1. DATTA MEGHE COLLEGE OF ENGINEERING
COMPARITIVE STUDY OF PRE-ENGINEERED BUILDING AND TRUSS
ARRANGEMENT BUILDING FOR VARYING SPANS
PRESENTED BY
ROSHNI RAMAKRISHNAN
GUIDED BY
Dr.Dode PrasadKumar Avinash
Professor
Department of Civil Engineering
YEAR

2. Presentation Outline:
1) Introduction
2) Literature Review
3) Problem Statement
4) Aims & Objectives
5) Scope of work
6) Methodology

3. Introduction
Pre- Engineered buildings are those which are engineered/manufactured at factories and assembled at site.Built-up,hot rolled and cold formed sections are used in such buildings and the sections that are used in such buildings differ along length as the section size is dependent on the bending moment profile.Past research has shown that for large spans,a reduction of 20%-30% in steel quantity and also 30%-50% saving in time of project occur due to faster delivery and quicker site erection.

4. VARIOUS COMPONENTS OF PEB
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5. Literature Review
1) Beedle et al.(1) The research discusses the improvements that can be done in steel design. The optimization techniques are efficient capitalization of strength and ductility,exploit potential of load factors and limit states of design,stiffness contribution of walls,increased shear strength at beam column connections and geometric configuration optimization.
2)Andrew W Charleson(2)The research study was done on RESIST a program used by architects to do preliminary design of steel buildings.It provides the details needed for preliminary design.Some assumptions are height assumed less than 30m,one structural system assumed along each direction,Structural diaphragm action assumed at the floor leveletc.

6. 3)Balwant Kumar et al.(4)The study showed the benifits of PEB in BOQ like
increased speed of construction and quicker returns,good quality control,easy construction,maintenance and refurbishing and single source responsibility.
4)Doanld W. White et al. (8)The research paper focusses on the extend of optimization done across the steel building and the need for optimisation.The paper describes the ways the second order effects are considered in steel structuresThe various elastic analysis and design methods for stability analysis are:
1)Direct Analysis Method
It can be applied to all types of frames.It includes two modifications to include second order effects. It uses a reduced Elastic modulus of 0.8 factor and the initial out of plumbness is taken as L/500

7. 2)Effective length method
The method is related to elastic buckling stress equation. It is used when Δ2/Δ1 < 1.5 where Δ2 is displacement due to second order effects and Δ1 is displacement due to first order effects.
5)Cyrille F.Dunant et al.(16)1)Improving structural design helps to lower carbon foot print.It depends on capabilities of design firm,the norms and codes,time alloted, the budget and preferences of client. Using plastic design helps to save the structural steelwork.It has been concluded that the shear force,bending moment and displacements are comparitively lower in PEB than in using hot rolled steel section

8. 2)79 steel framed buildings were analysed and reasons for high Utilisation Ratio are
1)Rationalisation- It involves using the same sections over large spans. Usually the section used is the one following highest requirements:
2)Usage of standard sections sections instead of built up sections
3)Members at ends can use lighter sections
4)Secondary beams can be optimised
6)Anil V. Bandre et a.(18)The study intends to see the variation in results on using PEB built up sections as compared to hot rolled sections.It has been concluded that the shear force,bending moment and displacements are comparitively lower in PEB than in using hot rolled steel section

9. 7)Ajizaz et al. (3), Aditya P Mehendale et al. (11),Vishal Kumar et al
7)Ajizaz et al.(3), Aditya P Mehendale et al.(11),Vishal Kumar et al.(12),Mittal
Parmar et al(17),Kavya Rao et al.(20)
The research studies involved comparison between PEB and Conventional
Steel Buidings with rigid frames.The following observations were made:
1)PEB gave lighter sections and hence reduced seissmic forces.
2)PEB gave comparitively lesser analysis forces.
3)PEB is to be checked for varying spans & most economical span is to be
arrived at.
4)A 25-35% steel reduction has been noticed in general.
5)Arched slopes gave saving of 8.84% and monoslope roof consumed 1.3 times
more steel.
6)Approx 30% around cost saving could be achieved.

