Question

1. How to design a primary steel beam and a secondary steel beam? In term of mechanical properties

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2. How can built up c steel section be designed as a primary beam?

3. Why not using I steel section to design a primary beam?

Answer 1

1)

Primary Beam: A horizontal beam connecting columns (simply supported or shear connected.) Function: It will transfer the load from secondary beam(if present) to the columns. Secondary Beam: A horizontal beam connecting primary beams(simply supported or shear connected.)

Design of beams in structural steel

Introduction

Beams are an important class of structural element, and are normally horizontal.The primary function of building structures is to support the major space enclosing elements:commonly these are floors, roofs and walls. The total behaviour of any building structure can becomplicated but frequently two types of sub-structure can be identified; vertical elements(associated with walls) and horizontal elements (associated with floors and roofs).Vertical elements are columns, walls and lift cores etc. Horizontal elements include slabs,trusses, space frames and most importantly beams.

2)

Channel (C-Shaped)
Channel beams (also known as C-beams) are created with top and bottom flanges that create a C shape. Over the years C-beams was most known for being used with bridges. However, C-beams are starting to be used for a variety of building applications including, but not limited to marine piers.

3)

An I-beam, also known as H-beam (for universal column, UC), w-beam (for "wide flange"), universal beam (UB), rolled steel joist(RSJ), or double-T (especially in Polish, Bulgarian, Spanish, Italian and German), is a beam with an I or H-shaped cross-section. The horizontal elements of the "I" are known as flanges, while the vertical element is termed the "web". I-beams are usually made of structural steel and are used in construction and civil engineering.

The web resists shear forces, while the flanges resist most of the bending moment experienced by the beam. Beam theory shows that the I-shaped section is a very efficient form for carrying both bending and shear loads in the plane of the web. On the other hand, the cross-section has a reduced capacity in the transverse direction, and is also inefficient in carrying torsion, for which hollow structural sections are often preferred.