A building roof truss is formed by a statically determinate pin jointed, triangulated framework,and loaded by two variable actions as shown in Figure 1. The structural elements are manufactured from

mild steel circular hollow sections (CHS). The section designation and steel grade of the CHS sections is an individual parameter. Please note that the section designation will depend upon whether a member is subjected to tension or compression force sunder the described load case of Figure 1. (a) State the three Laws of Static Equilibrium and calculate the values of the three reactions. (b) Stating your sign convention, obtain the sense and magnitude of the internal forces in all the framework elements. Show your answer diagrammatically. The applied forces, FB and FC are individual parameters. The geometry of the truss inFigure 1 are individual parameters as well. © Use Castigliano's Theorem to determine the vertical deflection at joint F. State whether you consider the stiffness of this framework to be adequate for the building roof truss, giving reasons for your decision. e For the loading direction shown, determine whether element DE is adequate for strength according to EN1993. Assume that joints E and D are positions of lateral restraint about the y-y axis and z-z axis. To check strength a load partial safety factor of 1.5 should be applied to the internal forces calculated in (b) above.