Enesteel - Modern Structural Steel

MODERN STRUCTURAL STEEL

www.enesteel.com

WHAT YOU WILL GAIN FROM THIS PRESENTATION?

• The primary objective of this

presentation is to reflect the

latest updates in using structural

steel in modern projects.

• Identify the advantages of steel

for design & construction.

• In addition to show some

important structural steel details

& requirements.

CONTENT

PART 1

• STRUCTURAL STEEL HISTORY

• FAMOUS LANDMARKS

• ADVANTAGES OF STRUCTURAL STEEL

• DISADVANTAGES OF STRUCTURAL STEEL

• STANDARDS & CODES

• STEEL SECTIONS

• ASTM SPECIFICATIONS FOR STEEL SECTIONS

• ASTM SPECIFICATIONS FOR BOLTS

• WELDING

• STRUCTURAL STEEL DESIGN METHODS

• CONSTRUCTION PROCESS

PART 2

• STRUCTURAL SYSTEMS

• MULTI-STOREY BUILDINGS

• LONG-SPAN STRUCTURES

• FIRE PROTECTION SYSTEMS

• CORROSION PROTECTION SYSTEMS

MODERN STRUCTURAL STEEL HISTORY

• The use of steel for structural purposes

was initially slow.

• The Bessemer process in 1855 made steel

production more efficient, and cheap

steels.

• High tensile and compressive strengths

plus good ductility were available from

about 1870.

• In the United States, the first steel framed

building was the Rand McNally Building in

Chicago, erected in 1890.

• The Royal Insurance Building in Liverpool

was the first to use a steel frame in the

United Kingdom, erected in 1903.

Rand McNally Building

Royal Insurance Building

FAMOUS LANDMARKS OF STEEL STRUCTURES

Statue of Liberty

Location: U.S.A

Completed: 1886

Eiffel Tower

Location: France

Completed: 1889


Golden Gate Bridge

Location: U.S.A

Completed: 1937

Atomium Building

Location: Belgium

Completed: 1958


Oita Stadium

Location: Japan

Completed: 2001

Swiss Re Tower

Location: England

Completed: 2004

ADVANTAGES OF STEEL AS STRUCTURAL MATERIAL

• Ductility property; that means extensive deformation without

failure.

• High strength of steel per unit of weight; this fact is great

importance for long-span & tall buildings.

• Sustainable; steel is the most recycled material on the planet,

accordance to international organizations, such as (AISC).

• Additions to existing structures.

• Speed of erection.

DISADVANTAGES OF STEEL AS STRUCTURAL MATERIAL

• Brittle fracture; if steel lose its ductility the brittle fracture may

occur at places of stress concentration.

• Fatigue; steel strength may be reduced if the steel is subjected to

a large number of stress reversal.

• Susceptibility to buckling.

• Maintenance cost.

• Fireproofing cost.

Several organizations publish recommended practices for structural

steel, such as:

ASTM: American society for testing & materials.

AISC: American institute for steel construction.

AISI: American iron & steel institute.

AWS: American welding society.

STANDARDS & CODES

STEEL SECTIONS

• Hot-rolled shapes.

Suitable for primary members

(columns, girders, beams…etc.)

Hot-rolled steel column

Hot-rolled steel beam

STEEL SECTIONS

• Cold-formed shapes.

Suitable for secondary members

(purlins, girts, studs…etc.)

Cold-formed steel purlin

Cold-formed steel girt

STEEL SECTIONS

• Built-up shapes.

Suitable for primary members

(columns, girders, beams…etc.)

Built-up steel column

ASTM SPECIFICATIONS FOR STEEL (SHAPES & PLATES)

• Carbon steel; carbon percentage (0.15 to 0.29)%, the very

common steel A36 (Fy=36ksi & Fu=58ksi); suitable for buildings

& bridges.

• High strength Low-alloy steel; this type has much greater

atmospheric corrosion resistance than the carbon steel. A572

Gr.50 (Fy=50ksi & Fu=60ksi); suitable for buildings & bridges.

