Nonlinear Numerical Assessment of Exterior Beam-Column Connections with Low-Strength Concrete

Abstract

The ductility and capacity of reinforced concrete beam-column connections depend mainly on the concrete’s strength and the provided reinforcements. This study investigates numerically the role of low-strength concrete in beam-column joints utilizing ABAQUS software. In this simulation, a newly developed stress-inelastic strain relationship for both confined and unconfined low-strength concrete is used. This study recommended a specific value of the concrete dilation angle for both substandard and standard joints. Also, stirrups’ yield strength value was found to play an insignificant role in improving the shear resistance of such joints with low-strength. In addition, the joint shear strength prediction using empirical models that implicitly consider the stirrups contribution in improving joint resistance was found to be better than the prediction of other models that explicitly consider the stirrups’ presence. The numerical results also showed that the use of a diagonal steel haunch as a joint retrofitting technique significantly increases the joint shear capacity and changes its brittle shear failure into a ductile beam flexural failure.

Exploring strength and ductility responses of beam-column joints using UHPC and UHPFRC employing concrete damaged plasticity

“…Factors such as ultimate strength, damage progression, and ductility behavior are assessed and contrasted. The beam-column joint under examination was experimentally investigated by Cosgun et al [22], and its numerical model was previously validated by Abdelwahed et al [23]. Initially, the study validates numerical outcomes from Abaqus against experimental results for LSC.…”

“…Step-2 60 mm UR =U =0 To characterize the LSC, we applied the constitutive laws outlined in Figs. 8 and 9, formulated by Abdelwahed et al [23], to Cosgun et al's experiment [22].…”

“…4 for the beam and column. Initially a numerical calibration based on Cosgun et al [22] , followed by the calibration conducted by Abdelwahed et al [23]. Subsequently, a parametric numerical analysis was extended to evaluate the performance of UHPC and UHPFRC, explicitly focusing on assessing strength and ductility.…”

“…Cosgun et al [22] and Abdelwahed et al [23] adopted the assumption of perfect plasticity to model the behavior of the reinforcement elements (Tab. 2).…”

“…Consequently, this research delves into the impact on ductility and strength of a beam-column joint composed of Ultra-High-Performance Concrete (UHPC) and UHPFRC. The numeric simulation is supported by the expansion of the numerical-experimental model crafted from Low-Strength Concrete (LSC) as formulated by Cosgun et al [22] and subsequently numerically simulated by Abdelwahed et al [23]. The nonlinear behavior of concrete can be effectively represented by the Concrete Damaged Plasticity (CDP) model developed by Lubliner et al [24] and Lee and Fenves [25], catering to both static and dynamic loadings in low cycles.…”