to the sub menu and press the start button. Turn the screw jack handle to apply loads in the downward direction and observe the readings of the screw jack. When the desired load is reached, press the stop button and stop turning the screw jack.

5. Data Sheet:

|Member |Reading (volt) | |Jack |2.51 |4.42 |6.34 |8.26 |10.18 |12.09 |14.01 | |1 AB |-2.88 |-0.96 |0.96 |2.88 |3.84 |5.75 |8.63 | |2 BC |3.83 |5.75 |9.59 |10.55 |12.46 |16.30 |18.22 | |3 CD |-2.88 |-4.79 |-7.67 |-9.59 |-9.59 |-11.50 |-13.42 | |4 DE |0 |-2.84 |-7.67 |-11.51 |-13.42 |-17.25 |-20.13 | |5 AD |1.92 |3.84 |6.71 |9.59 |10.55 |14.38 |17.26 | |6 BD |-0.96 |-2.88 |-5.75 |-6.71 |-8.62 |-10.54 |-11.51 |

Table 1 Readings in volts

|Member |Reading (kN) | |Jack |251 |442 |634 |826 |1018 |1209 |1401 | |1 AB |-288 |-96 |96 |288 |384 |575 |863 | |2 BC |383 |575 |959 |1055 |1246 |1630 |1822 | |3 CD |-288 |-479 |-767...
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