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Previous studies have shown that most link-to-column connections fail before achieving the required plastic link rotation capacity. To avoid such connection failures, a semi-rigid connection is proposed for use as a long link-to-column connection. A top and seat bolted angle connection with a web angle is a desirable candidate for a semi-rigid connection since no welding is needed. Experimental tests and finite-element simulations were conducted in this study. The accuracy of the finite-element model predictions was verified using the results of the experimental testing conducted by the authors and good agreement was achieved. The effects of angle thickness and bolt diameter were also numerically studied. The results showed desirable behaviour of the proposed connection in eccentrically braced frames with a long link connected to column. [ABSTRACT FROM AUTHOR]

This paper is focused on the performance of a proposed scheme for seismic strengthening of shear deficient joints of 3D reinforced concrete (RC) corner beam-column connections. This technique is composed of a combination of GFRP sheets and a steel cage, and does not require perforating the existing concrete elements to anchor the FRP sheets. Two similar full-scale beam-column connections were made without any transverse reinforcement in their joint region. One of which was tested in its as-built condition, taken as the control specimen, while the other one was tested after strengthening. Seismic behaviour of these specimens was studied under a cyclic loading pattern imposed simultaneously with a constant column’s axial load. Comparison of the test results of these specimens revealed a noticeable improvement in the seismic response of the strengthened specimen. This achievement along with the application feasibility of this technique indicates the suitability of the proposed strengthening scheme for practical applications. Finally, the experimentally obtained joint shear strength of the control and retrofitted specimens are compared to the one estimated by the relationships of the softened strut-and-tie model and ACI-318, respectively. This comparison revealed a satisfactory prediction of joint shear strength for both specimens, the as-built and the strengthened one. [ABSTRACT FROM AUTHOR]

In this study, effects of panel zone yielding on the seismic performance of welded-flange-plate (WFP) connections are investigated. In this work, four full-scale beam-to-column connections were used to run the experiments under cyclic loading. The obtained results can potentially lead to a better understanding of the influence of the panel zone inelastic shear deformation on the cyclic behavior of WFP connections for external joints in steel moment resisting frames (SMRFs). The main parameter in the testing program was the panel zone strength having a wide variation to gain the different levels of panel zone yielding. Results showed that all specimens had a high connection rotation capacity to satisfy the requirements of special moment frame connections. However, specimens with different panel zone strengths could provide the different amount of energy dissipation. Severe beam buckling was followed by tearing along the k-line region of the beam in the plastic hinge location, as well as tearing of the beam at the nose of the bottom flange plates which were both observed as a predominant failure mode in the specimens with a stronger panel zone. However, specimens with weak panel zone could develop a significant plastic rotation without causing any major problem to the beam-to-column connection groove welds. Based on mentioned observations and considering the effect of panel zone yielding because of different panel zone strengths on the hysteresis behavior of specimens, failure modes, plastic rotation capacity, and energy dissipation, some modifications were proposed for design requirements of the panel zone strength. [ABSTRACT FROM AUTHOR]

Link-to-column connections in steel eccentrically braced frames must sustain large moments and shear forces to support link rotation. Recent studies showed that link-to-column connections are prone to failure at low drift levels due to their susceptibility to fracture at the link flange-to-column connections. The most promising method to overcome this problem is to utilize reduced beam section in link, in order to keep away stress concentration from the link ends. In this investigation, the application of reduced beam section in long link beams is studied experimentally. Two full-scale specimens with different reduced beam section locations are constructed and tested under cyclic loading. In one specimen, reduced beam section is placed at both ends of the link beam; and in the other specimen, reduced beam section is solely placed at the link end which is near the column. The results show that both specimens have satisfied the seismic code requirements for the link inelastic rotation, which in turn leads to improvement in seismic performance. [ABSTRACT FROM AUTHOR]

In this study the effects of different levels of column axial load on seismic performance of Welded Flange Plate (WFP) connections with different panel zone strength are presented. Finite element method was used to do this investigation and reliability of the modelling method was verified by comparison with experimental available records in documents. Fifteen sub-assemblages of WFP connections were generated by means of ABAQUS software. The aim was to enhance the knowledge about the consequence of column axial load level on cyclic behaviour and fracture potential of the connections with different panel zone strength for external joints in Steel Moment Resisting Frames (SMRFs). Results showed that cyclic behaviour including hysteresis loops and energy dissipation were not affected significantly by increasing column axial load regardless of the panel zone strength. It was also found that increase of the fracture potential due to increase in column axial load became less pronounced when the panel zone strength was decreased. [ABSTRACT FROM AUTHOR]

The effectiveness of fibre reinforced polymer (FRP) jackets for increasing the compression strength, shear strength and ductility of reinforced concrete (RC) columns has been demonstrated in many studies, but the influence of fibre reinforced polymer jacketing on the flexural capacity of columns is minimal. In this paper, a new retrofit method, which utilises near-surface mounted (NSM), fibre reinforced polymer, is developed to improve the flexural capacity of reinforced concrete columns subjected to bending and compression. This technique is based on bonding fibre reinforced polymer bars into grooves cut in the cover of reinforced concrete columns. For this purpose, seven reinforced concrete column specimens were designed, constructed and subjected to constant axial compression and lateral cyclic loading. In addition, the strengthened columns were wrapped with carbon composites to satisfy seismic detailing requirements. The test results show that the proposed strengthening technique is feasible and effective for improving the flexural capacity and energy dissipation capacities of reinforced concrete columns. [ABSTRACT FROM AUTHOR]