ISSN Vol.03,Issue.18 August-2014, Pages:

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1 ISSN Vol.03,Issue.18 August-2014, Pages: Analysis and Design of High-Rise Reinforced Concrete Building with Basement under Seismic Load SOE THU PHAY 1, DR.KYAW MOE AUNG 2 Dept of Civil Engineering, Mandalay Technological University, Mandalay, Myanmar. Abstract: This paper presents dynamic analysis and design of earthquake resistant reinforced concrete building in Mandalay area. Structural analysis is done by ETABS software using response spectrum analysis. Special moment resisting frame (SMRF) is considered for the proposed fifteen storeyed building in seismic zone 4. Dead load, live load, wind load and earthquake load are considered based on UBC- 97. Concrete strength of all structural members is 3000 psi and reinforcing yield strength of psi are used for rebar. All structural members are designed according to ACI (318-99) Code. Slab thickness is considered 5in for all slabs. The overall height of the building is 172ft and it is rectangular shaped. Basement wall is subjected the lateral soil pressure. Ranking Earth Pressure theory is considered for basement wall to calculate the lateral soil pressure. Steel schedules for designed members such as column, beam, slab, stair and basement wall are summarized in this study. Design results are checked for safety, P-Δ effect, story drift, torsional irregularity, sliding and overturning. Keywords: Dynamic Analysis, Lateral Soil Pressure, Basement Wall, Steel Schedules. I. INTRODUCTION Now a days, there are many congestion of transit vehicles at road and many place. Parking space and bus stop is not enough to stop the vehicles. Therefore, basements are considered at high-rise buildings. High-rise buildings are also constructed to provide the business and private living activities with the increased urbanization of the city. Highrise buildings are constructed with basement to get additional space in the buildings for various purposes such as warehouse storage or underground car parks. With increasing height, the extra ordinary forces of natures (wind, earthquake, fire and blast), tend more and more dominated the structural system. Myanmar is situated in inherent major earthquake hazards and therefore, earthquake load is being considered in the design structure stability as a vital effect in this study. In high-rise building, it is important to ensure earthquake stiffness to resist lateral forces induced by wind or seismic effects. The high-rise building structure is a vertical cantilever so that elements of structure are; To resist axial loading by gravity and, To resist transverse loading by wind or earthquake. It is considered high seismic hazard because Mandalay located near Sagaing fault situated in the seismic zone 4 by UBC-97.The main duty of structural engineer is to design the structures safely, economically and efficiently. Analysis and design of seismic resistance building depends on analysis and complicated design processes. The building must resist vertical load of gravity and horizontal load of wind and earthquake resistance high-rise building. II. OBJECTIVE OF THE STUDY The objectives of the study are as follows; To analyze and design of high-rise reinforced concrete building with basement under seismic load. To know the behaviour of the basement effect. To get the detail design of the structural members such as column, beam, slab, stair and basement wall. III. PREPARATION FOR ANALYSIS AND DESIGN A. Site Location and Structural System The location of proposed building is in Mandalay area. The type of occupancy is residential building. Longer direction in X is 138ft and the shorter direction in Y is 100ft in this building. The overall height of the structure is 172ft. The value of response modification factor, R is 8.5. Typical floor plan and 3D view of proposed building are shown in Fig.1 and 2. Fig.1. Typical Floor Plan SEMAR GROUPS TECHNICAL SOCIETY. All rights reserved.

