Repair and Strengthening of Reinforced Concrete Beam-Column Joints State of the Art




INTRODUCTION

The performance of beam-column joints has long been

recognized as a significant factor that affects the overall

behavior of reinforced concrete (RC) framed structures

subjected to large lateral loads.

The first design guidelines for reinforced concrete

beam-column joints were published in 1976 in the U.S.

(ACI 352R-76 1) and in 1982 in New Zealand (NZS 3101:1982 2

). Buildings constructed before 1976 may have

significant deficiencies in the joint regions. Especially since

the 1985 Mexico earthquake, a considerable amount of

research has been devoted to identifying the critical details of

nonseismically designed buildings as well as to developing

methods of strengthening. Through their reviews of detailing

manuals and design codes from the past five decades and

their consultation with practicing engineers, Beres et al.

(among others) identified seven details (shown in Fig. 1) as

typical and potentially critical to the safety of gravity loaddesigned

(GLD) structures in an

earthquake. Most of the repair and strengthening schemes proposed thus far,

however, have a very limited range of applicability either due

to lack of consideration of floor members or to architectural restrictions.

The current recommendations by Joint ACIASCE

Committee 352 4 reads: “These joints need to be

studied in detail to establish their adequacy and to develop

evaluation guidelines for building rehabilitation. Methods

for improving performance of older joints need to be

studied. Scarce information is available on connection

repair and strengthening.” 3


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