TABLE OF CONTENTS Some structures consist of beams that are stiffened by trusses in which the beam portion of the structure is capable of resisting shear forces and bending moments in addition to axial forces. Generally, however, displacements produced by shear forces are negligibly small and may be ignored. Therefore, in such structures we shall assume that the members of the truss portion of the structure resist axial forces only while the beam portion resists bending moments and axial forces; in some cases the axial forces in the beam are also ignored since their effect, due to the larger area of cross section, is small.
The beam ABC shown in Fig. 16.21(a) is simply supported and stiffened by a truss whose members are capable of resisting axial forces only. The beam has a cross-sectional area of 6000 mm 2 and a second moment of area of 7.2 10 ?6 mm 4. If the cross-sectional area of the members of the truss is 400 mm 2, calculate the forces in the members of the truss and the maximum value of the bending moment in the beam. Young's modulus, E, is the same for all members.
We observe that if the beam were capable of resisting axial forces only, the structure would be a relatively simple statically determinate truss. However, the beam, in addition to axial forces, resists bending moments (we are ignoring the effect of shear)...
