A steel I-beam column with a cross sectional area of A= 11200 mm2 supports an axial force of P. If the average normal stress in the steel column must not exceed 150 MPa, determine the minimum required dimension of the base plate (a) so that the bearing stress between the base plate and the concrete slab does not exceed 19 MPa.

Respuesta :

Explanation:

Formula to calculate the maximum column load is as follows.

          [tex]P_{max} = \sigma \times A[/tex]

                      = [tex]110 N/mm^{2} \times 11200 mm^{2}[/tex]

                      = 1232000 N

Over a large area, the column load has to be distributed such that the bearing stress between base plate an concrete slab does not exceed 8 MPa. Hence, we will calculate the minimum plate area as follows.

              [tex]A_{min} = \frac{P}{\sigma_{b}}[/tex]

                          = [tex]\frac{1232000 N}{8 N/mm^{2}}[/tex]

                          = 154000 [tex]mm^{2}[/tex]

As the plate is of square shape. Hence, the minimum plate dimension "a" must be calculated as follows.

                     [tex]A_{min} = a \times a[/tex]

                     [tex]154000 mm^{2} = a^{2}[/tex]

                              a = 392.42 mm

Thus, we can conclude that minimum required dimension of the given base plate is 392.42 mm.

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