Structural Steel and Timber Design
Double Storey Steel Building
Student Name : Herry Hartono
Student ID : 1001128753
Course : Civil Engineering
Lecturer : Mr. Taha MJ Aleisawy
Date of Submission : Monday, 5th
of August 2013
Faculty of Engineering, Technology and Built Environment
I hereby declare that design project entitles “Double Storey Steel Building” submitted
to Mr. Taha, has followed the procedure as mentioned in British Standard 5950-1:2000. The
design here submitted is original work done by the guidance of Mr. Taha, STAADPro lab
tutor and Mr. Lee, Structural Steel and Timber Design lecturer. This design has applied the
ethics from design process until the final proposed design. Safety measures have also been
included in the design so as to uphold the public safety. This design is submitted in the
fulfilment of the completion of the Structural Steel and Timber Design course. Designs
embodies in this report have not been submitted by any other person, university or institute.
This project is to design a double storey steel building by using structural design software,
STAAD Pro 2007. Design of this building follows the British Standards 5950-1:2000.
Several dead loads and live load are imposed on columns, beams, purlins and truss members
that are made of Universal Beam and angle section. The design is checked for its maximum
capacity (compression, tension and shearing) to guarantee its safety. Most importantly, the
section was not merely chosen, but it satisfies certain important criteria. The design obtained
from the STAAD.Pro analysis was verified by the hand-calculation and it was proven to be
an effective design for the building.
I owe a debt of gratitude to Mr. Taha, my STAAD.Pro lab tutor, for his assistance,
supports, guidance and advices which inspired me throughout this semester. He has taught
me many things that I need to complete this design project.
It is also my duty to record my thankfulness to Mr. Lee, my Structural Steel and
Timber Design lecturer, who has given us precious knowledge and made the subjects easily-
Without the assistances and guidance from both my lecturer and my tutor, completion
of this design project would not have been possible.
TABLE OF CONTENTS
Chapter 1 – Introduction to Steel Structure
1.1. Steel Definition ……………………………………………………………… 1
1.2. History of Steel ……………………………………………………………… 3
1.3. Steel Structure Element
1.3.1. Truss ……………………………………………………………… 4
1.3.2. Beam ……………………………………………………………… 5
1.3.3. Column …………………………………………………………… 7
1.4. Merits and Limitations of Steel Structure …………………………………… 9
1.5. STAAD.Pro 2007 Review …………………………………………………… 10
Chapter 2 – Project Design
2.1. Problem Statement …………………………………………………………... 11
2.2. Problem Formulation ………………………………………………………… 12
2.3. Design Specification ………………………………………………………… 13
2.4. Potential Problem ……………………………………………………………. 15
2.5. Safety Measures ……………………………………………………………... 16
Chapter 3 – STAAD.Pro Analysis and Results
3.1. Project Design Approach ……………………………………………………. 17
3.2. Detailed Engineering Analysis and Design …………………………………. 19
3.3. STAAD.Pro Analysis Results ……………………………………………….. 24
Chapter 4 – Hand Calculation Results 30
CHAPTER 1 – INTRODUCTION TO STEEL STRUCTURE
1.1. STEEL DEFINITION
Gary S. Berman (n.d.) stated that steel is a common building material used throughout
the construction industry. It forms the skeleton for the building or structure and basically
holds everything together.
Steel is widely used as a building material. It is because of its design simplicity,
mechanical properties and ease and speed of construction. If there is any extension needed on
a steel structure, the new structures can be just welded or bolted to the existing structure.
And, still it will give the same strength. Steel has a variety of properties to suit different
requirements which are strength, ductility, weldability and corrosion resistance. Besides, steel
has also a special feature. It will not break directly when it is loaded with excessive loading.
It will buckle first, until it reaches its maximum capacity, then only it fails. This feature is
explained in the Figure 1.1. (William, n.d., Chapter 1)
Figure 1.1. Stress – Strain Curve of Steel (“True Stress – True Strain Curve,” n.d.)
Steel will go through the yield point before it reaches the ultimate stress. Usually, the
steel structure will be designed on its yield point. Reason being is to save cost since the steel
structure is expensive. So, basically, the steel is stretched until it deforms to its yield point.
Thus, the steel structure length is extended and the needs of more steel pieces can be reduced.
Steel is shaped into several sections for the construction purposes which are I-section
(Universal Beam), H-section (Universal Column), circular hollow section (CHS), rectangular
hollow section (RHS), square hollow section (SHS), unequal angles, equal angles, double
angles and many other shapes. This is why steel is preferred to be used in the construction as
compared of concrete and timber. There are many sections available in the market. The
engineer only needs to choose which design suits his design requirements. Other than that,
this might cut off the cost of construction as well. The chosen design unquestionably satisfies
the building requirements.
Figure 1.2. Steel Structure Shapes (“Structural Steel,” n.d.)
1.2. HISTORY OF STEEL
During the Pre-100 AD, steel has been produced on a small scale for thousands of
years. Turkey was the first location of the first steel excavated. It was 4000 years old. Roman,
Iberian and Chinese civilisations used steel to construct weapons. However, they were not
capable in production steel yet, therefore, its uses was limited and subject to very long
production times. Comes to year 300 BC – 1700 AD, steel called Damascus had been
produced. It was back in India around 300 BC, during the Crusades of the Middle Ages that it
required its legendary status. Damascus steel could be bent under pressure without breaking
but could also hold its edge and the civilisation that mastered its production were feared.
