This is to prove that the thesis entitled "What happens to the design when two more floors are added on top of an existing six-storey residential structure in Khulna?" submitted by Nazibullah Hossain Shourov Spring Session 2017) Mohamed Abdirisak Said Fall Session 2017), Md. The thesis contains no material previously published or written by another person, to the best of our knowledge and belief, except where references are made in the thesis itself. Mohammad Hannan Mahmud Khan, Assistant Professor, Head of Department of Civil Engineering and all faculty members and staff of Daffodil International University.
We are also grateful to our fellow classmates for sharing knowledge and information and for their assistance in the success of this field study for the Civil Engineering Department of DIU. The research was conducted at the Department of Civil Engineering, Daffodil International University, Bangladesh with the aim of preparing a project and thesis for the partial fulfillment of the requirements for the degree of Bachelor of Science (B.Sc.) in Civil Engineering. The specific purpose of the study is to analyze residential construction, taking into account the lateral forces of a six-story structure, then compare the deflection caused by wind loads and earthquake loads, and then change the fixed structure into eight stories and compare the design differences and the changes to compare. deflection in the eight-storey structure due to wind loads.
It was noted that the design of the structure changed to the design of the eight-story structure and the average per floor. Also, the dominant force in both structures was the wind due to the high exposure and the deflection due to the wind was more in the 8-story structure, exactly 21% in the X direction and 134% in the Y direction.
LIST OF TABLES
83 Fig 8.2.5: Deflection of 6 storey structure due to Earthquake-EQX load 84 Fig 8.2.6: Maximum deflection point in EQX of 6 storey structure. 84 Fig 8.2.7: Deflection of 6 storey structure due to Earthquake EQY load 84 Fig 8.2.8: Maximum deflection point in EQY of 6 storey structure.
CHAPTER ONE: INTRODUCTION
- INTRODUCTION
- BACKGROUND OF THE STUDY
- OBJECTIVE
- SCOPE OF STUDY
- LIMITATIONS
Both of these forces produce equal amounts of damage to the structures over a long period of time. In Dhaka city, the effects of a huge earthquake will be devastating mostly in old cities as the structures there are old and closely built to other structures. This study is an attempt to compare the effect of lateral forces on a residential building.
Theoretical knowledge of structures was limited, and construction techniques were supported only by experience. The general scope of this study is to acquire general knowledge of structural design using advanced software such as ETABS. This study will also help to know the effects of lateral forces affecting the structures and compare these forces.
A detailed overall analysis of the structure could not be done due to lack of time. This study was conducted for a theoretical scenario so the dimensions of the structure were largely unrealistic.
CHAPTER TWO: REVIEW OF LITERATURE
INTRODUCTION
LITERATURE REVIEWS
Kodag (2013) has made studies on the sensitivity of the lateral load forces on the structure. Lateral displacement of the building is reduced by 40 to 60% using a Type III and X Type steel bracing system. Steel bracing can be used as an alternative to the other available strengthening techniques, as the overall weight of the structure changes significantly.
The capacity of the steel bearing structure is extra compared to the shear wall structure. According to the researcher Erdal, Irtem, Kaan Turker and Umut Hasgul (2007), to make a real assessment about the severe damage and the reasons for the collapse of reinforced concrete buildings during strong earthquake using the Turkish Earthquake Code, the SAP2000 program is used. Structural Analysis. Pushover analyzes are performed to determine the nonlinear behavior of buildings under earthquake loads. To perform the analysis of a building with a moment-resisting frame with a shear wall and a beam-column resisting frame is considered for the comparison of the high-rise building.
He clearly noticed that the buildings in the higher seismic zone require a greater amount of steel to increase the stiffness of the elements when subjected to higher seismic forces. They observed that the effect of both earthquake forces and wind forces on multistory structures increases with an increase in the height of the structure.
CHAPTER THREE: METHODOLOGY
METHODOLOGY
WORK FLOW CHART
CHAPTER FOUR: ETABS MODEL AND SECTION DETAILS
ETABS MODEL DETAILS
LOADS APPLIED ON THE MODEL .1 NORMAL LOADS
- WIND LOADS
- EARTHQUAKE LOAD CALCULATIONS
SECTIONS USED
This happened due to O/S #45 Shear stress due to shear force and torsion together exceed the maximum allowable value. NOTE: Center of clear cover to rebar in 6-story and 8-story structure for beam was 87.5mm and for column was 62.5mm.
CHAPTER FIVE: DESIGN OF BEAM SECTIONS
CALCULATIONS
Area (in2) Positive side (in2) No. Note: The value of shear reinforcement was very low, so minimal shear reinforcement was provided) We use #3 bars as stirrups.
