Advances in Structural Engineering Research

Full Session with Abstracts

337103-10 - Analytical Evaluation of Seismic Performance of a Reinforced Concrete Building Designed Only for Gravity Loads Prior to and After Repair

Friday, April 20
1:30 PM - 3:00 PM
Location: 202CD

How does this session impact and improve the Structural Engineering Profession?
A unique and effective modelling approach is presented to accurately capture the local behaviour of deficient or repaired members, while considering the overall structural response. Application of the method to analysis of reinforced concrete buildings with inadequate seismic performance improves the decision making process on the necessity of the repair and choosing a proper repair strategy.

Inadequate seismic performance of reinforced concrete (RC) buildings designed only for gravity loads have been shown through several research studies and also have been reported in recent earthquakes. One common approach to repair these structures is to use fibre-reinforced-polymer (FRP) wraps. An effective repair process requires having a good understanding of the structural behaviour prior to and after the repair. This includes accurately computing the local response of deficient or repaired members, the influence of these members on other structural components, and the overall structural behaviour. However, most of the existing analytical studies are limited to the member-level behaviour, and the ones that consider the structural-level response use oversimplified models to represent repaired members. With modern design codes, specific performance-based objectives should be met at both the member-level and structural-level, requiring a comprehensive analysis of the repaired structure.
In a recent study, the authors proposed a unique modelling approach, known as multi-platform simulation, which enables accurate analysis of complex reinforced concrete structures locally and globally. In this modelling approach, each critical member is modelled with a proper advanced finite element tool, while the remainder of the structure is modelled with a global analysis software. An integrated analysis procedure is used to combine all the sub-models and consider the interactions between them. The proposed modelling method was verified through analysis of several test specimens including a series of reinforced concrete columns repaired with FRP wraps. Although, the multi-platform analysis results agreed well with the experimentally reported data, the verification study was limited to the member-level behaviour.
Recently an experimental program was conducted at the University of Toronto to investigate the seismic performance of a reinforced concrete building repaired with FRP wraps. The building was designed only for gravity loads with insufficient seismic detailing, particularly at the first storey columns. The tests were performed in a hybrid (numerical-experimental) manner which enabled considering both the member-level and structural-level behaviour. In this study, the proposed multi-platform modelling method is employed to capture the behaviour of the building prior to and after the repair. Modelling the critical columns with an advanced finite element tool (VecTor2) enables accurate analysis of RC-related mechanisms (e.g., stress conditions at the crack, damage effects, and buckling of longitudinal bars) and FRP-related mechanisms (e.g., tension stiffening effects, confinement enhancement, and bond-slip effects at the interface of concrete and FRP). In addition, modelling the remainder of the building with a global analysis software (OpenSees) allows considering the overall structural response, without using computationally expensive numerical procedures. The multi-platform analysis results are compared against those obtained from the hybrid test and the stand-alone global analysis. Also, the influence of important local mechanisms and force redistribution effects due to stiffness changes between structural members are discussed in detail.

Is this topic of regional, national or international interest?
International interest.

Who is the target audience?
Structural engineers and researchers who are interested in the behaviour of reinforced concrete structures repaired with fibre-reinforced-polymer wraps.

What will the audience take away from your presentation?
1. Familiarity with a newly developed multi-platform simulation approach; 2. Important mechanisms influencing the behaviour of reinforced concrete columns repaired with FRP wraps; 3. Impact of FRP retrofit to intact, repaired, or retrofitted structures.

Oh-Sung Kwon

Associate Professor
University of Toronto

Prof. Kwon has investigated topics on hybrid (numerical-experimental) simulation method, numerical model integration, multi-resolution analysis, and soil-structure-interaction analysis. His research group has applied the simulation methods to various systems including nuclear power plant subjected to internal pressure and earthquake excitation, a structure under fire scenario, seismic performance assessment of various building structures, and geographically distributed hybrid simulations.


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337103-10 - Analytical Evaluation of Seismic Performance of a Reinforced Concrete Building Designed Only for Gravity Loads Prior to and After Repair

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