On the year 1855 AD, the production of steel was eased by the invention of Bessemer
process in 1866 by British metallurgist, Sir Henry Bessemer. He realised that the molten iron
unites readily with oxygen. So a strong blast of air through molten pig iron should convert the
pig iron into steel by reducing its carbon content. At first, the carbon content was reduced too
much, and further experimentation led to the addition of spiegeleisen – a compound of iron,
manganese and carbon – to the Bessemer process. The manganese removes the excess
oxygen in the form of manganese oxide, which passes into the slag and the carbon remains
behind, converting the molten iron into steel. The blast of air through the molten pig iron,
followed by the addition of a small quantity of molten Spiegel, converts the large mass of
molten pig iron into steel in just minutes, without any additional fuel. (Spoerl, n.d.)
In 1950, Bessemer process has become outdated, and was replaced by the introduction
of basic oxygen steelmaking (BOS) which limits impurities and can even process old scrap
metal into steel, lowering wastage and increasing efficiency. Nowadays, BOS has been
widely used for steelmaking process. (Serisier, 2011)
Steel is a predictable material and during the 1990’s, the industry had implemented
new procedures for designing steel structures. Structural design has evolved, mostly due to
the necessity caused by earthquakes. Until the 1970’s, structures were designed using proven
formulas, but the calculations were done by hand. Today, software is already available on the
PC for the structural analysis which provides faster calculation compared to hand. (Berman,
1.3. STEEL STRUCTURE ELEMENT
A truss is a triangular framework of elements that act primarily in tension and
compression. When loads are applied to a truss only at the joints, forces are transmitted only
in the direction of each of its members. Hence, the members only experience tension or
compression force. There is not bending moment occurred. Truss has a high strength to
weight ratio and consequently is used in many structures, from bridges, to roof supports, to
space stations. (“Bridge Designer,” n.d.)
Truss usually is very light, but very stiff form of construction. Before the welding was
developed (pre 1930s), the truss was connected by truss girders. Rolled section and plate
sizes were of limited range as well. (“Truss Bridges,” n.d.)
Truss is considered expensive to fabricate today, being labour intensive, and
maintenance issues have to be carefully addresses. However, they can still show advantages
in particular application such as footbridges and railway bridges. Typical spans in one form
or other can range from 40 m to 500 m. (“Truss Bridges,” n.d.)
Figure 1.3. State Highway Bridge No. 16 over the Kickapoo River, Vernon County, WI (“Bridge Contest,” n.d.)
The benefits of using trusses in the construction are: (“Construction Component,”
Time saving – delay minimization
Cost saving – easily remodelled, repair and maintain
Materials saving – less material, high bearing strength
Labor saving – construction time reduction
However, the truss has also disadvantages. It needs to be wasted if not properly
designed. Other than that, sometimes, the structure can have a zero member force. It means
the member does not carry any internal force. So it can be considered as material waste.
(“Advantages of Truss Bridges,” n.d.)
On this project, truss was used to design the roof of the double storey steel building.
Truss will carry the all loading imposed on the roof, including wind load, live load and roof
insulation (dead load). From loading applied on the roof, will be transferred into compression
and tension loading in the truss members and will eventually go to the column that supports
it. Most of the times, the roof truss comes with purlins to connect or become a bridge
between a roof truss to another.
A structural beam is a component used in construction to add strength to any structure
or design. Manufactured of steel, concrete or wood, the structural beam is typically used to
span an open element of a structure, as well as to give support underneath a very heavy
component of a structure. I beam (Universal Beam) is the most common type of beam used.
Concrete structural beam manufacture often involves a steel I beam as the reinforcement in
concrete for use in building bridges, buildings, and other concrete structures. Besides,
channel section and angle are sometimes used also for the beam. (“What is a Structural
Beam,” n.d.). Beside concrete and steel, beam can be made of plastic and wood.
Below are the common sections that are used for the beam design.
Figure 1.4. Beam Sections (“Members Subjected to Flexural Loads,” n.d.)
On the construction, there are some combinations of beam supports that can be
installed. Different combination of the supports, the response of the beam towards the applied
load would be different as well. The most common combinations used are cantilever beam
(fixed – free) and simply-supported beam (pin – roller or pin – pin).
Figure 1.5. Cantilever Beam (“Understanding Calculus,” n.d.)
Figure 1.6. Simply-Supported Beam (Prashant, 2013)
Problem that usually beam has is bending. Why bending? Because it is loaded with
lateral loading. Therefore, if it is observed from the cross sectional area of the beam (assumed
the loading is imposed from the top), the top part of the beam will experience axial
compression, whereas the bottom part will experience axial tension.
According to the Tata Steel (n.d.), the bending strength may be limited by material
strength, lateral-torsional buckling or local buckling. Three types of failure on beam structure
are material failure causing a plastic hinge to form (bending), lateral torsional buckling along
the length of the beam, and local buckling of the beam cross section.
Figure 1.7. Types of Beam Failure: (a) Plastic Hinge, (b) Side Buckling, (c) Web Buckling and (d) Flange Buckling
(Tata Steel, n.d.)
On this project, the beam section used is Universal Beam (I-Beam). Since the beams
are all primary beams, therefore, they have to be checked for its web bearing and web
buckling. Most importantly, the shear buckling, shear capacity, moment capacity and
allowable deflection must be checked first before assigning a section. This is to ensure the
safety of the building constructed.
Column is a vertical structural member that transmits the load from ceiling/ roof slab
and beam, including its self-weight to the foundation. Columns are normally subjected to a
pure compressive load. The most common used columns are RCC (Reinforced Concrete)
columns. (Arun, n.d.)
Caprani (n.d.) mentioned two main parameters governing column design.
