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Design of a steel building
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UNIVERSITY OF MAURITIUS
DEPARTMENT OF CIVIL ENGINEERING
Module Name: Structural Design I Module Code: CIVE 2016 Y (3)
Student Name & ID: 131 0372 – Veeramah Avinaash
131 8156 – Bhirugnath Yashveer
Name of Assessor: Mr. Sailesh Kumar Nunkoo Signature of Assessor:
Date: 6th March 2015
WRITTEN REPORT ASSESSMENT FORM
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CIVIL ENGINEERING DEPARTMENT
CIVE 2016 Y (3)
COURSEWORK:
Analysis of the load transfer sequences of the UoM Gymnasium.
By:
Veeramah Avinaash – 131 0372
Bhirugnath Yashveer – 131 8156
6th March 2015
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1. PRESENTATION, STYLE, LANGUAGE
(40%)
i. Presentation and style
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ASSESSOR TO
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2. CONTENT (60%)
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Acknowledgements
We seize this opportunity to express our gratitude to Mr. S.Nunkoo, our lecturer, who provided us with a
unique chance to work on this assignment. Being new to the concept of steel design, we’ve been able to
enrich our understanding of the subject matter and are now able to describe the components of any steel
framed building along with describing the load paths taken by different load systems acting on it.
Furthermore, this assignment has led us to appreciate the use of steel as a structural material in the
construction of specific buildings.
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Table of Contents
1.0 Introduction ............................................................................................................................................. 1
1.1 Aim ..................................................................................................................................................... 1
1.2 Objectives ........................................................................................................................................... 1
2.0 Desk study ............................................................................................................................................... 2
2.1 Gymnasium sketches .......................................................................................................................... 2
2.1.1 General layout of gymnasium ...................................................................................................... 2
2.1.2 Top view of gymnasium .............................................................................................................. 3
2.1.3 Side view of gymnasium .............................................................................................................. 3
2.1.4 Front view of gymnasium ............................................................................................................ 4
2.1.5 Overall view of gymnasium steel structure .................................................................................. 4
2.2 Description of the structural members of UoM gymnasium ............................................................... 5
2.2.1 Purlins .......................................................................................................................................... 5
2.2.2 Rafters and haunched joints ......................................................................................................... 5
2.2.3 Bridges ......................................................................................................................................... 6
2.2.4 Braces ........................................................................................................................................... 7
2.2.5 Cylindrical beams ........................................................................................................................ 9
2.3 Method of design of steel framework of UoM Gymnasium ............................................................. 10
2.4 Load transfer mechanisms ................................................................................................................ 10
2.4.1 Transfer of gravity loads ............................................................................................................ 11
2.4.2 Transfer of wind loads ............................................................................................................... 12
3.0 Conclusion ............................................................................................................................................ 14
References ................................................................................................................................................... 15
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List of figures
Figure 1 - General layout sketch of UoM gymnasium. ................................................................................. 2
Figure 2 - Top view of UoM gymnasium. .................................................................................................... 3
Figure 3 - Side view of UoM gymnasium. .................................................................................................... 3
Figure 4 - Front view of UoM gymnasium. .................................................................................................. 4
Figure 5 - Overall view of the UoM gymnasium. ......................................................................................... 4
Figure 6 - Purlins used in the UoM gymnasium. .......................................................................................... 5
Figure 7 - Rafter connected to a column via a haunched joint. ..................................................................... 6
Figure 8 - Bridges, fixed to purlins, at the UoM gymnasium. ...................................................................... 6
Figure 9 - Fly brace at the UoM gymnasium. ............................................................................................... 7
Figure 10 - Roof braces at UoM gymnasium. ............................................................................................... 8
Figure 11 - Side braces (K-shaped) at the UoM gymnasium. ....................................................................... 9
Figure 12 - Cylindrical beams at UoM gymnasium. ..................................................................................... 9
Figure 13 - Representative diagram of load path for gravity load system. ................................................. 11
Figure 14 - Representative diagram of load path for wind loading along the steel frame. ......................... 12
Figure 15 - Representative diagram of load path for wind loads perpendicular to the gable ends. ............ 13
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1.0 Introduction
Structures are designed in such a way that they are able to resist the applied loads onto them as well as
providing a pathway to channelize these loads to a safe medium. This pathway is called a load path. A load
path is, in a more technical jargon, a passageway that transfers loads on a building structure to the
foundation system and transmits them to the ground. This ensures that there is no collapse of the structure
or any other structural damage.
1.1 Aim
The main aim of this assignment is to be able to describe the load paths taken by different load systems
acting on a steel frames structure. The chosen steel structure is the gymnasium of the University of
Mauritius.
1.2 Objectives
The objectives set out to be able to meet the specified aim are as follows:
a) Visiting the above-named gymnasium.
b) Producing sketches of the gymnasium using a CAD software. In this case, the chosen software was
AutoCAD.
c) Recognizing and describing the different structural members of the building.
d) Analysing the different types of load systems acting on the building.
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2.0 Desk study
Following a site visit to the gymnasium, we were able to identify the main structural members of the
structure as well as producing its sketches.
2.1 Gymnasium sketches
The 2-D sketches were produced using AutoCAD and then plotted as pictures in this document.
Furthermore, an overall view of the gymnasium was produced using another CAD software, namely Sketch
Up, has been included.
2.1.1 General layout of gymnasium
Figure 1 - General layout sketch of UoM gymnasium.
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2.1.2 Top view of gymnasium
Figure 2 - Top view of UoM gymnasium.
Note: The red lines represent the braces of the steel structure.
