Upload
scott-malone
View
227
Download
4
Tags:
Embed Size (px)
Citation preview
BUILDING MATERIALBUILDING MATERIAL
PALESTINE UNIVERSITY PALESTINE UNIVERSITY
chapter No.#4 chapter No.#4
SteelSteel
STEEL STEEL General General
Steel is a structural material Steel is a structural material which consists mostly of iron which consists mostly of iron and carbon. It can, however, and carbon. It can, however,
contain other additives which contain other additives which might change the steel's might change the steel's
properties. Steel can be hot properties. Steel can be hot rolled or cold formed into rolled or cold formed into
structural shapes, such as the structural shapes, such as the familiar "I" beam known familiar "I" beam known
today as a wide flange. Steel today as a wide flange. Steel has the same strength in has the same strength in
tension as it has in tension as it has in compression, unlike concrete.compression, unlike concrete.
STEELSTEELGeneral General
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.
STEELSTEELGeneral General
Some types of steel are specifically for use in Some types of steel are specifically for use in fabricating large structures. They are called ‘fabricating large structures. They are called ‘high-strength high-strength lowlow alloyalloy’ or ’ or HSLAHSLA steels. These steels are: steels. These steels are:
much stronger and tougher than ordinary carbon much stronger and tougher than ordinary carbon steels steels
ductile ductile highly formable highly formable weld able weld able Highly resistant to corrosion - which is important Highly resistant to corrosion - which is important
since the structure may be in place for a long time.since the structure may be in place for a long time.
STEELSTEEL Why HSLA Steels are Why HSLA Steels are Strong:- Strong:-
The starting point in achieving the desirable properties of The starting point in achieving the desirable properties of
structural steels is to get the composition of the alloy right. structural steels is to get the composition of the alloy right.
The extra strength can be achieved through various The extra strength can be achieved through various
combinations of alloying elements which means that there combinations of alloying elements which means that there
can be some choice in the other properties that the steel will can be some choice in the other properties that the steel will
have. have.
A typical HSLA steel will contain about 0.15% carbon, 1.65% A typical HSLA steel will contain about 0.15% carbon, 1.65%
manganese and low levels (under 0.035%) of phosphorous manganese and low levels (under 0.035%) of phosphorous
and sulphur and additions of other elements:and sulphur and additions of other elements:
STEEL STEEL Microstructure of HSLA steelsMicrostructure of HSLA steels
The strength of all steels, The strength of all steels, including including HSLAHSLA steels, steels, comes from their comes from their microstructure. Strength is microstructure. Strength is increased by: increased by: increasing the amount of increasing the amount of pearlite pearlite increasing the fineness increasing the fineness of the grains structure of the grains structure increasing the amount of increasing the amount of hard precipitate.hard precipitate.
STEEL STEEL Chemical Composition of Structural Chemical Composition of Structural
SteelsSteels The primary types of structural steel are usually classified The primary types of structural steel are usually classified
according to the following chemical composition according to the following chemical composition
categories:categories:
Carbon-manganese steelsCarbon-manganese steels
High-strength, low-alloy (High-strength, low-alloy (HSLAHSLA) steels) steels
High-strength quenched and tempered alloy steelsHigh-strength quenched and tempered alloy steels
STEELSTEELCarbon manganese Steels Carbon manganese Steels
whose primary chemical components are carbon andwhose primary chemical components are carbon and
manganese in addition to iron, are referred to as manganese in addition to iron, are referred to as carbon carbon
steelssteels or or mild structuralmild structural steels steels. The materials of this type are . The materials of this type are
generally least expensive; they have quite adequate strength generally least expensive; they have quite adequate strength
and ductility characteristics, and are therefore by far the most and ductility characteristics, and are therefore by far the most
widely used grades. One of the most prominent of these steels widely used grades. One of the most prominent of these steels
are ASTM grade A36, with a specified minimum yield stress are ASTM grade A36, with a specified minimum yield stress
of36 of36 ksiksi..
STEELSTEELHigh-strength, low-alloy (HSLA) steelsHigh-strength, low-alloy (HSLA) steels
represent a relatively recent development in steelmaking. The higher represent a relatively recent development in steelmaking. The higher
strength (42 to 65 strength (42 to 65 ksiksi) is achieved by adding small amounts of additional ) is achieved by adding small amounts of additional
chemical elements. Two of the most common HSLA steels are ASTM chemical elements. Two of the most common HSLA steels are ASTM
grade A572 and A588.grade A572 and A588.
High-strength quenched and tempered alloy steels:- High-strength quenched and tempered alloy steels:-
used for structural purposes are essentially available only as grade A514 used for structural purposes are essentially available only as grade A514
today. With a yield stress level of 90 to 100 today. With a yield stress level of 90 to 100 ksiksi, the increase in strength is , the increase in strength is
achieved through heat treatment. A514 is available only in plate form, up achieved through heat treatment. A514 is available only in plate form, up
to 6 inches thick.to 6 inches thick.