Bracing: if the column can sway, additional moments are generated through the P – δ
effect. This does not affect braced column.
Slenderness ratio: The effective length divided by the lateral dimension of the
column. Low values indicate a crushing failure, while high values denote buckling.
Figure 1.8. Effective Length of Different Supports Combination of Column (“Basic Calculation of Column Buckling,” n.d.)
There are many sections that can be used for the column such as channel section and
angle section. However, H-section (Universal Column) is the most commonly used section.
Figure 1.9. H-Section Steel Column (“H-Section Steel Column,” n.d.)
The steel column can also fail if the design is not done properly. A long compression
member may fail due to buckling stress whereas the short compression member may fail due
to yielding of material. Buckling of a column may occur even the maximum stresses in the
material are less than the yield point of the material. Buckling means lateral deflection of the
column. (“Definition of Column,” 2011)
Figure 1.10. Column Buckling (“The Cardington Fire Test,” n.d.)
On this project, the column is designed by using Universal Beam instead of Universal
Column. Universal Beam will be more vulnerable to buckle as compared of Universal
Column. Universal Column has approximately the same magnitude of flange width and web
length, whereas, the Universal Beam has the web length greater than the flange width.
Therefore, web buckling might happen on UB column. Nevertheless, if the design is done
properly according to the specification, it is hoped the section will not show any sign of
1.4. MERITS AND LIMITATIONS OF STEEL STRUCTURE
Steel structures have been the main choice nowadays in the construction because of
many advantages that it offers. Fast construction is the main reason why many company or
contractor goes for steel structure instead of concrete or timber. Other than that, steel
structure can be extended easily if necessary.
According to Adeli (n.d.), the following are the advantages of adapting steel structures
in the construction:
High strength/ weight ratio – dead weight of steel structures is relatively small. Thus
property makes steel a very attractive structural material for high-rise buildings, long-
span bridges, and structures located on soft ground.
Ductility – steel passes through large plastic deformation before failure.
Predictable material properties – steel properties do not change considerably with
Quality of construction – produced high-quality product.
Ease of repair
Adaptation of prefabrication – suitable for mass construction.
Repetitive use – can be reused after being disassembled.
Expanding existing structures – easily expanded by adding new bays or wings.
Fatigue strength – steel has good fatigue strength.
However, steel structure has also some disadvantages that have to be taken into
consideration of choosing as the building materials:
More expensive compared to concrete and timber.
Need to have fireproofing in order to not lose its strength.
Susceptible to corrosion. There might need to apply corrosion-resistant chemicals.
Susceptible to buckling (more slender).
Thereafter, a structural engineer must be very wise in choosing the section of
materials for the building. Steel structures do give a lot of advantages as compared to the
concrete and timber, but it still depends on the application and location of the building itself.
1.5. STAAD.PRO 2007 REVIEW
STAAD in STAADPro stands for Structural Analysis and Design. It is the most well-
known engineering structural design software. According to “STAAD.Pro V8i” (n.d.),
STAAD.Pro is the structural engineering professional’s choice for steel, concrete, timber,
aluminium and cold-formed steel design of virtually any structure though its flexible
modelling environment, advanced features, and fluent data collaboration.
Figure 1.11. STAAD.Pro 2007 New Project Interface
STAAD.Pro is a comprehensive integrated FEA (Finite Element Analysis) and design
solution, including a state of the art used interface, visualization tools and integrated codes. It
is able to analyse a structure exposed to dynamic response, soil structure interaction of wind,
earthquake and moving loads. (Ramkumar, n.d.)
CHAPTER 2 – PROJECT DESIGN
2.1. PROBLEM STATEMENT
A two storey building is going to be constructed in urgent. Both storey of the building
will be used as an office where there will be loading imposed on it. A lot of documents will
be stored in the office for the administrative work. Other than that, there will be many
computers, photocopy machines and shelves on the office room. In order to get the office
building finish earlier, steel structures is the best choice. Hence, the beam, column and the
roof truss are designed by using the steel structures. However, there are only 2 sections
available in the market; angle section and UB (Universal Beam) section. It is decided to use
the UB section for the all beams and columns, and angle section is used for the roof truss
members and purlins.
Before determining the size of UB or angle to be used, it is needed to calculate the
actual loading on respective beam or column or truss. The roof truss will be loaded by wind
uplift, the weight of roof insulation membrane. Additionally, first storey slab will be loaded
by ¾” acoustical hung ceiling, mechanical, electrical and lighting, roof insulation membrane,
finished flooring from second storey floor and live load. For the first storey floor, it will be
loaded by finished flooring and live load.
After all the loadings have been considered, only then the section of the UB or angle
used can be determined. Section chosen must have the capacity larger of the actual so that the
building will not fail.
Figure 2.1. Double Storey Building Design
2.2. PROBLEM FORMULATION
Office of double storey building is designed with trusses supporting the roof. The
building dimension is as follow:
Spacing between trusses is 3.5 m (2 bays)
Truss (triangular) of length of bottom chord of 6 m and height of 1.5 m
Length and width of the building are 7 m and 6 m, respectively
Height of first storey and second storey are 4 m and 3.5 m, respectively
Each storey supported by four columns at every corner
The loading at roof, first storey slab and first storey floor are as follow:
First Storey Slab
First Storey Floor
The section chosen and design procedure for the building design must follow the BS
5950-1:2000. The steel grade is S275. Universal Beam is used for all columns design (first
storey and second storey). Universal Beam is also used for all beams design. In addition, for
the roof truss, angle section is chosen for the design of all the internal members, assuming all
the connection in the truss is welded.
