ES1960 STATICS AND STRUCTURES 2020
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ES1960
2020
STATICS AND STRUCTURES
1. The structure shown in Figure 1 has a pin joint at point A, a roller at point B, has a point load of magnitude 20 kN applied to point D and a uniformly distributed load applied between points A and C.
(i) Determine the reaction forces at A and B (6 marks)
(ii) Derive the equations for calculating the internal axial force, shear force and
bending moment at any point along the structure. (10 marks)
(iii) Draw the three diagrams for the internal axial force, shear force and bending
moment. (9 marks)
Figure 1
2. Figure 2 shows a plane pin-jointed truss supported by a pin at H and a roller at F. Dimensions of the structure are as given in Figure 2, and all the angles between members are either 60 or 30 degrees. The frame is subjected to one vertical force of 30 kN at point A and force of 50 kN at point D with an inclination of 45 degrees. All members have the same cross section area A of 300 mm2 and modulus of elasticity, E, of 210 GPa.
(i) Determine the reaction forces at F and H (6 marks)
(ii) Find the forces in truss members AB, AF, DG, GH and CD, stating explicitly
whether they are in tension or compression. (14 marks)
(iii) Calculate the strain in member CD, stating explicitly whether it is contracting or
extending. (5 marks)
Figure 2
3. A tower is built in an area with high-speed winds and it is shown in Figure 3. It is schematised as a cantilever column of height H equal to 5 m with applied a horizontal distributed load of magnitude 4 kN/m. The tower has a rectangular cross section area of dimensions b equal to 120 mm and h equal to 200 mm. Modulus of elasticity E is equal to
180 GPa.
(i) Calculate the second moment of area I of the cross-section about the x axis.
(3 marks)
(ii) Calculate the maximum horizontal deflection of the column (3 marks)
(iii) Calculate the maximum absolute values of direct stress and shear stress found in
the column (flexure formula is given by G = − and formula for shear stress is
given by y = ( – y 2 ), where y is the distance from the neutral axis to either
the top or the bottom surfaces of the cross section, M is the bending moment and
V is the shear force at the considered location). (14 marks)
(iv) Draw the distribution of both direct and shear stresses as function of h. (5 marks)
Figure 3
4. The double pinned column shown in Figure 4(a) has an initial length L0 = 12 m and is subjected to an increasing vertical point load acting at point B. The cross section of the column has all dimensions specified in Figure 4(b). The modulus of elasticity is 90 GPa.
(i) Determine the two second moments of area of the cross-section about the two neutral axes (parallel to Cartesian axes x and z). (12 marks)
(ii) Determine the elastic critical Euler load for which the column will buckle. (5 marks)
(iii) In one of the bolts connecting the column to the ground, the state of stresses shown
in Figure 4(c) is generated. Using a method of your choice (if Mohr’s circle method
is chosen, the circle has centre of coordinates C = ( , 0) and radius
R = √()2 + Tx(2)y), calculate the principal stresses 1 and 2 and the orientation
of the element in the configuration representing the principal
stresses. (8 marks)
(a)
(b)
Figure 4
(c)
2022-08-16