BT Part 4.1 - Structural Steel Construction, Steel Columns & Beams, Metal Decking, Steel Trusses, Framing, Finishing Systems

American Standard Steel (ASS)

The most common shapes of structural steel used in buildings are the ____________.

I-Beams

The use of a standard I-beam as a column is uneconomical because the whirl or revolving action of the member about an axis through the centroid of the web

1. Square Bars

2. Round Bars

3. Plate Bars

4. Angle Bars

Structural Steel Shapes such as:

Channels 

The shape of unsymmetrical balance consisting of two flanges on one side. It requires lateral support to prevent its tendency to buckle.

Wide Flanges

Sections are designated as W 12 x 24 which mean that the flange has a depth of 24 cm and weighs 12 kg per meter length

>  With parallel face flange except those with 5% slope 

Zees

Another structural form in a letter Z which is not frequently used in building construction except for the fabrication of steel windows and other frame

Structural steel girders, beams, and columns

Used to construct a skeleton frame for structures ranging in size from one-story to skyscrapers.

Structural steel

May be left exposed in unprotected non-combustible construction, but because steel can lose strength rapidly in a fire, fire-rated assemblies or coatings are required to qualify as fire-resistive construction.

1. One-Way Beam System

2. Two-Way Beam System

3. Three-Way Beam System

The three major types of framing systems are the following:

One-Way Beam System

Each pair of external columns supports a long-spanning beam or girders.

> Suitable for long, narrow buildings, especially when a column-free space is desired

> Absence of columns in the interior is an advantage in structures such as car parks

Two-Way Beam System 

A two-layer system, where beams frame into girders, increases floor depth considerably and provides more space for mechanical systems

Three-Way Beam System

Used when a large column-free space is required, where long-spanning plate girders or trusses  can be used to carry the primary beam

> support a layer of secondary beams

Struts of one or two angles

Used for compression members in roof trusses, light towers, and lattice girders

double struts

The two angles of ______ are riveted together by rivets driven through washers placed between the two angles at intervals of 4 to 6 ft.

Starred angles of two or four

Connected by batten plate spaced at intervals of 3 to 4ft.

> These are used to support the light loads

Latticed Columns

Made up of channels or angles connected by lattice bars are often used where light loads are to be supported on long columns.

Rolled H-columns

Obtainable with depths ranging from 6” to 16”

> Now commonly used instead of built-up columns in steel skeleton construction

c. Built-up Columns

These are usually of H- shaped section formed by a combination of plates and angles although box columns with two or more webs

Top Chord

Sections of heavy trusses are usually unsymmetrical

> Made of two rolled or built-up channel sections and a cover plate

Columns for bents

Up of a pair of channels and an I – beam with batten plates at intervals of 3 to 4 ft. connecting the flanges of the channels

Battened columns

Component parts of the column are connected only by batten plates

>  Inferior to latticed columns and should be avoided if a continuous plate

Tie-plates

To have not less than 4 rivets and are to be spaced so that the ratio of length to the least radius of gyration of the parts connected does not exceed 40

Base plates

________ for steel column are usually made of steel plates and shapes

Lally Columns

Made up of a cylindrical steel pipe shell filled with 1:1-1/2:3 Portland cement concrete

>  with only the steel pipe shell

Composite Columns

Further reinforced with a steel or cast-iron core to support a part of the load.

Steel cores

_______ may be structural H-sections or four angles, latticed or battened; cast-iron cores are usually either solid shafts or hollow pipe sections. 

Steel Beams

May be rolled in the shape of the letter I (I-beams), channel beams or angles.

Girders

May be built up of angles and plates riveted together for long spans and for unusual cases of very heavy loading

Plate Girders

A beam composed of a wide plate, known as a web, at the top and bottom of which are riveted angles and plates.

> Simplest type

Stiffener Angles

The web may be frequently reinforced against buckling by angles riveted to its sides

Box Girders

A built-up beam in which more than one web plate is used.

Seated connection

Bottom flange of the beam rests on and is field-riveted to an angle shop-riveted to the flange or web of the column

Frammed connection

The web of the beam or girder is connected by angles or by gusset- plates to the column

Moment Connections

AISC Type 1 - also called Rigid Frame connections

> are able to hold their original angle under loading

Shear Connections

AISC Type 2 – Simple Frame connections are made to resist only shear and are free to rotate under gravity loads. 

Semi Rigid Connections

AISC Type 3 – Cconnections assume beam and girder connections possess a limited but known moment resisting capacity.

