Introduction b Structural Design and Analysis, and Code ... · PDF file2 INTRODUCTION b. Structural Design & Analysis, & Code Specifications Slide No. 2 Engineering Systems ENCE 355

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Fifth EditionReinforced Concrete Design
A. J. Clark School of Engineering Department of Civil and Environmental Engineering
Introduction
b
STEEL.com
ENCE 355 - Introduction to Structural DesignDepartment of Civil and Environmental Engineering
University of Maryland, College Park
Structural Design and Analysis, and Code Specifications
FALL 2002
By
Dr . Ibrahim. Assakkaf
INTRODUCTION b. Structural Design & Analysis, & Code Specifications Slide No. 1ENCE 355 Assakkaf
Structural Design
Structural design can be defined as a Structural design can be defined as a mixture of art and Science, combining mixture of art and Science, combining the engineers feeling for the behavior the engineers feeling for the behavior of a structure with a sound knowledge of a structure with a sound knowledge of the principles of of the principles of staticsstatics, dynamics, , dynamics, mechanics of materials, and structural mechanics of materials, and structural analysis, to produce a safe economical analysis, to produce a safe economical structure that will serve its intended structure that will serve its intended purpose.purpose. (Salmon and Johnson 1990)

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Engineering SystemsEngineering structural systems are of variety that they defy any attempt to enumerate them.The many problems which arise in their design have prompted engineers to specialize in the design of particular structure or groups of related structures.A complete design requires the coordinated efforts of several branches of engineering.
Engineering Systems
Civil Engineering Structures Among the structures that are design by
civil engineers are Buildings Bridges Transmission Towers Dams Highway Pavements Aircraft Landing Runways (strips) Retaining Walls

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Engineering Systems
Eiffel TowerEiffel Tower
Paris Paris 18991899
984 ft. high984 ft. high
Engineering Systems
Sears TowerSears TowerChicago Chicago -- 197419741450 ft.high1450 ft.high

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RHINE BRIDGE, COLOGNERHINE BRIDGE, COLOGNE--RODENKIRCHEN, (1946RODENKIRCHEN, (1946--47), SPAN 94.547), SPAN 94.5--378378--94.5 m94.5 m
Engineering Systems
Engineering Systems

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Hoover DamHoover Dam
ArizonaArizona--Nevada BorderNevada BorderNear Las VegasNear Las Vegas
Engineering Systems
Transmission TowersTransmission Towers
Engineering Systems

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Engineering Systems
Highway & AircraftHighway & AircraftLanding StripLanding Strip
Engineering Systems
Retaining WallsRetaining Walls

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Engineering Systems
The design of the previous groups of structures require the coordination of various disciplines in engineering, and is too large for convenient study as a unit.In this course, we will focus on the design of the individual structural elements or members that make up the whole structural system.
Engineering Systems
Such members or elements include the following: Beams Columns Trusses Shear Structural Elements Steel Rods Connection Elements

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Engineering Systems
Structural Elements Bending Structures
Engineering Systems
Structural Elements Compression Structures

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Engineering Systems
Structural Elements Trusses
Engineering Systems
Structural Elements Tension Structures

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Engineering Systems
Engineering Systems
Structural Elements Shear Structures

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Analysis Versus Design
Structural Analysis: Structural Analysis is the prediction of the
performance of a given structure under prescribed loads and/or other effects, such as support movements and temperature change.
Structural Design: Structural design is the art of utilizing
principles of statics, dynamics, and mechanics of materials to determine the size and arrangement of structural elements under prescribed loads and/or other effects.

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Design Procedure Design procedure consists of two parts:
Functional Design Structural Framework Design
Functional design ensures that intended results are achieved such as adequate working area, elevators, stairways, etc.
Structural framework design is the selection of the arrangement and sizes of structural elements so that service loads may be carried.

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Example 1: Analysis Determine the maximum flexural stress
produced by a resisting moment Mr of +5000 ftlb if the beam has the cross section shown in the figure.
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6
2
2
Example 1: Analysis (contd)First, we need to locate the neutral axis from the bottom edge:
( )( ) ( )( )
x
r
C
IyM
yyy
y
max
maxcomten
Stress Max.
5326 3
32472
62626232621
=
==+==
==+
++=
5
6
3 C
2

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Example 1: Analysis (contd)Find the moment of inertia Ix with respect to the x axis using parallel axis-theorem:
( ) ( )( ) ( ) ( )( )4
23
23
in 1364836484
13621262226
1226
=+++=
+++=xI
( ) ksi 21.2136
512)(5(com) Stress Max. ==
5
6
3 C
2
2
Example 1: Analysis (contd) An alternative way for finding the moment
of inertia Ix with respect to the x axis is as follows:
5
6
3 C
( ) ( ) ( ) 1363122
352
336 333
=
+=xI
2
2

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Example 2: DesignA pair of channels fastened back-to-back will be used as a beam to resist a bending moment Mr of 60 kN m. If the maximum flexural stress must not exceed 120 MPa, select the most economical channel section listed in Appendix B of the textbook.
Example 2: Design (contd)
2
2
hence channels, twohave weHowever, ,
MSS
MSM
==
=
( )3336
6
3
mm10250m10250101202
1060==
= S
channel 30C254Select :ledesign tab a From

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Example 2(contd)
Select
Loads
The objective

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Introduction b Structural Design and Analysis, and Code ... · PDF file2 INTRODUCTION b. Structural Design & Analysis, & Code Specifications Slide No. 2 Engineering Systems ENCE 355