1. ME 520 Fundamentals of Finite Element Analysis
8-Beam Element
Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department
Gebze Institute of Technology

2. Mechanical Engineering Department, GYTE
8-Beam Element
Simple Plane Beam Element
L: Length
I: Moment of inertia of the cross-sectional area
E: Elastic modulus
v=v(x): Deflection (lateral displacement) of the neutral axis
F=F(x): Shear force
M=M(x): Moment about z-axis
: Rotation about the z-axis
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

3. Mechanical Engineering Department, GYTE
8-Beam Element
Simple Plane Beam Element
Elementary Beam Theory:
Direct Method
Using the results from elementary beam theory to compute each column of the stiffness matrix. Element stiffness equation (local node: i, j or 1, 2):
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

4. Mechanical Engineering Department, GYTE
8-Beam Element
Example 1
Find;
The deflection and rotation at the center node
the reaction forces and moments at the two ends
Solution:
Connectivity table: E# N1 N2 1 2 3
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

5. Mechanical Engineering Department, GYTE
8-Beam Element
Example 1
Boundary conditions:
Displacement boundary conditions:
Force boundary conditions:
Element Stiffness Matrices:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

6. Mechanical Engineering Department, GYTE
8-Beam Element
Example 1
Global FE equation is:
Applying BC’s:
Reaction Forces:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

7. Mechanical Engineering Department, GYTE
8-Beam Element
Example 1
Stresses in the beam at the two ends can be calculated using the formula,
Note that the FE solution is exact according to the simple beam theory, since no distributed load is present between the nodes.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

8. Mechanical Engineering Department, GYTE
8-Beam Element
Equivalent Nodal Loads of
Distributed Transverse Load
2 element case:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

9. Mechanical Engineering Department, GYTE
8-Beam Element
Example 2
Find ;
The deflection and rotation at the right end
The reaction force and moment at the left end.
Solution:
Connectivity table:
Equivalent system: E# N1 N2 1 2
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

10. Mechanical Engineering Department, GYTE
8-Beam Element
Example 2
Boundary conditions:
Displacement boundary conditions:
Force boundary conditions:
The structure FE equation:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

11. Mechanical Engineering Department, GYTE
8-Beam Element
Example 2
Reaction forces:
This force vector gives the total effective nodal forces which include the equivalent nodal forces for the distributed lateral load p given by :
The correct reaction forces can be obtained as follows,
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

12. Mechanical Engineering Department, GYTE
8-Beam Element
Example 3
Given;
Find ;
Deflections, rotations
reaction forces
Solution:
Connectivity table: E# N1 N2 1 2 3 4
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

13. Mechanical Engineering Department, GYTE
8-Beam Element
Example 3
Boundary conditions:
Displacement boundary conditions:
Force boundary conditions :
The spring stiffness matrix :
Adding this stiffness
matrix to the global
FE equation:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

14. Mechanical Engineering Department, GYTE
8-Beam Element
Example 3
Aplying BC’s:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

15. Mechanical Engineering Department, GYTE
8-Beam Element
Example 3
Reaction Forces:
Checking the results: Draw free body diagram of the beam:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

16. Mechanical Engineering Department, GYTE
8-Beam Element
Solution procedure with matlab
It is clear that the beam element has 4 degrees of freedom (2 at each node)
The sign convension used is that the displacement is positive if it points upwards and the rotation is positive if it is counterclockwise.
For a structure with n nodes, the global stiffness matrix K will be of size 2nx2n.
The global stiffness matrix K is obtained by making calls to the Matlab function BeamAssemble which is written for this purpose.
Once the global stiffness matrix; K is obtained we have the following structure equation;
where U is the global nodal displacement vector and F is the global nodal force vector.
At this step boundary conditions are applied manually to the vectors U and F.
Then the matrix equation is solved by partitioning and Gaussion elimination.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

17. Mechanical Engineering Department, GYTE
8-Beam Element
Solution procedure with matlab
Finally once the unkown displacements and and reactions are found, the force is obtained for each element as follows:
where f is the 4x1 nodal force vector in the element and u is the 4x1 element displacement vector.
The first and second elements in each vector are the transverse displacement and rotation, respectively, at the first node, while the third and fourth elements in each vector are the transverse displacement and rotation, respectively, at the second node.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

18. Mechanical Engineering Department, GYTE
8-Beam Element
Matlab functions used
The 5 Matlab functions used for the beam element are:
BeamElementStiffness(E,I,L)
This function returns the element stiffness matrix for a beam element with modulus of elasticity E, moment of inertia I, and length L. The size of the element stiffness matrix is 4 x 4.
Function contents:
function y = BeamElementStiffness(E,I,L)
%BeamElementStiffness This function returns the element
% stiffness matrix for a beam
% element with modulus of elasticity E,
% moment of inertia I, and length L.
% The size of the element stiffness
% matrix is 4 x 4.
y = E*I/(L*L*L)*[12 6*L -12 6*L ; 6*L 4*L*L -6*L 2*L*L ;
-12 -6*L 12 -6*L ; 6*L 2*L*L -6*L 4*L*L];
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

