ANALYSIS OF UNDAMPED IRREGULAR RCC BUILDING USING SAP2000

Transcription

1 ANALYSIS OF UNDAMPED IRREGULAR RCC BUILDING USING SAP2000 B.satish 1, Sunil kumar 2 1M.Tech scholar, Department of Civil Engineering, Chintalapudi Engineering College, 2Head of Department of Civil Engg, Chintalapudi Engineering College, Ponnur, Andhra Pradesh (India) *** Abstract: Structures these days are constructed with irregularities along the height for architectural views. The structure is said to be irregular when the distribution of its mass, stiffness and strength varies along its configuration. Seismic load is considered to be an important load that the structure must be analyzed. From the past earthquake records it can be observed that the structures with irregularity show poor seismic performance. This project work is concerned about analyzing and studying the behavior of irregular building and different models of vertically irregular building when subjected to seismic loads. For the study one model of vertical irregular structure of G+ 40 s is considered. The analysis is carried out by using Sap2000 software by time history method. The results of various parameters like time period, displacement, and stiffness are obtained and the graphs are plotted. From the results it can be observed that regular structure possess better seismic performance as compared to vertically irregular structure. INTRODUCTION 1. GENERAL The primary purpose of all kinds of structural systems used in the building type of structures is to support gravity loads. The most coon loads resulting from the effect of gravity are dead load, live load and snow load. Besides these vertical loads, buildings are also subjected to lateral loads caused by wind, blasting or earthquake. Lateral loads can develop high stresses, produce sway movement or cause vibration Therefore, it is very important for the structure to have sufficient strength against vertical loads together with adequate stiffness to resist lateral forces. 1.2 SEISMIC ZONE MAP OF INDIA & RECENT EARTHQUAKES rule to arrangement of a satisfactory tremor protection in developed offices. the main thorough seismic zoning map was produced by the Bureau of Indian Standards in Later in the ensuing years it was evaluated coonly and along these lines a four zone seismic zoning map was embraced in Is 1893:2002. The guide depends on expected force of shaking yet does not think about the recurrence of the event. Current seismic zoning map according to IS says that around 60% (Zone V= 12%, Zone IV=18%, Zone III = 26% and Zone II 44%) of India is inclined to direct to significant earthquakes. As needs be, zone factors (z) are characterized for each zone to touch base at the plan seismic power following up on the structure. Zone II relates to force VI or lower and zone V compares to power IX or higher. Zone II has most reduced threat or hazard while Zone - V has most astounding perils. Since harm controlled point of confinement state has been acknowledged, the zone factor, z has been decreased to half (z/2) of Maximum Considered Earthquake (MCE) for Design Basis Earthquake (DBE). Structures are expressly intended for DBE and most extreme considered seismic tremor is dealt with through finished quality and pliability arrangements. Earthquakes have been happening in the Indian sub landmass from the time iemorial however dependable chronicled records are accessible throughout the previous 200 years (Oldham, 1883). From the earliest starting point of the twentieth century, more than 700 earthquakes of size at least 5 have been recorded and felt in India. The seismicity of India is separated into four gatherings, to be specific Himalayan locale, Andaman Nicobar, Kutch Region, and Peninsular India. The objective of seismic zoning is to outline districts of plausible power of movement in a nation, for giving a Fig: 1 Seismic zoning maps of India I.S. 1893:1966 and IS1893: OBJECTIVE OF STUDY Time History Analysis of Buildings. To compare the following aspects of the buildings. 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 861

2 Lateral Displacements at joints. Acceleration. Base shear-x direction Beam Line element Torsion Velocity 1.4 CASE STUDY In the present work, a 40-storied reinforced concrete building situated in Hyderabad city which falls in Zone IV, is taken for the purpose of study. The plan area of building is 54x54m and 3.0m as height of typical. It consists of 9 bays in X-direction and 9 bays in Y-direction. The total height of the building is 120.2m along parapet wall. The building is considered as a Special Moment Resisting Frame. The plan of building is shown in fig. 4.1 and the front elevation along x-z axis is shown in Fig n the elevation along y-z axis is shown in Fig Also the isometric view of the building is shown in the Fig.41. As the structure is regular and relatively simple, the identification of the differences in results can be known in easy and can be discuss in depth. All dimensions are in meters Fig 2: Plan of Model-1, Mass as-syetric structure in regular shape as shown in figure. All dimensions are in meters Fig 3. Plan of Model-2, Mass as-syetric structure in irregular shape as shown in figure All dimensions are in meters Fig 4.Plan of Model-3, Mass as-syetric structure in irregular shape as shown in figure 2. GENERAL DATA COLLECTION OF MASS AS- SYMMETRIC STRUCTURE Table 1: General data collection and condition assessment of the building. S. No. Description MODEL - 1 MODEL - 2 MODEL Plan size 54x54m 54X54m 54X54m 2. Building height 120.2m 120.2m 120.2m Number of stories above Type of structure Open 6. Falling hazards 7. Type of building 8. Beam sizes 9. Column sizes 10. Mass load 40 RC Yes Parapet wall Regular with open 450x x x x12 00 Loads are RC Yes Parapet wall Regular with open 450x x x x12 00 All loads are same RC Yes Parapet wall Regular with open 450x x x x12 00 All loads are same 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 862