Note:

Fy: Yield stress.

Fu: Ultimate strength.

ASTM SPECIFICATIONS FOR (BOLTS & ANCHOR BOLTS)

Common bolts:

• A307: (Ft=20ksi) (for secondary connections & anchor bolts).

• A325: (Ft=44ksi) (for primary connections & anchor bolts).

• A490: (Ft=54ksi) (for primary connections & anchor bolts).

Note: Grade of bolt

Ft: Tension stress.

All bolts shall be galvanized.

WELDING

• Welding is a process in which metallic

parts are connected by heating their

surfaces to fluid state, and allowing the

parts to flow together and join.

• The two main types of welds

are fillet & groove welds.

• Welding strengths accordance

to AWS standard:

E60XX, E70XX to E110XX

E60XX: Electrode 60ksi (410Mpa)

1st X : Welding position

2nd X: Coating current & condition

STRUCTURAL STEEL DESIGN METHODS

American institute for steel construction (AISC) presented two

structural design methods:

• ASD: Allowable stress design method.

• LRFD: Load & resistance factor design method.

Note:

You cannot switch between the two

design philosophies in a given project!

CONSTRUCTION PROCESS

1. Engineering (Design).

2. Engineering (Detailing).

3. Fabrication.

4. Erection.

Discussion

• The structural designer arranges

the structural systems & their

parts so that they satisfactorily

support the loads.

• Maintaining the architectural &

MEP requirements.

• Finally, present that in design

drawings & reports.

1. Engineering (Design)

• During the detailing process, the

detailer develops shop drawings

for each member & part for

fabrication & erection purposes.

• Each member is assigned a

unique piece mark for

identification & tracking.

• The detailer also prepares a

(BOM) list.

2. Engineering (Detailing)

3. Fabrication

• Raw steel used for fabrication shall well-stored in stockyard.

• After preparation of raw material; structural steel members are

fabricated by precisely cutting, shearing, punching, drilling,

bending, fitting and welding in order to produce the

configurations detailed in the shop drawings.

• Each member is labeled with a piece mark, length, and job

number for identification & tracking.

3. Fabrication (Continue)

• Surface preparation of fabricated members to be ready for

applying paint or galvanization.

• After fabrication, finished structural steel members are stored in

the storage yard according to erection sequences.

• The practice of planning and storing by sequence improves the

efficiency of loading, delivery, offloading and erection.

4. Erection

• Anchor bolts are placed in exact locations, & accordance to

erection drawings.

• Cranes are placed in suitable locations.

• The structural steel members are hoisted into position &

preliminary bolted.

4. Erection (Continue)

• Temporary bracing is used to provide lateral stability to the

structure.

• Plumbing up the structure,

• Finally bolt-up using torque - wrench.

4. Erection (Continue)

Note:

Safety cables & safety mesh, shall be installed during construction.

GENERAL STRUCTURAL SYSTEMS

Rafter

Column

Ground Beam

Bracing

Stringer Beam

For Staircase

Purlin

Foundation System

Studs

Girt

Framed Openings

Floor Beams

Runner

STRUCTURAL SYSTEMS

The material of the next few slides gives a general idea for two types

of structural steel systems:

1. MULTI-SOREY BUILDINGS.

2. LONG-SPAN STRUCTURES.

• Office buildings, hotels, apartments &

other multi-storey buildings are quite

common at present time!

• All of these buildings have the same

structural systems:

1.A. Gravity loads resisting system.

1.B. Lateral loads resisting system.

Discussion

1. MULTI-STOREY BUILDINGS

The most common types of floor systems currently used for (GLRS) are:

Cast in situ concrete slabPrecast – concrete planksConcrete fill on metal deck

21Supporting system option:

1- Girder or beam.

2- Open web steel joist.

* The spacing of columns

depends on the load-bearing

resistance of the floor

structures. It can vary from 3

to 12m. (With Limitations).

1.A. GRAVITY LOADS RESISTING SYSTEM (GLRS).

