INVESTIGATIONS ON LATERAL LOADS AND BASE SHEAR OF G+ 8 MULTI STOREYS BUILDING IN SEISMIC ZONE III CITY
Sodan Singh Anjana1; Rahul Sharma2
1PG Research Scholar; 2Assistant Professor
Department of Civil Engineering, Prashanti Institute of Technology and Science, Ujjain (M.P.)
Abstract- Present research work is based on the analysis of seismic forces in a G+8 building located in zone III city, Indore (Madhya Pradesh). For this purposes both analytical approach was used and the results were validated from simulation approach. For this purpose, the specifications were provided by the building contractor. As the result of analyses lateral forces and base shear were obtained. The targeted solution technique is equivalent static method. The codes used for this purpose were IS 1893: 2002/2005, and the software used was STAAD. Pro V8i.
Keywords: Seismic analysis, seismic zone-III, building, lateral forces, base shear.
1. INTRODUCTION
Engineering that deals with the construction of buildings like homes is known as building construction. A simple structure is one that has walls, a roof, supplies for food and clothing, and other necessities for human habitation. To shelter themselves from wild animals, rain, sun, and other elements in the early parts of human history, people lived in caves, above trees, or beneath trees. As time went on, people began to dwell in huts made of timber branches. The old shelters have been transformed now into lovely homes. Rich folks reside in luxuriously appointed homes. Buildings are a key gauge of a country's socioeconomic development. Every person wants to live in a pleasant home because, on average, people spend a third of their lives in their residences. These are a few of the factors that motivate people to exert their maximum work and invest their hard-earned savings on home ownership:
security, civic responsibility. Building new homes is currently a key component of the county's social advancement. Every day, new methods are being created to build homes affordably, swiftly, and in accordance with community needs.
Architects and engineers are responsible for the buildings' design, planning, and other aspects of construction (Kavya, 2020).
In present research work, seismic analysis of a G+8 building has been targeted in a seismic zone III city, Indore (Madhya Pradesh), because Indore comes in Earthquake Hazard Zone III based on the Vulnerability Atlas of India – 2nd
Edition, BMTPC (Building Materials and Technology Promotion Council). Further, according to the government analysis and seismic revision, Indore is marked under zone III out of total of five zones under earthquake threats. Latest earthquake strike Indore on 24th February, 2022, at 14.11 IST, with 3.5 magnitudes on the Richter scale. During the research work, analysis of seismic forces on each floor, using both analytical and simulation approaches were targeted. The targeted solution technique is equivalent static method, which is considered as a one of the unique techniques for substituting the effect of dynamic loading of an expected earthquake by a static force distributed laterally on a structure. The codes used for this purpose were IS 1893:
2002/2005, and the software used was STAAD.Pro V81.
1.1 Objectives of the Research
Following points represent the objectives of the research work:
a) To determine lateral forces on each floor of the building;
b) To determine the base shear of the building.
2. LITERATURE REVIEW
Present section is based on academic aspects in the field of multistory buildings as well as gaps in the existing research, the details of which are presented in upcoming sub-sections.
2.1 Scenario of Research on Seismic Analysis
Figure 2.1 shows the radar graph of research papers published during last five years, on the topic seismic analysis, as per www.scholar.google.com.
Figure 2.1 Radar Graph of published research papers in last five years 2.2 Contributions of Researchers in the field of Seismic Analysis of Buildings Following are the summaries of contributions of researchers in the field of seismic analysis of buildings:
Wanjari et al. (2022)
Due to the expanding population and the limited availability of land, multistory structures are being built to accommodate more people in a smaller area. This project's primary objective is to analyse and create an ETABS for victimisation in a (G+13) high-rise building. is to provide accurate knowledge of the proper style and architectural aspects of the structure. Using AutoCAD, the design is finished. Manual load calculations are required for style, hence ETABS is used to assess the structure.
The project's reference codes are NBC IS (456-2000). Use of concrete combination is M30. Fe-415 steel is used for all of the members' steel strength. The hundreds are essential for assessing the structure because they are calculated victims (875).
The approach that has been used is the LIMIT STATE approach. The manual process is difficult and takes more time.
The project's goal is to achieve the data in a practical way and to present the entire experience in the field of style.
