High Rise Steel Structure Building Technology In Ethiopia
AOT, a brand of PEBs, Prefabricated house and Modular container house, is Trusted & Tested.
COMPARISON OF BEHAVIORAL ASPECTS OF HIGH RISE MULTISTORIED STEEL BUILDING WITH MASS PENDULUM SYSTEM AND X- BRACING SYSTEM
High Rise Multistory steel building developments have been rapidly increasing throughout Ethiopia and worldwide. The lateral deflections of buildings includes bending and shear deflection are challenging part to the designed and existed building. Previously the X-bracing system is more effective to control the deflection of the high rise steel building. In this research, the new system called Mass pendulum Mechanism is introduced to control the lateral deflection of the steel building and the same compared with the X –bracing system. Mass pendulum system which is proved to be the better deflection controlling system is studied in depth and the overall comparison of the system with other deflection controlling mechanisms is outlined and analyzed. The use of this mechanism for design of high rise steel building can increase the lateral stiffness of building and decrease lateral displacements. The maximum reduction in the lateral displacement occurs at an angle of mass 45 degree with the weight of mass equal to 50% of the lateral load. In addition the Mass Pendulum Mechanism reduces bending moments and shear forces in the vertical and horizontal members of load transferring system. Moreover, stability of this system increases and the P-Delta effects decline. So, the columns will be protected against reaching nonlinear state. Finally the mass Pendulum system proved that it's economical compare with X-bracing system in terms of structural steel material.
Keywords: High-rise steel building, X-bracing system, Mass-pendulum mechanism, Deflection, Lateral deflection, lateral stiffness and Plate stress.
Abbreviations:- XBS:-X-Bracing System, e-Eccentricity, M-self weight of building, MPS-30 DEGREE- Mass pendulum system at 30 degree, MPS-45 DEGREE- Mass pendulum system at 45 degree, MPS-60 DEGREE- Mass pendulum system at 60 degree.
1. INTRODUCTION
The introduction of structural steel to building construction in the late 19th and early 20th centuries, Engineers have recognized that steel building and structures have performed extremely well compared with structures of other types of construction. The selection of structural steel for a building’s framing system brings numerous benefits to a project. Speed of Construction, sustainability, strength and aesthetic, efficient design flexibility are some advantage of steel structure.
Comparatively high rise multi story steel buildings are light in weight which makes steel structure very susceptible to lateral load. Engineers overcome the deflection in multistorey steel building by providing bracing. Steel braced frame is one of the structural system used to resist lateral loads in multi-storeyed buildings. X-bracing is more effective system of controlling deflection than the other bracing system. Even though this system controls the deflection of the building caused by the lateral loads, one needs a large quantity material used as a bracing element.
Generally, in multistorey steel building, there may be high deflection due to relative light weight of steel to that of concrete and the height of the building. Many researchers steel bracing is a high efficient and economical method of resisting horizontal forces in a frame structure. Bracing has been used to stabilize lateral for the majority of the world’s tallest building structures. Bracing is efficient because the diagonals work in axial stress and therefore call for minimum member sizes in providing stiffness and strength against horizontal shear. The effectiveness of varies types of steel bracing on the structure has also been investigated. More importantly, the reduction in lateral displacement has been found out for different types of bracing system in comparison to building with no bracing. From the present studying, it has been found that the mass pendulum reduces more lateral displacement and X-bracing system significantly contributes to greater structural stiffness to the structure.
2. OBJECTIVES
To Compare vertical deflection of high rise multistoried steel building with a new technique (mass pendulum system) with old system(X-bracing system)
To Compare the overall effectiveness and plate stress of high- rise steel building with both methods
3. METHODOLOGY
In the study, STAAD PRO V8i software is used to model and analyze the data. By using this software, the properties of the members are assigned. The structure is later analyzed to evaluate vertical deflections and overall effectiveness and plate stresses of high rise steel building.
The general data for the frame is as follows:
3.1 Specimens
This research is studied using three specimens. The specimens are compared with the control building modelled using old system (x-bracing).
The building is:-
A high rise multistory steel building and symmetrical in plan and elevation.
Has 25 typical floors
The different stages used in the simple Mass pendulum of high-rise steel building
AOT Steel Structure Building | Steel Structure Factory
3.1.1 Case one
In case 1 we used: - single channel section X- Bracing
3.1.2 Case Two
In case two we used:
The weight of pendulum is 50% of the wind load in the Z-direction
The angle of swing is 30 degree
3.1.3 Case Three
In case three we used:
The weight of the pendulum is 50% of the wind load in the Z-direction
The angle of swing is 45 degree.
3.1.4 Case Four
In case four we used:
The weight of the pendulum is 50% of the wind load in the Z-direction
The angle of swing is 60 degree
3.2 Data Considered for Model
Building Function: Commercial shopping
Terrain: Category :IV
No. of Floor: 25
Floor Height: 4m typical
Regularity in plan : Symmetry about both axes
Floor Plan: Typical all floors
Type Of Floor: Solid slab
Structural System: Moment resisting frame
Assumed depth of foundation: 4m from ground level
Software: STAAD Pro.v8i
Design Code: Ethiopian Building Code of Standard- EBCS Code
AOT Steel Structure Building | High rise steel structure building Multi floor steel structure
If you would like to discuss your requirements further, simply get in touch with the team on ken@aotintlcn.com
3.3 Material Property
Material used: structural steel
Modules of elasticity =205kN/mm2
Yield strength (py) = 550 N/mm2
Ultimate strength (fu) = 600 N/mm2
Net area = 85% of cross sectional area.
