Comparative Analysis of Multistory Building of Conventional Slab and Grid Slab with Shear Wall and Bracings on Seismic Zone V

Abstract

In the present study, response spectrum analysis is performed on various structural configurations using ETABS software. The primary objective is to investigate the seismic behaviour and response of different models subjected to earthquake forces as per the IS 1893:2002 standard. The structural configurations considered are as follows: Regular Structure: A basic building model with a regular grid of columns and beams. Grid Slab: The regular structure with the addition of a grid-type concrete slab system. Grid Slab with Shear Wall: The grid slab model augmented with shear walls. Grid Slab with Bracings: The grid slab model equipped with diagonal bracings. In the present project G+10 building having 3m storey height is considered. By considering the medium soil. Here the seismic analysis is conducted for the seismic zone ? as per IS 1893:2002. The analysis focuses on evaluating displacement, story shear, and auto lateral loads under seismic conditions.

Introduction

I. INTRODUCTION

An Rcc framed structure is basically an assembly of slabs, beams, columns and foundation inter-connected to each other as a unit. A Grid slab is a type of reinforced concrete slab with a grid-like pattern of ribs and recessed panels. It is known for its lightweight, longer spans, and economical material usage. Grid slabs are widely utilized in commercial and residential construction, especially in areas where there is a need to reduce in general overall weight of the structure or achieve longer spans between supports. Shear walls are vertical load-bearing elements designed to withstand lateral forces. They are typically located at strategic positions within the building's layout to provide stability and resistance against lateral movements caused by seismic forces. X bracing consists of diagonal braces that are typically connected between vertical columns in the building's frame. These braces work to transmit lateral loads to the foundation, providing lateral stability to the structure.

Figure 5 Shows the "Grid slab with shear wall" model did not meet the requirement of achieving a base reaction of at least 84%, just grid slab, were able to achieve a base reaction above 84% with good performance.

On the other hand, the grid slab models performed well and achieved a base reaction above 84%. This indicates that the lateral resistance in these models is provided primarily by the overall grid slab system.

Figure 6 Shows all models have passed the response reduction factor using the modal participating mass ratio of 90% or above. This indicates that the structural systems in each model are providing adequate lateral resistance and damping under the response spectrum analysis.

Figure 11 and 12 Shows the regular model is also demonstrating good performance in terms of auto lateral loads in the y-axis. Consistent good performance in both the x and y directions is a strong indicator of the regular structure's stability and robustness under lateral forces.

RESULT SUMMARY

1. Grid Slab Model:

a. The grid slab model has demonstrated better performance in terms of displacement.

b. Consider the grid slab model as a favourable option if minimizing displacements is a critical design objective.

2. Regular Structure:

a. The regular structure has shown good performance in story shear and auto lateral loads.

b. If maintaining balanced and predictable lateral resistance is a key requirement, the regular structure is a suitable choice.

3. Shear Walls and Bracings:

a. The models with shear walls and bracings have not met certain performance criteria, such as base reactions.

b. If lateral resistance from shear walls or bracings is deemed essential, further optimization and design modifications are required to meet performance objectives.

Conclusion

After carefully evaluating the performance of various structural models under different criteria, the final recommendation is to consider the \"Grid Slab Model\" for the following reasons: 1) Superior Displacement Performance: The grid slab model has demonstrated better performance in terms of displacement when compared to the other models. Minimizing displacements is often a crucial design objective, especially in areas prone to seismic activity. The grid slab\'s efficient distribution of lateral loads allows it to exhibit reduced displacements, ensuring better occupant comfort and reduced structural damage during seismic events. 2) Feasibility and Simplicity: The grid slab model without shear walls or bracings offers a simplified and cost-effective solution for lateral load resistance. Without the need for additional lateral resisting elements, the construction process becomes more straightforward and less resource-intensive. This can result in reduced construction costs and shorter project timelines, making it an attractive choice for budget-conscious projects. 3) Optimal Regularity: The regularity of the grid slab model allows for a more predictable and balanced distribution of lateral forces. This inherent symmetry and uniformity contribute to stable lateral performance in both x and y directions. The regularity of the structural layout ensures that the structure can efficiently handle lateral loads, providing added reliability and safety during seismic events. 4) Flexibility in Architectural Design: The absence of shear walls or bracings in the grid slab model offers greater flexibility in architectural design. The lack of intrusive lateral resisting elements allows architects to explore a wide range of design possibilities without compromising structural integrity. This design freedom can lead to more aesthetically appealing and functional buildings.

References

[1] Athira. M.V. PG Studen Shruthi K Chandran, Assistant Professor, “Seismic analysis of Flat slab building with shear wall” Jan 2017. [2] Avinash Patel, And Seema Padamwar, “Studying the Response of Flat Slab and Grid Slab Systems in Conventional RCC Buildings”, Indian J.Sci.Res. 14 (2): 516-521, 2017 ISSN: 2250-0138. [3] Chandurkar and pajgade, Shear Deformations of slender reinforced concrete walls under seismic loading by katrin beyer, Alessandro Dazio, and M J Nigel Priestley. [4] Chintha Santhosh et al. “Analysis and Design of Multi-storey building with grid slab using Etabs” (2016) [5] CH. Rajkumar, Dr. D. Venkateswarlu, “Analysisnand Design of Multistorey Building with Grid slab using Etabs”, Volume ?/ Issue 5/ Jun2017. [6] D. M Patil and K. K Sangle, “Seismic Behaviour of Different Bracings Systems in High Rise 2-D Steel Buildings”, Structures, vol.3, pp. 282-305, A ug. 2015. [7] Harish M K, Ashwini B T, Chethan V R, Sharath M Y, “Analysis and Design of Grid slab in building using Response Spectrum Method”, Volume 2, Issue 6. [8] Markandeya RajuPonnada, “Analytical Study on Economic Effect of Grid Floor Geometric Parameters”. [9] NavjotKaur Bhatia and TusharGolait, “Studying the Response of Flat Slabs & Grid Slabs Systems in Conventional RCC Buildings”, Volume 3, ISSN 2394-9333. [10] Uzma A. Shaikh, Prof. Mohd. Shahezad, Study on Economical Aspect of R.C.C Beam Slab Construction and Grid Slab Construction”, ISSN: 2277-9655.

Copyright

Copyright © 2023 Shilpa R, Raghu M E. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.