Investigation of Diagonal Strut Actions in Masonry-Infilled Reinforced Concrete Frames

Abstract

This study analytically investigated the behavior of reinforced concrete frames with masonry infills. For the analysis, VecTor2, a nonlinear finite element analysis program that implements the Modified Compression Field Theory and Disturbed Stress Field Model, was used. To account for the slip behavior at the mortar joints in the masonry element, the hyperbolic Mohr–Coulomb yield criterion, defined as a function of cohesion and friction angle, was used. The analysis results showed that the lateral resistance and failure mode of the infilled frames were significantly affected by the thickness of the masonry infill, cohesion on the mortar joint–brick interface, and poor mortar filling (or gap) on the masonry boundary under the beam. Diagonal strut actions developed along two or three load paths on the mortar infill, including the backstay actions near the tension column and push-down actions near the compression columns. Such backstay and push-down actions increased the axial and shear forces of columns, and ultimately affect the strength, ductility, and failure mode of the infilled frames.

Analytical study on behaviour and performance of infilled frame structure with reinforced eccentric opening

“…The infilled wall with shell elements modelling is carried out in more detail, where the frame is modelled as a frame element, while the infill wall is modelled as a shell element. The contact area (link) of the frame and wall model is modelled as a gap element with gap stiffness proposed by Dorji & Thambiratnam [17] as in Equation 7below: (7) where Kg is the gap element stiffness (N/mm/mm), Ki is the infill wall stiffness (N/mm), Ei is the modulus of elasticity of the wall (N/mm2) and t is the wall thickness (mm). For concrete materials, the value of the modulus of elasticity is based on SNI 2847-2019 [21]: (8) where Ec is the modulus of elasticity of the concrete, wc is the volume weight of the concrete, fc' is the concrete ultimate compressive strength.…”

“…The shell element method can describe the behaviour of structures such as stresses that occur in walls. Meanwhile, the diagonal strut method is simpler in its modelling because it is considered as a diagonal bar but can still predict the behaviour of the infilled frames [7] to [9]. Many studies have been conducted to find the equation of diagonal strut widths, but still cannot represent all variations of infill panels.…”

A total‐strain based orthotropic continuum model for the cyclic nonlinear behavior of unreinforced brick masonry structures

“…Similar to concrete, it is assumed that tensile cracks parallel to a compressive strut reduce the compressive strength capacity of that strut. 19,53 The presented model adopts the reduction model proposed by Reference 54 for concrete. Hence, the compressive strength is reduced after cracking as:…”

Influencing Parameters of Exterior Reinforced Concrete Beam-Column Joint Shear Strength: A Depth Review of Recent Advances

“…Lee et al [28] suggested the diagonal strut actions on masonry in-fill RC frames. Customized Compressions Field Theory together with Disturbed Stress Fields design was employed.…”