5 A steel roof consists of 12 steel purlins each with a leng

5) A steel roof consists of 12 steel purlins each with a length of 40m and mass 12kg/m, and steel roof sheeting of mass 8kg/m2. Calculate the total dead load of the roof system per unit area (kPa), where the roof total length is 40m and width is 10m (ignoring the small roof slope).

Solution

length of putlins=l_p=40m

mass per unit length for purlin=m_p=12kg/m

mass density of roof sheet=m_s=8kg/m²

total area of roof=a=40*10=400m² (ignoring small roof slope)

total mass of purlin=m_p*l_p=12*40=480kg

total mass of roof sheet=m_s*a=8*400=3200kg

total mass of roof per unit area=(480+3200)/400 = 9.2 kg/m² =9.2*9.81*10^-3 kPa=0.090252 kPa

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