Question

1. Develop a MATLAB code to determine, (a) the support reactions, RAy, RFy of the king post truss shown below using the given variables. (b) the member forces FAD, FAB, FBD, FBc, FcD, FCE, FDE, FEF, and FoF by considering the equilibrium of each node and setting up equilibrium equations using the given variables. 2. Run your MATLAB program for two load cases (while keeping the truss geometry the same) and two truss geometries (while keeping the load the same) and obtain the output in tabular format. Include a column in your output table to indicate the members that are in compression with a "C" and members that are in tension with a "T" H/2 H/2 L/2 L/2

Answer 1

MATLAB CODE:

clc;
clear all;
P1=input ('Enter P1:'); %For Entering load P1
P2=input ('Enter P2:'); %For Entering load P2
P3=input ('Enter P3:'); %For Entering load P3
H=input ('Enter H:'); %For Entering value of H
L=input ('Enter L:'); %For Entering value of L
RFY = (P1/4)+(P2/2)+(3*P3/4); %Calculating RFY
RAY = (P3/4)+(P2/2)+(3*P1/4); %Calculating RAY
disp('RAY:');disp(RAY); %diaplaying value on output screen
disp('RFY:');disp(RFY);
hyp = sqrt((H/2)^2+(L/4)^2); %calculating a constant to be used later
FAB = -2*RAY*hyp/H; % calculating value of force
FAD = RAY*L/(2*H);
FBD = -P1*hyp/H;
FBC = -(FAB+FBD);
FCE = -FBC;
FCD = -(FBC*H/hyp+P2);
FEF = RFY*hyp*2/H;
FDF = -RFY*L/(2*H);
FDE = P3*hyp/H;

%Displaying Forces
disp('FAD:');disp(FAD);
disp('FAB:');disp(FAB);
disp('FBD:');disp(FBD);
disp('FBC:');disp(FBC);
disp('FCD:');disp(FCD);
disp('FCE:');disp(FCE);
disp('FDE:');disp(FDE);
disp('FEF:');disp(FEF);
disp('FDF:');disp(FDF);

Sample Results :

Enter P1:12
Enter P2:12
Enter P3:12
Enter H:6
Enter L:6
RAY:
18

RFY:
18

FAD:
9

FAB:
-20.1246

FBD:
-6.7082

FBC:
26.8328

FCD:
-60

FCE:
-26.8328

FDE:
6.7082

FEF:
20.1246

FDF:
-9

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