Effect of Windload on Tall Structures in Different Terrain Category

Effect of Windload on Tall Structures in Different Terrain Category

Nagraj S Airani

PG Student

Dept. of Civil Engineering, SDMCET, Dharwad, India

Dr. D. K Kulkarni

Professor,

Dept. of Civil Engineering, SDMCET, Dharwad, India

Abstract Wind is a perceptible natural movement of air relative to earth surface mainly within the shape of air cutting- edge blowing in a specific route. The major dangerous factor which problem to civil engineering systems is that, it will load any and every item that comes in its way. Wind blows with much less speed in rough terrain and better speed in smooth terrain. This paper gives Storey Displacement, Storey Drift, Storey Shear occurring in special storey due to wind in special terrain category. Four models are analysed using of ETABS 2019 package. Present works gives an excellent source of facts about variation in Storey Displacement, Storey Drift, Storey Shear in different terrain categories.

Keywords: Wind Load, ETABS, Terrain, Storey displacement, Storey Shear, Storey Drift.

1. INTRODUCTION

   No obvious definition for tall building is there. From the features of the building, it is quite difficult to term it as "Tall Building". Number of floors or height are not the factors for a building to be said as tall. A structure which is bounded by floors, roof top, walls & commonly windows can be named as tall or short building depending on many factors. "A tall building" is a multi-storey arrangement in which maximum of the occupier's rest on elevators to fulfil their purposes.

   Maximum noticeable structures are known as high rise buildings in many nations. On the basis of operational approach, it is quite easier to account a structure as high when their plan and structural examination are somewhat exaggerated by the crosswise loads. This can be explained by an example such as sway which it experiences due to wind load or earthquake load which all are horizontal loads. As elevation rises, the wind forces start to govern. Hence, basic outline for high rise buildings is established about ideas related totally to the resistance experienced by turbulent wind. High rise structures, which are commonly planned for workplace or marketable use, are one of the best well-known descriptions in the history of Indian urban development in 12th era.

   There are four distinct wind classifications for tall constructions that can be built

   • Terrain category 1

   • Terrain category 2

   • Terrain category 3

   • Terrain category 4

     Category 1: Exposed open area where there are few or no obstacles and when the average height of any nearby objects is less than 1.5 meters.

     Terrain Category 01

     Category 2: Open terrain with well scattered obstruction having heights generally between 1.5 to 10m.

     Terrain Category 02

     Category 3: Terrain with numerous, widely spread obstacles that are the size of buildings and can reach heights of 10 meters, with or without a few lone, tall obstructions.

     Terrain Category 03

     Category 4: Terrain with numerous large high closely spaced obstructions.

     Terrain Category 04

2. OBJECTIVES

   In the present work following objectives are considered:

   • To analyse the multistorey building by considering the effect of wind load with different terrain categories.

   • To compare the results of Storey displacement, Storey drift, Storey shear in different terrain category.

     Assigning Supports

     Defining Response Spectrum

     Analyzing the building

     STEP-BY-STEP METHOD FOR MODELLING OF THE STRUCTURE

     Step1: Collection of data related to structure considering software implementation

3. METHODOLOGY

   This chapter describes the standard step-by-step method for modelling the four different regular structure

   • Model Type 1- Structure in Terrain Category 1

   • Model Type 2- Structure in Terrain Category 2

   • Model Type 3- Structure in Terrain Category 3

   • Model Type 4- Structure in Terrain Category 4

     Architectural Drawings

     Creating grid Lines

     Defining Material Properties

     Defining Section Properties

     Slab Details

     Assigning Properties

     Definition and assigning Loads

     Flow Chart

     Number of Stories	G+15
     Plan Dimension	16m*15m
     FL to GL	1.5m
     F to F height	3m
     Materials	M30 grade concrete and Fe500 Steel
     Size of Column	300mm X 800mm
     Size of Beam	300mm X 600mm
     Slab Thickness	150mm
     Seismic Zone	Zone IV

     Table 1: G+15 Specification

     Step2: Modeling of structure in ETABS

     Fig-1: Plan of RCC Building

     Fig-2: Elevation View

     Fig-3: Storey Data

     Step 3: Generating Material Properties (M40 & HYSD500)

     Fig-4: M-30 Concrete

     Fig-5: HYSD500

     Step 4: Creating beam and column section of the structure

     Fig-6: Section Properties of a Frame

     Step 5: Design loads

     The weight of materials shall be computed using the unit weights specified in IS: 875 (part-1)-1987. The imposed load or otherwise live loads are calculated using the occupancy classes defined in IS: 875(Part-2)-1987, which are as follows:

     	Floor loading as per IS: 875(Part-2)-1987	Live Load in KN/m2.	FF+CP KN/m2.
     I	Ground Floor to story 15
     A	All rooms & kitchens.	2.0	1.5
     B	Stair	3.0	1.5
     C	Lobby / Corridor	3.0	1.5
     D	Toilets	2.0	1.5
     II	Terrace
     A	Floor	1.5	1.0

     Step 6: Defining Wind Load

     The loading due to wind is assessed based on the provisions of IS: 875 Part 3

     Wind Speed = 50 m/s

     Importance Factor = 1.00

     Risk Co-efficient (K1 factor) = 1

     Topography (K3 factor) =1

     Step 8: Defining Terrain Category

     Terrain Category 1

     Step 9: Load Combinations

     Load Cases

     Terrain Category 2

     Terrain Category 3

     Terrain Category 4

     Fig-11: Load combinations for RCC structure

4. RESULTS AND DISCUSSION

   In the present study, high rise Reinforced Cement Concrete structural system is modelled and analyzed using ETABS 2019. Structures are analyzed and core results are extracted and presented in the present chapter 4 as below and conclusions are made in chapter 5 based on the brief discussion of results. Followin Tables demonstrates the maximum Storey displacement, Storey Drift, Base Shear.

   1. STOREY DISPLACEMENTS

      Chart-1: Storey vs Displacement

      Storey displacement results are presented in the form of graphs in Chart 1. From the results, it can be seen that

      Height of Structure or Building is directly proportional to Displacement of that structure i.e., more the height more will be displacement

   2. STOREY DRIFT

      Chart -2: Storey vs Drift

      Storey Drift results are tabulated in below Table 4 and presented in the form of graphs in Fig.4.2 From the results it can be seen that, Terrain Category 1 have the maximum Storey drift at Storey 3 i.e., 0.001915. After Storey 3 storey drift keeps on decreasing.

   3. STOREY SHEAR

   Chart-3: Storey shear

   Storey Shear is shown in chart-3, from the results it can be seen that, Storey shear increases as the height of the structure increases

   .

5. CONCLUSIONS

The following conclusions are drawn from the present study:

• Height of Structure or Building is directly proportional to Displacement of that structure i.e., more the height more will be displacement. Story displacement is greatest in Terrain Category 1 and lowest in Terrain Category 4. There is 24.62 percentage decrease in displacement from Terrain Category1 to Terrain Category 4.

• Terrain Category 1 have the maximum Storey drift at Storey 3. After Storey 3 Storey drift keeps on decreasing. At Storey 3 there is 28.82 percentage decrease in Storey drift from Terrain Category 1 to Terrain Category 4.

• Storey shear increases as the height of the structure increases. Story shear is greatest in Terrain Category 1 and lowest in Terrain Category 4. There is 63.36 percentage decrease in Storey shear from Terrain Category1 to Terrain Category 4.

REFERENCES

[1] Abdur Rahman, Saiada Fuadi Fancy, Shamim Ara Bobby Analysis of drift due to wind loads and earthquake loads on tall structures by programming language c International Journal of Scientific & Engineering Research, Volume 3, Issue 6, June-2012 1 ISSN 2229-

5518

[2] RAHUL KUMAR MEENA, RITU RAJ and S ANBUKUMAR Effect

of wind load on irregular shape tall buildings having different corner configuration https://doi.org/10.1007/s12046-022-01895-2

[3] Ashish Padiyar1, Vipin Verma2 Effect of Wind Load on High Building with Different Aspect Ratio Using Staad Pro (IRJET)

Volume: 07 Issue: 08 | Aug 2020

[4] Shraddha J. Patil, Mahesh Z. Mali, Dr.R.S.Talikoti Effect of Wind Load on High Rise Structure International Journal of Engineering and Technical Research (IJETR) ISSN: 2321-0869 (O) 2454-4698 (P),

Volume-3, Issue-7, July 2015

[5] P.V. Muley, A.S. Radke (2019) Performance of high rise building under seismic and wind excitation for the different plan configurations of same area International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 11 | Nov 2019

[6] IS 875-Part 1 2016: Design Loads (other Than Earthquake) For Buildings and Structures Bureau of Indian standard, New Delhi, (2016).

[7] IS 875-Part 2 2016: Design Loads (other Than Earthquake) For Buildings and Structures Bureau of Indian standard, New Delhi, (2015).

[8] IS – 456 Code of practice for plain and reinforced concrete.

[9] IS 875 (Part-5) 2016, Design Loads (other Than Earthquake) For Buildings and Structures Bureau of Indian standard, New Delhi, India.

[10] IS 875-Part 3 2016: Design Loads (other Than Earthquake) For Buildings and Structures: Wind Load Bureau of Indian standard, New Delhi, (2015).