Grade of steel reinforcement (raft foundation): S-400
Grade of concrete (raft foundation): C-30
3.4 Loading Details
Dead Load (DL) = 4.5KN/M2
Dead Load From Wall = 4KN/M2
Back Fill = 45KN/M2
Live Load (LL) = 5KN/M2 [EBCS-1-1995]
LL At The Top Story = 1.5KN/M2
Min Wind Pressure = 1.53 KN/M2
Max Wind Pressure = 2.97 KN/M2
4. ANALYSIS, RESULTS AND DISCUSSION
The different behavioral aspects of high rise multistory building is analyzed for four cases with MPS system and X- Bracing system and the results are as given below :
4.1 Quantity Comparison
The Structural steel, reinforcement steel and reinforced concrete quantity variation for the four cases as mentioned in Table 1 is compared and the results are presented in the graphs as shown below.
As shown on quantity comparison diagrams above; structural steel, reinforced steel and reinforced concrete quantity required for case:3-[MPS-60] is lower as compared to other cases of XBS-Control building and mass pendulum bracing systems at different angles.
4.2 Bending Behavior
In the design and analysis of building, the bending behavior of four cases are studied in depth. The result shows that the bending behavior of building is more with XBS for case 1, where as the bending behavior of mass pendulum is less for cases 2 to 4 as shown in the figure 10.
4.3 Transverse Shear Behavior
The analysis and design of the multi-story building has extended by comparing the transverse shear behavior by two
methods for all the four cases. The results indicates that the transverse shear behavior is maximum for case 1 with XBS system as compared to MPS system for cases 2 to 4 as shown in the figure 11
4.4 Base Pressure
In the analysis, base pressure is also compared for all the four cases with both the methods. The results shows that the base pressure is maximum for case 1 with XBS system and it is minimal for other cases with MPS system as shown in the figure 12
4.5 Displacement of Storey
The displacement of each storey is examined and is observed that the displacement is more for case 2 with MPS system and is less for case 1 with XBS system. This clearly indicates that the MPS system is less efficient in keeping the displacement less with 30 degrees but it is more efficient both for 45 and 60 degrees as compared to XBS system as shown in the figure 13
5. CONCLUSION
In the present study, high rise steel building is analyzed with XBS system (old system) and MPS system (new system) in order to evaluate the steel and concrete quantity, bending behavior, shear behavior, base pressure and displacement. The data considered for the above study is analyzed by both the methods of XBS and MPS systems with four cases. Case 1 is considered for XBS system and other cases are considered for MPS system in the analysis. The various graphs are developed for different behaviors. It is concluded that MPS system with cases 2 to 4 is giving efficient results for all the behaviors of high rise steel building as compared to XBS system, except in case of displacement behavior for 30 degree angle as shown in the figure 13. The efficiency is again more with MPS system for case 3 and case 4 with 45 and 60 degree angle as compared to XBS system. This clearly indicates that MPS system will give good results for displacement with more than 45 degree angle.
On comparision of both the methods, it is finally concluded that the behavior analysis for high rise steel buildings is more appropriate with MPS system as compared to XBS system. decrease after the application of In general, the total construction cost of the building and general stresses developed like base pressure, base bending moment and the overall shear behavior of building can be significantly reduced by providing an effective mass pendulum at the top of the story irrespective of the cost of Mass Pendulum arrangement.
AOT Steel Structure Building | Multi storey car parking steel structure
REFERENCES
[1] Ethiopian Building Code Of Standard, (EBCS,1995)
[2] EBCS-1 Basis of Design and Actions on Structures, Ethiopian Building Code Of Standard
[3] EBCS-3 Analysis and Design of Steel Structures, Ethiopian Building Code Of Standard
[4] AISC-ASD Steel Design Manual, 13th edition, American Institute of Steel Construction.
[5] Edwin H. Gaylord ET. al. (1992), Loads and Structures, Design of Steel Structures, 3rd Edition, McGraw Hill Inc.
[6] American Institute of Steel Construction (1986),
Load and Resistance Factor Design, AISC, Chicago.
[7] ArcelorMittal Technical Brochure, Earthquake Resistant Steel Structures, Long Carbon Europe Sections and Merchant Bars, Europe.
[8] EN 1998-1:2004, Design of Structures for Earthquake Resistance, Part 1: General Rules, Seismic Actions and Rules for Buildings, (Euro code 8), CEN, European.
[9] EN 1993-1-1 (1993), “Euro code 3: Design of Steel
Structures.”
[10] Ronald O. Hamburger, R.O. (November 2009), Earthquakes and Seismic Design, AISC.
[11] 2009, American Institute of Steel Construction, Washington, DC.
[12] Schueller, W. (1986), High-Rise Building Structure
(2nd end), Malabar, Florida: Krieger.
As experts on Pre-engineered steel structure building, Prefabricated house and Modular container house system, AOT is providing complete customized solutions including consulting, R&D, design, manufacture, installation, supervision service for overseas project, export and service.
We specialize in creation of high-quality Pre-engineered steel structure building such as: warehouse, workshop, factory, cold storage, high-rise building, shopping mall, power plants, distribution centers, pedestrian bridge, hotels, public schools, sports arenas, car parking center, airplane hangars, church building, farm building, agricultural building, storage shed, self-storage building, poultry farm and green house; Prefabricated house and Modular Container house such as: portable cabin, labor camp, labor quarter, worker dormitory, construction site office, accommodation, recreation, clinic, medical facilities, quick-assemble container, sanitary container, toilet container, shower container, canteen, portable living units, portable office. We provide our time-tested PEBs, Prefabricated house and Modular container house to clients in the sectors of oil & gas, mining, Energy, Infrastructure and Construction projects. AOT built his reputation upon Profession, Reliability and Service.
