Scientific Journal of Impact Factor (SJIF): 4.72 International Journal of Advance Engineering and Research Development Volume 4, Issue 5, May-217 e-issn (O): 2348-447 p-issn (P): 2348-646 COMPARATIVE STUDY ON PODIUM STRUCTURE AND NORMAL STRUCTURE UNDER SEISMIC BEHAVIOUR Soham H. Patel 1, Nihil Sorathia 2, Vaibhav patel 3 1 Postgraduate student, Department of civil engineering, Parul University, Vadodara 2 Assitant Professor, Department of civil engineering, Parul University, Vadodara 3 Structural& Architect, Benchmark Consultant, Ahmedabad Abstract-This study investigates the Earthquakes are natural hazards which cause destructionto life and property. The placement of beams and columns of the podium are very important under both static and dynamic analysis. In this study attempt is made to understand the effect of responsespectra (Dynamic analysis), Static analysis and a time history analysis with 3 different time history Bhuj, chamoli and Uttarkashi taking for study. Present study includes four different podium structure and compare the base shear, storey stiffness, storey displacement short column effect with their normal structure under both the dynamic and static analysis, earthquake data is used as an input motion for different modes to get an acceleration time history of the building as well as response spectra. ETABS was used to perform response spectra and time history analysis. Total 5 models were analyzed like 4 different column placed structure and one normal structure. Keywords- response spectra, Time history, Short column effect, Baseshear, ETABS I. INTRODUCTION Now a day we live in such era where population is a major problem and increasing day by day thus resulting in construction of more vertical housing due to shortage of land. Earthquake is a common disastrous phenomenon that each and every structure on earth may suffer to certain damage. The seismic waves affect the building more violently that leads to building collapse. The aim of the structural engineer is to know the reason of building collapse due to earthquake and find out appropriate solution for that may be designing a structure to withhold the lateral forces etc. Among the different structures available Podium structure is one among them which can solve the above mentioned problem. For the reason engineer has to focused on both the static and dynamic analysis and analysed base shear, storey displacement, short column effect, storey stiffness and so on. Podium, in terms of architecture, it means various elements form as the foot or base of a structure; or it means the structurally or decoratively emphasized the lowest portion of a wall (Oxford, 212). The word Podium Structure is an architectural building typology which a podium in few stories height at the bottom, while one or more towers on top of the podium to form a special building typology. Some of the podium-tower structures will be used as commercial purpose, while many of them are mainly mix-used with the podium as commercial activities and the towers as offices, hotels or residential units. 2.1 Problem definition II. MODELLING Static and dynamic methods are adopted in the study and the time histories of some Indian earthquakes have been considered. In the present study time histories of the different locations in India is specified such as Bhuj, Chamoli, Uttarkashi. The magnitude acceleration of each and every earthquake is given in tabular form below: Location Year Magnitude Time step (s) Records Duration (s) Bhuj 21 7.9.5 2676 133.55 Chamoli 1999 6.6.5 875 227.95 Uttarkashi 1991 6.6.2 166 322.95 Table: 1 Time histories of different location in India 2.2 Different models and position In the present work the analysis of following structures is been carried out: A) Podium 1 B) Podium 2 C) Podium 3 @IJAERD-217, All rights Reserved 21
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 D) Podium 4 E) Normal Figure 1. Podium 1Figure 2. Podium 2 Figure 3. Podium 3 Figure 4. Podium 4 Figure 5. normal The materials such as Poisson ratio, Density of Rcc, Density of masonry, Young s modulus, compressive strength of steel and concrete etc. are kept constant in all buildings. Generally, here taking 4 x 32 m plan area for conducting the structure area, after the 3 rd floor plan area become 3 x 24 m plan. For the structure we are taking 13 th floor. @IJAERD-217, All rights Reserved 22
