A differential element is subjected to the stresses (in kpsi): σ1 = 10, σ2 = 0, σ3 = –20. A brittle material has the strengths (in kpsi) Sut = 50, Suc = 90. Calculate the safety factor and draw σ1– σ3 diagrams of each theory showing the stress state using:(a) Coulomb-Mohr theory.(b) Modified-Mohr theory.

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c