2 Fig.2. 3D View of Proposed Building. B. Material Properties The strength of the structure depends on the strength of the materials from which it is made. So, it is used as the following data to design the proposed structure. Weight per unit volume of concrete : 150pcf Modulus of elasticity : 3.122x10 6 psi Poisson s ratio : 0.2 Coefficient of thermal expansion :5.5x10 6 in/in / F Reinforcing yield stress, f y : 50000psi Shear Reinforcement yield stress, f y : 50000psi Concrete cylinder strength, f c : 3000psi C. Load Considering The applied loads are dead loads, live loads, earthquake load and wind load. Dead load consists of the weight of all materials and fixed equipment incorporated into the building. Earthquake excitation and wind excitation are calculated according to UBC-97.To obtain the safe design, maximum portable values must be established before the design process can proceed. Gravity Loads: Data for dead loads; Unit weight of concrete = 150 pcf 4.5in thick brick wall weight = 55 psf 9in thick brick wall weight = 100 psf Superimposed dead load = 25 psf Weight of elevator = 2tons Data for live loads; Live load on floor = 40psf Live load on stair-case =100psf Live load on roof = 20psf Wind Loads: Exposure type = Type B Basic wind velocity = 80mph Overall height = 172ft Method used = Normal Force Method Windward coefficient = 0.8 Leeward coefficient = 0.5 Important factor = 1 SOE THU PHAY, DR.KYAW MOE AUNG Earthquake Loads: Seismic zone =4 Soil type = SD Seismic zone factor = 0.4 Seismic coefficient, C a = 0.44 C v = 0.64 I = 1 C t = 0.03 R = 8.5 Structural system = SMRF Seismic source type = A Near-source factor, N a = 1 N v = 1 D. Load Combination Design codes are considered according to ACI (318-99) and UBC-97, the following load combinations is considered for dynamic analysis. 1) 1.4DL 2) 1.4DL+1.7LL 3) 1.05DL+1.275LL+1.275WX 4) 1.05DL+1.275LL-1.275WX 5) 1.05DL+1.275LL+1.275WY 6) 1.05DL+1.275LL-1.275WY 7) 0.9DL+1.3WX 8) 0.9DL-1.3WX 9) 0.9DL+1.3WY 10) 0.9DL-1.3WY 11) 1.33DL+1.275LL SPEC X 12) 1.33DL+1.275LL SPEC Y 13) 1.33DL+1.275LL SPEC Y 14) 1.33DL+1.43SPEC X IV. DESIGN RESULTS FOR STRUCTURE The proposed building is designed by using ETABS software, ACI (318-99) and based on UBC-97. The design results are as follow: A. Design Results for Beams and Column The whole structure consists of 2520 beams. The beam sizes are 10"x12", 10"x14", 10"x16, 12"x16" and 12"x18". According to ACI code, reinforcements are provided not to be less than the minimum required steel area and not to exceed the maximum steel area. In this study, square column are used. The whole structure consists of 1320 columns. The columns sizes are12"x12", 14"x14", 16"x16", 18"x18", 20"x 20", 22"x22", 24"x24", 26"x26", 28"x28" and 30"x30".Design principles are based on ACI (318-99). It is also manually checked whether the ratio of longitudinal steel area to gross cross-sectional area be within the ranges from 0.01 to B. Design Result of Slabs and Stairs Only gravity load is considered in slab design. Design principles are based on ACI There are seven types of slab according to span length. Slab thickness is 5 inches for the all slab. No.3 bars are used for reinforcement. There are two type of stairs in the building. The stair-1 is 10 ft and stair -2 is 12 ft height. The waist thickness is 5 inches for all stairs

3 Analysis and Design of High-Rise Reinforced Concrete Building with Basement under Seismic Load and #3 bars are used. Longitutinal steel spacing is between 5in and 6in. Distribution steel spacing is 10in. C. Design Result of Basement wall The basement wall is designed with the lateral earth pressure and surcharge pressure, ω=250 psf. Unit weight of soil is 120pcf and angle of internal friction, Ø=35 are considered and lateral soil pressure on the wall is calculated based on Rankine Earth Pressure Theory as shown in Fig. 3. TABLE I: Sample Beam Steel Schedule (Longitudinal Reinforcing Bar) Fig.3. Lateral soil pressure on the basement wall. Basement wall is considered as cantilever frame. Thickness of basement wall is 10''. There are No.4 bars for all steel. Longitudinal reinforcing bar and shear reinforcing for structural elements such as beams, columns, slabs, stairs and basement walls are shown in table 1, table 2, table 3, table 4 and table 5 and Figs.4 to 16. TABLE II: Sample Beam Steel Schedule (Shear Reinforcingbar) Fig.4. Typical Beam Layout Plan of Proposed Building.

4 SOE THU PHAY, DR.KYAW MOE AUNG TABLE III: Column Steel Schedule For Proposed Building Fig.5. Steel schedule for typical beam for B2. Fig.8. Steel schedule of typical column for C1. Fig.6. Steel schedule for typical beam for B3a. Fig.7. Typical Column Layout Plan of Proposed Building. Fig.9. Steel schedule of typical column for C2.

