# Assessment of a Substandard Reinforced Concrete Frame's Beam-Column Joint Using Shake Table Testing
## 1 Introduction
[7] conducted a series of rigorous experiments on unreinforced exterior beam-column joints using plain bars, revealing pronounced shear cracking, significant concrete spalling, and the severe degradation of stiffness under cyclic loading conditions. In parallel, [PERSON] et al. [16] performed comprehensive shake table tests on RC waffle-flat plate structures. Their experiments highlighted critical phenomena such as substantial stiffness reduction and strength deterioration approaching 30% under seismic loading. The collapse process of RC frames has also been scrutinized in a scaled experimental setting. [PERSON] et al. [17] conducted shake table tests on a three-story RC frame, systematically capturing the progressive deterioration and eventual collapse mechanism under severe seismic actions. Moreover, the work by [PERSON] et al. [5] on non-compliant special moment-resisting frames (SMRFs) further elucidates the impact of deficient seismic detailing on structural performance. Their shake table experiments demonstrated that RC frames not designed in accordance with modern seismic codes exhibit marked performance degradation, including reduced energy dissipation and increased susceptibility to brittle failure modes. Complementing these studies, [PERSON] et al. [18] compared the seismic performance of compliant and non-compliant special moment-resisting frames through extensive experimental campaigns. Their results highlight significant performance differentials, with non-compliant frames exhibiting lower ductility and greater strength losses during cyclic loading. In a broader context, [PERSON] et al. [3] examined the seismic fragility of both the structural and non-structural components of RC buildings in developing countries, employing scaled experimental techniques to quantify vulnerability. The comparative studies of international seismic design codes and standards represent the third key domain of research, highlighting the importance of analyzing and harmonizing variations in global seismic design practices. [PERSON] and [PERSON] [19] extensively reviewed shear strength criteria for beam-column joints across multiple international codes, identifying significant inconsistencies and recommending unified guidelines to enhance global seismic safety standards. [PERSON] [20] underscores that the CEB/FIP (Seismic Model Code) [21] and Eurocode 8 (2004) [22] utilize varying models for assessing the shear strength of RC joints. In this study, a novel rational model was introduced to characterize the cyclic shear strength of RC joints. [PERSON] et al. [23] concluded that exterior RC beam-column joints lacking ties that are mandated by building codes within the joint core demonstrate considerable susceptibility to seismic forces. This vulnerability results in possible failure mechanisms that could undermine the structural integrity in the occurrence of seismic activities. [PERSON] and [PERSON] [24] presented an implicit framework for the evaluation of joint shear strength in RC beam-column connections. This framework incorporates a range of factors, including strut width, compression depth, axial loading, and bending moments at both ends of the beam and column at the point of failure. The primary objective of this approach is to ensure compliance with seismic design criteria while offering a structured methodology for accurately estimating the shear strength of the joints. [PERSON] [25] introduced simplified evaluation methodologies for joint strengths across various international codes, advocating practical yet accurate assessment tools suited for real-world engineering applications. Such comparative analyses contribute significantly toward advancing and standardizing global seismic design provisions, ensuring robust structural safety and resilience across diverse regions. [PERSON] et al. [26] indicated that the shear capacity exhibited by steel-reinforced concrete (SRC) column-steel beam joints demonstrates an upward trend in correlation with an increase in the axial compression ratio.