Speaking about the connection, the four first storey columns are welded to the
foundation at the bottom part and they are fixed-supported. It is fixed-supported to prevent
the building from swaying that might occur due to wind loading from the side and most likely
cause the building to collapse. Equally important, the connection between the other beams
and columns on the intermediate nodes of the building are welded too, but they are pin-
connected since the rotation of one beam or column will affect another beam or column
connected in the same joint.
The adequate sections for the building are to be determined by hand calculation and
STAAD.Pro analysis. The analysis is to be done using STAAD.Pro software. At the same
time, sections need to be checked for its maximum capacity (shear, bending, flexural, etc.).
The results of software analysis and hand calculation are compared.
2.3. DESIGN SPECIFICATION
This project is to design a building by using structural design software,
STAAD.Pro 2007 (Structural Analysis and Design). This software allows
the user to determine the section of the structure and eventually will analyse
and simulate the designed structure to determine the structure response to
the applied load.
The objective of this project is to design double storey steel office building
with an adequate section of steel structure. Both storeys will be used as
office room for all the employees. Therefore, it will carry a lot of loadings.
All columns, beams and roof truss members are designed by using steel
material of different sections. Beams and columns will be designed by using
Universal Beam whereas the roof truss members and purlins will be
designed by using angle section.
o Four columns at corners (4 @4 m) – UB Section
o Floor made of steel with thickness of 0.03 m
o Height of first storey office is 4 m
o Width and length of first storey office are 6 m and 7 m, respectively
o Four column at corners (4 @3.5 m) – UB Section
o Floor made of steel with thickness of 0.03 m
o Beams supporting floor (2 @6 m and 2 @7 m) – UB Section
o Height of second storey office is 3.5 m
o Width and length of first storey office are 6 m and 7 m, respectively
o Roof truss has the length of bottom chord of 6 m
o Height of roof truss is 1.5 m
o Angle roof slope is 26.57o
o Spacing between trusses is 3.5 m (2 bays)
o Truss members is designed using single unequal angle section
(compression and tension members)
o Purlins connected the trusses is also designed using angle section
All the steel structures chosen for the building design must be able to
support all the loadings applied on the building or at least adequate, not to
let the building to collapse. The loading has actually been multiplied to the
factor for the conservative purposes. Sometimes, the loading might be more
or less to the actual loading. If it is less, it does not matter, if it is more, it
has been controlled by the factored loading. The failure can be therefore
The whole construction project is estimated to worth 40 million Malaysian
Ringgit. High budget is due to the usage of the steel structures.
Table 1. Design Specification
2.4. POTENTIAL PROBLEM
The main potential problem of this project is the delay in completion. The reasons to
the problem can be explained more clearly by fish bone diagram below.
Figure 2.2. Fish Bone Diagram
From the fish bone diagram above, the factors causing the construction problem can
be observed. Resource is the usual problem that a construction project has. Lack of workers
especially skilled workers normally will affect the speed of construction. Besides, the
unproductive machineries such as old machineries will also slow down the speed construction
since it cannot promise the good efficiency while operating. On the other hand, requirements
from local authority can become a barrier on the flexibility of building design. The design
needs to be revised and the designer has to come out with new drawings that follow the local
building codes. Ultimately, this will drag following process of construction.
Environment is one of the concerns in the construction. Bad environment can delay
the construction as well. For the steel structure, if it rains the whole day during the
construction, the welding of the structure joins cannot be done. Other than that, the rain might
corrode the steel structure too if there is no extra care put on the structure. However, the
environmental problem is an inevitable problem. What human can do is try to set the time of
Hard to get
construction properly, for example do the construction not in a rainy season or conserve the
steel structure by using anti-corrosion chemicals.
Equally important, the on-time arrival of the materials will actually speed up the
construction process. Yet it is still subject to the availability of the materials themselves. If
the section is available, it is expected to arrive early and the construction can be preceded.
However, sometimes, the section chosen by the structural engineer is rare. Hence, it is needed
to get it ordered from some other place. The arrival of the materials will then depend on some
factors. There might be interruption in the middle of transportation. This will then lead to the
delay of construction.
Lastly, the geotechnical problem (soil) will have effect on the construction. A proper
site investigation will actually reduce the delay caused by this factor. Site investigation is
done to determine the bearing capacity of the soil and then to determine the type of
foundation needed. Since this project only covers a small area of ground, most of the times, a
geotechnical engineer will not check every section of small area of the building, and assume
that all the bearing capacity is the same throughout the whole area of the building stands on.
Yet, in real case, this might not be correct. A strength of the soil can differ significantly even
in a small area of coverage. Therefore, a proper site investigation will prevent the
construction delay by removing the foundation problem.
2.5. SAFETY MEASURES
Although the design has confirmed the BS 5950-1:2000, some factors of safety still
have to be considered. Factors of safety for this project are as follow:
Loading must not exceed the loading capacity of the section chosen for the building.
Section must be inspected frequently to check if there is any defect (corrosion). If
there is, a prompt action must be immediately taken in order to prevent the collapse.
Roof truss slope angle is designed not more than 30o
. If it is changed to more than
, the serviceability of the purlins needs to be checked.
Steel structure must not be in contact with high temperature objects such as fire. It
might lose its strength.
CHAPTER 3 – STAAD.PRO ANALYSIS AND RESULTS
3.1. PROJECT DESIGN APPROACH
a. Two dimensional design of the building was drawn.
