The three beams shown have approximately the same cross-sectional area. Beam 1 is an IPN 400 with flange plates; beam 2 consists of a web plate with four angles; and beam 3 is constructed of 2 UPN...

The three beams shown have approximately the same cross-sectional area. Beam 1 is an IPN 400 with flange plates; beam 2 consists of a web plate with four angles; and beam 3 is constructed of 2 UPN shapes with flange plates.

(a) Which design has the largest moment capacity?

(b) Which has the largest shear capacity?

(c) Which is the most economical in bending?

(d) Which is the most economical in shear?

Assume allowable stress values are:

_a
= 120 MPa and

_a
= 75 MPa. The most economical beam is that having the largest capacity-to-weight ratio. Neglect fabrication costs in answering parts (c) and (d) above. Note: Obtain the dimensions and properties of all rolled shapes from tables in Appendix F.