FIGURES OF THE BEAM SECTIONS: BEAM FIGURES FOR 6 STORIED STRUCTURE
BEAM FIGURES FOR 8 STORIED STRUCTURE
COMPARISON OF 6 FLOOR AND 8 FLOOR DESIGN
When comparing the design of 6-story structure and 8-story structure, it was noted that to compensate for the increase in reinforcement requirements for the beams, higher no bars had to be used to design the 8-story structure, where lower no bars satisfied loads of 6 storey structure.
Variation of Bars of different sizes used per floor in Avg
Using these rebar prices, we can calculate the total price increase per floor in 6-storey and 8-storey designs. It was observed that the design cost of the 8-storey structure per floor reinforcement increased by almost 39% than that of the design of the 6-storey structure.
CHAPTER SIX: DESIGN OF COLUMN SECTIONS
CALCULATIONS
For top and bottom 23 inch tie spacing will be less than 4 inches or ¼ of minimum column dimension = 4.5 inches so tie spacing will be #3 bars @4 inches c/c for top and bottom 23 inches.
FIGURES OF COLUMN SECTIONS: COLUMN FIGURES FOR 6 STORIED STRUCTURE
Column figures for 8 storied structure
COMPARISON OF 6 FLOOR AND 8 FLOOR DESIGN
When comparing the columns of the 6-story and 8-story structure, it was noted that the required longitudinal reinforcement at the base of the corner and at the exterior columns almost doubled in the 8-story structure due to the additional load. To compensate for this, the design of the lower 4 floors had to be changed and 4 additional #9 bars were added. But the requirements gradually decreased as we went up the floors, the constant being 3.139 in2, so the remaining 4 floors were given the same design as 6-storey structures.
The longitudinal reinforcement requirement for the interior columns in the 8-story structure increased, but not by much, so that the same column design could be used. It was found that the design cost of the floor reinforcement of an 8-story structure increased by almost 75% on average.
CHAPTER SEVEN: DESIGN OF SLAB
CALCULATIONS
FIGURES OF SLAB SECTIONS
CHAPTER EIGHT: COMPARISON BETWEEN WIND AND EARTHQUAKE LOADS
- METHOD OF COMPARISON
- COMPARISON OF EQ AND WL IN 6 STORIED STRUCTURE
- COMPARISON OF EQ AND WL IN 8 STORIED STRUCTURE
- COMPARISON OF WL BETWEEN 6 AND 8 STORIED STRUCTURE
Deflection of structure at ROOF due to wind loading was observed as: 0.24in at X direction and 0.82in at Y direction. Deflection of structure at ROOF due to earthquake loading was observed as: 0.21in at X direction and 0.18in at Y direction. It was observed that due to wind load in X direction the structure deflects 12.5% more and at Y direction the structure bends 78% more than Earthquake load in X, Y direction respectively.
So the X axis gets a higher exposure to the wind compared to the Y axis and therefore the structure deflects more in the Y direction. It was observed that the deflection of the structure at the ROOF due to wind loading was: 0.29 inches in the X direction and 1.92 inches in the Y direction. It was observed that the deflection of the structure at the ROOF due to the earthquake load was: 0.14 inches in the X direction and 0.23 inches in the Y direction.
It was found that due to the wind load in the X direction, the structure bends 51.72% more, and in the Y direction 88.02% more than the seismic load in the X and Y directions, respectively. It was found that the maximum deflection due to the wind load in 6-story structure 0.24 inches in the X direction and 0.82 inches in the Y direction, and the maximum deflection due to wind load in the 8-story structure was 0.29 inches in the X direction and 1.92 inches in the Y direction. So , due to the addition of two additional floors, the deflection increased by 21% in the X direction and 134%.
CHAPTER NINE: CONCLUSION AND RECOMMENDATION
This is only a study conducted by considering a fictitious building with unreal dimensions as a result, there may be many errors in the design. Also, only the preliminary and basic design was made in this study and the structure may need many revisions and corrections to be made. Updated software and materials (such as codes) must be used to make the survey more up-to-date and realistic.
It should be noted that the design of beams and columns was done by considering the plate deflection m11,m22 and m12 to be 1 instead of considering it close to zero for more accurate results. It is highly recommended that the design should be done considering plate modifiers close to zero. In the case of this study of Group 1.A, the values of longitudinal reinforcement for beam and column were not so different and the design was carried out in such a way that there was some margin of safety considering the reinforcement.
Due to time constraints, only two beam sections from each floor were designed in this study. One on the X-axis and One on the Y-axis and the beams were chosen based on the highest reinforcement requirement. It should also be noted that the rebar percentage for the structure in Group 1 was very low (on average 1.5%).
Because this structure was unrealistic, that couldn't happen. Much has been done for this problem, but it is good to keep the reinforcement percentage around 4% to make the design more efficient. In the case of group 1. a structure GF was considered because it contained the highest moment which was still very low and had minimal reinforcement in slabs. Since this is the case, all other floors will produce similar results, so the same design can be applied to all floors).
APPENDICES
