IJSTE - International Journal of Science Technology & Engineering | Volume 4 | Issue 3 | September 2017 ISSN (online): 2349-784X
Comparative Studies on Construction Cost of High Raise Buildings (Designed under RC Frame and Shear Wall Systems) T. Anil Kumar PG Student Department of Civil Engineering GVPCOE(A)
K. Padmanabham Associate Professor Department of Civil Engineering GVPCOE(A)
Abstract The present construction practice of high raise buildings, mostly adopting beam column slab (BCS) moment resistance framed system. From the observations of recent happenings, geographical changes are rapidly happening in India, causing high floods, cyclones and earthquakes which seriously influencing the performance of tall structures. Shear wall flat slab system (SWFS) is recent advancement in the construction of tall structures, where the system provides an efficient structural configuration to distribute lateral loads through shear walls and flat slab. Even the performance of SWFS system is well established in the design of tall buildings, a limited scope of studies are made against economic viability. This paper discussed about the relative costbenefits and material consumption of SWFS system compared with BCS framed system, in a reinforced concrete multi storied buildings. The proposed 18 storied residential building located at Visakhapatnam (seismic zone-II) of Andhra Pradesh India and the design followed by ETABS software. The study concludes that SWFS system is economically viable than BCS frame system and the cost of construction and material consumption are relatively 3% less in SWFS system. Hence the designers need to promote SWFS system for better performance and economic viability of tall buildings. Keywords: Economic studies, Shear wall, Beam column, Tall buildings, ETABS ________________________________________________________________________________________________________ I.
INTRODUCTION
Rapid growth of urban population in India demands vertical growth of RC multi storied buildings. Irrespective of the location and geographical conditions of buildings, the combination of gravity and lateral forces due to seismic and wind intensity, seriously influence the structural performance of high raised buildings. In this context the recent advancements in high raised constructions promotes the use of RC shear wall flat slab system and discourage the routine practice of RC beam column slab framed system. The relevant studies made in the past also emphasized the significance of shear wall system for efficient performance of multi storied buildings against lateral forces. But due to lack of economic studies, much awareness is not promoted to adopt shear wall system in multi storied buildings. Most of the builders are in wrong inception that shear wall system is more cost than beam column framed system. To verify this fact, economic studies are conducted on 18 storied residential building, which was proposed to construct at Visakhapatnam city of Andhra Pradesh-India (seismic zone II). The structure is designed by ETABS software. Two numerical models are developed under different structural configurations such as beam column slab (BCS) system of RC moment resistance frame, and shear wall flat slab (SWFS) system. It was well established fact that SWFS system shows good structural performance and less construction time than BCS system. Hence detailed studies need to verify the economic aspects and material consumption of SWFS system. The present study conducts relative comparison of structural material consumption between SWFS and BCS system so as to promote the advantage of economic system required for high raised constructions in seismic zones. II. LITERATURE REVIEW Akash D.shah, conducted parametric study of multi-storey tall building using composite member and conventional member. In the study, thirty storey tall building of three different models designed based on RCC structure, steel structure and composite structure. The analysis is done by ETABS software and results such as storey drift, joint displacement and base shear are verified. He concluded that composite structures are more economical and effective than RC and steel structures in multi storied buildings Khushboo K. Soniet et al.[1], developed structural models for 12 storey, 15 storey and 18 storey building with and without shear walls , to assess the comparative seismic performance of buildings in terms of displacement, storey drift, base shear, and cost. The seismic analysis proceed through static analysis method for earthquake zone II. They concluded that high rise buildings with shear wall are economical as compared to without shear wall.