Divya and Murali (2021)
Time is more valuable than money in today's society, yet there are many construction techniques available that are time-consuming. Due to its fast construction, steel structural structures are regarded as a revolution in the
modern construction era. The best course of action is to select the type of building based on the relevant conditions and functional needs in order to have a wise and effective structure design. Choosing the form of construction that best fits the circumstances and type of structure will be made easier with the aid of "The Comparative research on design of Steel Structures and RCC frame Structures based on columns span." The main goal of this study is centred on the crucial element, the column span, which can also have a significant impact on the building's cost together with its height during design and analysis. This article's focus is on a comparison of the design, analysis, and construction costs of RCC structures with steel structures for columns with long and short spans. ETABS-2018 software is used in this project for the design and analysis of the G + 8 RCC structure and steel structure.
Daniel (2021)
The ability of the designer to produce a building with sound structural modelling and construction absolutely depends on their depth of knowledge in seismic effects and the efficient manufacturing of the structure. The seismic impact, such as places that are prone to earthquakes, are more likely to be targeted in favour of describing an efficient construction planning, which is explored in detail in this paper by using an Ethiopian code shopping complex building as a study.
This analysis is carried out with the aid of a software programme called Finite Element, which enables the designer to anticipate material requirements based on seismic impacts across the six seismic zones in the county. The effectiveness of the analysis is confirmed by hand calculations, and it complies with Ethiopian code requirements. The shear and bending impact patterns, the building's seismic base weight, and the need for concrete and steel materials for the six seismic zones are taken into account while approving the performance standards.
Uikey and Satbhaiya (2020)
This project's primary goal is to use Staad Pro software to do a seismic response analysis of tall buildings. Manual load calculations are performed, and STAAD Pro Software analyses the entire
structure. STAAD-Pro analysis for designing employs the Limit State Design approach in accordance with the Indian Standard Code of Practice. The programme of choice for professionals is STAADPro. I had performed the frame analysis and manually verified the software's accuracy using the results we had acquired. The outcomes appeared to be extremely exact and precise. A G+4, G+9, G+14, and G+19 storey building was studied, constructed, and tested for every conceivable load combination (Dead, live, wind and seismic loads). Users of STAAD.Pro may easily draw the frame and provide the load values and dimensions thanks to its very intuitive and dynamic user interface. The entire structure is then analysed in accordance with the provided criteria, as well as the structures in the various seismic Zones established by our code. The materials were selected, and the beam and column members' geometric cross-sections were allotted.
For the entire analysis, the fixed support has been fixed. Along with other crucial information, the codal provision that must be observed has been given for design purposes. The structure has then been examined using STAAD.Pro. It can quickly calculate parameters like axial force, shear force, bending moment, and lateral forces.
Lingeshwaran and Poluraju (2020) The primary goal of this work is to examine the approaches used in the literature to determine unreinforced masonry walls' seismic susceptibility using linear static analysis. Analysis (using the Staad.Pro software) has been done as part of this research to do this.
Under uniaxial loading, two identically sized walls made of bed type reinforced masonry and unreinforced masonry were both analysed. Each specimen was subjected to a constant axial compressive load throughout the examination. The maximal stresses and wall deflections that resulted from employing STAAD.Pro are described using idealised Load vs Deflection charts. The end result of this performance research states that reinforced masonry walls are more effective than unreinforced masonry walls under both axial and seismic stresses (Load vs Maximum shear stress).
Maraveas and Tsavdaridis (2019) Old, corroded steel structures built near the sea where wind speeds can be extremely high are seriously at risk from wind loads. The case study of a wind- induced failure analysis of an existing steel structure is presented in this research, along with some suggested retrofitting techniques. The steel structure under examination served as an athletic facility when it was built in Syros, Greece, in the 1970s. This study's initial section covers the examination of wind-induced collapse, which led to the observation of a domino effect. Before several other steel members failed owing to buckling, a corroded bracing that buckled due to wind stress controlled the decline of vertical load carrying capacity of the steel structure and created an asymmetry under horizontal loading. Failure analysis, time history analysis, incremental dynamic analysis, and performance analysis were all carried out to comprehend the structure's performance.
