Shear strength of reinforced concrete beam with embedded steel trusses

Abstract

A steel truss might be embedded in reinforced concrete (RC) beam to enhance strength and stiffness of the beam under extremely high force demands within limited space. Shear strength of such beam construction has not yet been well investigated. This research aims to predict shear strength of RC beam with embedded steel trusses. Several approaches were considered: 1) conventional shear formula; 2) strut-and-tie model (STM); and 3) finite element (FE) method. Shear strength formula and STM follow ACI 318 (2014) and AASHTO LRFD (2012). These approaches were implemented, and results were compared with reference to shear strength test results of physical specimens by Zhang et al. (2016). Four beam specimens were considered including RC beam with and without embedded truss and variations of stirrup reinforcements. Nonlinear finite element analysis was carried out to study on the shear capacity provided by concrete, stirrups and steel trusses. In FE models, concrete and steels were assumed as perfectly bonded. STM per AASHTO provides a better estimate of shear strength than other approaches and more suitable to be used in design of such beams. FE models over-estimate shear strength of the reinforced concrete beam with embedded steel trusses. More investigation should be conducted to obtain better estimation of shear strength by FEM before it can be used in practice.