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Comparative Studies on Construction Cost of High Raise Buildings (Designed under RC Frame and Shear Wall Systems) (IJSTE/ Volume 4 / Issue 3 / 016)
III. OBJECTIVE OF THE STUDY The scope and objective of this study is to evaluate the material consumption and cost of construction of 18 storied residential building designed under RC shear wall-flat slab and RC beam column framed system .Comparison of the two systems are made for economic viability. The layout of the structure is shown in Fig 1
Fig. 1: Layout of the structure
IV. BRIEF REVIEW ON DESIGN MODELS Description: Two types of numerical models are developed for sixteen storied buildings of plan area 27m x 38m, which is proposed to construct at seismic zone II in Visakhapatnam city-India. The proposed two models are designed for different geometric configuration based on their structural performance. Model-I consists of RC beam column slab framed system and Model-II consists of RC shear wall flat slab system. The design loads are considered as per the building code IS 875-2015 (Part-I, II & III) and the design methodology is followed by IS 456-2000 Limit state method. Influence of bot lateral and gravity loads are taken into consideration in the design. Performance studies of both models are evaluated with respect to displacement, inter storey drift and stiffness aspects .Geometry and design considerations of the building models are as mentioned below Model I: 18 storied RC beam column slab framed structure with brick walls: plan area 27m x 38m, cellar floor height 3.5m and rest of the floor height 3m each (Typical). Model II: 18 storied RC shear wall flat slab structure with plan area 27m x 38m, cellar floor height 3.5m and rest of the floor height 3m each (Typical).
Fig. 2: Model I: Typical Floor Plan (27x38m)
Fig. 3: Model II: Typical Floor Plan (27x38m)
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Comparative Studies on Construction Cost of High Raise Buildings (Designed under RC Frame and Shear Wall Systems) (IJSTE/ Volume 4 / Issue 3 / 016)
Fig 4: Model 1-Elevation of building
Fig 5: Model II- Elevation of building
Geometry & Material Properties of models: The modeling of the RC structure done by ETABS 2015 software. The Member dimension and applied loads are presented in Table I. Critical combination of both gravity, seismic and wind loads are taken into consideration during the analysis. Table - 1 Structure type Size Of Building No Of Storey Storey Height Cellar height Thickness of RC slab Shear Wall Thickness Beam Size B1 (Model I) Beam Size B2 Beam Size B3 Column Size C1 (Model I) Column Size C2 Column Size C3 Column Size C4 Seismic Zone Soil Type Importance Factor (I) Response reduction Factor Zone factor Live Load External Wall Load Internal Wall Load Grade of concrete used Grade of steel used
RC Moment resistance framed structure 38mx27 m 18 (Sub cellar+cellar+16 storey) 3m (Typical) 3.5m 0.15m 0.15m 0.3x0.6m 0.3x0.51m 0.3x0.43m 0.3x1.1m 0.3x0.83m 0.3x0.69m 1.2x1.2m II medium coarse grained granular soils 1.0 5 0.1 3Kn/m 16.2 KN/m 8.1 KN/m M25 Fe415
Studies on Structural Performance of Design Models: The relative performance of design models are evaluated with respect to lateral displacement, inter storey drift, and strength aspects. It is oserved that shear wall flat slab models of RC high raised buildings provides efficient structural system than beam column framed system.Shear wall system provides high strength, stiffness and good limitations of lateral displacements and inter storey drift.Also load transfer mechanism in shear wall system is more compatiblein shear wall system than framed system.It is one of the important factor to be consider for the delay in progressive collapse of the structure.
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Comparative Studies on Construction Cost of High Raise Buildings (Designed under RC Frame and Shear Wall Systems) (IJSTE/ Volume 4 / Issue 3 / 016)
V. ECONOMIC STUDIES ON DESIGN MODELS Material Consumption and Cost calculation: Table: 2 shows the quantities of different structural materials consumed for the structural systems designed under beam column slab framed system (Model-1) and shear wall flat slab system (Model-II). Table - 2
6014 328
Cost of Model -1 (Rupees) 399.16x105 145.80x105
Cost of Model -II (Rupees) 511.19x105 196.80x105
-
128.4x105
-
49976
79.33x105
124.94x105 832.92x105
Material
Unit
RateIndian Rupees
Model -1 Beam-column
Model–II Shear wall flat slab
Concrete Steel Brick work (Include5% wastage) Cement Plaster Form-work.& Shuttering
M3 M.Ton
8,500 60,000
4696 243
Nos
6
21.40x105
M2 M2
50 158667 250 38810 TOTAL COST- Rs
97.02x105 849.71x105
VI. RESULTS AND DISCUSSIONS ON ECONOMIC MODELS Following graphs shows the comparison of material consumption between the models Model-I: Beam column slab framed structure. Model-II: Shear wall-flat slab structure.
