The strong column–weak beam design philosophy in reinforced concrete frame structures: A literature review

Abstract

<jats:p> This article presents a literature review of existing research on the strong column–weak beam design philosophy, which has been widely adopted in the seismic design of frame structures. A comprehensive review of this design philosophy, including its concept and research history, especially factors affecting the accurate calculation of the flexural capacity of beams [Formula: see text] and the determination of the column-to-beam flexural strength ratio [Formula: see text], is presented first. The development of design provisions of four representative countries for this design philosophy is also reviewed. The implementation of strong column–weak beam hierarchy in real structural design is then discussed, and existing problems are pointed out. Finally, different techniques for the seismic retrofit of existing reinforced concrete frames are reviewed. </jats:p>

Behaviour of RC beams with a fibre-reinforced polymer (FRP)-strengthened web opening

“…The performance enhancement of the RC T-section beam with a web opening due to the existence of the FRP strengthening system can be attributed to the following three reasons: (1) the CFRP wrap on the web chord can provide shear contribution to the web chord and thus enhance the load-carrying capacity of the beam; (2) the FRP U-jackets with spike anchors can restrict/mitigate the initiation/development of diagonal cracks at the opening corners and the horizontal cracks between the flange and the web, and therefore avoid the brittle behaviour of the beam caused by such cracks; and (3) the concrete in the web chord is effectively confined by the CFRP wrap and thus the compressive strength and ductility of the web chord can be enhanced significantly.…”

“…Therefore, beam-sway mechanism is preferred to story-sway mechanism if the failure of RC frames cannot be avoided. The strong column-weak beam design philosophy which can realize the beam-sway mechanism has been widely adopted in the seismic design of RC frames, according to a comprehensive literature review conducted by the authors [1]. To achieve the strong column-weak beam hierarchy in RC frames, a flexural strength ratio (i.e., ratio of the sum of flexural capacities of the columns at a joint to that of the beams framing into the joint) greater than 1 has been stipulated in the relevant design codes from different countries [1].…”

“…The strong column-weak beam design philosophy which can realize the beam-sway mechanism has been widely adopted in the seismic design of RC frames, according to a comprehensive literature review conducted by the authors [1]. To achieve the strong column-weak beam hierarchy in RC frames, a flexural strength ratio (i.e., ratio of the sum of flexural capacities of the columns at a joint to that of the beams framing into the joint) greater than 1 has been stipulated in the relevant design codes from different countries [1]. For instance, the current ACI code [2] and Eurocode [3] specify a flexural strength ratio of 1.2 and 1.3 respectively, and the current Chinese code [4] specifies a range of flexural strength ratio from 1.1 to 1.7.…”

“…Against the above background, a novel seismic retrofit method was proposed to achieve good seismic performance of cast-in-place RC frames which violate the strong column-weak beam requirement, based on the concept of Beam-end Weakening in combination with FRP Strengthening (referred to as BWFS method hereinafter for simplicity) [29]. Three specific techniques were proposed to implement the BWFS method [29]: (1) the beam opening (BO) technique; (2) the slab slit (SS) technique; and (3) the beam section reduction (SR) technique. More details of the above three techniques can be found in Ref.…”

Influencia de la relación momento resistente columna – viga en el mecanismo de colapso de una edificación de tipología mixta ubicada en zona de alto peligro sísmico

“…Además, aunque los códigos de diseño actuales consideran el efecto de las losas hormigonadas in situ en la capacidad de flexión de la viga, el valor de sobrerresistencia dado en estos códigos de diseño sigue siendo menor que los sugeridos por los investigadores (Quintana-Gallo, 2019). Por lo tanto, las estructuras diseñadas en base a las últimas versiones de los códigos de diseño probablemente todavía no pueden alcanzar completamente la jerarquía de "columna fuerte-viga débil" (Nie et al, 2020).…”