STEELSTEEL some elements used in structural some elements used in structural
steels:steels: Carbon Carbon (C)(C) Manganese Manganese (Mn)(Mn) Aluminum Aluminum (Al)(Al) Chromium Chromium (Cr)(Cr) Columbium Columbium (Cb)(Cb) Copper Copper (Cu)(Cu) Molybdenum Molybdenum (Mo)(Mo) Nickel Nickel (Ni)(Ni) Phosphorus Phosphorus (P)(P) and Sulfur and Sulfur (S)(S) Silicon Silicon (Si)(Si) Vanadium Vanadium (V)(V) Other chemical elementsOther chemical elements
STEELSTEELSteel AlloysSteel Alloys
Steel Alloys can be divided into five groupsSteel Alloys can be divided into five groups Carbon SteelsCarbon Steels High Strength Low Alloy SteelsHigh Strength Low Alloy Steels Quenched and Tempered SteelsQuenched and Tempered Steels Heat Treatable Low Alloy SteelsHeat Treatable Low Alloy Steels Chromium-Molybdenum SteelsChromium-Molybdenum Steels
Carbon steels are normally classified as shown Carbon steels are normally classified as shown below.below.
Low-carbon steelsLow-carbon steels:-:-
contain up to 0.30 weight percent C. The largest category contain up to 0.30 weight percent C. The largest category of this class of steel is flat-rolled products (sheet or strip) of this class of steel is flat-rolled products (sheet or strip) usually in the cold-rolled and annealed condition. The usually in the cold-rolled and annealed condition. The carbon content for these high-formability steels is very carbon content for these high-formability steels is very low, less than 0.10 weight percent C, with up to 0.4 low, less than 0.10 weight percent C, with up to 0.4 weight percent Mn. For rolled steel structural plates weight percent Mn. For rolled steel structural plates and sections, the carbon content may be increased to and sections, the carbon content may be increased to approximately 0.30 weight percent, with higher approximately 0.30 weight percent, with higher manganese up to 1.5 weight percent.manganese up to 1.5 weight percent.
STEEL STEEL classification of Carbon steel classification of Carbon steel
Medium-carbon steels:- Medium-carbon steels:-
are similar to low-carbon steels except that the carbon are similar to low-carbon steels except that the carbon
ranges from 0.30 to 0.60 weight percent and the manganese ranges from 0.30 to 0.60 weight percent and the manganese
from 0.60 to 1.65 weight percent. Increasing the carbon from 0.60 to 1.65 weight percent. Increasing the carbon
content to approximately 0.5 weight percent with an content to approximately 0.5 weight percent with an
accompanying increase in manganese allows medium-accompanying increase in manganese allows medium-
carbon steels to be used in the quenched and tempered carbon steels to be used in the quenched and tempered
condition.condition.
STEEL STEEL classifications of Carbon steelclassifications of Carbon steel
High-carbon steels:- High-carbon steels:-
contain from 0.60 to 1.00 weight percent C with manganese contain from 0.60 to 1.00 weight percent C with manganese
contents ranging from 0.30 to 0.90weight percent.contents ranging from 0.30 to 0.90weight percent.
STEEL STEEL classifications of Carbon steelclassifications of Carbon steel
High-strength low-alloy (HSLA) steels, High-strength low-alloy (HSLA) steels,
or micro alloyed steels, are designed to provide better or micro alloyed steels, are designed to provide better
mechanical properties than conventional carbon steels. They mechanical properties than conventional carbon steels. They
are designed to meet specific mechanical properties rather are designed to meet specific mechanical properties rather
than a chemical composition. The chemical composition of than a chemical composition. The chemical composition of
a specific HSLA steel may vary for different product a specific HSLA steel may vary for different product
thickness to meet mechanical property thickness to meet mechanical property
STEEL STEEL classifications of Carbon steelclassifications of Carbon steel
Requirements. The HSLA steels have low carbon contents Requirements. The HSLA steels have low carbon contents
(0.50 to ~0.25 weight percent C) in order to produce (0.50 to ~0.25 weight percent C) in order to produce
adequate formability and weld ability, and they have adequate formability and weld ability, and they have
manganese contents up to 2.0 weight percent. Small manganese contents up to 2.0 weight percent. Small
quantities of chromium, nickel, molybdenum, copper, quantities of chromium, nickel, molybdenum, copper,
nitrogen, vanadium, niobium, titanium, and zirconium are nitrogen, vanadium, niobium, titanium, and zirconium are
used in various combinations.used in various combinations.
STEEL STEEL classifications of Carbon steelclassifications of Carbon steel
Steel Material with Large Cross-sectionSteel Material with Large Cross-section
STEEL STEEL Structural Steel Sections Structural Steel Sections
Steel material with large cross-section
Thin Steel Plate:-Thin Steel Plate:-
STEEL STEEL Structural Steel Sections Structural Steel Sections
STEEL STEEL Structural Steel Sections Structural Steel Sections
Tee Bares
STEEL STEEL Structural Steel Sections Structural Steel Sections
Flat baresSquare bares
Round baresHexagon bares Square tubing
STEEL STEEL Structural Steel Sections Structural Steel Sections
Round ShaftingHoned Shafting
I Beam Section
STEEL STEEL Structural Steel Sections Structural Steel Sections
Bar Size Shapes
Structural-Size Shapes
"W" Shapes
"HP" Shapes
• "L" Shapes
STEEL STEEL Market forms of SteelMarket forms of Steel
•"S" Shapes
•"C" Shapes
•"M" Shapes
•"MC" Shapes
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 STEEL Basic DefinitionsBasic Definitions
STEEL STEEL Loads Loads
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 STEEL TrussesTrusses
STEEL STEEL Trusses Trusses
STEELSTEEL
ENDEND