External beam–column joints: design to Eurocode 2

Abstract

In practice external beam-column joints are seldom designed for monotonic loading. The current authors believe that this is an oversight which should be addressed. This paper presents a simple strut and tie model for the analysis and design of external reinforced concrete beam-column joints. The strut and tie model is developed from first principles using the concrete design strengths given in Eurocode 2. The main difficulty in developing strut and tie models for beam-column joints is in determining the node dimensions. The novel feature of the authors' analysis is that the joint strength is related to the flexural capacity of the beam at the face of the column which is defined in terms of the maximum moment which can be transferred through the joint into the upper and lower columns. The model is shown to give better predictions of joint shear strength than existing simple design models. A case study is presented which shows that it is often sufficient to provide only minimum shear reinforcement in beam column joints.

Interior wide beam-column connections in existing RC frames subjected to lateral earthquake loading

“…Second, the post-tensioning compressive force applied to the columns may have assisted the behaviour of the joints, as suggested by Paulay (1989), although counter-evidence exists that questions the existence of this beneficial effect (Kim and LaFave 2007). Besides the aforementioned references, many other studies focus on the seismic behaviour of the beam-column joint (Paulay and Park 1984;Ichinose 1991;Vollum and Newman 1999;Bakir and Boduroglu 2006;Bakir 2003;Vollum and Parker 2008). The columns remained in the elastic range with minor cracking.…”

A 2D beam‐column joint macro‐element for the nonlinear analysis of RC frames

“…More recently, Hwang and Lee 55 proposed a strut‐and‐tie equivalent model while Kim and LaFave 65 proposed a joint shear strength and deformation model for different types of RC beam‐column connections based on a statistical analyses of a wide range of experimental tests. For exterior joints, the models proposed by Scott et al 56 and Vollum and Parker 57 based on a single diagonal strut and on a strut‐and‐tie scheme, respectively, are worth mentioning together with the model proposed by Bakir and Boduroğlu, 58 which is based on a statistical fitting approach. More recently, Park and Mosalam 59 proposed a double‐strut mechanical model and Jeon et al 53 proposed a model based on multiple linear regression and advanced machine‐learning methods.…”

“…The main parameters are selected based on De Risi et al, 9 Celik and Ellingwood, 20 Lowes et al, 36 and Vollum and Parker. 57 The first branch, up to concrete cracking (τ y , γ y ), identifies the joint undamaged elastic response and is followed by the pre-peak branch up to the ultimate state (τ u , γ u ) that corresponds to the joint failure. The critical drift (γ cr ) corresponding to the beginning of concrete spalling is identified by the initial point of the softening branch that ends at the residual strength point (τ R , γ R ).…”

Capacity models for shear strength of exterior joints in RC frames: state-of-the-art and synoptic examination

“…Russo and Somma (2006) proposed a theoretical model taking into account the three following contributions to joint shear strength: the vertical stresses transmitted by the column to the concrete, the longitudinal beam reinforcement and the possible passive confinement due to the stirrups into the joint panel. The commonly used strut-and-tie model was revised by Tsonos (2007), while Vollum and Parker (2008) adopted a rotational strut-and-tie model for designing exterior beam-to-column joints. A very recent empirical model useful for evaluating the shear capacity of both unreinforced and reinforced exterior joints has been developed by as an evolution of a previous one proposed by the same authors , in which the ultimate shear strength was evaluated on the basis of the results of a wide experimental database including only reinforced joints.…”