1 BUILDING MATERIAL PALESTINE UNIVERSITY chapter No.#5 Steel.

1

BUILDING MATERIAL

PALESTINE UNIVERSITY

chapter No.#5

Steel

2

STEEL General

Steel is a structural material which consists mostly of iron and carbon. It can, however,

contain other additives which might change the steel's

properties. Steel can be hot rolled or cold formed into

structural shapes, such as the familiar "I" beam known

today as a wide flange. Steel has the same strength in

tension as it has in compression, unlike concrete.

3

STEELGeneral

There are some tests for steel must be applied as :

• Tension test: this test used to measure the material

properties of a steel (or really any material, for that

matter),

• Beam bending test: this test used to measure the

material properties of a specimen and the effectiveness

of the orientation of the beam.

4

STEELGeneral

Some types of steel are specifically for use in fabricating large structures. They are called ‘high-strength low alloy’ or HSLA steels. These steels are:

– much stronger and tougher than ordinary carbon steels

– ductile

– highly formable

– weld able

– Highly resistant to corrosion - which is important since the structure may be in place for a long time.

5

STEEL Why HSLA Steels are Strong -:

The starting point in achieving the desirable properties of

structural steels is to get the composition of the alloy right.

The extra strength can be achieved through various

combinations of alloying elements which means that there

can be some choice in the other properties that the steel will

have.

A typical HSLA steel will contain about 0.15% carbon, 1.65%

manganese and low levels (under 0.035%) of phosphorous

and sulphur and additions of other elements:

6

Advantages of steel as a construction material

• High load resisting

• High ductility

• Easy control for steel structure

• No formed as in a concrete structure

• Elastic properties

7

Disadvantages of steel as a construction material

1. No ability to resist the fire

2. No ability to resist the corrosion

3. High cost

4. Engineering properties of steel

8

STEEL Microstructure of HSLA steels

The strength of all steels, including HSLA steels, comes from their microstructure. Strength is increased by:

•increasing the amount of pearlite

•increasing the fineness of the grains structure

•increasing the amount of hard precipitate.

9

STEEL Chemical Composition of Structural Steels

The primary types of structural steel are usually classified

according to the following chemical composition

categories:

• Carbon-manganese steels

• High-strength, low-alloy (HSLA) steels

• High-strength quenched and tempered alloy steels

10

STEELCarbon manganese Steels

whose primary chemical components are carbon and

manganese in addition to iron, are referred to as carbon

steels or mild structural steels. The materials of this type are

generally least expensive; they have quite adequate strength

and ductility characteristics, and are therefore by far the most

widely used grades. One of the most prominent of these steels

are ASTM grade A36, with a specified minimum yield stress

of36 ksi.

11

STEELHigh-strength, low-alloy (HSLA) steels

represent a relatively recent development in steelmaking. The higher

strength (42 to 65 ksi) is achieved by adding small amounts of additional

chemical elements. Two of the most common HSLA steels are ASTM

grade A572 and A588.

High-strength quenched and tempered alloy steels:-

used for structural purposes are essentially available only as grade A514

today. With a yield stress level of 90 to 100 ksi, the increase in strength is

achieved through heat treatment. A514 is available only in plate form, up

to 6 inches thick.

12

STEEL some elements used in structural steels:

Carbon (C) Manganese (Mn) Aluminum (Al) Chromium (Cr) Columbium (Cb) Copper (Cu) Molybdenum (Mo) Nickel (Ni) Phosphorus (P) and Sulfur (S) Silicon (Si) Vanadium (V) Other chemical elements

13

STEELSteel Alloys

Steel Alloys can be divided into five groups

• Carbon Steels

• High Strength Low Alloy Steels

• Quenched and Tempered Steels

• Heat Treatable Low Alloy Steels

• Chromium-Molybdenum Steels

Carbon steels are normally classified as shown below.

