Center of Diploma StudyDepartment : Dept. of Civil
EngineeringTitle :FORCE IN A STATICALLY DETERMINATE CANTILEVER
TRUSS Page01EditionChecking NoEffective Date01/12/2007AmendmentDate
1.0OBJECTIVE1.1To examine a statically determinate frame and to
analyze the frame usingsimple pin joint theory.2.0LEARNING
OUTCOME2.1The application the engineering knowledge in practical
application2.2To enhance technical competency in structural
engineering throughlaboratory application.2.3To communicate
effectively in group2.4To identify problem, solving and finding out
appropriate solution throughlaboratory application 3.0THEORYA truss
is a structure composed of slender member joined together at their
end points to form one or more triangles. The joint connections are
considered as pinned joint without friction. In order to determine
the forces developed in the individual members at a truss, the
following assumptions should be make: 1. The members are connected
to each other at their ends by frictionless pins, that is only a
force and no moment can be transferred from one member to another.
2. External loads are applied to the truss only at its joints. One
of the methods to calculate the forces in the member of a truss is
using Method of Joint. Center of Diploma StudyDepartment : Dept. of
Civil EngineeringTitle :FORCE IN A STATICALLY DETERMINATE
CANTILEVER TRUSS Page02Edition2 Checking NoEffective
Date01/12/2007AmendmentDate Method Of Joints - Suitable to use in
calculating all of the member forces for a truss. - This method
entails the use of a free body diagram of joints with the
equilibrium equations Fx = 0 and Fy = 0. - Calculation only can be
started for joint where the numbers of unknowns are two or less.
4.0PROCEDURES1. Unscrew the thumwheel on the redundant member. Note
that it is effectively no longer part of the structure as the
idealised diagram illustrates. 2. Apply the pre-load of 100N
downward, re-zero the load cell and carefully apply a load of 250N
and check that the frame is stable and secure. 3. Return the load
to zero (leaving the 100N preload), recheck and re-zero the digital
indicator. Never apply loads greater than those specified on the
equipment. 4. Apply load in the increment shown in Table 1
recordding the strain readings and the digital indicator readings.
Complete Table 2 by subtracing the initial ( zero) strain readings.
(be careful with your sign) 1 582743F Center of Diploma
StudyDepartment : Dept. of Civil EngineeringTitle :FORCE IN A
STATICALLY DETERMINATE CANTILEVER TRUSS Page03Edition2 Checking
NoEffective Date01/12/2007AmendmentDate 5.0RESULT1.
TablesLoadStrain
ReadingDigital(N)indicator12345678reading(mm)005001000150020002500Table
1: Strain Readings and Frame Deflection for Experiment 1
Load12345678(N)0000000005001000150020002500Table 2: True Strain
Reading for Experiment 12. Graphsi.Choose a member (except member
6), and on the same axis plot agraph of Recorded Strain against
Load (N) and True Strain against Load (N).ii.On another graph, do
the same for a different member (non member6).iii.Plot a separate
graph of deflection (mm) against Load (N).iv.Comment on your
graphCenter of Diploma StudyDepartment : Dept. of Civil
EngineeringTitle : FORCE IN A STATICALLY DETERMINATE CANTILEVER
TRUSS Page04Edition2 Checking NoEffective
Date01/12/2007AmendmentDate Using the Youngs Modulus relationship,
calculate the equivalent member force. complete the experimental
force inTable 3. (ignore member 6 at this stage) E = / Where; E =
Youngs Modulus (Nm-2) = Stress in the member (Nm-2) = Displayed
strain and = F/A where, F = Force in member (N) A = cross section
area of the member (m2) Rod diameter = ---------------- mm and
Esteel = 2.10x105 N/mm2Experimental ForceMember(N)12345678
Theoretical Force (N) Table 3: Measured and Theoretical Force in
the Cantilever Truss Calculate the theoretical force using method
of joint and write it down in Table 3 above Center of Diploma
StudyDepartment : Dept. of Civil EngineeringTitle : FORCE IN A
STATICALLY DETERMINATE CANTILEVER TRUSS Page05Edition2 Checking
NoEffective Date01/12/2007AmendmentDate 6.0 DISCUSSION AND
CONCLUSION 1. Compare the experimental and theoritical result. . .
. . . 2. From your result and the theoritical member force,
identify which members are in compression and which member are in
tension. Explain your choice. . . . . . 3.Observe the reading of
member 5. Explain why the readings is almostzero.. . . . . Center
of Diploma StudyDepartment : Dept. of Civil EngineeringTitle :
FORCE IN A STATICALLY DETERMINATE CANTILEVER TRUSS Page06Edition2
Checking NoEffective Date01/12/2007AmendmentDate 4. Are the strain
gauges are an effective tranducersfor measurement forces in the
framework. . . . . . 5. Does the framework comply with pin joint
theory even though the joint are not truly pin joint?. . . . .
.
