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V
http://doi.org/10.22214/ijraset.2020.5207
May 2020
International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429 Volume 8 Issue V May 2020- Available at www.ijraset.com
Comparative Analysis of RCC and Steel Building Using STAAD Pro Ankush Dod1, Prof. V. M. Sapate2 1
Student of M.E structure Department of Structural Engineering, Raisoni University, Amravati 2 Professor at Department of Structural Engineering, Raisoni University, Amravati
Abstract: During occurrence of earthquake various types of structural failure occurs in structure due to some weak points and this weak points arises due to creation configuration of structures such as discontinuity bin mass, geometry and stiffness of structure and this discontinuities are termed as Irregularities. In the Present project work an attempt will be made to study the effect of vertical Irregularity for RCC and steel framing for low medium and high rise construction. Comparative analysis will be done between this two framing material systems. After analyzing and studying various structural parameters of RCC and Steel building it is found that for same earthquake zone and same geometric configuration steel structures gives less magnitude of axial force and base shear as compared to RCC structures. While comparing displacement ad time period RCC structure shows lower values than steel structures. So from the analysis it is clear that if steel structures are used in vertically irregular zone special displacement control provisions are to be done. Keywords: Structural Parameters, Irregularities, Axial force, Displacement, Base shear. I. INTRODUCTION During earthquake, structural failure starts off-evolved at factors of weak spot this weak spots arises due to structural discontinuity in mass, stiffness and structural geometry. Buildings which have any one or all of this discontinuities are termed as Irregular structures contribute large number of building constructions. most of building failure are found to be due to some kind of irregularity in building. Changes in structural mass variation or geometric variation affects the behavior of building during earthquake. Mean while framing material also affect the seismic behavior of vertically irregular building. To study the effect of structural irregularity during earthquake in rcc and steel framing the building model is prepared as per IS 1893:2002 (part1) II. AIM The aim of present work is to analyze various models with varying framing material and height of building for most stable and Economical framing system. III.
OBJECTIVE
The main objectives of our work are as follows :A. To evaluate the seismic behavior of RC building having different types of irregularities, mainly vertical geometric irregularity. B. To design and compare RCC and steel structure for various heights and irregularities. C. To obtain and compare results based on parameters i.e. displacement, Base shear Time Period, and Axial Forces IV.
TYPES OF IRREGULARITY
A. Plan Irregularities 1) Torsion Irregularity - To be considered when floor diaphragms are rigid in their own plan in relation to the vertical structural elements that resist the lateral forces. Torsional irregularity to be considered to exist when the maximum storey drift, computed with design eccentricity, at one end of the structures transverse to an axis is more than 1.2 times the average of the storey drifts at the two ends of the structure 2) Re-entrant Corners - Plan configurations of a structure and its lateral force resisting system contain re-entrant corners, where both projections of the structure beyond the re-entrant corner are greater than 15 percent of its plan dimension in the given direction
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International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429 Volume 8 Issue V May 2020- Available at www.ijraset.com 3) Diaphragm Discontinuity- Diaphragms with abrupt discontinuities or variations in stiffness, including those having cut-out or open areas greater than 50 percent of the gross enclosed diaphragm area, or changes in effective diaphragm stiffness of more than 50 percent from one storey to the next 4) Out-of-Plane Offsets - Discontinuities in a lateral force resistance path, such as out-of-plane offsets of vertical elements 5) Non-parallel Systems - The vertical elements resisting the lateral force are not parallel to or symmetric about the major orthogonal axes or the lateral force resisting elements B. Vertical Irregularities 1) Stiffness Irregularity —Soft Storey- A soft storey is one in which the lateral stiffness is less than 70 percent of that in the storey above or less than 80 percent of the average lateral stiffness of the three storeys above 2) Stiffness Irregularity —Extreme Soft Storey-A extreme soft storey is one in which the lateral stiffness is less than 60 percent of that in the storey above or less than 70 percent of the average stiffness of the three storeys above. For example, buildings on STILTS will fall under this category, 3) Mass Irregularity - Mass irregularity shall be considered to exist where the seismic weight of any storey is more than 200 percent of that of its adjacent storeys. The irregularity need not 4) Vertical Geometric Irregularity be considered in case of roofs Vertical geometric irregularity shall be considered to exist where the horizontal dimension of the lateral force resisting system in any storey is more than 150 percent of that in its adjacent storey 5) In-Plane Discontinuity in Vertical Elements Resisting Lateral Force A in-plane offset of the lateral force resisting elements greater than the length of those elements 6) Discontinuity in Capacity — Weak Storey, A weak storey is one in which the storey lateral strength is less than 80 percent of that in the storey above, The storey lateral strength is the total strength of all seismic force resisting elements sharing the storey shear in the considered direction. V.
