High Institute for Engineering & Technology - New Damietta Civil Engineering Department 2014-2015.

Dr. Eng. Ashraf I. M.

El-Sabbagh

Dr. Eng. Ashraf I. M.

El-Sabbagh

DESIGN OF STEEL STRUCTURES (1)

CIE402

DESIGN OF STEEL STRUCTURES (1)

CIE402

High Institute for Engineering & Technology - New Damietta

Civil Engineering Department

2014-20152014-2015

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LAYOUT OF STEEL STRUCTURES

2.1 Structural Systems

Structures can be classified into two main

categories with respect to the way that the

loads act on the structure as well as the

simplicity of structural analysis:

1- Plane structures.

2- Space structures.

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The steel structures can be classified according to

type of members and their connections in to

three categories:

1- Truss structures.

2- Frame structures.

3- Combined truss and frame structures.

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a – Plane truss

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b- Single story plane frame

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c – Multistory plane frame

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d- Multistory space frame

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e – Space truss, industrial building

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f- Space truss, stadium shed

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We shall concentrate on the design of plane trusses and frames

because they are frequently used in steel structures in Egypt.

Plane structures have the following advantages:

1-Simple structural system leads to easier structural analysis.

2-Easy and fast fabrication in workshop.

3-Simple connections and fast construction.

4-Structure can be extended in future without any complications.

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2.2 Parts of Plane Steel Building

The structure is mainly composed of four main

elements:

1- Main (primary) framing system.

2- Secondary members.

3- Wind bracing system.

4- Cladding.

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2.2 Parts of Plane Steel Building

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2.2 Parts of Plane Steel Building - Cladding

The construction of the external skin of a building can

take several forms, the most prevalent being:

(1) Single-skin trapezoidal shell

(2) Double-skin trapezoidal shell

(3) Standing seam with concealed fixings

(4) Composite panels.

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2.2 Parts of Plane Steel Building - Cladding

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2.2 Parts of Plane Steel Building – Secondary Elements

Secondary members are mainly:

• Purlins which carry roof cladding.

• Side-girts and end-wall-girts which carry wall cladding.

A combination of cladding performance, erect-ability

and the restraint requirements for economically-

designed main frames dictates that the purlin and rail

spacing should be 1.5–2m.

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2.2 Parts of Plane Steel Building – Secondary Elements

SIB IPE Channel

Cold Formed Channel

Cold Formed Z

Cold Formed Lipped Channel

Cold Formed Lipped Z

Stiffened Unstiffened

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2.3 Main Framing Systems

Trusses for Building Roof

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Pratt (N) Truss with Non-Parallel Chords

Span (L ≤ 34 m)

h

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H

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Pratt (N) Truss with Parallel Chords

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Sub-divided Pratt (N) trussSpan ≥ 35 m

Sub-divided Howe trussSpan ≥ 35 m

Sub-divided Warren (W) trussSpan ≥ 35 m

2.5 – 4.5 m

2.5 – 4.5 m

2.5 – 4.5 m

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Non-Parallel Chords

Parallel Chords


Span (L = n x a)

h

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The spacing: of the main system frames is normally in the range: S= 5 8m, with 6.0 m and

7.5 m as the most common spacings.

Panel length, a = 1.5 2.5 m, anL , number of panels (n) must be even number (10, 12,

14, …),. To satisfy the angle of web members ( 5535a ) the panel length shall satisfy

Hah . If a>2.5 m use subdivided truss.

Slope of upper chord of truss, 5:1 20:1, but 10:1 is commonly used (Slope k:1).

Non-Parallel Chords

Parallel Chords


Span (L = n x a)

h

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H

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Depth of main truss, 1610

L

H , where, L =span of main truss.

,25.11

2 min mhk

LHh otherwise, increase the depth (H).

Or simply take mhah 25.1min

Non-Parallel Chords

Parallel Chords


Span (L = n x a)

h

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1k

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2.4 Wind Bracing Systems

The main functions of bracing systems are:

1- Resist and horizontal forces in the out-of-plane

direction of the main system (long direction of the

building).

2- Hold the structure during construction.

3- Reduce buckling length of upper chord out-of-plane.

4- Brace the whole structure in the long direction.

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2.4 Wind Bracing Systems

Bracing system must be made in the first and last panels

with spacing between 25 – 30 m in the long direction.

Horizontal bracing works as a horizontal truss to

withstand wind forces and transmit them to the

vertical bracing which in turn transmits them to

foundation.

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2.5 End Gable

It is the system that carries the walls, windows, and

doors at the end sections of the building.

It consists of: end gable columns that carry the end

gable girts (beams) that are carry the cladding,

windows, and doors.

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2.5 End Gable

• The spacing between columns is

commonly between (4.0 – 8.0 m).

• The vertical spacing between girts (1.5 – 2.0 m).

• Window height is taken (1.0 – 1.5 m).

• Brick wall height (2.0 – 4.0 m) with minimum

thickness (25 cm).

• They are most of the common forms provide

resistance to sidesway forces such as wind loads

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2.6 Structural Layout

Structural layout is the drawing that shows the main

dimensions and components of the structure.

The typical scale of steel layout drawing is usually 1:100

or 1:200 for large areas.

The main components that must be shown after

removing of all cladding:

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The main components that must be shown after

removing of all cladding:

1- Plan view

2- Elevation view

3- Side view.

4- End gable side view.

5- Intermediate vertical bracing (truss system).

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High Institute for Engineering & Technology - New Damietta Civil Engineering Department 2014-2015.

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Transcript of High Institute for Engineering & Technology - New Damietta Civil Engineering Department 2014-2015.