Comparative Study of RCC and Composite Multistoreyed Buildings

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1 Comparative Study of RCC and Composite Multistoreyed Buildings Shashikala. Koppad, Dr. S.V.Itti Post Graduate Student, Department of Civil Engineering, KLEMSSCET, Belgaum, Karnataka, India, Professor and Head of the Department of Civil Engineering, KLEMSSCET, Belgaum, Karnataka, India Abstract Steel concrete composite construction means the concrete slab is connected to the steel beam with the help of shear connectors so that they act as a single unit. In the present work steel concrete composite with RCC options are considered for comparative study of B+G+15 storey of residential building which is situated in earthquake zone 3 and for earthquake loading, the provisions of IS:1893(Part1)-2002 is considered. For modeling of composite and RCC, STAAD-proV8i software is used. The results of this work shows that, the cost of composite beam is less by 27% as compared to RCC beam. The maximum shear force and maximum bending moment are less in composite beam as compared to RCC beam. The node displacement is on higher side in composite structure as compared to RCC structure. The weight of composite structure is also less compared to RCC structure. Composite are the best solution for high rise structure as compared to RCC structure. R.C.C. and masonry buildings due to earthquake has forced the structural engineers to look for the alternative method of construction. Use of composite or hybrid material is of particular interest, due to its significant potential in improving the overall performance through rather modest changes in manufacturing and constructional technologies. In India, many consulting engineers are reluctant to accept the use of composite steel- concrete structure because of its unfamiliarity and complexity in its analysis and design. But literature says that if properly configured, then composite steel-concrete system can provide extremely economical structural systems with high durability, rapid erection and superior seismic performance characteristics. Index Terms Composite beam, RCC column, RCC beam, Staad-pro Software. I. INTRODUCTION AND OBJECTIVES An important and economic combination of construction materials is that of steel and concrete, with applications in medium to high-rise buildings as well as bridges. In India reinforced concrete members are mostly used in the framing system for most of the buildings since this is the most convenient & economic system for low-rise buildings. However, for medium to high-rise buildings this type of structure is no longer economic because of increased dead load, less stiffness, span restriction and hazardous formwork. Steel-concrete composite frame system can provide an effective and economic solution to most of these problems in medium to high-rise buildings. The objectives of the study are To provide a brief description to various components of steel concrete framing system for buildings. To investigate the cost effectiveness of steel-concrete composite frames over traditional reinforced concrete frames for building II. COMPOSITE CONSTRUCTION In the past, for the design of a building, the choice was normally between a concrete structure and a masonry structure. But the failure of many multi-storied and low-rise Fig 1: Typical Composite Beam Slab Details Formally the multi-story buildings in India were constructed with R.C.C framed structure or Steel framed structure but recently the trend of going towards composite structure has started and growing. In composite construction the two different materials are tied together by the use of shear studs at their interface having lesser depth which saves the material cost considerably. Thermal expansion (coefficient of thermal expansion) of both, concrete and steel being nearly the same. Therefore, there is no induction of different thermal stresses in the section under variation of temperature. 1) Composite beam definition A steel concrete composite beam consists of a steel beam, over which a reinforced concrete slab is cast with shear connectors. The composite action reduces the beam depth. Rolled steel sections themselves are found adequate frequently for buildings and built up girders are generally unnecessary. The composite beam can also be constructed 341

2 with profiled sheeting with concrete topping or with cast in place or precast reinforced concrete slab. 2) Composite Column definition A steel concrete composite column is conventionally a compression member in which the steel element is a structural steel section. There are three types of composite columns used in practice which are Concrete Encased, Concrete filled, Battered Section. III. BUILDING DETAILS The building considered here is an residential building having B+G+15 storied located in seismic zone 3 and for earthquake loading, the provisions of IS:1893(Part1)-2002 is considered. The wind velocity 39m/s. The plan of building is shown in fig.2 the building is planned to facilitate the basic requirements of an residential building. he plan dimension of the building is 27.1X32.575m. Height of each storey for composite and RCC is 3m and 3.15m. The study is carried out on the same building plan for RCC and composite construction with some basic assumptions made for deciding preliminary sections of both the. The basic loading on both types of are kept same, other relevant data is tabulated in table1 & 2 Fig. 2 Plan showing typical floor Fig.3 Elevation of Building Fig. 4 3D Model of Building Table 1: Data for Analysis of RCC Structure Plan dimension 27.1X32.575m Total Height of building 54.90m Height of each storey 3.15m Height of parapet 1m Size of beams at plinth level 0.25X0.6m Size of beams at floor level 0.25X0.75m Size of column 0.25x1.25m Thickness of slab 0.15m Thickness of wall 0.2m Seismic zone III Wind speed 39m/s Importance factor 1 Zone factor 0.16 Floor finish 1kN/m 2 Live load 3kN/m 2 Grade of concrete for slabs Grade of concrete for beams and columns Grade of reinforcing steel Fe415 Density of concrete 25kN/m 2 Density of brick 20kN/m 2 Damping ratio 5% Grade of structural steel Fe250 Concrete cover to reinforcement(slab) 0.025m Concrete cover to reinforcement 0.025m (beams) Concrete cover to reinforcement(columns) 0.040m Table 2: Data for Analysis of Composite Structure Plan dimension 27.1X32.575m Total Height of building 52.50m Height of each storey 3m Height of parapet 1m Size of beams at near shear wall ISMB450 Size of other beams ISMB300 Size of column 0.25x1.25m Thickness of slab 0.15m Thickness of wall 0.2m Seismic zone III Wind speed 39m/s Importance factor 1 Zone factor 0.16 Floor finish 1kN/m 2 Live load 3kN/m 2 Grade of concrete for slabs 342