STRUCTURAL PARAMETERS
Table 1 Detail Structural Parameters Parameter Value Live load 3 kN/m2 Density of concrete 25 kN/m3 Thickness of slab 130 mm Depth of beam 300 mm Width of beam 230 mm 230 x 300 mm (Model M1) Dimension of column 230 x 380 mm (Model M3) 300 x 450 mm (Model M5) Thickness of outside wall 230 mm Thickness of inner side wall 150 mm Height of floor 3.05 m Earthquake zone II Damping ratio 5% Type of soil II Type of structure Special moment resisting frame Response reduction factor 5 Importance factor 1 Roof treatment 1 kN/m2 Floor finishing 1 kN/m2 In case of Steel structure suitable ISMB section will be selected and will be reduced by using OPTIMIZE command of staad pro.
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International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429 Volume 8 Issue V May 2020- Available at www.ijraset.com VI.
Material Grade Mass Density Unit Weight Modulus of Elasticity Poisson’s Ratio
VII.
MATERIAL PROPERTIES: Table 2 material properties Concrete M 25 2549.3 25 25,000,000 0.15
Steel Fe 415 7849 76.97 20,000,000 0.3
MODEL NOMENCLATURE
Each model according to its specific floor and material condition are labeled as follows :Table 3 Model Description Model Description G+4 RCC Frame Building G+4 Steel Frame Building G+6 RCC Frame Building G+6 Steel Frame Building G+10 RCC Frame Building G+10 Steel Frame Building
VIII. A.
Label M1 M2 M3 M4 M5 M6
RESULTS FOR LOW RISE MODELS (G+4)
Axial Forces Table 4 Axial Force comparison for model M1 & M2 Parameter M1 Fx 17.398 Fy 1229.253 Fz 16.362
Sr No 01 02 03
M2 28.445 1187.267 13.543
30 25 20 15
M1
10
M2
5 0 Fx
Fy
Fz
As the intensity of Fy is large it is take as (1229.25 = 12.29 x 103) From the above graph it can be observed that model 2 shows higher values in X direction while in all other side i,e Z and Y it has values on lower side which will result in low requirement of structural steel.
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International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429 Volume 8 Issue V May 2020- Available at www.ijraset.com B.
Displacement Table 5 Displacement comparison for model M1 & M2 Displacement M1 X 41.318 Y 0.165 Z 25.345 Resultant 25.624
Sr No 01 02 03 04
M2 22.335 0.14 38.393 38.438
50 40 30
M1
20
M2
10 0 X
Z
Resultant
From the graph of Displacement it can be observed that Steel structure shows less displacement values compared to RCC structures in Z direction. While In X direction its value is almost half of RCC structure. C.
Time Period
Sr No 01 02 03 04 05 06
Table 6 Time Period comparison for model M1 & M2 Mode M1 1 1.309 2 0.94 3 0.482 4 0.397 5 0.272 6 0.259
M2 1.622 0.89 0.8 0.642 0.604 0.521
2 1.5 M1
1
M2
0.5 0 Mode 1
Mode 2
Mode 3
Mode 4
Mode 5
Mode 6
The comparative graph of time period shows that RCC structure shows less period of oscillation compared to steel structures which requires high time period this is may be due ductile behavior of structural steel
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International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429 Volume 8 Issue V May 2020- Available at www.ijraset.com D.
Base Shear Table 7 Base Shear comparison for model M1 & M2 Parameter M1 Base Shear 129.743
Sr No 01
M2 124.58
Above base shear comparison represents that steel structures shows lower values than rcc structure. There is nearly 4.14 % reduction in base shear for steel structures. IX. A.
RESULTS FOR MEDIUM RISE MODELS (G+6)
Axial Forces Table 8 Axial Force comparison for model M3 & M4 Parameter M3 Fx 19.135 Fy 1691.311 Fz 16.331 Mx 26.81 My 0.501 Mz 22.069
Sr No 01 02 03 04 05 06
M4 31.876 1640.971 15.081 22.291 0.003 131.056
35 30 25 20
M3
15
M4
10 5 0 Fx
Fy
Fz
Graph of axial forces shows that there is no considerable difference in magnitude of forces in Z direction and Y direction but has significant change in X direction. Model M3 has high horizontal values but have lower values on in Y direction. B.
Displacement Sr No 01 02 03 04
Table 9 Displacment comparison for model M3 & M4 Displacement M3 X 64.06 Y 0.326 Z 41.556 Resultant 42.267
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M4 33.57 0.252 59.21 59.416
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International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429 Volume 8 Issue V May 2020- Available at www.ijraset.com 70 60 50 40 M3 30
M4
20 10 0 X
Z
Resultant
From the above graph of displacement it can be clearly seen that model M4 have high displacement values than model M3. So, from this comparison it can be conclude that steel structures should not be used for irregular type structure for medium rise building. C.
