Simply Supported Truss Apparatus: Engineering Mechanics Laboratory Manual Experiment#7

 

ENGINEERING MECHANICS EXPERIMENT NO.7

OBJECTIVE:

To determine the reactions of a Simply Supported Truss.

APPARATUS:

Weight Balance, weights, hanger. 

Figure 7.1: Simply Supported Truss Apparatus

THEORY:

A Truss is a triangulated system of members that are structured and connected in a way such that they only incur axial force. These members are considered two-force members as the forces are only applied at either end of the member, resulting in either a compression or tension force. They are commonly used as bridge designs, given their ability to efficiently span long distances.

PROCEDURE:

Step#1: Place the truss on the set of weighing balances.

Step#2: Adjust the balance measuring to zero by adjusting the screw. Step#3: Apply point load with the help of steel hook at:

 

•      Mid span of the truss as shown in the figure.

•      L/4 distance as shown in the figure.  

Step#4: Record the value of R₁ and R₂ on the balance scale provided on both supports.

Step#5: Now apply three point loads at L/4 distance as shown in the figure.

Step#6: Repeat Step 1.      

 OBSERVATIONS:

	Load			Analytical Result		Practical Result		Percentage Error(%)
S.No.	F1 (N)	F2 (N)	F3 (N)	R1 (N)	R2 (N)	R1 (N)	R2 (N)	R1	R2

CALCULATIONS:

Calculate the reactions when one, two and three point loads are applied on the truss.

PRECAUTIONS:

1.      The Truss should remain in a straight line that is should not lose its alignment (get curved) in direction perpendicular to the loading plane.

2.      Accuracy of the weighing balance.

CONCLUSION:

Discuss 

•      The change in value of R₁ and R₂ when one, two and three point loads are applied.

•      The ratio of load transfers on both sides when the distance changes from both ends.