International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 12 | Dec 2025
p-ISSN: 2395-0072
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Effect of Column Load on Exterior Concrete Beam-Column Joint Strengthened with Ribbed Steel Angles Ammar Ali Fejlat 1,Abdul-Karim Al-Jerf 2 ,Mohammad Ali Issa 3 1 Doctorate Student at Structural Department in Faculty of Civil Engineering, Homs University, Homs, Syria 2 Assistant Professor at Structural Department in Faculty of Civil Engineering, Homs University, Homs, Syria 3 Lecturer at Structural Department in Faculty of Civil Engineering, Homs University, Homs, Syria
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Abstract - This study aims to investigate the efficiency of steel ribbed-angles in strengthening external concrete beamcolumn joint. The bearing capacity and final deflection of this joint are studied for improving its behavior, moving the plastic hinge away from the face of column and choosing a suitable strengthening pattern. Numerically, using Abacus finite element software, by simulation of experimented concrete joint which is not designed according to seismic codes (without additional shear reinforcement in joint area), this research aims to compare between behaviors of joints supported with two ribbed angles at the external faces from top and bottom of the joint by several different shapes of angles. No study has been reported in open literature on geometrical dimensions of external steel angles and correlated effects on bearing capacity of concrete joint. The results of this study indicates that supporting technique with steel ribbed-angles increases bearing capacity about (11120%) depending on angle length but decreases final deflection of the concrete joint. Before strengthening, bearing capacity of the joint increases with increasing of column-load, but the final deflection decreases. After strengthening, there is no effect of column-load because the failure occurs in the beam with existence of steel angles .Increasing the length of ribbed-angle plates increases bearing capacity and consequently strengthening effectiveness by about (20-120%) according to anglelength but the final deflection decreases by about (7-50%). Increasing the rib-thickness (from 4mm to 30mm) has a very little effect but without a rib the strengthening effectiveness decreases and the final deflection increases. Also, a case study from Tartu’s city is executed and presented in this paper supplied by photos of strengthening of joints in five-story concrete building. By 500mm-length, 250mm-width and 10mm-rib angle, bearing capacity will increase by about 283% but displacement of beam end at failure is decreased by about 31 %. Keywords: reinforced concrete frame - beam column joint - steel angles - ribbed angles - strengthening.
1. Introduction The RC (reinforced concrete) frame is an effective and commonly used system in RC buildings for resisting both vertical and horizontal load effects. Beam-column joints are important chains in transferring and resisting different buildings’ loads [2]. The subject of studying a (column-beam) joint is one of the most important topics in the study of structural structures, especially when these structures are exposed to seismic loads, where the joint shows nonlinear behavior when subjected to large monotonic loads, and increases the degree of non-linearity in the behavior of the Moment-Resistant composite joint, as a result of multiple components within the joint in addition to the interdependence with each other in different ways.[5] One of the central constituents of reinforced concrete moment-resisting frames are the beam-column joints which are responsible for the stability of the frames when it is under the influence of seismic excitation [4]. In many instances, postearthquake inspections of structures with RC moment resisting frames damaged during earthquakes, have shown that the damage inflicted upon the frames was mostly concentrated in the beam-column joints [4]. Also, it has been noted that external beam-column joints are more exposed to damage compared to internal beam-column joints because of their geometrical discontinuity and subpart confinement [4]. Most of the buildings that have been built prior to the adoption of the Syrian Arab Code in 1995 and its Annex (2) in 2005 are structurally inadequate to withstand seismic loads. Many of these buildings are still in use with varying levels of seismic deficiencies. Development of knowledge and techniques related of seismic resistance and rise the efficiency of reinforced concrete frame buildings led to achieve more accurate codes.[12] After war in Syria, there are a lot of buildings with damaged faces, which have exterior joints need to be fixed and retrofitted. Some of these joints are shown in Figure (1). Rehabilitation of buildings has very economical benefits. Also, there are a lot of seismically undersigned buildings and have inadequate shear reinforcement at joints areas.
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