3 Grade of concrete for beams and columns Grade of reinforcing steel Density of concrete 25kN/m 2 Density of brick 20kN/m 2 Damping ratio 5% Grade of structural steel Fe250 Concrete cover to reinforcement(slab) 0.025m Concrete cover to reinforcement 0.025m (beams) Concrete cover to reinforcement(columns) 0.040m Concrete 3032m Fe415 Total cost of RCC beams() IV. ANALYSIS The explained 3D building model is analyzed using Equivalent Static Method. The buildings models are analyzed by using Staad-Pro V8i software. In composite structure the beam is modeled as composite beam element and column is modeled as RCC beam element and shear wall is modeled as RCC plate element. In RCC structure the beam and column is modeled as RCC beam element and shear wall is modeled as RCC plate element. The different parameters such as node displacement, maximum shear force, axial force and maximum bending moment are studied for the models. The dead load and live load are considered as per IS-875(part 1 &2) and wind load is considered as per IS-875(part 3).For earthquake loading IS: 1893 (Part1)-2002 is used. V. RESULTS AND DISCUSSIONS In the present study, the B+G+15 composite and RCC multistory residential building is considered. An effort has been made to calculate the cost effectiveness of composite and RCC structure elements. The parameter considered is nodal displacement, maximum shear force, axial force and maximum bending moment is considered and their variation in the form of graph is shown. A. Cost of Beams The quantity of composite beams and RCC beams are taken from the design and total quantity is shown below. The rate of reinforcing steel, structural steel and concrete are taken from market. The table 3 and table 4 show the total cost of composite beams and RCC beams. Table 3.Cost of Composite beams composite Rate Amount in beams Structural /MT Steel (ton) Reinforcing /MT Steel (ton) Concrete m Total cost of composite beams() Material Reinforcing Steel Table 4.Cost of RCC beams Quantity of Rate Amount in RCC beams /MT (ton) Fig 5. Cost Variation Graph for Composite and RCC Beams B. Cost of Columns The quantity of RCC column for Composite structure and RCC structure are taken from the design and total quantity is shown below. The rate of reinforcing steel and concrete are taken from market. The table 5 and table 6 show the total cost of RCC columns for RCC and composite structure. Table 5.Cost of RCC columns for composite structure RCC column Rate Amount in for composite structure Steel /MT (ton) Concrete m Total cost of RCC column for composite structure Table 6.Cost of RCC columns for RCC structure RCC column Rate Amount in for RCC structure Steel (ton) 51500/MT Concrete m Total cost of RCC column for RCC structure Fig 6. Cost Variation Graph for Composite and RCC Related RCC Columns C. Axial Forces for Composite and RCC Structures From the analysis results axial forces are taken for composite and RCC structure at different floor. The table 7 shows the maximum axial forces in Composite and RCC structure. 343

4 Table7. Composite and RCC Structure Axial Forces at Different Floor Level Type of Column No floor Maximum Axial forces in Composite (kn) Maximum Axial forces in RCC (kn) Plinth rd th th th table 9 shows the maximum bending moment and shear force in composite and RCC structure. Table 9: Maximum Shear Force and Bending Moment in RCC and Composite Beams Comparison Property Composite RCC beam beam Maximum Shear force(kn) Maximum bending moment Z-direction(kN-m) Fig 7.Axial Forces Variation for Composite and RCC Structure Related to RCC Columns D. Node Displacement for Composite and RCC From the analysis results node displacement are taken for composite and RCC structure. The node displacement for composite and RCC structure are given in table 8. Table 8: Composite and RCC Structure Node Displacement at Different Floor Level Type of floor Composite (mm) RCC (mm) Plinth rd th th th Fig 8: Displacement Variation Graph for Composite and RCC Structures E. Maximum Moment and Shear Force in Composite and RCC Beams From the analysis results maximum bending moment and shear force are taken for composite and RCC structure. The Fig 9: Maximum Shear Force for Composite and RCC Beams Fig 10: Maximum Bending Moment Variation for Composite and RCC Beams VI. DISCUSSIONS From table 3, 4 and figure 5 it is clear that the cost of composite beams is 27% less than the RCC beams. This is because, the composite beam does not require formwork, and thus no stripping time. From table 5, 6 and figure 6 it is clear that the cost of composite structure related RCC column is 20.45% less than the RCC structure related RCC column. This is because; in composite structure related RCC column having less axial forces so less reinforcement steel is required. From table 7 and figure 7 it is clear that the axial forces in RCC columns for composite structure is less compared to RCC columns for RCC structure. This is because, RCC sections are bulky in size thus their self-weight as compared to thin steel sections is more. This results in the higher axial force on the columns in case of RCC frame structure. From table 8 and figure 8 it is clear that, node displacements in composite structure is more compared to RCC structure. This is because, composite structure is more flexible as compared to RCC structure. The beam 344