Figure 3.1. Two Dimensional Drawing of the Building
b. The two dimensional drawing was rendered to get the three dimensional drawing. Beams
and purlins of roof truss were added. Plates were assigned to the roof, first storey floor
and second storey floor.
Figure 3.2. Three Dimensional Drawing of the Building
c. The supports (fixed at the bottom) were assigned to the structure. The plate thickness was
assigned (4 mm of aluminium for roof and 30 mm of steel for flooring). Other than that,
the section for the structure was also chosen.
i. UB for columns and beams
ii. Single unequal angle for truss members and purlins
Figure 3.3. Building with Assigned Section and Plate Thickness
d. The mesh was created on the plate to analyse the response of elements of the structure to
the applied loading.
Figure 3.4. Mesh Plates in the Structure
e. Loadings were applied to the structure
Figure 3.5. Building with Plate Loading
3.2. DETAILED ENGINEERING ANALYSIS AND DESIGN
On this building design, the section, thickness and material chosen are as follow.
Figure 3.6. Roof Purlins
Number of Purlins 10
Purlins Spacing 1.68 m
Length of Purlin 3.50 m
Section Single Unequal Angle
Section Designation 80 x 60 x 7 L
Thickness 7.00 mm
Moment of Inertia 59.0 cm4
rb 2.51 cm
ra 1.74 cm
rv 1.28 cm
Elastic Modulus 10.7 cm3
Area of Section 9.38 cm2
Table 2. Roof Purlin Details
Figure 3.7. Roof Truss
Number of Trusses 3
Trusses Spacing 3.50 m
Length of Truss Bottom Chord 6.00 m
Height of the Truss 1.50 m
Roof Sloping Angle 26.57o
Section Single Unequal Angle
Section Designation 65 x 50 x 5 L
Thickness 5 mm
Moment of Inertia 23.2 cm4
rb 2.05 cm
ra 1.47 cm
rv 1.07 cm
Elastic Modulus 5.14 cm3
Area of Section 5.54 cm2
Table 3. Roof Truss Details
Figure 3.8. Beams
Number of Beams 4
Length of Beam 2 @6 m and 2 @7 m
Section Universal Beam (I-Beam)
Section Designation 356 x 171 x 57 UB
Depth of Section 358.0 mm
Width of Section 172.2 mm
Web 8.10 mm
Flange 13.0 mm
Moment of Inertia 16000 cm4
rx 14.9 cm
ry 3.91 cm
Elastic Modulus 896 cm3
Plastic Modulus 1010 cm3
Area of Section 72.6 cm2
Table 4. Beam Details
Figure 3.9. Columns
Number of Columns 8
Length of Column 4 @4 m and 4 @3.5 m
Section Universal Beam (I-Beam)
Section Designation 406 x 178 x 54 UB
Depth of Section 402.6 mm
Width of Section 177.7 mm
Web 7.70 mm
Flange 10.9 mm
Moment of Inertia 18700 cm4
rx 16.5 cm
ry 3.85 cm
Elastic Modulus 930 cm3
Plastic Modulus 1060 cm3
Area of Section 69.0 cm2
Table 5. Column Details
Figure 3.10. Aluminium Roof Plate
Number of Plate 8
Thickness of Plate 4.00 mm
Unit Weight 27.0 kN/m3
Table 6. Roof Details
Figure 3.11. Steel Floor/ Slab Plate
Number of Plate 2
Thickness of Plate 30.0 mm
Unit Weight 77.0 kN/m3
Table 7. Floor/ Slab Details
3.3. STAAD.PRO ANALYSIS RESULTS
After the analysis, STAAD.Pro was able to show if there is any failed members. Yet
with the design above, there was no failed beams detected. However, the plate bending and
the beam stresses were clearly observed.
Figure 3.12. Deflected Shape of Structure after Analysis on STAAD.Pro
Table 8. Deflection of First Storey Slab
Table 9. Deflection of First Storey Floor
Figure 3.13. Forces Acting on the Structure
1 2 3 4
1 2 3 3.5
Figure 3.14. First Storey Column Stress
Figure 3.15. Bending Moment Diagram of First Storey Column
Figure 3.16. Second Storey Column Stress
Figure 3.17. Bending Moment Diagram of Second Storey Column
0.2 0.4 0.6 0.7
Figure 3.18. 7 m Beam Stress (Middle Element of the Mesh Beam)
Figure 3.19. Bending Moment Diagram of 7 m Beam (Middle Element of the Mesh Beam)
Figure 3.20. 6 m Beam Stress (Middle Element of the Mesh Beam)
Figure 3.21. Bending Moment Diagram of 6 m Beam (Middle Element of the Mesh Beam)
0.2 0.4 0.6
0.5 1 1.5
0.1 0.2 0.30.335
Figure 3.22. Truss Member Stress (Maximum Tension)
Figure 3.23. Bending Moment Diagram of Truss Member (Maximum Tension)
Figure 3.24. Truss Member Stress (Maximum Compression – End Element of the Member)
Figure 3.25. Bending Moment Diagram of Truss Member (Maximum Compression – End Element of the Member)
0.2 0.4 0.6 0.7
Figure 3.26. Purlin Stress (Middle Element of the Mesh Beam)
Figure 3.27. Bending Moment Diagram of Purlin (Middle Element of the Mesh Beam)
On this project, a double storey steel building was designed by using STAAD.Pro
2007, structural analysis software. The double storey is to be used as an office. The whole
building is made of steel, including the beams, columns, roof truss members, roof purlins and
slabs. This is to accelerate the construction process since the office building is needed
urgently. As aforementioned on the problem formulation, there are types of loading imposed
to the structure; wind load, live load and dead load. Wind load is the load that hit the roof and
usually causes an uplift force. The dead load mostly comes from the structure weight and
finishing or lighting suspended on the slab. Dead load can be said as the permanent load that
will always be on the structure. On the other hand, live load comes from the weight of
employees in the office. Live load is the temporary load since the employees only will be in
the office during working hours.
