Assessment of Seismic Response and Structural Performance of a Retrofitted G+9 Reinforced Concrete Building Utilizing RCC Jacketing and Steel Wrapping Techniques

Abstract

A seismic design is based upon combination of strength and ductility. Frequent seismic disturbances, thestructure are expected to remain in the elastic range. By considering the actual dynamic nature of environmentaldisturbances, more improvements are needed in the design procedures. And some advance techniques are usedtostrengthen the existing structuresi.e. differentretrofittingmethods.Allthese methodshave their ownadvantages. The main objective of the present study is to analyze the behavior of Retrofitted building i.e.provision of steel jacketing in increasing the performance of building. The present study aims at checking theadequacy of multi-storey frame structures using retrofitting methods for the seismic excitations. The Retrofittedbuilding i.e. provision of steel jacketing is analyzed and compared with bare frame structure by using timehistory and pushover analysis method by using Commercial software SAP2000 v16 is used for analysis. Theresponses of thestructure arecompared by consideringdifferentparametersi.e.displacement,base shear,plastic hinges, time period of mode shapes from FEMA – 356. The result shows that plastic hinge formationduring earthquake at beam-column junction can improved performance with use retrofitting method i.e. steeljacketing.

Introduction

General:
Seismic design balances strength and ductility. Structures are expected to remain elastic under minor earthquakes, but major earthquakes cause inelastic behavior. Design codes incorporate lateral force and inelastic methods to enhance building survivability by accounting for dynamic seismic effects, leading to improved structural protection systems.

B. Retrofitting Techniques:
Various retrofitting methods exist, including RCC and steel jacketing, fiber-reinforced polymer (FRP) jackets, composite jacketing, shortcreting, energy dissipation devices, and base isolation. Each has pros and cons, requiring careful selection based on specific needs.

C. Fiber Reinforced Polymer (FRP) Technique:
FRP is a modern alternative to steel jacketing, offering advantages such as lightweight, ease of installation, and durability. It works well for circular/elliptical columns but is less effective for rectangular columns due to poor confinement.

D. Composite Jacketing System:
Composite materials, like carbon fiber and E-glass fiber, are increasingly used for retrofitting bridge piers, improving seismic strength and ductility. Various wrapping methods have been validated experimentally.

E. Steel Jacketing Technique:
Short concrete columns often fail in shear during earthquakes, especially shorter columns that attract more seismic force. Steel jacketing enhances shear strength and deformability. Different jacket shapes (tube, elliptical, rectilinear) offer varying confinement efficiencies, with recent innovations improving retrofit designs for square/rectangular columns.

II. Modelling and Analysis of Building:
A 3D G+9 storey RC moment-resisting frame building is modeled, with material properties per IS standards. Steel jacketing is applied at potential hinge zones for retrofitting. Nonlinear static (pushover) and linear time-history analyses are used to assess seismic performance.

Pushover Analysis & Lateral Load Patterns:
Pushover analysis estimates structural strength and seismic demand, incorporating various lateral load patterns (uniform, first elastic mode, code-based, multi-modal/SRSS) to simulate earthquake forces realistically.

III. Results and Discussion:
Comparisons between bare frame and retrofitted models are made using pushover and time-history analyses, evaluating parameters like displacement, drift, shear force, moments, and dynamic characteristics to demonstrate the effectiveness of retrofitting techniques.

Conclusion

Basedon this analytical studyfollowingconclusion aredrawn: 1) ThefundamentaltimeperiodismoreforBareFramethanRetrofittedbuilding. 2) Thedisplacement ofRetrofitted buildingis(20 %-40 %)less than bareframe. 3) Exteriorcolumnshear forcesofRetrofitted buildingare(5%-20 %)less thanbareframe. 4) BaseshearofRetrofitted buildingwithsteeljacketingismorethanthe BareFrame. 5) InelasticcapacityofRetrofitted buildingwith steeljacketingismorethantheBareFrame. 6) TheRetrofittedbuildingperformswell inearthquakethanbareframe duetoprovisionofsteel jacketing.

References

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Copyright

Copyright © 2025 Prof. Pallavi Bhende, Mr. Sanjay Ghate . 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.