5 ISSN: defection is also more in composite beam as compared to RCC beam. From table 9 and figure 9 it is clear that the maximum shear force and maximum bending moment in composite Building beam is less compared to RCC beam. This is because, the dead load of composite sections is less, as compared to RCC sections. Also the stiffness of the composite sections is less as compared to RCC sections, thus less bending moment is transferred to the beam from the beam-column joint. VII. CONCLUSION In this study, the comparative study of RCC and Composite multistoried building (B+G+15) is presented. Parameter considered are cost of beams, cost of columns, node displacement, beam deflection, maximum shear force, axial force and maximum bending moment is considered. The axial forces in RCC structure is on higher side of composite structure Composite are more economical than that of RCC structure. Weight of composite structure is quite low as compared to RCC structure which helps in reducing the foundation cost. Composite are the best solution for high rise structure as compared to RCC structure. Speedy construction facilitates quicker return on the invested capital and benefits in terms of rent. The node displacement and deflection in composite structure is more compared to RCC structure but the Deflection is within permissible limit. The maximum bending moment in composite beam is less compared to RCC beam. The maximum shear force in composite beam is less Compared to RCC beam. The cost of composite beam is reduces by 27% compared to RCC beam. The cost of composite structure related RCC column is reduces by 20.45% compare to RCC column.. REFERENCES [1] D. R. Panchal, P. M. Marathe, Comparative Study of R.C.C, Steel and Composite (G+30 Storey) Building'', Institute Of Technology, Nirma University, Ahmedabad , December, 2011, pp [2] Mahbuba Begum, Md. Serajus Salekin, N. M. Tauhid Belal Khan, W.Ahmed, Cost Analysis of Steel Concrete Composite Structures in Bangladesh, Asian Journal of Civil Engineering (BHRC), Vol.14, No.6, 2013, pp [3] Anish N. Shah, Dr. P. S. Pajgade, Comparison of RCC and Composite Multi-storied Buildings'', International Journal of Engineering Research and Application (IJERA), ISSN: , Vol.3, Issue 2, March-April 2013, pp [4] P. Kmiecik, M. Kaminski, Modeling of reinforced concrete and composite with concrete strength degradation taken into consideration'', Wroc law University of Technology, Wybrzeze Wyspianskiego Wroc law, Poland 25, [5] D. R. Panchal, Dr. S. C. Patodi, Steel-Concrete Composite Under Seismic Forces", Applied Mechanics Department, Faculty of Technology and Engineering, The M. S. University of Baroda, Vadodara and Professor, Civil Engineering Dept. Parul Institute of Engineering & Technology, Limda Vadodara. [6] Waldemar St. Szajna, Numerical Analysis of Steel-Reinforced Concrete Composite Girder'', University of Zielona Gora, Prof. Z. Szafrana St. 2, Zielona Gora, Poland (2005) [7] Zhaohui huang, Ian W. Burgess and Roger J. Plank, Behaviour of reinforced concrete in re''. [8] Sandeep Chaudhary, Umesh Pendharkar and A. K. Nagpal, Hybrid Procedure for Cracking and Time-Dependent Effects In Composite Frames at Service Load, /(ASCE) (2007)133:2(166). [9] IS 456:2000, Indian Standard code of practice for Plain and Reinforced concrete", Bureau of Indian Standards, New Delhi, [10] SP 16:1980, Design Aids for Reinforced Concrete to IS: ", Bureau of Indian Standards, New Delhi, [11] IS 800:2007, Indian Standard code of practice for General Construction in steel" Bureau of Indian Standards, New Delhi, [12] IS 875(part1 to 5):1987, Code of Practice for design loads for buildings and ", Bureau of Indian Standards, New Delhi, [13] IS criteria for Earthquake Resistant Design of Structures. [14] IS 1893(part1):2002, Criteria for Earthquake Resistant Design of ", Bureau of Indian Standards, New Delhi, [15] IS 11384:1985, Code of Practice for Design of Composite Structure, Bureau of Indian Standards, New Delhi, [16] SP 34:1987, Handbook on Concrete Reinforcement and Detailing" Bureau of Indian Standards, New Delhi, [17] Euro code 3, Design of Steel Structures", European committee for Standardization committee European de normalization europaisches committee fur normung. [18] Euro code 4, Design of composite steel and concrete ", European committee for standardization committee European de normalization europaisches committee fur normung. [19] R.P.Johnson, Composite of steel and concrete'' Volume, Blackwell Scientific publications, UK [20] R. Narayanan, Composite steel " Advances, Design and Construction, Elsevier, Applied sciences, UK, [21] Handbook of composite construction Multi-storey Buildings" INSDAG publications No.INS/PUB/