The recommended retrofitting techniques for enhancing the vertical load carrying capacity under wind loads are discussed in the second section of this study. To meet with modern European design requirements, it was necessary to increase the structure's load-bearing capability. Modal analysis were also used to show how the strengthened structure's dynamic qualities have improved.
Through incremental static studies and non-linear wind time-history, the structural behaviour was more precisely characterised. The emergence of failures in the current structure is explained by the analytical results.
Nirmal and Jaiswal (2018)
The structural construction business is expanding like never before; there is always something being built, even in weird habitats, therefore it is important to pay close attention to the individual strains that are produced by different loads in structures, whether they are Dead load or Live load. Though occasionally acting under internal ground mass disturbance, seismic forces have a significant impact on a building's structurally sound unity. With less dead load, improved seismic structural response, shallower sections, lower story heights, structural members, and a
smaller proportion of reinforcing steel in the substructure and superstructure, structural lightweight concrete works offers design flexibility, ductility, and significant cost savings while also shortening the construction process.
Saleem and Tengli (2018)
The behaviour and numerous design parameters of buildings that begin at the sites of the structural weak planes existent in the building systems, as a result of various asymmetries/
irregularities, must be identified. In order to improve design and prevent structural damage, the contribution of the lateral load resisting system, number of storeys, type, and degree of asymmetry must be accurately identified and quantified. The goal of this work is to examine the various parametric behaviours of asymmetric structures through the analysis and modelling of different storey buildings utilising the Response Spectrum Method and three linear analysis (RSA) techniques. This paper models and analyses an asymmetric circular diagrid construction with and without core shear walls. The conclusions are offered at the end of the study after all the models and structures have been analysed and contrasted for outcomes such maximum storey drifts, storey displacements, and storey shear.
Sorathiya and Pandey (2017)
Globally, the number of multi-story buildings being built is rising quickly. The diagrid structural system has recently become popular for tall structures due to the structural effectiveness and aesthetic potential offered by the system's distinctive geometric layout. The most recent development in diagrid structure technology is currently in development.
Buildings with diagonal grids at specific angles and in modules that span the building's height are known as diagrid structures. In the peripheral of a diagrid structure, triangulated grids are used in place of vertical columns. So when designing tall buildings, methods that are more effective at achieving stiffness against lateral stresses are preferred. In order to estimate the preliminary member sizes of r.c.c. diagrid structures for tall buildings, this research proposes a stiffness-based design methodology. For the analysis, a G+24, G+36, G+48, and
G+60 storey RCC building with a plan dimension of 18 m 18 m in Surat is taken into consideration. For modeling and analysis of structural members, STAAD.Pro software is employed. All structural components are created in accordance with IS 456:2000, and seismic force load combinations are taken into account in accordance with IS 1893(Part 1):2002. Analysis results are compared with regard to beam displacement, storey drift, and bending moment. This results in a more cost-effective diagrid structure than a traditional structure.
Choudhary (2017)
The frequency of earthquakes has increased, severely harming both human life and property. As a result, the requirement for precise seismic evaluation of structures arises. Seismic co-efficient technique and response spectrum method are two of the static and dynamic approaches for seismic inquiry that are employed in this study. These methods are coupled in this study for a seismic investigation of a G+10 multistory building. While seismic coefficient analysis is performed manually using calculations from the Codal formula, response spectrum analysis of the building is performed using the enhanced version of the software STAAD-PRO-V8i.
Here, a comparative analysis of these earthquake methodologies is conducted, presented, and explained.
2.1 Gaps in the Research
Following points represented the investigated gaps in the research:
a) There is very limited research which focuses on investigations on floor wise seismic forces in the buildings;
b) There is very limited research which focuses on investigations on shears in the buildings.
3. SOLUTION METHODOLOGY
Present section focuses on the details of software used to perform the analysis, as presented in upcoming sub-sections.
Figure 3.1 shows the solution methodology adopted in the research problem.
Figure 3.1: Flowchart for Solution Methodology of the Research Problem 3.1 Investigated Terms in the Analysis During the analysis, following terms were investigated:
a) Seismic Load
Seismic loading is one of the basic concepts of earthquake engineering which means application of a seismic oscillation to a structure. It happens at contact surfaces of a structure either with the ground or with adjacent structures.
