Design of Flexural Members:

In the previous units, you learnt about the design of members subjected to axial loads. In this unit, you are going to learn about members which are mostly subjected to loads acting transverse to its axis. Such loads result in bending moments and shearing forces. Those transversely loaded elements are given several names, depending upon their size, situation, etc. Commonly known as beams when they are used in buildings, they are also known as girders when larger in size and used in bridges, etc. The similar thing is called purlins when used to support roof covering on roof trusses. Therefore, the loading pattern, behaviour and design principles remain the same. The beam is subjected to bending moments which cause bending stresses in the section, such that part of the cross section is under compression and part is in tension at the same time. The behaviour of steel section, especially thin section and plates, is different in tension and in compression as you have seen in the previous chapter, their simultaneous existence in beams causes a number of problems in the design and analysis of such section.

Objectives

After studying this unit, you should be able to

• Design easy beams under transverse loading,
• Appreciate an effect of flange, lateral support and lateral buckling,
• Design sections along with flange plates, and their connection,
• Check a stresses in the flanges and webs due to bending moments and shearing forces,
• Design easy sections under biaxial bending, and
• Design unsymmetrical section, example for channels and angles under flexure.