3 10. Grade of concrete used 11. Software used different from span to span. M40 SAP200 0 vs RESULTS AND DISCUSSION from floor to floor M40 SAP2000 vs. 16 from floor to floor M40 SAP2000 vs. 16 The results of the analytical investigations are presented in the Tables. The results are also shown graphically in the Figures Displacement at point 1: After modeling and analyzing the structure, the displacements at the joints in the structure were checked out. In this chapter, joints of the extreme columns of comparison of three buildings are checked for displacement and they are compared. Table 2: Time vs. Displacement at joint 1 in the buildings. The table below shows the Displacement values with respect to time for 25s at joint 1 in the buildings. Mass as-syetric Mass as-syetric Mass as-syetric Time (s) Displacement(m) Time (s) Displacement(m) Time (s) Displacement(m) E E Mass as-syetric Mass as-syetric Mass as-syetric Time (s) Displacement(m) Time (s) Displacement(m) Time (s) Displacement(m) Fig 5: time vs. displacement at joint: 1 in the buildings The above table shows the variation of displacement values at the interval of 0.5 second in the three different types of structures i.e., syetric structure to asyetric structure. It is observed that there is minor change in the displacement 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 863

4 GRAPH: In the below figure shows the variation of displacement with time for all the three types of Mass as-syetric buildings are: 1. Model-1 in regular shape 2. Model-2 in irregular shape 3. Model-3 in irregular shape In this variation of stiffness as-syetric is very high when compared to syetric structure & mass as-syetric but the values of syetric structure is quite greater than the mass as-syetric structure.(i.e., stiffness as-syetric > syetric structure > stiffness as-syetric). Table: 3. it shows the maximum displacement with respect to time for three types of the buildings: STRUCTURES MAXIMUM DISPLACEMENT At point IN (M) TIME(S) Model Model Model The maximum displacement with respect to time when compared with 3 types of buildings is 2.36m at 11s in Model- 2. Fig.7: 3D Model of 40 building. Table 4: Time vs. Acceleration in columns at joint-1 in buildings. The table below shows the Acceleration values with respect to time for 25s at joint 1 in the buildings Mass as-syetric Mass as-syetric Mass as-syetric Time (s) Accleration(m/s2) Time (s) Accleration(m/s2) Time (s) Accleration(m/s2) Fig 6: Graph showing Time vs. displacement at joint no.1 in the buildings. The above graph shows the variation of displacement values at the interval of 0.5 second in the three different types of structures i.e., syetric structure to asyetric structure. It is observed that there is minor change in the displacement 3.2 ACCELERATION AT JOINT: 1: And the values of these accelerations were compared with the values of corresponding columns of the buildings. The values of acceleration in UX direction are shown. Mass as-syetric Mass as-syetric Mass as-syetric Time (s) Accleration(m/s2) Time (s) Accleration(m/s2) Time (s) Accleration(m/s2) , IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 864

5 The above table shows the variation of acceleration values at the interval of 0.5 second in the three different types of structures i.e., syetric structure to asyetric structure. It is observed that there is major change in the acceleration GRAPH: 3.3 VELOCITY AT JOINT 1: After modelling and analyzing the structure, the velocity at the joints: 4 in the structure were checked out. In this chapter, joints of the extreme columns of comparison of three buildings are checked for velocity and they are compared. The below figure shows the variation of acceleration with time for all the three types of buildings are: 1. Model-1 in regular shape 2. Model-2 in irregular shape 3. Model-3 in irregular shape In this, variation of stiffness as-syetric is very high when compared to stiffness as-syetric structure but the value of stiffness asyetric structure is high than mass assyetric (i.e., stiffness as-syetric > stiffness assyetric > mass as-syetric structure.) Table: 5: It shows the maximum Acceleration with respect to time for three types of the buildings: STRUCTURE MAX. ACCELERATION AT POINT 1 IN m/s 2 TIME(S) Model Model Model The maximum Acceleration with respect to time when compared with 3 types of buildings is 71m/s2 at 6.5s in Model-2. Fig 8: Graph showing Time vs. acceleration at joint1 in buildings. The above graph shows the variation of acceleration values at the interval of 0.5 second in the three different types of structures i.e., syetric structure to asyetric structure. It is observed that there is major change in the acceleration Figure 9 : 3D Model of 40 building. Table 6: Time vs. velocity at joint: 1 in the buildings. The table below shows the Velocity values with respect to time for 25s at joint 1 in the buildings. Mass as-syetric Mass as-syetric Mass as-syetric Time (s) Velocity(mph) Time (s) Velocity(mph) Time (s) Velocity(mph) , IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 865