Time Period
Sr No 01 02 03 04 05 06
Table 10 Time Period comparison for model M3 & M4 Mode M3 1 1.804 2 1.288 3 0.7 4 0.564 5 0.374 6 0.288
M4 2.123 1.178 0.882 0.848 0.654 0.632
2.5 2 1.5 Series 1 1
Series 2
0.5 0 Mode 1
Mode 2
Mode 3
Mode 4
Mode 5
Mode 6
Above time period comparison shows that in medium rise structures rcc structures shows low time period while for same zone and same structural geometry steel structure requires more time. From this it can be concluded that steel should not be used in this case from the view point of time period.
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Base Shear Table 11 Base Shear comparison for model M3 & M4 Parameter M3 Base Shear 139.85
Sr No 01
M4 139.32
Above table of base shear values show nearly same magnitude for both type of structural framing material. But steel structures has a slight lower values than rcc structures. X. A.
RESULTS FOR HIGH RISE MODELS (G+10)
Axial Forces Table 12 Axial Force comparison for model M5 & M6 Parameter M5 Fx 22.353 Fy 2602.216 Fz 15.713
Sr No 01 02 03
M6 29.78 2435.561 17.029
35 30 25 20 M1 15
M2
10 5 0 Fx
Fy
Fz
From the above graph t can be clearly seen that there is reduction of 6.84 % in steel structures when compared to rcc structure. While in horizontal force magnitude rcc structures has lower values. From this it can be concluded that steel structures can be used in high rise construction as compared to rcc structure for same geometric configuration. B.
Displacement
Sr No 01 02 03 04
Table 13 Displacement comparison for model M5 & M6 Displacement M5 X 83.835 Y 0.543 Z 67.315 Resultant 68.179
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M6 59.311 0.528 104.648 105.09
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International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429 Volume 8 Issue V May 2020- Available at www.ijraset.com 120 100 80 M1
60
M2 40 20 0 X
Z
Resultant
Above graph shows that resultant displacement of steel structures are significantly high than rcc structure this is because of the composite behavior of reinforcement and concrete. Also it can be concluded that form displacement point of view steel structures are not suitable in high rise construction of building and if used special displacement controls measure should be followed. C.
Time Period
Sr No 01 02 03 04 05 06
Table 14 Time Period comparison for model M5 & M6 Mode M5 1 2.545 2 1.717 3 0.996 4 0.757 5 0.521 6 0.381
M6 2.953 1.632 1.283 0.801 0.796 0.723
3.5 3 2.5 2
Series 1
1.5
Series 2
1 0.5 0 Mode 1
Mode 2
Mode 3
Mode 4
Mode 5
Mode 6
Above graph shows that like in low and medium rise structures steel structures shows high values of time period in comparison with rcc structure.
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Base Shear
Sr No 01
Table 15 Base Shear comparison for model M5 & M6 Parameter M5 Base Shear 159.78
M6 158.07
Though there is negligible difference in magnitude of both structures steel structures has lower value than rcc which shows that steel structures reduces self-weight of structure. XI. CONCUISONS From all results and discussions in previous chapter following conclusions are drafted :A. From consideration of axial forces steel structures can be used for low, medium and high rise irregular building as it gives lower amount of axial forces than Rcc structure. B. From Displacement consideration steel structures will not be recommended as they gives high displacement values than Rcc structures. Still if one wishes to use steel structural framing proper measures should be taken for displacement control. C. Even in low risk Zone and varying height irregular structure under dynamic loading Steel structures oscillates for more time than Rcc structures. So steel structures should be avoid, and if used they can be properly braced to minimize time period. D. Results shows that steel structures in all height variation gives less dead weight and helps to reduce intensity of lateral earthquake forces. So, Steel structures should be used In case of Irregular buildings in low risk zones under dynamic loading. XII. ACKNOWLEDGEMENT No undertaking of the magnitude involved in the preparation of this project can be accomplished alone. Many have contributed till the successful acknowledge the assistance of the following individuals and would like to thank each one of them. I am Very thankful to Prof. N. N. Mandagale Principal G.H.R University, Amravati. They were constant source of encouragement to all of us. I am Also thankful to Prof. H.B. Dahake H.O.D. civil dept. For showing me the way to create the track towards new horizon. I express my deep sense of gratitude and sincere regards to my guide Prof. V.M.Sapate for giving me his valuable time, & Knowledge for my Project. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8]
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