Before the analysis was done, the design was modelled out. The two dimensional
drawing of the building was constructed. Thereafter, the two dimensional drawing was
rendered to obtain the three dimensional building. All necessary beams or purlins and plates
were added. Aluminium plate of 4 mm thickness was used for the roof plate. In addition, steel
plate of 30 mm thickness was used for the floor or slab of the first storey and second storey of
the building. After the thickness of the plates was assigned, the section of the beams,
columns, purlins and truss members was chosen.
Purlins supporting the roof plates were designed by using the 80 x 60 x 7 L single
unequal angle section. These roof purlins were supported by the three roof trusses which
were designed by using 65 x 50 x 5 L single unequal angle section. The roof trusses were
supported by four columns at every corner with the length of 3.5 m (height of second storey).
The section chosen for column design is 406 x 178 x 54 UB. On the second storey, the steel
plate floor is supported by the four beams at every side. For these beams, 356 x 171 x 57 UB
was chosen. These beams will carry the loading from the steel plate floor of second storey
and transferred it to the first storey columns. The columns for the first storey are using the
same section as the second storey columns (406 x 178 x 54 UB). This is to simplify the
construction process and not to confuse the worker. From the first storey columns, the
loading will be transferred to the foundation. Talking about the first storey steel plate floor, it
was not supported by any beam at the side. This is because the plate is supported wholly by
the ground underneath it.
After the section assignment has been done, the supports were assigned to the
structure. The structure was fixed-supported at the bottom (first storey columns to the
foundations). Thereafter, the loading was assigned accordingly to the structure. Before that,
mesh has to be generated on all plates on the structure so that the response of the plates to the
loading can be easily observed after the analysis has been done.
Preceding this, the analysis was run. The results of the analysis were plotted on
section 3.3 of the report. From Figure 3.12, the deflection of the structure can be observed.
The deflection of the columns, beams, purlins and truss members was not too obvious. There
was only a slight displacement observed. The most obvious deflection was observed on the
first storey floor. It was recorded to be 59 mm downwards (node 91, exactly at the centre of
the plate) which was considered as a very large deflection. The reason why this plate
deflected so much is because it was not supported by any beams at the side. As far as this
plate is concerned, it was actually supported by the ground underneath it. Therefore, the
deflection of the plate depends on the degree of compaction of the soil below it. If the soil is
not well-compacted which has many voids and is not stable, a long-term loading on the floor
might cause the plate to fail. However, the deflection was also observed on the second storey
floor. But, for this plate, the deflection was not that much as compared to the first storey
floor. From the result in Table 8, the maximum deflection observed was 22 mm downwards.
This deflection can still be decreased by adding secondary beam in between the main beam,
to support the centre part of the floor plate.
On the other hand, axial stresses of the structure were analysed as well. For the
column stresses, only one column was chosen from each storey for analysis by considering
other three beams experiencing the same stresses and loading. From Figure 3.14, the stresses
of the first storey column were observed. The maximum compression stress was determined
to be 252.38 N/mm2
whereas the maximum tension stresses was determined to be 209.09
. Both maximum stresses were found near the top end of the column span. Moreover,
from Figure 3.16, the stresses of the second storey column were observed. The maximum
compression stress was determined to be 182.10 N/mm2
, whereas the maximum tension stress
was determined to be 178.33 N/mm2
. Both maximum stresses were found near the bottom
end of the column span.
For the beam stresses, one 6 m beam and one 7 m beam was chosen for the analysis.
The beam chosen was not the whole beam since mesh has been generated on the plate
causing the beam to be separated by many nodes. Thus, the middle element of mesh beam
was chosen, assuming the maximum stresses occurred there. 7 m beam which supports the
longer side of the floor has the maximum compression stress of 193.47 N/mm2
at its top
flange and 193.54 N/mm2
of maximum tension stress at its bottom flange (Figure 3.18).
Besides, for the 6 m beam, it has the maximum compression stress of 85.09 N/mm2
maximum tension stress of 84.85 N/mm2
at its top flange and bottom flange, respectively
(Figure 3.20). From the analysis results, it can be explained that the loading caused the beam
to bend downwards resulting in compression stress at the top flange and tension stress at the
For the truss member stresses, only members that experienced the maximum tension
and maximum compression axial stresses were taken into analysis (assuming other members
will experience smaller stress). Those two members are located near to the support of the roof
truss. For these two members, even though they are tension or compression member, they
still experience the opposite stress within the member e.g. compression member experiences
tension stress. For the tension member, the maximum tension stress was determined to be
while the maximum compression stress was determined to be 48.98 N/mm2
(Figure 3.22). For the compression member, only a small element of the truss member was
taken since the mesh has been generated on the roof plate. The element chosen was the
element having the largest stresses (element near the support of the truss). The maximum
tension stress of the element was determined to be 58.14 N/mm2
, whereas the maximum
compression stress was determined to be 155.93 N/mm2
Lastly, the stresses on the purlins were observed as well. Same as beam, since the
mesh has been generated on the roof plate, the purlin was separated by many nodes.