19. Mechanical Engineering Department, GYTE
8-Beam Element
Matlab functions used
BeamAssemble(K,k,i,j)
This function assembles the element stiffness matrix k of the beam element with nodes i and j into the global stiffness matrix K. This function returns the 2nx2n global stiffness matrix K after the element stiffness matrix k is assembled.
Function contents:
function y = BeamAssemble(K,k,i,j)
%BeamAssemble This function assembles the element stiffness
% matrix k of the beam element with nodes
% i and j into the global stiffness matrix K.
% This function returns the global stiffness
% matrix K after the element stiffness matrix
% k is assembled.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

20. Mechanical Engineering Department, GYTE
8-Beam Element
Matlab functions used
K(2*i-1,2*i-1) = K(2*i-1,2*i-1) + k(1,1);
K(2*i-1,2*i) = K(2*i-1,2*i) + k(1,2);
K(2*i-1,2*j-1) = K(2*i-1,2*j-1) + k(1,3);
K(2*i-1,2*j) = K(2*i-1,2*j) + k(1,4);
K(2*i,2*i-1) = K(2*i,2*i-1) + k(2,1);
K(2*i,2*i) = K(2*i,2*i) + k(2,2);
K(2*i,2*j-1) = K(2*i,2*j-1) + k(2,3);
K(2*i,2*j) = K(2*i,2*j) + k(2,4);
K(2*j-1,2*i-1) = K(2*j-1,2*i-1) + k(3,1);
K(2*j-1,2*i) = K(2*j-1,2*i) + k(3,2);
K(2*j-1,2*j-1) = K(2*j-1,2*j-1) + k(3,3);
K(2*j-1,2*j) = K(2*j-1,2*j) + k(3,4);
K(2*j,2*i-1) = K(2*j,2*i-1) + k(4,1);
K(2*j,2*i) = K(2*j,2*i) + k(4,2);
K(2*j,2*j-1) = K(2*j,2*j-1) + k(4,3);
K(2*j,2*j) = K(2*j,2*j) + k(4,4);
y = K;
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

21. Mechanical Engineering Department, GYTE
8-Beam Element
Matlab functions used
BeamElementForces(k,u)
This function calculates the element element force vector using the element stiffness matrix k and the element displacement vector u. It returns the 4x1 element force vecor f
Function contents:
function y = BeamElementForces(k,u)
%BeamElementForces This function returns the element nodal force
% vector given the element stiffness matrix k
% and the element nodal displacement vector u.
y = k * u;
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

22. Mechanical Engineering Department, GYTE
8-Beam Element
Matlab functions used
BeamElementShearDiagram(f, L)
This function plots the shear force diagram for the beam element with nodal force vector f and length L.
Function contents:
function y = BeamElementShearDiagram(f, L)
%BeamElementShearDiagram This function plots the shear force
% diagram for the beam element with nodal
% force vector f and length L.
x = [0 ; L];
z = [f(1) ; -f(3)];
hold on;
title('Shear Force Diagram');
plot(x,z);
y1 = [0 ; 0];
plot(x,y1,'k')
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

23. Mechanical Engineering Department, GYTE
8-Beam Element
Matlab functions used
BeamElementMomentDiagram(f, L)
This function plots the bending moment diagram for the beam element with nodal
force vector f and length L.
Function contents:
function y = BeamElementMomentDiagram(f, L)
%BeamElementMomentDiagram This function plots the bending moment
% diagram for the beam element with nodal
% force vector f and length L.
x = [0 ; L];
z = [-f(2) ; f(4)];
hold on;
title('Bending Moment Diagram');
plot(x,z);
y1 = [0 ; 0];
plot(x,y1,'k')
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

24. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
Consider the beam as shown
Given
E=210 GPa
I=60x10-6 m4
P=20 kN
L=2 m
Determine:
the global stiffness matrix for the structure
vertical displacement at node 2
rotations at nodes 2 and 3
the reactions at nodes 1 and 3
the forces (shears and moments) in each element
the shear force diagram for each element
the bending moment diagram for each element
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

25. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
Solution:
Use the 7 steps to solve the problem using beam element.
Step 1-Discretizing the domain:
We will put a node (node2) at the location of the concentrated force so that we may determine the required quantities (displacements, rotation, shear, moment) at that point.
The domain is subdivided into two elements and three nodes. The units used in Matlab calculations are kN and meter. The element connectivity is: E# N1 N2 1 2 3
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

26. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
Step 2-Copying relevant files and starting Matlab
Create a directory
Copy
BeamElementStiffness.m
BeamAssemble.m
BeamElementForces.m
BeamElementShearDiagram.m
BeamElementMomentDiagram.m
files under the created directory
Open Matlab;
Open ‘Set Path’ command and by using ‘Add Folder’ command add the current directory.
Start solving the problem in Command Window:
>>clearvars
>>clc
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

27. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
Step 3-Writing the element stiffness matrices:
The two element stiffness matrices k1 and k2 are obtained by making calls to the Matlab function BeamElementStiffness. Each matrix has size 4x4.
Enter the data
>>E=210e6
>>I=60e-6
>>L=2
>>k1=BeamElementStiffness(E,I,L)
k1 =
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

28. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>k2=BeamElementStiffness(E,I,L)
k2 =
Step 4-Assembling the global stiffness matrix:
Since the structure has 3 nodes, the size of the global stiffness matrix is 6x6.
>>K=zeros(6,6)
>>K=BeamAssemble(K,k1,1,2)
>>K=BeamAssemble(K,k2,2,3)
K =
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

29. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
Step 5-Applying the boundary conditions:
Finite element equation for the problem is;
The boundary conditions for the problem are;
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

30. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
Inserting the above conditions into finite element equation
Step 6-Solving the equations:
Solving the above system of equations will be performed by partitioning (manually) and Gaussian elimination (with Matlab)
First we partition the above equation by extracting the submatrices in rows 3 to 4 and column 6, row 6 and columns 3 to 4, and row 6 and column 6. Therefore we obtain:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

31. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
The solution of the above system is obtained using Matlab as follows.
Note that the ‘\’ operator is used for Gaussian elimination.
>>k=[K(3:4,3:4) K(3:4,6) ; K(6,3:4) K(6,6)]
k =
>>f=[-20 ; 0 ; 0]
f =
-20
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

32. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>u=k\f
u =
1.0e-03 *
0.7937
It is now clear that
the vertical displacement at node 2= m (downward)
rotation at node 2 = rad (clockwise)
rotation at node 3 = rad (counterclockwise)
Step 7-Post-processing:
In this step we obtain the reactions at nodes 1 and 3 and the forces (shears and moments) in each beam element using Matlab as follows.
First we set up the global nodal displacement vector U, then we calculate the nodal force vector F.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

33. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>U=[0 ; 0 ; u(1) ; u(2) ; 0 ; u(3)]
U =
1.0e-03 *
0.7937
>>F=K*U
F =
6.2500
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

34. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
thus the recations are;
Force at node 1=13.75 kN
Moment at node 1=15 kNm (countereclockwise)
Force at node 3=6.25 kN
Next we set up the element nodal displacement vectors u1 and u2 then we calculate the element force vectors f1 and f2 by making calls to the Matlab function BeamElementForces.
>> u1=[U(1) ; U(2) ; U(3) ; U(4)]
u1 =
1.0e-03 *
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

35. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>> u2=[U(3) ; U(4) ; U(5) ; U(6)]
u2 =
1.0e-03 *
0.7937
>>f1 =BeamElementForces(k1,u1)
f1 =
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

36. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>f2 =BeamElementForces(k2,u2)
f2 =
6.2500
Shear force at centilever region=13.75 kN
Bending moment at centilever region=15 kNm
Shear force at pin joint=6.25 kN
Finally we call the Matlab functions BeamElementShearDiagram and BeamElementMomentDiagram, respectively for each element.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

37. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>BeamElementShearDiagram(f1,L)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

38. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>BeamElementShearDiagram(f2,L)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

39. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>BeamElementMomentDiagram(f1, L)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

40. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 4 with Matlab
>>BeamElementMomentDiagram(f2, L)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

41. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Consider the beam as shown
Given
E=210 GPa
I=5x10-6 m4
w=7 kN/m
Determine:
the global stiffness matrix for the structure
rotations at nodes 1, 2 and 3
the reactions at nodes 1, 2, 3 and 4
the forces (shears and moments) in each element
the shear force diagram for each element
the bending moment diagram for each element
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

42. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Solution:
Step 1-Discretizing the domain:
We need first to replace the distributed loading on element 2 by equivalent nodal loads. This is performed as follows for element 2 with a uniformly distributed load. The resulting beam with eqivalent nodal load is shown below:
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

43. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
The units used in Matlab calculations are kN and meter.
The element connectivity is: E# N1 N2 1 2 3 4
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

44. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Step 2-Copying relevant files and starting Matlab
Create a directory
Copy
BeamElementStiffness
BeamAssemble
BeamElementForces
BeamElementShearDiagram
BeamElementMomentDiagram
files under the created directory
Open Matlab;
Open ‘Set Path’ command and by using ‘Add Folder’ command add the current directory.
Start solving the problem in Command Window:
>>clearvars
>>clc
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

45. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Step 3-Writing the element stiffness matrices:
The two element stiffness matrices k1 and k2 are obtained by making calls to the Matlab function BeamElementStiffness. Each matrix has size 4x4.
Enter the data
>>E=210e6
>>I=5e-6
>>L1=3
>>L2=4
>>L3=2
>>k1=BeamElementStiffness(E,I,L1)
k1 =
1.0e+03 *
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

46. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>k2=BeamElementStiffness(E,I,L2)
k2 =
1.0e+03 *
>>k3=BeamElementStiffness(E,I,L3)
k3 =
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

47. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Step 4-Assembling the global stiffness matrix:
Since the structure has 4 nodes, the size of the global stiffness matrix is 8x8.
>>K=zeros(8,8)
>>K=BeamAssemble(K,k1,1,2)
>>K=BeamAssemble(K,k2,2,3)
>>K=BeamAssemble(K,k3,3,4)
K =
1.0e+03 *
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

48. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Step 5-Applying the boundary conditions:
Finite element equation for the problem is;
The boundary conditions for the problem are;
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

49. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Step 6-Solving the equations:
Solving the above system of equations will be performed by partitioning (manually) and Gaussian elimination (with Matlab)
First we partition the above equation by extracting the submatrices in rows 2, 4 and 6 and columns2, 4 and 6. Therefore we obtain:
The solution of the above system is obtained using Matlab as follows.
Note that the ‘\’ operator is used for Gaussian elimination.
>>k=[K(2,2) K(2,4) K(2,6) ; K(4,2) K(4,4) K(4,6) ; K(6,2) K(6,4) K(6,6)]
k =
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

50. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>f=[0 ; ; 9.333]
f =
9.3330
>>u=k\f
u =
0.0027
0.0039
It is now clear that
rotation at node 1 = rad (counterclockwise)
rotation at node 2 = rad (clockwise)
rotation at node 3 = rad (counterclockwise)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

51. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Step 7-Post-processing:
In this step we obtain the reactions at nodes 1, 2, 3 and 4 and the forces (shears and moments) in each beam element using Matlab as follows.
First we set up the global nodal displacement vector U, then we calculate the nodal force vector F.
>>U=[0 ;u(1) ;0 ; u(2) ; 0 ; u(3); 0 ; 0]
U =
0.0027
0.0039
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

52. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>F=K*U
F =
1.2850
6.6954
9.3330
4.0578
thus the recations are;
Force at node 1= kN
Force at node 2= kN
Force at node 3= kN
Force at node 4= kN
Moment at node 4 (at fixed support)= kNm (counterclockwise)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

53. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Next we set up the element nodal displacement vectors u1, u2 and u3 then we calculate the element force vectors f1, f2 and f3 by making calls to the Matlab function BeamElementForces.
>> u1=[U(1) ; U(2) ; U(3) ; U(4)]
u1 =
0.0027
>> u2=[U(3) ; U(4) ; U(5) ; U(6)]
u2 =
0.0039
>> u3=[U(5) ; U(6) ; U(7) ; U(8)]
u3 =
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

54. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>f1 =BeamElementForces(k1,u1)
f1 =
1.8937
>>f2 =BeamElementForces(k2,u2)
f2 =
0.6087
1.2173
>>f3 =BeamElementForces(k3,u3)
f3 =
6.0867
8.1157
4.0578
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

55. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Note that the forces for element 2 need to be modified because of the distributed load. In order to obtain the correct forces for element 2 we need to subtract from f2 the vector of equivalent nodal loads given in equation (**). This is performed using Matlab as follows:
>>f2=f2-[-14 ; ; -14 ; 9.333]
f2 =
5.6810
Element 1 has a shear force of kN and a bending moment of 0 kNm at its left end while it has a shear force of kN and a bending moment of kNm at its right end.
Element 2 has a shear force of kN and a bending moment of kNm at its left end while it has a shear force of kN and a bending moment of kNm at its right end.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

56. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
Element 3 has a shear force of kN and a bending moment of kNm at its left end while it has a shear force of kN and a bending moment of kNm at its right end.
Obviously the roller at the left end has zero moment.
Finally we call the Matlab functions BeamElementShearDiagram and BeamElementMomentDiagram, respectively for each element.
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

57. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>BeamElementShearDiagram(f1,L1)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

58. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>BeamElementShearDiagram(f2,L2)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

59. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>BeamElementShearDiagram(f3,L3)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

60. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>BeamElementMomentDiagram(f1, L1)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

61. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>BeamElementMomentDiagram(f2, L2)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE

62. Mechanical Engineering Department, GYTE
8-Beam Element
Solution of Example 5 with Matlab
>>BeamElementMomentDiagram(f3, L3)
ME Dr. Ahmet Zafer Şenalp
Mechanical Engineering Department, GYTE