Fig. 6: concrete comparisons in volumes
Fig. 7: steel comparisons in tonnes
Fig. 8: Form work and scaffolding area
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Comparative Studies on Construction Cost of High Raise Buildings (Designed under RC Frame and Shear Wall Systems) (IJSTE/ Volume 4 / Issue 3 / 016)
Cost comparison graph for both the models. In the graph blue indicates the framed structure (model 1) and red indicates the shear wall-flat slab structure (model 2). It shows the cost comparison of various materials such as concrete, steel, formwork, bricks and cement mortar etc.
Fig. 9: Cost comparison of materials
Observations from the graphs:
Consumption of concrete is 28.1% more in shear wall system than framed system Consumption of steel reinforcement is 34.9% more in shear wall system than framed system Area of shuttering & formwork is 28.5% more in shear wall system than framed system Total material cost in Shear wall system (Model-2) is Rs 4196/- per m2 floor area and in framed system (Model-1) is Rs 4326/per m2 floor area. The super structure cost decreased by 2% in shear wall system (Rs 17 lakhs) compared with Beam column framed system. VII. CONCLUSIONS
Shear wall –Flat slab system is more adoptable than framed system in the construction of RC high raised structures. Optimum construction time and economy achieved in shear wall system than RC framed system The cost of super structure is decreased by 2% in shear wall system (Rs 17 lakhs) when compared to beam column framed system. Both designers and builders recommended to adopt shear wall system in high raised structures for efficient performance and economic cost of the project. REFERENCES
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
Agarwal.P and Shirkhande. M., “Earthquake Resistant Design of Structures” Prentice hall of India private ltd. New Delhi, India. Bryan Stafford Smith Alex coull., “Tall Building Structures analysis and design”, published by John Wiley and sons, New York, 2000. ETAB 2009, “Technical Structural Software and Reference Manual”. K. Navyashree and Sahana T. S., “Use of Flat Slabs In Multi-Storey Commercial Building Situated In High Seismic Zone”, International Journal of Research in Engineering and Technology, Vol.03 Issue 08, 2014,pp. 439-451. N.Krishnaraju“Structural Design and Drawing: Reinforced Concrete and Steel”, published by Universities Press (India) Private Limited Hydrabad, 3rd edition, S.S. Patil, Rupali A. Sigi “Flat Slab Construction in India“, International Journal of Engineering and Innovation Technology (ISSN: 2277-3754), Vol. 3, (10), April 2014, pp. 138-141. V. L. Shah and S. R. Karve “Illustrated Design of Reinforced Concrete Buildings”, published by Structure Publications Pune, India. Y. H. Luo and A. Durrani “Equivalent Beam Model for Flat-Slab Buildings: Exterior Connections,” American Concrete Institute( Structural Journal), vol. 92(2), January 1995, pp. 250-257. IS: 875(Part 1-3)-1987, “Code of practice for design loads(other than earthquake) for buildings and structures”, published by Bureau of Indian standards, New Delhi, IS: 875(Part 1-3)-1987, “Code of practice for design loads”, published by Bureau of Indian standards, New Delhi, IS: 456-2002, “Code of practice for plain and reinforced concrete”,published by Bureau of Indian standards, New Delhi, IS 1893-2002 “Indian standard criteria for earthquake resistant design of structures”, published by Bureau of Indian Standards NEW Delhi. “SP 34: Handbook on concrete reinforcement and detailing,” published by Bureau of Indian standard, New Delhi, 1987.
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