Open web joist systemFloor truss systemFloor beam system

Shear studsDuctwork & piping systemDuctwork & piping system

1.A. GRAVITY LOADS RESISTING SYSTEM (GLRS).

The most common types of frame systems currently used for (LLRS) are:

Braced frame by bracings or shear wallRigid frame

1.B. LATERAL LOADS RESISTING SYSTEMS (LLRS).

Other samples of (LLRS) frame systems:

Braced frameRigid frame

1.B. LATERAL LOADS RESISTING SYSTEMS (LLRS).

• When it becomes necessary to use very

large spans between columns as for

hangars, halls, exhibitions, auditoriums,

hotel ballrooms, theaters, stadium

roof…etc. The usual skeleton

construction may not be sufficient. The

below systems are the most common

for these long-spans:

2.A. Girders.

2.B. Vierendeel girders.

2.C. Rigid frames.

2.D. Arches.

2.E. Trusses.

2.F. Space structures.

2.G. Latticed shells.

Discussion

2. LONG-SPAN STRUCTURES

• Girders are large I or box-shaped.

• Typically used for long-span floor

in buildings, bridges & roof

systems.

• Suitable for spans up to 20m.

(With Limitations).

2.A. GIRDERS

• Vierendeel girder is moment

truss with or without diagonals.

• Typically used for long-span floor

in buildings, bridges & roof

systems.


(With Limitations).

2.B. VIERENDEEL GIRDERS

• Rigid frame consisting of

members joined together with

moment connections.

• Used for hangars, factories,

warehouses & roof systems.


(With Limitations).

2.C. RIGID FRAMES

• Arches consisting of members

joined together with moment

connections.

• Used for hangars, factories,

warehouses & roof systems.


(With Limitations).

2.D. ARCHES

• Trusses consisting of members

joined together with pinned

connections.

• Used for long-span floors,

hangars, bridges & roof systems.


(With Limitations).

2.E. TRUSSES

• Space structures consisting of

members joined together in

three dimensional.

• Used for long-span canopies,

domes & roof systems.


(With Limitations).

2.F. SPACE STRUCTURES

• Latticed shells consisting of

members joined together

diagonally in three dimensional.

• Used for long-span canopies,

domes, vaults & roof systems.


(With Limitations).

2.G. LATTICED SHELLS

FIRE PROTECTION FOR STEEL STRUCTURES

• GypsumThis material takes several forms

to be used for fire protection,

such as:

(Plaster applied over metal lath

or gypsum lath, & Wallboard)

FIRE PROTECTION SYSTEMS


• Spray-AppliedThe most widely used

materials are (mineral fiber and

cementations materials) that are

spray applied directly to steel

members.

• Suspended CeilingWide variety of proprietary

suspended ceiling systems are

also available for protecting

floors beams and girders.


• Concrete & BricksOnce widely used for fire

protecting structural steel, is not

particularly efficient for this

application because of its weight

and relatively high thermal

conductivity.

As a result, concrete is rarely

used when the purpose is fire

protection only!!

• Intumescent CoatingsIntumescent coatings are epoxy based paint-like mixtures applied

to the primed steel surface, which at elevated temperatures

expand to many times their applied thickness.

CORROSION PROTECTION

• Typical Atmospheric corrosion occurs when steel is exposed to

a continuous supply of water and oxygen.

• The rate of corrosion can be reduced if a barrier is used to keep

water and oxygen from contact with the surface of bare steel.

• Painting is a practical and cost effective way to protect steel

from corrosion, by using (Polyester, Alkyd & Epoxy

paints…etc.).

• Dry film thickness (DFT) & number of coats depends on type of

structure, environment …etc.

• Each paint color has a unique RAL number.

CORROSION PROTECTION

• Galvanized steel is another alternative protection system.

• Duplex System, Galvanized Steel & Painted.

• Electrical methods (Cathodic & Anodic) protection systems are

suitable for marine steel structures.

Any Question

Thank You

Prepared By:

Eng. Osama Al-Bustanji

[email protected]

[email protected]