Seismic loading depends, primarily on seismic hazard, geotechnical parameters of the site, and structure's natural frequency etc.
b) Seismic Shear
Seismic shear or base shear is defined as the estimate of maximum expected lateral force on the base of structure due to seismic activity, which is calculated on the basis of seismic, zone, type of soil, and building lateral force.
3.2 Software used in the Research In the present research work, the software used was STAAD. Pro, the details of which are presented as follows:
Structural Analysis and Design Pro is referred to as STAAD Pro. Buildings, bridges, towers, transit, industrial, and utility structures are all commonly analysed and designed using STAAD Pro v8i software. The structural analysis and design software programme STAAD or (STAAD.Pro) was created by Research
Engineers International in 1997. Bentley Systems acquired Research Engineers International before the end of 2005.
STructural Analysis and Design is referred to as STAAD. One of the most popular structural analysis and design software programmes worldwide is STAAD.Pro. in this software, more than 90 international design codes for steel, concrete, wood, and aluminium can be used.
It may employ a range of analytical techniques, including classic static analysis as well as more contemporary techniques like p-delta analysis, geometric non-linear analysis, Pushover analysis (Static-Non Linear Analysis), or buckling analysis. It can also leverage a variety of dynamic analytic techniques, including response spectrum analysis and time history analysis. Both user-defined spectra and a variety of international code-specified spectra are supported by the response spectrum analysis capability. To further enhance collaboration amongst the various disciplines involved in a project, STAAD.Pro is compatible with programmes like RAM Connection, AutoPIPE, SACS, and many other engineering design and analysis programmes. In addition to plants, buildings, and bridges, STAAD can be used to analyse and design towers, tunnels, metro stations, water/
wastewater treatment plants, and other structural projects.
4 PROBLEM FORMULATION AND SOLUTION
Present section tells about the introduction to the research problem and its solution, the details of which are presented in upcoming sub-sections.
4.1 Problem Formulation
Based on the gaps in the research, following research problem has been formulated: Investigations on Lateral Loads and Base Shear of G+ 8 Multi storeys building in Seismic Zone III City
4.2 Solution of Problem
In order to solve the problem following procedure was obtained:
a) In the first step, specifications for the targeted building were obtained from the firm, the details of which are as follows:
Size of beam=600*300 mm
Size of column=300*600 mm
Size of building= 24*24 m
Number of storey= 9
Height of storey= 3 m
DL of slab including finishes=4 kN/m2
Weight of partition on floor= 2 kN/m2
Live load on each floor=3 kN/m2
Live load on the roof= 1.5 kN/m2
Soil type=Medium
Location= Indore (Madhya Pradesh)
For Indore (Zone III), zone factor Z=0.16
Importance factor, I=1.0
Type of Building: OMRF
Response reduction factor R=3, for OMRF
Percentage of live load to be considered=25 percent
Type of Concrete=M25
b) In next step, with the help of equivalent static method, lateral loads as well as shears on each floor were calculated as follows:
Total seismic weight on the floor,
𝑊 = 𝑊𝑖 (4.1)
...where, 𝑊𝑖 is the summation of loads from the all the floors, which includes dead loads and appropriate percentage of live loads.