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 Table 2: Material Specifications Grade of Concrete Grade of Steel Density of Concrete Density of Brick wall Slab thickness Column 1 Column 2 Beam size Storey height No. of floors Fck = 25 N/mm² Fy =415 N/mm² γc =25 kn/m³ γ = 2 kn/m³ 125mm.6 m X.6 m.5 m x.6 m.3 X.45 m 3mm 13 floor Table 3: Loading Earthquake zone II Importance factor 1 Response reduction factor 5 Wall load Parapet wall load Typical floor live load Terrace live load Floor finish on floor Floor finish on terrace 11.73kN/m 2.3kN/m 4kN/m 2kN/m kn/m 1.5kN/m III. RESULTS & DISCUSSION The following are the results derived from the static, response spectrum and time history method. The results show the difference between different types of building and parameters are compared with the normal building structure: 3.1 Base shear @IJAERD-217, All rights Reserved 23
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 BASE SHEAR 8 6 4 2 651.599 6319.8493 1115.6965 874.963 2225.4314 689.226 119.2426 9.1924 1785.134 729.9782 EQ RS Max BHUJ Max CHAMOLI Max UTTARKASHU Max Figure 6.Base shear for podium 1 7 6 5 4 3 2 1 69.6333 BASE SHEAR 4859.8235 1115.6965 875.766 219.889 625.898 119.269.317 16.11 699.1543 EQX RS Max BHUJ Max chamoli Max uttarkashi Max Figure 7. Base shear for podium 2 BASE SHEAR 8 6 4 2 651.513 6319.8466 1115.6965 875.767 2225.433 689.2198 119.269.315 1785.1298 729.9776 EQX RS Max BHUJ Max chamoli Max uttarkashi Max Figure 8. Base shear for podium 1 @IJAERD-217, All rights Reserved 24
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 BASE SHEAR 7 6 5 4 3 2 1 676.855 4726.4727 2124.5693 199.112857.855 1172.47 165.959 618.379 882.8336 674.876 EQ RS Max BHUJ Max chamoli Max uttarkashi Max Figure 9. Base shear for podium 4 Base shear 12 1 8 6 4 2-2 1461.259 621.5511 3484.2413 1645.9964 1397.9689 1767.3 2438.131 1484.7749-821.1295-134.568 EQ RS Max BHUJ Max CHAMOLI Max UTTARKSHI Min Figure 1. Base shear for normal Here define that time history gives more values compare to the static and dynamic analysis. Normal structure gives more base shear compare to podium structure. Above figure 6,7,8,9,1 are shows the Bhuj, chamoli and Uttarkashi time history base shear are found different values as per their magnitude and duration of earthquake. Maximum base shear found in bhuj time history for heavy seismic force over there. @IJAERD-217, All rights Reserved 25
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 3.2Storey displacement for dynamic analysis: 13 1.3 1.33 12 1.6 1.8 11 9.66 9.67 1 9.1 9.12 9 8.4 8.42 8 7.58 7.61 7 6.65 6.69 6 5.61 5.67 5 4.48 4.56 4 3.28 3.38 3 2.13 2.22 2 1.27 1.33 1.47.5 Base 13 1.3 1.33 12 1.6 1.8 11 9.66 9.67 1 9.1 9.12 9 8.4 8.42 8 7.3 7.65 7 6.64 6.69 6 5.61 5.67 5 4.48 4.56 4 3.29 3.33 3 2.13 2.22 2 1.27 1.33 1.44.5 Base Table 5 storey displacement podium 1 Table 6 storey displacement podium 2 13 1.34 1.33 12 1.1 1.12 11 9.65 9.6 1 9.9 9.1 9 8.4 8.42 8 7.55 7.54 7 6.66 6.68 6 5.66 5.67 5 4.5 4.55 4 3.28 3.38 3 2.1 2.12 2 1.27 1.33 1.48.55 Base 13 1.15 1.17 12 9.11 9.93 11 9.51 9.53 1 8.96 8.98 9 8.27 8.3 8 7.46 7.5 7 6.54 6.59 6 5.52 5.58 5 4.41 4.49 4 3.23 3.33 3 2.9 2.18 2 1.24 1.31 1.46.49 Base Table 7 storey displacement podium 3 Table 8 storey displacement podium 4 13 1.59 1.85 12 1.38 9.64 11 1.2 1.3 1 9.81 8.82 9 8.87 8.82 8 8.11 7.5 7 7.23 6.68 6 6.25 5.77 5 4.17 4.77 4 4. 3.69 3 2.76 2.54 2 1.63 1.52 1.6.58 Base Table 9 storey displacement normal @IJAERD-217, All rights Reserved 26
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 Here are the 5 tables of the storey displacement of the structure. It should found that displacement is increase as number of floors increase. 3.3 Comparison of short column effect: For the analysis here taking Bending moment and Shear force for the structure. A) Static analysis Bending moment(kn) 6 4 2 36.76 2.1 41.81 19.32 41.81 19.32 36.22 19.8 33.39 36.61 Series1 36.76 col11 col12 2.1 41.81 col21 19.32 col22 41.81 col31 19.32 col32 36.22 col41 col42 19.8 33.39 col51 36.61 col52 Bending moment (Static analysis) Shear force(kn) 3 2 1 17.83 23.67 23.67 17.57 22.26 23.24 9.76 8.83 8.83 9.61 Series1 17.83 col11 col12 9.76 23.67 col21 col22 8.83 23.67 col31 col32 8.83 17.57 col41 col42 9.61 22.26 col51 23.24 col52 Shear force (Static analysis) B) Dynamic analysis (Responsespectrum) Benading moment(kn) 3 2 1 23.21 26.33 26.33 22.83 14.4 13.47 13.47 13.8 25.19 28.55 Series1 23.21 col11 14.4 col12 26.33 col21 13.47 col22 26.33 col31 13.47 col32 22.83 col41 col42 13.8 25.19 col51 28.55 col52 Bending moment (Dynamic analysis) Shear force(kn) 2 1 11.59 15.19 15.19 17.12 18.64 7.93 7.33 7.33 11.39 7.78 Series1 11.59 col11 col12 7.93 15.19 col21 col22 7.33 15.19 col31 col32 7.33 11.39 col41 col42 7.78 17.12 col51 18.64 col52 Shear force (Dynamic analysis) @IJAERD-217, All rights Reserved 27