Assuming the largest stress occurred at the middle of the purlin, the element at the middle of
purlin was chosen. According to Figure 3.26, the maximum compression stress was
determined to be 102.44 N/mm2
, while the maximum tension stress was determined to be
From the STAAD.Pro analysis, although a significant plate deflection was detected on
the first storey floor, it was found out that there were no failed structures (beams) which
means all the sections assigned is adequate to support the loading. The STAAD.Pro
simulation result was then verified by the hand calculation.
For the hand calculation, the design was started from the purlin. There are two
methods in designing purlin; Empirical Method and Beam Method. Empirical Method can
only be used if the sloping angle of the roof is less than 30o
, whereas Beam Method is used
when the sloping angle is more than 30o
. For this building design, sloping angle is 26.57o
Therefore, the purlin was designed by using Empirical Method. All the loadings imposed to
the roof were changed to the slope loading and was totalled up to get unfactored load.
Thereafter, the required elastic modulus, depth and breadth of the section were calculated.
The section chosen must be larger than the required in order to not fail.
Properties Required 80 x 60 x 7 L
Elastic Modulus, Zx (cm3
) 3.823 10.70
Depth, D (mm) 77.78 80.00
Breadth, B (mm) 58.33 60.00
Table 11. Purlin Properties Comparison
Since all the properties from the section chosen are larger, the purlins were then
designed by using 80 x 60 x 7 L single unequal angle section.
Afterwards, the roof truss members were designed. Firstly, the internal forces at all
members were determined and member that has maximum compressive and tensile force was
taken to be analysed. Maximum compressive force and tensile force were calculated to be
18.46 kN and 16.51 kN, respectively. By assuming the connection between truss members is
welded, the truss member was designed. First, the required area for the compression member
was calculated. The section chosen must have a larger section area than the required area.
After that, the section classification was done to check whether it falls under class 4 (slender).
Thereafter, the critical slenderness was calculated to find the compressive resistance. At the
same time, the required are for the tension member was calculated as well. It was then
compared to the area of section chosen. Subsequently, the tensile capacity was determined.
Properties Required 65 x 50 x 5 L
Area, A (cm2
) 3.356 5.540
Compressive Force (kN) 18.46 45.86
Table 12. Truss Member (Compressive) Properties Comparison
Properties Required 65 x 50 x 5 L
Area, A (cm2
) 0.600 5.540
Tensile Force (kN) 16.51 133.457
Table 13. Truss Member (Tensile) Properties Comparison
It was observed from Table 12 and Table 13 that the compressive resistance of the
section chosen is much larger than the maximum compressive force experienced by the truss
member. On the other hand, the tension capacity offered by the same section is much larger
than the tensile force experienced by the truss member. Therefore, 65 x 50 x 5 L single
unequal angle section was then adopted for all the truss members.
After the section chosen for the truss was verified, the section for beam supporting the
second storey floor was calculated. Firstly, all the loading imposed on the floor was
calculated. Since the slab is a two-way slab ( ⁄ ), therefore the loading was
distributed or supported by all four beams surrounding it. The required plastic modulus was
then calculated. At the same time, the shear force and bending moment were calculated as
well for the purpose of bearing and buckling checking. The section was chosen from the
STAAD.Pro was then analysed. The shear buckling, shear capacity, moment capacity,
deflection, bearing capacity and buckling resistance was needed to be checked to ensure the
adequacy of the section.
Properties Required 356 x 171 x 57 UB
Plastic Modulus, Sx (cm3
) 834.0 1010
Shear Buckling No need to check
Shear Capacity (kN) 98.29 478.5
Moment Capacity (kNm) 229.4 277.8
Deflection (mm) 13.73 19.44
Bearing Capacity (kN) 98.29 145.2
Buckling Resistance (kN) 98.29 107.7
No stiffener is required at the support
Table 14. 7 m Beam Properties Comparison
Properties Required 356 x 171 x 57 UB
Plastic Modulus, Sx (cm3
) 711.3 1010
Shear Buckling No need to check
Shear Capacity (kN) 97.80 478.5
Moment Capacity (kNm) 195.6 277.8
Deflection (mm) 8.643 16.67
Bearing Capacity (kN) 97.80 145.2
Buckling Resistance (kN) 97.80 107.7
No stiffener is required at the support
Table 15. 6 m Beam Properties Comparison
It was observed from Table 14 and Table 15 that all the properties of the beam chosen
from STAAD.Pro are larger than the required value (shear, moment, deflection and plastic
modulus). Hence, 356 x 171 x 57 UB was adopted for the beams.
Lastly, the section chosen for the column was verified. There were two different loads
that the columns on this building carry. Four columns at the second storey of the building will
only carry the load from the roof, whereas the other four columns at the first storey will carry
the load from second storey floor and the roof. The section for the columns can be different.
But, in order to avoid confusion to the workers (having different sizes of beams), the columns
were designed by using the same section even though the loads carried are different. The
verification was then done on the column that carries the largest loading (first storey column).
Initially, a table was constructed to calculate the loading transfer (Table 10). The load carried
by the first storey column was determined to be 181.217 kN. The section chosen from
STAAD.Pro was then verified for its adequacy.
Properties Required 406 x 178 x 54 UB
Compression Force, Fc (kN) 181.2 1134
Table 16. First Storey Column Properties Comparison
Properties Required 406 x 178 x 54 UB
Compression Force, Fc (kN) 32.45 1095
Table 17. Second Storey Column Properties Comparison
From comparison on Table 16, the section chosen was able to support the
compressive force applied on it, thus, this section is adequate for the first storey column
design. Simultaneously, on Table 17, the same section was checked if it is able to support the
second storey column. Since it has a much larger compressive resistance as compared of the
compressive loading that the columns carry, 406 x 171 x 54 UB was adopted for the column
The verification was done and all members were checked to be adequate for the
building. Therefore, the building construction can be preceded.