Open web joists

Lightweight; shop fabricated steel members having a trussed web.

K series joist

______ has a web consisting of a single bent bar, running in a zigzag pattern between the upper and lower chords.

Metal decking

Corrugated steel panels used as a working platform during construction and eventually as formwork for site cast concrete slab.

Form Decking 

Serves as a permanent formwork for a reinforced concrete slab until the slab can support itself and its live load

Composite Decking

Serves as a tensile reinforcement for the concrete slab to which it is bonded with embossed rib pattern.

Cellular Decking

Manufactured by welding a corrugated sheet to a flat steel sheet, forming a series of spaces or raceways for electrical and communications wiring;

Complete Frame

A complete structural frame, or truss, is one in which is made up of the minimum number of members required to provide a complete system of triangles fixing

Incomplete Frame

One in which the number of members is less than that required by the equation given above

Redundant Frame

One which contains more members than that required by the equation given above.

Simple Truss

A truss supported at each end-point.

Overhanging end span

A truss supported at one end-joint and other joint not an end-joint.

Cantilever span

 A truss where the entire support is at one end only.

Petit

What type of truss is this?

Warren

What type of truss is this?

Deck Warren

What type of truss is this?

Parker or Camel-back

What type of truss is this?

Pratt

What type of truss is this?

Baltimore

What type of truss is this?

Pennsylvania or Petit

What type of truss is this?

K Truss

What type of truss is this?

Rigid frames

Consist of two columns and a beam or girder that is rigidly connected at their joints.

> Applied loads produce axial, bending and shear forces in all members of the frame 

The structure is composed of rigid frames which may comprise some hinged joints but there must be sufficient rigid joints to ensure that none of the nodes of the frame is free to move sideways.

What type of method us this for framing system?

A bracing system which consists of a triangulated framework of rolled sections will hold the joints together and further strengthen the framework against lateral loads. 

What type of method us this for framing system?

Finally, shear walls in the form of more or less solid diaphragms, usually of reinforced concrete,vtransmit the wind and earthquake forces by shear and bending.

What type of method us this for framing system?

Tubular Frame

The high-rise building conceived as a rigid tube.

> This stiffening system is particularly effective and economical.

external lattice bracing or with spandrel girders

If a high-rise building is of suitably compact shape on plan (circular, square, rectangle), the external columns can be structurally merged with the ___________ so as to form a vast rigid tube.

Riveting

A short pin, of malleable metal such as iron, steel, or copper, with a head at one end; used to unite two metal plates by passing it through a hole in both plates

Countersunk, raised

What type of rivet is this?

Countersunk, flat

What type of rivet is this?

Button, coned neck

What type of rivet is this?

Button, straight neck

What type of rivet is this?

Pan, coned neck

What type of rivet is this?

Pan, straight neck

What type of rivet is this?

Carbon-steel bolts

Having no specified minimum content of alloying elements

>  minimum copper content not exceeding 0.40%.

High-strength bolts

Bolts made of either high-strength carbon steel or quenched and tempered alloy steel; tempered meaning, heat treated during manufacture

• Turn-of-nut method

• Load indicator washer

• Tension control bolts

There are several ways to achieve proper tightening:

Round head stove bolt

What type of bolt?

Flat head stove bolt

What type of bolt?

Carriage Bolt

What type of bolt?

Square head machine bolt

What type of bolt?

Welding

Fully accepted as a means of joining steel structural members in buildings because it has the inherent advantage of fusing the metals to be joined

Fusion welding

Process employs an electric arc, wherein energy in the form of heat is supplied by establishing an arc between the base or parent metal

Coated Electroades

The function of the coating is to form a gaseous shield, which protects the arc and molten metal from contact with the air.

Oxides and nitrides

________ resulting from contact with the air tend to produce brittle welds. 

Fillet Weld

Approximately triangular section joining two surfaces approximately at right angles to each other

Groove Weld

Made by depositing filler material in a groove between two members to be joined.

> Types: square, V, bevel-U, and J

Plug or Slot Weld

Made of a circular hole (plug) or an elongated hole (slot) in one member of a lap joint

Overhead welds

Which are the most difficult, should be avoided whenever possible

C-Studs

A vertical, C-shaped galvanized steel component used to build non-load-bearing partition walls and drylining systems

Channel Studs

Cold-formed, U- or C-shaped galvanized steel profiles used to frame interior and exterior partitions