Grade of Bolts

Dear Readers,

Being a construction engineer, we very often use the bolts. Generally the grades of bolts are starts from 4.6 to 12.9. Also known as Ordinary bolt (Commercial Grade),  HT Bolt (High Tension) & HSFG Bolts (High Strength Friction Grip).

The bolt designation system is based on two numbers. The first number represents the ultimate tensile strength of the bolt, 400 MPa, 800 MPa or 1200 MPa respectively. The second number represents the point at which the bolt will permanently stretch. A 4.6 grade bolt permanently stretches at 60% of its ultimate, an 8.8 grade bolt at 80% and a 12.9 grade bolt at 90 % of its ultimate.

Technically it can be quoted that the first number is the tensile strength of the bolt material (N² )/100. The second number is = 1/100.(the ratio of the Proof (or Yield ) stress and the Tensile strength expressed as a percentage = 100.[Yield (Proof stress) /Tensile strength] /100

For Example the tensile and proof strength of the steel for a 8.8 bolt is therefore calculated as follows

Tensile strength = 8 X 100 N/mm² = 800 N/mm² and Proof strength = 0.8*800 * 100 /100 = 640 N/mm² (generally speaking 80% of 800N/mm2)

The lowest grade is 4.6, commonly known as commercial grade. Next comes grade 8.8, known as structural grade, and finally, the highest grade is 12.9, known as HT / HSFG bolt.

Available grade of bolts are 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9 & 12.9

For More Details about Torque Click Torque

For More Details about Torqe Calculation Click Calculation

For More Details about Slip Factor Click Factor

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Properties of ISMB

This is continuation with my earlier post unit weight of ISMB, self would like to post the sectional properties of ISMB. My earlier post, Unit weight of ISMB has been one of the popular post. In the same way, I am expecting this post would be a next popular post and also helpful to all engineeres. 

Properties of beams are having two parts. One part is Physical dimensions and another part is sectional properties of ISMB.Basically dimensional part contains depth and width of section, Thickness of Web and Flange and Root Radius. Where as sectiononal properites contains Moment of Inertia, Radius of Gyration and Section Modulus. These are usefull for design engineers.

For View Table, Please Click on Picture

For More Details about Unit Weight of Medium Weight Beam Click ISMB

For More Details about Sectional Properties Click Properties

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Sectional Properties

Important and common sectional properties of rolled steels are Moment of Inertia, Radius of gyration & Elastic Modulus. The purpose of usage and definitions are below. Generally, the centimetre (cm) is used for the calculated properties.

Moment Of Inertia (I)
Area Moment of Inertia, also known as Second Moment of Inertia - I, is a property of shape that is used to predict deflections and stresses in beams. The larger the Moment of Inertia the less the beam will bend. The moment of inertia is a geometrical property of a beam and depends on a reference axis and has been calculated taking into account all tapers, radii and fillets of the sections.

Radius of gyration (r)

The radius of gyration is a parameter used in buckling calculation. It can be calculated by roots of Moment of Inertia divided by Area

r = (I / A)^1/2

Elastic modulus (Z)

The elastic modulus is used to calculate the moment capacity based on the design strength of the section or the stress at the extreme fibre of the section from a known moment. It is derived as follows:

Z =I/e

Where e is the distance to the extreme fibre of the section from the elastic neutral axis.

Other sectional properties are used in engineering are

Buckling parameter (u), Torsional index (x), Warping constant (H), Torsion constant (J), Plastic modulus (S), Torsion modulus constant

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