14

• Low-carbon steels:-

contain up to 0.30 weight percent C. The largest category of this class of steel is flat-rolled products (sheet or strip) usually in the cold-rolled and annealed condition. The carbon content for these high-formability steels is very low, less than 0.10 weight percent C, with up to 0.4 weight percent Mn. For rolled steel structural plates and sections, the carbon content may be increased to approximately 0.30 weight percent, with higher manganese up to 1.5 weight percent.

STEEL classification of Carbon steel

15

• Medium-carbon steels:-

• are similar to low-carbon steels except that the carbon

ranges from 0.30 to 0.60 weight percent and the manganese

from 0.60 to 1.65 weight percent. Increasing the carbon

content to approximately 0.5 weight percent with an

accompanying increase in manganese allows medium-

carbon steels to be used in the quenched and tempered

condition.

STEEL classifications of Carbon steel

16

• High-carbon steels:-

contain from 0.60 to 1.00 weight percent C with manganese

contents ranging from 0.30 to 0.90weight percent.


17

• High-strength low-alloy (HSLA) steels,

or micro alloyed steels, are designed to provide better

mechanical properties than conventional carbon steels. They

are designed to meet specific mechanical properties rather

than a chemical composition. The chemical composition of

a specific HSLA steel may vary for different product

thickness to meet mechanical property


18

• Requirements. The HSLA steels have low carbon contents

(0.50 to ~0.25 weight percent C) in order to produce

adequate formability and weld ability, and they have

manganese contents up to 2.0 weight percent. Small

quantities of chromium, nickel, molybdenum, copper,

nitrogen, vanadium, niobium, titanium, and zirconium are

used in various combinations.


19

• Steel Material with Large Cross-section

STEEL Structural Steel Sections

Steel material with large cross-section

20

• Thin Steel Plate:-


21


Tee Bares

22


Flat baresSquare bares

Round baresHexagon bares Square tubing

23


Round ShaftingHoned Shafting

I Beam Section

24


25

– Bar Size Shapes

– Structural-Size Shapes

– "W" Shapes

– "HP" Shapes

• "L" Shapes

STEEL Market forms of Steel

•"S" Shapes

•"C" Shapes

•"M" Shapes

•"MC" Shapes

26

Introduction -Steel Design

• Standard cross-sectional shapes Cross-sections of some of the more commonly used hot-rolled shapes :

W- shape OR Wide –flange Shape.For example :(w 18×50)

W-type of shape.18 section depth in inches .

50 section weight in pounds per foot .

27


• Standard cross-sectional shapes S- shape OR American standard S

For example :(S 18×70) S-type of shape

18 -section depth in inches .70 section weight

in pounds per foot .

28


• Standard cross-sectional shapes L- shape OR Angle shape .

For example :

(L6× L6× ¾’’)

(L6× L3× 5/8’’)

SEE FIGURE

29


• Standard cross-sectional shapes C- shape .

For example :

(C18× 70)

SEE FIGURE

30


• Standard cross-sectional shapes C- shape OR-American standard channel.

For example :

(C9× 20)

SEE FIGURE

C9×20

31


• Standard cross-sectional shapes T- shape OR- standard Tee .

For example :

(WT18× 115)

SEE FIGURENote

This section produced by cutting an I-shape member at middepth

(WT18× 115) (W36× 230)

32

The nominal loads and load combinations shall be as

stipulated by the applicable code under which the structure

is designed or dictated by the conditions involved. In the

absence of a code, the loads, including impact and crane

loads, and load combinations, shall be those stipulated in

ASCE 7. For design purposes, the loads stipulated by the

applicable code or ASCE 7 shall be taken as nominal loads.

STEEL Basic Definitions

33

STEEL Loads

34

Trusses are structures composed entirely of two force members .

They consists generally of triangular sub-element and are

constructed and supported so as to prevent any motion.

STEEL Trusses

35

STEEL Trusses

36

STEEL

END

1 BUILDING MATERIAL PALESTINE UNIVERSITY chapter No.#5 Steel.

Documents

Transcript of 1 BUILDING MATERIAL PALESTINE UNIVERSITY chapter No.#5 Steel.