Step 1 -- Calculate shear and moment at the wall.

Input := 

w1[x_] = 0;
w2[x_] = 100;
w3[x_] = 0;
w4[x_] = (x-100) * 100 / 50;

Input := 

V0 = Integrate[ w1[u], {u,0,30} ] +
     Integrate[ w2[u], {u,30,60}] +
     Integrate[ w3[u], {u,60,100}] +
     Integrate[ w4[u], {u,100,150}]

Output =

5500

Input := 

M0 = Integrate[ u w1[u], {u,0,30} ] +
     Integrate[ u w2[u], {u,30,60}] +
     Integrate[ u w3[u], {u,60,100}] +
     Integrate[ u w4[u], {u,100,150}] //N

Output =

468333.