Now, effective weight at each floor except the roof = DL of slab including finishes + weight of partition + 25 percent of live load
= 4+2+0.25*3 = 6.75
kN/m2 (4.2)
Now, weight of beams at each floor and the roof = Size of column*Total length of the beam*Density of concrete
= 0.3*0.6*240*25=1080 kN (4.3) Now, Weight of columns for each floor = Size of column*(Overall height of the floor – Overall depth of the floor)*Density of concrete* No. Of columns
= 0.3*0.6*2.4*25*25=270 kN (4.4) Weight of the column at
the roof = ½*270 = 135 kN
(4.5)
Total plan area of the building is 24 m * 24 m
= 576 m2
(4.6)
Equivalent load at roof level = DL*total plan area + weight of beams at each floor and room*weight of column at the roof
= 4*576+1080+135=3519 kN (4.7) Equivalent load at each floor = effective weight at each floor except the roof* Total plan area of the building + weight of beams at each floor and the roof + Weight of columns for each floor
= 6.75*576+1080+270=5238 kN
(4.8)
Seismic weight of the building W = Equivalent load at roof level + Equivalent load at each floor * Number of story except roof one
= 3519+5238*8 = 45423
kN (4.9)
Now, Fundamental natural period of vibration of a moment-resting frame without infill
𝑇𝑎 = 0.075 ×ℎ0.75 = 0.075 × 270.75 = 0.89s
(4.10)
Average response acceleration coefficient and Sa/g for 5% damping and type II soil is 1.53 (from IS 1893 (Part I): 2002 code, for medium soil, Sa/g = 1.36/T if 0.55
<=Ta<=4)
Design horizontal seismic coefficient = 𝐴ℎ = 𝑍𝐼
𝑆𝑎 𝑔 2𝑅 =
0.16×1×1.53
2×3 = 0.0408
(4.11)
Base shear VB = Ah.W = 0.0408*45423 = 1853.258 kN
(4.12)
Lateral load and shear force at various load levels
Design lateral force at floor i = 𝑄𝑖 = 𝑉𝐵
𝑊𝑖ℎ𝑖2 𝑊𝑖ℎ𝑖2 𝑛 𝑖=1
Table 4.1 Design Lateral Force (floor wise) Mass
Number Wi hi Wihi2 𝑾𝒊𝒉𝒊𝟐
𝑾𝒊𝒉𝒊𝟐
𝒏 𝒊=𝟏
Qi Qi (cumulative)
1 3519 27 2565351 0.210 390.258 390.258
2 5238 24 3017088 0.247 458.980 849.238
3 5238 21 2309958 0.189 351.406 1200.645
4 5238 18 1697112 0.139 258.176 1458.821
5 5238 15 1178550 0.096 179.289 1638.111
6 5238 12 754272 0.0619 114.745 1752.856
7 5238 9 424278 0.0348 64.544 1817.400
8 5238 6 188568 0.015 28.686 1846.086
9 5238 3 47142 0.003 7.171 1853.258
Total 12182319 1
c) In next step, with the help of simulation approach, results of analysis were obtained on one of the popular static analysis software, STADD.Pro V8i, the details of which are presented as follows:
First of all, a model of building was created in the software, as presented below:
Figure 4.1 Model of Building
In the next step, assignments of concrete dimensions were provided to different beam and columns, as shown below:
Figure 4.2 Assignment of Properties to Different Building Elements
In next step, different load cases were declared. The declared load cases were seismic loads (EQX and EQZ), direct load (DL), live load (LL), and roof live load (RLL).
In next step, allocation of building elements to different types of loads were accomplished, as presented below:
Figure 4.3 Building under Seismic Loads
Figure 4.4 Building under Direct Loads
Figure 4.5 Building under Live Load
Following seismic definitions were used to solve the problem:
Figure 4.7 Seismic Definitions Used
In next step, the results from simulation approach were obtained.
5 RESULTS AND DISCUSSION
Present section deals with the details of results and discussion, the details of which are presented in upcoming sub- sections.
5.1 Results
Following results were obtained from analytical approach:
Base shear VB=1853.258 kN
Floor wise Lateral Forces (please refer Table 5.1)
Table 5.1: Floor wise Lateral Forces S. No Floor Number Lateral Force (kN)
1 9 390.258
2 8 458.980
3 7 351.406
4 6 258.176
5 5 179.289
6 4 114.745
7 3 64.544
8 2 28.686
9 1 7.171
Following results were obtained from simulation approach (Please refer Figures 5.1 and 5.2):
Figure 5.1 Details of Base shear VB
Floor Number 1 2 3 4 5 6 7 8 9
Figure 5.2 Details of Lateral Floor wise Loads
5.2 Discussion
Figure 5.3 presents the comparison among the obtained values of base shear. Percentage difference between the two results was found as 0.106 percent.
Figure 5.3: Comparison of analytical and simulation results for Base Shear Table 5.2 shows the comparison of floor wise lateral forces using both, analytical and simulation approaches.
Table 5.2 Comparison of floor wise Lateral Forces Using Analytical and Simulation Approaches
S.