10. 8)Swapnil N Dhande et al. (5),Rasool Owais et al(10),Khuzaim J
8)Swapnil N Dhande et al.(5),Rasool Owais et al(10),Khuzaim J.Sheikh et al.(13),Umesh L.Mali et al.(14) The studies were done on various lateral load resisting systems and following conclusions were arrived at:
1)Cross diagonal bracing gave better performance than single diagonal,V bracing and Inverted V bracing.
2)Bracing system reduces relative displacements,analysis to a huge extend as compared to shear wall system. Shear wall reduces nodal displacements-translational and rotational better than bracing system.
3)Shear walls at corners,tube system gave the best performance against llateral loads
4)Bracing is most efficient till a height of 20m.Shear walls are used for a height range of 20-35m

11. Through the exhaustive literature study conducted ,it was observed that most of
the research studies have been related to the effectiveness of Pre-Engineered
Buildings over the Conventional Steel Buildings. There have not been many
research works related to the effectiveness of Pre-Engineered Building System
over the Truss arrangement building sysytem with respect to the span and size
of the building. Hence the present work touches upon the “ Comparitive study
of PEB and truss arrangement building system for varying spans”.

12. Problem Statement:
The study involves a comparative analysis of industrial pitched roof steel building designed as Pre- Engineered Building with Built-up I sections and Conventional Steel Building with truss arrangement for varying spans.For the analysis purpose, three plan dimensions of 15x30m,40x80m and 90x180m are considered. The loads are calculated using Indian Standard codal provisions.
In the following proposed study:
1)An industrial pitched roof steel building is designed for plan dimensions of 15x30, 40x80 and 90x180 as Pre- Engineered Building and truss arrangement structure.In total 6 models are prepared for the analysis purpose.
2) For the design guidelines, the codes used are IS ,IS 875:Part 1:1987 (Second Revision),IS 875:Part 2:1987(Second Revision),is 875:Part 3:2015(Third Revision),is 1893(Part 1):2002

13. 3) The structural models are designed for Dead loads,Live loads,Wind loads and Earthquake loads.
4) The models are analyzed and designed in software STAAD.Pro Connect Edition.
5) The results from the analysis are studied in detail.

14. Aims & Objectives:
1) To study the effectiveness of Pre-Engineered Building for small span building
Most of research studies in the particular area of concern usually involved mid span buildings and there was no much research done on the effectiveness of Pre-Engineered Building system for smaller spans.The span of 15x30m is checked for Pre-Engineered system and truss arrangement system and a comparitive study will be done on the two systems.
2)To study the effectiveness of Pre-Engineered Building for large span buildings
The economy in using Pre-Engineered Building system for a large span building will be checked against truss arrangement system for the same. The optimal location for the bracing system is to be found for economical behavior of building.The span considered is 90x180m and an economical building arrangement system
will be found on the basis of servicibility performance and steel take off.

15. 3)To do a comparitive study between the two structural building systems for varying spans
The spans of 15x30m,40x80m and 90x180m will be designed as Pre-Engineered building system and truss arrangement building system and the economy of the structural system will be checked by comparison of the deflections and steel take off.
4)To find the variation of analysis results between Pre-Engineered Building and Truss arrangement Building
The variation in analysis results and subsequent effect on the deformations and
steel takeoff will be checked. The advantages of using built-up sections against
standard hot rolled sections will be seen for the small span,mid span and large
span buildings.

16. Scope of work:
1)To arrive at the most efficient and economical structural configuration for an
industrial building with pitched roof for small span building.
2)To arrive at the most efficient and economical structural configuration for an
industrial building with pitched roof for large span building.
3) To do exhaustive comparitive study of results between PEB and truss
arrangement building.
4)To find the best structural configuration for an industrial building of given span
and size.

17. Detailed Methodology Skeletal modelling
The spans of 15x30m,40x80m and 90x180m are considered. A uniform height of 7m and bay spacing of 6m are considered for all models. Using these dimensions the primary members of columns,rafters,bracing and truss elements shall be modeled in STAAD.Pro Connect Edition software.The structures are modeled as 3-D structures. Hinged support is provided for the columns in PEB models as hinge support helps to get an optimal structural design. The grade of steel used is E350.

18. Loads:
A)Dead Loads: It consists of Self Weight,connections and other accessories.IS 875 (Part 1) will be used as reference for final dead loads.Roof load consists of sheeting (0.5 mm thick galvalume), purlins,sag rods & fly bracings.Column load consists of cladding (0.5mm thick galvalume),girts,sagrods & flybraces.
B)Live Load: Live loads are produced due to occupancy of the people and other structures which are movable. IS 875 (Part 2) will be used for calculation of live loads.Here the roof load is taken as per the provisions in code.The eaves gutter is not assumed in the model and hence all associated loads to be neglected.

