Structural retrofitting of reinforced concrete building using turnbuckle exterior post tensioning

College

Gokongwei College of Engineering

Department/Unit

Civil Engineering

Document Type

Conference Proceeding

Source Title

5th Asia Conference on Eartquake Engineering

Publication Date

10-2014

Abstract

Nowadays, the problem of aging and deterioration of reinforced concrete buildings is imminent. The structural performance of reinforced concrete members is affected because of long-term environmental exposure and excessive loading. Reinforced concrete beams deflect in time, where the flexural performance and serviceability are compromised. Structures become vulnerable against extreme loading conditions such as seismic loads, thus the overall seismic integrity of structures is affected. Instead of demolishing structures, retrofitting is usually done in order to resolve environmental and cost issues. A turnbuckle type of exterior post tensioning (T-EPT) is proposed as a retrofitting method wherein it was proven experimentally that it can be able to improve the serviceability of the beam and further increased its load carrying capacity. The T-EPT is an innovative way of retrofitting beams as it is comprised of a simple steel bracing configuration and makes use of a tumbuckle mechanism to provide the pre-stressing force, making flexural members externally post-tensioned. By modeling a reinforced concrete building into an integrated structural analysis program, the structural performance of the structure when applied with the T-EPT was evaluated and assessed.

The study was done in two phases, namely the experimental phase, which utilized real test specimens where different cases were tested with several loading cycles; and the computer modeling phase, which utilized the results from the experimental phase in order to model the T-EPT, wherein its effectiveness was evaluated. The external loads attributed by the T-EPT were modeled using a series of point loads along the beam corresponding to the configuration designed for the structure. By comparing experimental results to computer model results with the same loading conditions, an adjustment coefficient was obtained to consider all correction factors to effectively model the application of the T-EPT in the structural model of the building. Different T-EPT configurations were modeled and the most efficient design that can b applied in the structure was determined. A case study applying the T-EPT to a structural model of a building was conducted, and the results show that applying the T-EPT increases the stiffness of the main lateral resisting members, thereby improving the seismic integrity of the structure. Overall, the T-EPT was effective in improving the serviceability) condition, load carrying capacity, and seismic integrity of structures.

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Disciplines

Structural Engineering

Note

Abstract only

Keywords

Buildings—Retrofitting; Earthquake hazard analysis

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