5 Analysis and Design of High-Rise Reinforced Concrete Building with Basement under Seismic Load a) Shorter Direction Fig.10. Typical Slab Layout Plan of Proposed Building. TABLE IV: Slab Steel Schedule for Proposed Building b) Longer Direction Fig.12. Sample Steel Schedule of Slab -7 (One Way). TABLE V: Stair Steel Schedule for Proposed Building Fig.13. Steel schedule of Stair for12ft Height Storey. a) Shorter Direction b) Longer Direction Fig.11. Sample Steel Schedule of Slab -1 (Two Way). Fig.14. Steel Schedule of Stair for10ft Height Storey.

6 TABLE VI: Design Result for Basement Wall Fig.15. Steel Schedule of Basement Wall Plan. SOE THU PHAY, DR.KYAW MOE AUNG members for beams and columns, steel schedules are summarized only for floor beam B2 (10"x14") and B3a (10"x16") and column C 1 and C 2 in this study. Support conditions for this proposed building is considered as fixed type. For the design of reinforced concrete beams, an appropriate steel ratio between ρ min and ρ max is used. The main reinforcement for column and beam is used larger than #5 bars. The transverse reinforcement for column and beam is also used #3 bars. Stirrup spacing is considered between 3in to 6in for column and beam. There are seven type of slab in the proposed building according to span length. 5in slab thickness is used for all slabs. There are two type of stair in the proposed building. The main reinforcement steel of stair is #3 bar. In the design of Basement, lateral soil pressure acting on the basement wall. Active pressure is subjected 1/3 of the base and it is considered by using Rankine Earth Pressure Theory. The main reinforcement and the transverse reinforcement for Basement wall is used #4 bars and stirrup spacing is 10in spacing. By providing the basement wall, required steel area is increased at the column base and story drift is decreased at the base of the building. Finally, all the structural stabilities are carried out for the proposed building and safety factor are also within allowable limit. Fig.16. Steel Schedule for 3D view of Basement Wall. V. STABILITY CHECK Sliding, overturning moment, storey drift, P- effect and torsional irregularity are checked for structural stability of the proposed buildings. VI. CONCLUSION In this paper, analysis and design of fifteen-storeyed reinforced concrete building with basement is carried out by ETABS software using the response spectrum analysis. The structural system is special moment resisting frame (SMRF) and the design is considered for residential building in Mandalay area. The overall height is 172ft. Load consideration is based on UBC-97 and structural elements are designed according to ACI (318-99). The proposed building is designed with concrete cylinder strength of f c ' = 3000psi and reinforcing steel of f y = 50000psi. Among various design VII. ACKNOWLEDGEMENT The author would like to express his gratitude to Dr. Myint Thein, Rector, Mandalay Technological University, for his directions and managements. The author also wishes to record the greatest and special thanks and owe in gratitude to his supervisor, Dr. Kyaw Moe Aung, Associate Professor and Head, Department of Civil Engineering, Mandalay Technological University, for his careful guidance, advices and invaluable encouragement. The author specially thanks to his teachers from Civil Engineering Department for their supports and encouragements to attain his destination. Finally, the author specially thanks to all his teachers and his family. VIII. REFERENCES [1] Arthur H. Nilson. Design of Concrete Structures. 12 th edition. [2] American Building Code Requirement for Structural Concrete(318-99), Concrete Institute, Farmington Hills; M1. (1999). [3] Uniform Building Code, 1997, Volume 2. Structural Engineering Design Provision (19997). [4] Lindeburg, M.R Seismic Design of Building Structure. 8 th Edition.Belmont: Professional publication, Inc. [5] American Concrete Institute. Building Code Requirements for Structural Concrete (ACI ). [6] ETABS version (9.7.1), Computer & Structures Inc. [7] Nilson A.H. and Darwin, D. Design of Concrete steuctures, 12 th Edition. Singapore: McGrow-Hill Companies, Inc(1997). [8] U Nyi Hla Nge: Reinforced concrete Design, 1 st Edition, Win Toe Aung Offest, Yangon, (2010).