Question 1 Available for PV material of construction is steel material of tensile yield strength (y=400MPa) and shear yield strength (sy=200MPa ). In a test fixture, a piece of the steel material was loaded at 4kN and analyzed principal stresses were 1=100MPa and 2=200MPa. Calculate the test load at which the steel material will experience initial yielding according to the: i) Maximum-normal-stress theory [4 marks] ii) Maximum-shear-stress theory [4 marks] iii) Maximum-distortion-energy theory [4 marks] iv) Discuss the relative validity of each theory for this application [4 marks]