No Floor Number
Lateral Force (kN)
Percentage Difference (%) Analytical
Approach Simulation Approach
1 9 390.258 387.328 0.750
2 8 458.980 459.282 0.065
3 7 351.406 351.638 0.065
4 6 258.176 258.346 0.065
5 5 179.289 179.407 0.065
6 4 114.745 114.821 0.066
7 3 64.544 64.587 0.066
8 2 28.686 28.705 0.066
9 1 7.171 7.176 0.069
Figure 5.4 shows the graphical representation of results from both the approaches.
Figure 5.4 Graphical representation of Results from Analytical and Simulation
Approaches
From above analysis it can be seen that there is very less percentage difference in the results obtained from both, analytical as well as simulation approaches, due to
which the obtained results may be considered for further analysis.
6 CONCLUSION, LIMITATIONS AND FUTURE SCOPE OF THE RESEARCH Present section deals with the details of conclusion, limitations and future scope of the research, as presented in upcoming sub-sections.
6.1 Conclusion
Present research work was focused on the investigations on floor wise lateral loads as well as base shear for a G+8 residential building in a seismic zone III city, Indore (Madhya Pradesh). Following points represent the conclusion of the research work:
a) Investigated values of floor wise lateral forces are as follows:
Table 6.1: Floor wise Lateral Forces S. No Floor
Number Lateral Force (kN)
1 9 390.258
2 8 458.980
3 7 351.406
4 6 258.176
5 5 179.289
6 4 114.745
7 3 64.544
8 2 28.686
9 1 7.171
b) Investigated value of base shear is VB=1853.258 kN.
6.2 Limitations and Future Scope of the Research
Following points represent the limitations of the research work:
a) Present research work is based on seismic analysis of a particular building in a particular seismic zone;
and
b) Present analysis is also based on investigations on particular sets of properties.
Following points represent the future scope of the research work:
a) A detailed research involving all the seismic zones on different classes of buildings may be initiated; and
b) An extensive research involving a broader set of properties may be called.
REFERENCES AND WEB RESOURCES 1. Choudhary P, S. N. (2017). Dynamic Analysis
of Multistory Building Using Response Spectrum Method and Seismic Coefficient
Method-A Comparison. IJISET-International Journal of Innovative Science, Engineering &
Technology, 4(6).
2. Daniel, J. J. (2021). Effect of seismic bed rock acceleration ratio on the material, flexural and shear behavior of a building in ethiopia based on ES EN 1998–1: 2015. Materials Today: Proceedings, 45, 6115-6122.
3. Divya, R., & Murali, K. (2021). Comparative study on design of steel structures and RCC frame structures based on column span. Materials Today: Proceedings, 46, 8848- 8853.
4. Kavya, H. (2020). Analysis & design of multi- story building using STAAD PRO and E- TABS. International Research Journal of Engineering and Technology, 7(1), 1621-1627.
5. Lingeshwaran, N., & Poluraju, P. (2020).
Analytical study on seismic performance of bed joint reinforced solid brick masonry walls. Materials Today: Proceedings, 33, 136- 141.
6. Maraveas, C., & Tsavdaridis, K. D. (2019).
Assessment and retrofitting of an existing steel structure subjected to wind-induced failure analysis. Journal of Building Engineering, 23, 53-67.
7. Nirmal, C., & Jaiswal, D. S. (2018). Dynamic Analysis of High Rise Building Structure with Lightweight concrete. Int. Res. J. Eng.
Technol, 5, 368-372.
8. Saleem, I., & Tengli, D. S. K. (2018).
Parametric Study on Asymmetric Diagrid Structures. International Journal of Applied Engineering Research, 13(7), 61-66.
9. Sorathiya, R., & Pandey, P. (2017). Study on diagrid Structure of Multistorey Building. Development, 4(4).
10. Uikey, S., & Satbhaiya, E. R. (2020). Seismic Response Analysis of Tall Building Using STAAD Pro Software. Journal of Earthquake Science and Soil Dynamics Engineering, 3(1).
11. Wanjari, M. M. B., Dhavale, G. D., & Kedar, R. S (2022). A review on wind analysis of a multi storied structure. International Research Journal of Modernization in Engineering Technology and Science, 4 (2), 193-196.
12. www.scholar.google.com
