Seismic Analysis of RC Frame Structure with Diagrid using ETABS

Abstract

A 12-storey Diagrid building and a Bare-frame building are compared in this study. A 24 m x 24 m plus-shaped floor plan is taken into consideration. Structural member modelling and Response spectrum analysis are done with ETABS. Every structural member was designed in accordance with IS 456:2000, and the structure\'s analysis and design took into account load combinations like dead load, live load, and design earthquake loads & wind loads. A comparison was made between later RC frames with and without diagrid structural systems.

Introduction

Due to rapid urbanization and limited land availability, taller buildings are increasingly being constructed. These high-rises require efficient lateral load-resisting systems, especially in seismic zones. The diagrid structural system, characterized by a diagonal grid of structural members, is gaining popularity for its superior structural performance and architectural flexibility.

Unlike traditional vertical-column systems, diagrids:

• Improve seismic resistance by transferring loads through axial action.

• Enhance lateral stiffness and reduce drift.

• Eliminate the need for corner/interior columns, maximizing usable space.

• Are aesthetically pleasing and efficient in material usage.

Objectives

The study compares a G+11-storey RC bare frame with a diagrid RC frame using Response Spectrum Analysis (RSA) in ETABS, based on:

1. Storey displacement

2. Storey drift

3. Storey shear

4. Storey stiffness

Models were tested under Zone V seismic conditions, and also evaluated across Zones II–V.

Methodology

• Floor Plan: 24m × 24m, 12-storey, 3.5m floor height.

• Materials: M40 concrete, HYSD550 steel.

• Modelling: Conducted in ETABS 2022.

• Loads: Wind (44 m/s) and seismic loads per IS-875:2015 and IS-1893:2016.

• Comparative analysis between bare frame and diagrid frame structures using RSA.

Key Results

1. Storey Displacement

• Maximum displacement in top storey:

  • Bare Frame: 23.84 mm

  • Diagrid: 9.87 mm

• Reduction in displacement with diagrid: 58.56%

• ? Diagrids significantly enhance lateral resistance.

2. Storey Drift

• Maximum drift (storey 3):

  • Bare Frame: 0.000835

  • Diagrid: 0.000319

• Drift reduction with diagrid: 61.7%

• ? Diagrids limit inter-storey movement, reducing structural damage risk.

3. Storey Shear

• Maximum base shear:

  • Bare Frame: 760.36 kN

  • Diagrid: 2346.94 kN

• Increase in shear capacity: 67.6%

• ? Diagrids better absorb and transfer seismic forces.

4. Storey Stiffness

• Maximum base stiffness:

  • Bare Frame: 433,292.62 kN/m

  • Diagrid: 11,453,832.83 kN/m

• Stiffness increase: 96.21%

• ? Diagrids dramatically improve base stiffness, minimizing lateral sway.

Conclusion

Diagrid structures are well-known for being effective structural systems for buildings subjected to high lateral loads, like wind or seismic loads. It is possible to greatly increase the frame\'s lateral resistance by adding a diagrid system. Diagrid systems have the potential benefits of a relatively small mass increase and faster execution of application. A. Results on Comparison of RC Bare Frame and RC Diagrid Frame in Zone- ?. 1) The storey displacement and storey drift is maximum for RC bare frame and minimum for RC diagrid frame. 2) Storey displacement is decreased by 58.56% from RC bare frame to RC diagrid frame system. 3) Storey drift is decreased by 61.7% from RC bare frame to RC diagrid frame. 4) Maximum storey shear is observed at the base in the two models, storey shear is increased by 67.6% from RC bare frame to RC diagrid frame. 5) Storey stiffness is minimum for RC bare frame and maximum for RC diagrid frame. 6) Stiffness is increased by 96.21% from RC bare frame to RC diagrid frame.

References

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Copyright

Copyright © 2025 Thasmitha H. N., Dr. D. S. Sandeep Kumar. 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.