6 Mass as-syetric Mass as-syetric Mass as-syetric Time (s) Velocity(mph) Time (s) Velocity(mph) Time (s) Velocity(mph) The above table shows the variation of velocity values at the interval of 0.5 second in the three different types of structures i.e., syetric structure to asyetric structure. It is observed that there is minor change in the velocity GRAPH: The below figure shows the variation of velocity with time for all the three types of buildings are: 1. Model-1 in regular shape 2. Model-2 in irregular shape 3. Model-3 in irregular shape In this, variation of stiffness as-syetric is very high when compared to syetric structure & mass as-syetric but the values of syetric structure are quite greater than the mass as-syetric structure. Table 7. It shows the Maximum Velocity with respect to time for three types of the buildings. STRUCTURE MAXMUM VELOCITY(MPH) TIME(S) Model Model Model CONCLUSIONS The present practice in seismic design is to adopt Response spectrum method of structural analysis. The code leaves the application of method of dynamic analysis making use of Time History Analysis concept to the discretion of the designer. In this context in the present project, a 1- building has been analyzed Time History Analysis making use of Sap2000. In brief, In the syetric structure the centre of mass and centre of radius is coincides.in the mass as-syetric structure, the centre of mass is at an eccentricity and In stiffness as-syetric structure the centre of rigidity is at an eccentricity. A comparison of the three sets of results demonstrates both the capabilities and limitations of the proposed procedure. 1. Single stiffness asyetric buildings oscillate predominantly in the first mode than the mass asyetric building and the syetric building. 2. The comparison of results for the maximum displacement, velocity, acceleration, torsion obtains from the time history analysis of single asyetric building; show that the proposed procedure can estimate the response of multi- building model satisfactory. 3. It has been observed that the lateral displacements, more in stiffness asyetric structure. It has been noticed that the displacement values for building with syetric structure is less by 30% and mass asyetric structure is less by 77% when compared to building with stiffness asyetric structure. 4. The maximum velocity, is more in stiffness asyetric structure.it has been noticed that the maximum velocity values in syetric structure is less by 23% and in mass asyetric structure is less by 75% when compared to building with stiffness asyetric structure. 5. The base shear is more in syetric structure when compared to other two structures. It has been noticed that the base shear in stiffness asyetric structure is less by 28% and in mass asyetric structure is less by 47% when compared to building with syetric structure. 6. The maximum torsion, is more in stiffness asyetric structure.it has been noticed that the maximum torsion values in syetric structure is less by 33% and in mass asyetric structure is less by 77% when compared to building with stiffness asyetric structure. 5. REFERENCE 1. AdyAviram, BozidarStojadinovic, Armen Der Kiureghian, (2010), Performance And Reliability Of Exposed Column Base Plate Connections For Steel Moment- 2. Resisting Frames, PEER Report 2010/107 Pacific Earthquake Engineering Research Center College of Engineering University of California, Berkeley. 3. ASCE (2002), Standard Methodology for Seismic Evaluation of Buildings StandardNo. ASCE , IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 866

7 American Society of Civil Engineers, Reston, Virginia. 4. ATC 40,(1996). Seismic evaluation and retrofit of concrete buildings, Vol.1, Applied Technology Council, Redwood city, CA. 5. Bill Tremayne & Trevor E Kelly, (2005), Time History Analysis As A Method Of 6. Implementing Performance Based Design, Holmes Consulting Group, Auckland, New Zealand. 7. Chang S. and Kim. S.,(1994), Structural Behaviour Of Soft Story Buildings, National Earthquake Engineering Congress, pp SAP (2000), V14, Structural Analysis Program, Computers and Structures, Inc., Berkeley, CA. 2018, IRJET Impact Factor value: ISO 9001:2008 Certified Journal Page 867