From this project, the concept of building design was understood. The design of the
building has to be started from the top to the bottom as the bottom part will carry the load
from the top. Therefore, the design must be started from the roof. Then, the roof and slab will
transfer the loading to the column. Before designing the column, the beam needs to be
designed first because it is the one that supports the slab. After the beam is designed, the
loading from the slab and beam will be transferred to the column. Then only, the column
design can be started. The loading carried by the column will ultimately go to the foundation.
Therefore, the soil on which the building is built has to have a very good bearing capacity.
Otherwise, the building will just collapse.
Other than that, the advantages of steel structure as a building construction were
learnt. Since this office building was needed to be finished urgently, hence, steel structure is
the best choice. Unlike concrete, steel structure does not need time for curing or setting or
hardening. Steel structure can just be welded or bolted to the foundation to start construction
or to other steel structure for extension. After the connection is done, the structure is ready to
be used. In addition, it has a good ductility property that it bends first before it breaks.
Additionally, the software used for this project, STAAD.Pro 2007, was understood as
well. It was studied that the software is able to perform simulation and show if there are fail
members. There are many other things that the software can display. All the structural
response to the applied loading can be shown after the analysis has been done. All
information of the structural response can also be printed out for the design purpose. This
software is very useful for the design or structural engineer. This will help the design or
structural engineer in ensuring that his/her design is adequate and failure will not occur
during the construction. This will literally cut off the costly maintenance cost, especially if
the structure needs to be rebuilt because it is unable to be fixed anymore.
During the design using the STAAD.Pro, it was found that there were no failed beams
even though the section chosen was the very small. But, when the same section was verified
by using the hand calculation, for instance the roof truss member, the section area was found
out to be smaller than the required area. This means that the section chosen previously in the
STAAD.Pro will most likely fail. In addition, the section chosen for beam and column was
also smaller than the requirements. Therefore, during the design, it was needed to check for
the first requirement such as required area (truss member), plastic modulus (beam), and
elastic modulus (purlin) before assigning the section to the structure. This error might happen
because of some factors. Many assumptions taken in the hand calculation that was not
inputted onto the STAAD.Pro analysis such as the grade of the steel and the connection
between members, might affect the result of the analysis. Other than that, it was observed
from the rendered view, the structural arrangement for the angle section was not correct. The
longer side of the angle is supposed to be vertical and the other part of the angle is supposed
to be horizontal. But, on the rendered view, the angle of the section pointed upwards. This
was totally different from what was assumed in the hand calculation part in which the angle
was welded on its longer side to the gusset plate.
Equally important, during hand calculation, only the members that carry the largest
loading were taken into account. All members carrying smaller loading will have to follow
the same design section in order to avoid confusion of having various sections. The section
that was designed for the maximum force will be adequately able to support the smaller
loading applied on it.
For the truss members, only the members experiencing the maximum compression
and maximum tension were designed and the rest of the members will follow that design. For
the purlins, the middle purlin was chosen since that purlin will carry more loading compared
to the end purlin. For the beam, a beam of 6 m length and a beam of 7 m length were chosen
for calculation. Lastly, for the column, all four columns at each floor were assumed to carry
the same loading (which in real case, does not, due to the wind loading, columns located at
the leeward side of the building will have to carry more compressive force). Therefore, one of
the columns was chosen and the other three columns will follow the design. The compressive
resistance of section chosen for the columns was much bigger than the loading that it carries.
Therefore, the assumption will not affect the results significantly.
If the result from STAAD.Pro analysis is to be compared to the hand calculation
results, there were many factors that need to be equated. Some assumptions taken during
hand calculation were not put into the STAAD.Pro analysis. The results from both
calculations would not be similar or close. As aforementioned before, the factors such as
structure arrangement and the connection were the problems faced on the STAAD.Pro.
Although the difference between the STAAD.Pro simulation result and the hand calculation
result was detected, the factors affecting it were determined. However, the section chosen on
this building was proven to be adequate by simulation and hand calculation. Therefore, the
design project was successful.
At the end, the double storey steel building was designed successfully according to
the BS 5950-1:2000. The section chosen for purlins, roof truss members, beams and columns
are adequate to support the loading imposed on the building. The adequacy of the section has
been checked and verified by STAAD.Pro simulation and hand calculation.
From the results, the purlins will be constructed by using 80 x 60 x 7 L single unequal
angle section, roof truss members will be constructed by using 65 x 50 x 5 L single unequal
angle section, beams will be constructed by using 356 x 171 x 57 Universal Beam section and
columns will be constructed by using 406 x 178 x 54 Universal Beam section. Those sections
have been proven as safe sections to be used for this building.
On the other hand, during the completion of this project, the concept of steel structure
designing was obtained and understood. A building design has to be started from the top part
since the top part will only carry the loading from that area. The loading is then transferred to
the lower level. Thereafter, the design for the structure on the lower level can only be started.
The parameters, such as shear capacity on beam, compressive resistance on column, are to be
checked before the section is chosen are also understood.
Additionally, the merits and limitations of the steel structure were understood as well.
Despite of having many merits, there are still safety measures to the steel building itself. Steel
structure is known for its good ductility and ease of construction. But at the same time, it is
also susceptible to corrosion and loses its strength on high temperature. Therefore, good
maintenance and care will keep the steel structure on its highest performance.
To conclude, this design project was done successfully. The concept of designing
steel structure was fully understood.
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