A timber beam, 150 mm wide and 300 mm deep, has an effective span of 4,8 m. The density of the timber is 490 kg/m3 . Calculate the point load the beam can carry at the centre of its span if the stress in the timber is not to exceed 4,1 MPa. The mass of the beam must be taken into consideration.

A composite beam 225 mm wide x 300 mm deep x 4 m long is made by bolting two 100-mm- wide x 300-mm-deep timber planks to the sides of a 25 x 300-mm structural aluminium plate. The moduli of elasticity for the timber and aluminium are 8 GPa and 73 GPa, respectively. Determine the maximum tensile flexural stress in each of the materials if the composite beam is simply supported and carries a concentrated load 30 kN in the centre of the beam. 100 mm 25 mm 100 mm 11 300 mm

A simply supported post-tension beam as shown in Figure (1), span length is 14m, carries a uniformly distributed service live load of 10 kN/m. Find the value and location of initial pre-stress force (Pi), so that the mid span stresses in concrete at top fiber is zero at initial stage and zero stress at bottom fiber in service stage. Total losses in pre-stressed force are 15%. 100 200 100 750 100 400 Typical Cross section. Figure (1)