Experimental study on the behaviour of nonductile infilled RC frames strengthened with external mesh reinforcement and plaster composite

S Z Korkmaz,H H Korkmaz,M T Cogurcu,M S Donduren,M Kamanli

doi:10.5194/nhess-10-2305-2010

Abstract

Abstract. The aim of this paper is to report on an experimental study about Turkish Earthquake Code on suggested strengthening method. The proposed method uses existing brick infill walls and the strengthening is done with the application of external mesh reinforcement and plaster. 5 nonductile 1/2 scaled, one bay, two storey RC specimens were tested under a reversed cyclic loading. The first two specimens were reference specimens and the other ones were strengthened with the proposed method. The specimens contained several design and construction mistakes such as low concrete quality and improper steel detailing. Strength, stiffness and storey drifts of the test specimens were measured. The results of the test on these frames were compared with the reference specimens. The effects of the reinforced mesh plaster application for strengthening on behaviour, strength, stiffness, failure mode and ductility of the specimens were investigated. Unexpected failure modes were observed during the testing and the results were summarized in this paper.

Highlights

Many existing reinforced concrete (RC) frame structures, that were designed and constructed during the 1950s through to the 1990s, in many regions of the Turkey, do not meet the current seismic design requirements set forth by the Turkish Earthquake Code (2007) and have an inadequate safety assessment (Rocha et al, 2004)
A large number of those buildings exhibited fierce damage and some were on the verge of collapse (Oliveto and Decanini, 1998)
Reinforced concrete (RC) frame buildings with nonductile detailing represented a considerable hazard during recent earthquakes (Kaltakci et al, 2007)

Summary

Introduction

Many existing reinforced concrete (RC) frame structures, that were designed and constructed during the 1950s through to the 1990s, (according to the design codes of the 70s), in many regions of the Turkey, do not meet the current seismic design requirements set forth by the Turkish Earthquake Code (2007) and have an inadequate safety assessment (Rocha et al, 2004). Structure that is not designed for prescribed earthquake forces suffered severe damage and was responsible for most of the loss of life during seismic events such as 1999 Kocaeli (Turkey) earthquake (Ghobarah and Elfath, 2001; Binici et al, 2007). Those non-ductile RC frame structures may have inadequate lateral resistance and limited ductility. They possess an inherently low resistance to horizontal loads, resulting in large inelastic deformations (Zou and Teng, 2007) during recent earthquakes due to insufficient lateral load carrying capacity For those structures constructed with insufficient strength and ductility, the required stiffness was not provided. Older designs often do not have proper reinforcement details needed to ensure ductile behaviour (Geng et al, 1998; Ghobarah et al, 2000; Altin et al, 2007)

Objectives

Methods

Findings

Conclusion