2.1.3 Side view of gymnasium
Figure 3 - Side view of UoM gymnasium.
Note: The blue lines represent the side and fly braces of the steel structure.
44.3 m
34.0 m
8.0 m
mm
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34.0 m
2.1.4 Front view of gymnasium
Figure 4 - Front view of UoM gymnasium.
2.1.5 Overall view of gymnasium steel structure
10.0 m
10.0 m
Figure 5 - Overall view of the UoM gymnasium.
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2.2 Description of the structural members of UoM gymnasium
2.2.1 Purlins
It is a member subjected to biaxial bending. In the gymnasium, the purlins are connected to the steel
framework by using bolts through cleats. The latter are fixed to the columns or rafters. Its main purposes
are:
a. support external cladding of the gymnasium.
b. minimise lateral torsional buckling of the rafter at connecting joints.
Figure 6 - Purlins used in the UoM gymnasium.
2.2.2 Rafters and haunched joints
Rafters are the inclined structural members of the roof framework. They provide lateral and torsional
restraint at the supports. They are connected to columns by haunched joints. The latter are situated at the
rafter-to-rafter, apex and rafter-to-column connections. They increase the resistive moment at the joints
while adding stiffness to the frame. Excessive deflection is reduced and local buckling is prevented.
Purlins
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Figure 7 - Rafter connected to a column via a haunched joint.
2.2.3 Bridges
Bridges are members fitted midway between and fixed to the purlins to prevent twisting of the latter.
Moreover, the presence of ridges reduces deflection.
Figure 8 - Bridges, fixed to purlins, at the UoM gymnasium.
Bridge Bridge
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2.2.4 Braces
Braces are secondary members which stabilise the main members by providing a pathway for the transfer
of loads while also providing restraint to compression flanges. 3 main types of braces have been used in the
steel framework of the UoM gymnasium.
a. Fly-braces (V-shaped)
They are connected from the bottom flange of the rafter to the purlins and provide restraint to lateral
torsional buckling of the rafters.
Figure 9 - Fly brace at the UoM gymnasium.
b. Roof braces
These are plan braces which prevent lateral buckling of the compression flanges of the roof beams.
Fly-brace
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Figure 10 - Roof braces at UoM gymnasium.
c. Side braces (K-shaped)
They are found at the 4 extremities of the steel framework. Their main purpose is to resist torsional effects
on the columns which can occur mainly due to wind loads.
Roof
braces
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Figure 11 - Side braces (K-shaped) at the UoM gymnasium.
2.2.5 Cylindrical beams
These are secondary beams which link the columns and restrict the latter from moving sideways while also
helping to transmit horizontal forces.
Figure 12 - Cylindrical beams at UoM gymnasium.
Side
braces
Cylindrical
beam
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2.3 Method of design of steel framework of UoM Gymnasium
There are 3 main types of methods adopted for the design of a steel structure. They are:
1. Simple design – The joints are not required to resist moments.
2. Continuous design – Only the structural properties of the members need to be considered in global
analysis.
3. Semi-continuous design – The structural properties of both the members and connections need explicit
consideration in global analysis.
In this case, the continuous design method has been considered, which is exemplified by the use of
haunched joints. The end connections are assumed to be rigid and capable of transmitting moments and
shear forces between members. Also, the frame attains stability against side-sway by the bending of beams
and columns.
2.4 Load transfer mechanisms
The 2 main types of loads encountered by the gymnasium are:
1. Gravity loads – These include self-weights of the different components, the weight of finishes and wind
loads acting vertically.
2. Lateral loads – These include mainly wind loads acting in different directions.
The mechanism of transfer of the loads is described as per the following flow charts.
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2.4.1 Transfer of gravity loads
Figure 13 - Representative diagram of load path for gravity load system.
Load from cladding and self-
weights of members.
Rafters (in terms of bending
stresses)
Haunched joints (these take
the moments from the
rafters).
Columns
Foundation bases
Ground
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2.4.2 Transfer of wind loads
2.4.2.1 Case 1 – Wind loads along steel frame
Figure 14 - Representative diagram of load path for wind loading along the steel frame.
Wind loads
Roof braces (majority of
loads)
Beams (small portion of the
loads)
Columns Side braces
Foundation
base
Ground
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2.4.2.2 Case 2 – Wind loads perpendicular to gable ends.
Figure 15 - Representative diagram of load path for wind loads perpendicular to the gable ends.
Winds loads
Roof braces (with the haunched joints resisting
the moments caused by the wind loads)
Concrete columns
Foundation base
Ground
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3.0 Conclusion
It is definitely clear that loads within a building must find their way to the ground by some method. If
this does not happen, being inside of a building would never be a safe situation. Without a clear gravity
system, the loads due to the self-weight of the structural system and building materials would distribute
themselves randomly. Without a lateral system, a building would fall over like a stack of cards if a big
gust of wind came, or if an earthquake hit. This would also lead to many injuries and deaths in both
cases. Therefore, the load path process is essential to structural engineering and safety of the public.
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References
1. Kristen Lechner, M.,2007. Load Paths in a Braced Frame Steel Building [online].Available
from: http://www.personal.psu.edu/kml5016/blogs/kristen_lechners_e-
portfolio/Technical%20Description.pdf [Accessed on 1st March 2015].
2. Victor Saouma, E. Structural Concepts and Systems for Architects [online]. University of
Colorado, Boulder, CO 80309-0428 Available from:
http://ceae.colorado.edu/~saouma/Lecture-Notes/s4a.pdf [Accessed on 2nd March 2015].