19. C)Wind Load:
IS 875(Part 3) deals with wind loads to be considered when designing building structures and components thereof.
Wind load depends upon wind speed and pressure.
a)Basic Wind Speed(Vb)- IS 875(Part 3),fig-1 gives basic wind speed map of India, as applicable to 10mheight above mean ground level for different zones of the country.
b)Design Wind Speed(Vz)-The basic wind speed(Vb)for any site shall be obtained and shall be modified to include the following effects of design wind velocity at any height (Vz) for the chosen structure:
a)Risk Level
b)Terrain roughness,height and size of structure
c)Local topography
It can be mathematically expressed as follows:
Vz= Vbxk1xk2xk3
Vb=Design wind speed at any height z in m/s

20. k1=Probability factor (risk coefficient)
K2=Terrain,height and structure size factor
k3=Topography factor as per study
a)Design Wind pressure
The design wind pressure at any height above mean ground level shall be obtained by the following relationship between wind speed and wind pressure.
Pz=0.6Vz^2
Where
Pz= Design wind pressure in N/mm2 at height z and
Vz=Design wind velocity in m/s at height z

21. D)Static Seismic Analysis
Seismic load:The seismic forces shall be calculated in accordance with IS 1893(part 1)This code deals with assessment of seismic load on various structures and earthquake resistant design of buildings.Seismic load depends upon the following criteria:
a)Design Horizontal Acceleration Coefficient (Ah)
It is a horizontal acceleration co-efficient that shall be used for design of structures
Ah =(Z/2)x(I/R)X(Sa/g)
Where
Z= Zone factor
I=Importance factor
R=Response reduction factor
Sa/g=Avg response acceleration co-efficient

22. a)Design lateral force
It is the horizontal seismic force prescribed by this standard,that shall be used to design a structure.
b)Design Seismic Base Shear
The total design lateral force or design seismic base shear (Vb)along shall be determined by the following expression:
Vb=AhxW
Where Ah=Horizontal acceleration spectrum
W=seismic weight of all floors
b)Fundamental natural period(T)
It is the first longest model time period of vibration.

23. Review of modelling and analysis with STAAD.Pro Connect Edition:
STAAD.Pro is a comprehensive and integrated finite element analysis and design offering that includes a state-of-the-art user interface,visualization capabilities and international design codes.It is capable of analyzing any structure exposed to static,dynamic,wind,earthquake,thermal and moving loads.STAAD.Pro provides structural analysis and design for any type of project,including towers,buildings,culverts,plants,bridges,stadiums and marine structure.Certain salient features are:
-Interactive graphics.Linked tables and windows to get direct feedback from one item in related windows-
-Elastic.Traditional first-order including iterative one-way analysis
-P-Delta.Both large and small P-Delta including stress stiffening effects
-Imperfection.Account for imperfections in structural geometry
-Dynamic.Modal analysis including stress -stiffening eigen solution and steady-state options,time history and response spectrums

24. -Steel design.Choose from 50 codes from around the world
-Integrated steel drawing production using Steel Autodrafter(requires SELECT or ELS)

25. Procedure to perform analysis:
1)The industrial building will be modelled as a PEB with elements of varying section sizes so as to get optimum economy and as a truss configuration system in STAAD.Pro Connect Edition.
2)All section sizes are to pass as per Indian Standard Design Criteria with Utilization Ratio is than 1.
3)The deflection limits shall be considered from IS 800:2007 table 6 and the deflections are kept within limits.
4)The analysis results are studied and conclusions are made regarding the most economic .

26. Numerical Problem:
The industrial building having pitched roof is designed as a Pre-Engineered Building with built-up I sections and as a roof truss arrangement for the following data.
Plan dimensions- 15x30, 40x80 and 90x180
Height of building- 7m
Max bay spacing- 6m
Roof slope - 1 in 5(15x30,40x80), 1 in 10(90x180)
Location- Chennai
4 sided cladding
Cladding and roofing sheet- 0.5mm thick Galvalume Sheet
Purlin and girt section used is 200ZS60x2(Cold form steel section)
Steel design and Load combinations- IS and IS I893:2002

27. Models considered in the analysis are:
Model 1a)PEB for plan dimensions 15x30m
Model 1b)Truss building for plan dimensions 15x30m
Model 2a)PEB for plan dimensions 40x80m
Model 2b)Truss building for plan dimensions 90x180m
Model 3a)PEB for plan dimensions 90x180m
Model 3b)Truss building for plan dimensions 90x180m

28. Summary:
The study involves comparison of Pre-Engineered building system wIth truss arrangement building system for varying spans. After arriving at optimized model, the analysis results are compared and the most economical configuration is arrived at. The structural system is compared for steel takeoff and deflections to arrive at the same.

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