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 C) Bhuj time history analysis: Benading moment(kn) 3 2 1 221.19 11.76 27.92 17.9 222.55 188.97 113.48 116.6 135.23 147.1 Series1 col11 col12 col21 col22 col31 col32 col41 221.19 11.76 27.92 17.9 222.55 113.48 188.97 col42 116.6 col51 col52 135.23 147.1 Bending moment (Bhuj time history analysis) Shear force(kn) 15 1 5 128.52 55.1 118.56 55.2 128.83 57.43 92.93 64.5 9 92.15 Series1 128.52 col11 col12 55.1 118.56 col21 col22 55.2 128.83 col31 57.43 col32 92.93 col41 64.5 col42 col51 9 92.15 col52 Shear force (Bhuj Time history analysis) Here the above all graph shows that comparison of bending moment and shear force between podium and normal structure for the Static, Dynamic, and Bhuj time history analysis. Column11,12,21,22,31,32,41,42 are for the 4 podium and remaining for the normal. Here shows in fig11 Bending moment sudden change due to change in stiffness. figure11 @IJAERD-217, All rights Reserved 28
Volume 4, Issue 5, May-217, e-issn: 2348-447, print-issn: 2348-646 IV. CONCLUSION 1. Comparison of base shear values for time histories are shown in which the values for time history are higher than the Static and Dynamic (response spectrum) method, also the normal structure has more base shear compare to the podium structure. 2. In case of bhuj near field earthquake base shear is 329% higher than chamoli, keep in with chamoli is 135% higher value compare to Uttarkashi field earthquake, In addition Static analysis is 17% more than the dynamic analysis for podium structure. 3. For the Storey displacement it is clearly found that under seismic behavior the value of displacement is rise as increase the number of floors. Highest value found at the top floor. 4. For the static analysis podium structure has bending moment 82%, 116%, 116%, 82%difference happen for podium structure as well as Shear force 82%, 168%, 168%, 82% difference happen for podium structure between upper and lower column. 5. For the Dynamic analysis podium structure has bending moment 65%, 95%, 95%, 72%difference happen for podium structure as well as Shear force 46%, 17%, 17%, 46% difference happen for podium structure between upper and lower column. 6. For the Bhuj time history analysis podium structure has bending moment 99%, 94%, 96%, 62%difference happen for podium structure as well as Shear force 113%, 114%, 124%, 45% difference happen for podium structure between upper and lower column. 7. Short column effect for Bhuj, Dynamic analysis, and static analysis of structures, it is found that column located near the podium placement there is huge change in stiffness, for the reason it is more increase the bending moment and shear force for upper column compare to the below column. There comparatively graphs are shown above structure Normal structure has no any problem. 8. So we can conclude that the time history analysis is exact analysis is give us idea about the actual force developed in structure during ground shaking. The column near corner levels are subjected to short column effect so they must be properly placed and proper designed to resist earthquake force. REFERENCES [1] Dr. S.K. Dubey, P.D. Sangamnerkar., Seismic Behaviour of Asymmetric Rc Buildings, International Journal of Advanced Engineering Technology E-ISSN 976-3945 IJAET/Vol.II/ Issue IV/October-December, 211/296-31. [2] Mohit Sharma, Dr.SavitaMaru., Dynamic Analysis of Multi-storied Regular Building, IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-issn: 2278-1684,p-ISSN: 232-334X, Volume 11, Issue 1 Ver. II (Jan. 214), PP 37-42. [3] BahadorBagheri, Ehsan SalimiFiroozabad, and MohammadrezaYahyaei., Comparative Study of the Static and Dynamic Analysis of Multi-storey Irregular Building, World Academy of Science, Engineering and Technology Vol: 6 212-11-27. [4] Mohammad Umar., Reinforced concrete buildings of seismic behaviour under significance of fluctuating frequency, International Journal of Advance Research in Science and Engineering IJARSE, Vol. No.4, Issue 6, June 215 ISSN-2319-8354(E). [5] S.Zubair Ahmed, K.V.Ramana, Ramancharla Pradeep Kumar, Seismic Response of Rc Frame Structure With Soft Storey, IJRET: International Journal Of Research In Engineering And Technology Volume: 3 Issue: 9 Sep-214. [6] Mr.S.Mahesh, Mr.Dr.B.Panduranga Rao., Comparison of analysis and design of regular and irregular configuration of multi-story building in various seismic zones and various types of soils using etabs and staad, IOSR Journal Of Mechanical And Civil Engineering (IOSR-JMCE) E-issn: 2278-1684,p-issn: 232-334X, Volume 11, Issue 6 Ver. I (Nov- Dec. 214). [7] Dr.SaraswatiSetia And Vineet Sharma, Seismic Response Of R.C.C Building With Soft Storey, [8]IS 1893 (Part 1): 22, Indian Standard Criteria for Earthquake Resistant Design of Structures, Part 1: General Provisions and Buildings. [9] www.strongmotioncenter.org. [1] IITK BMTPC Earthquake tips, Indian Institute of Technology, Kanpur. [11] A. S.Patil and P. D. Kumbhar, Time history analysis of multistoriedrcc buildings for different seismic intensities. @IJAERD-217, All rights Reserved 29