Seismic performance of a new through rib stiffener beam connection to concrete-filled steel tubular columns: An experimental study

This paper proposes a new moment-resisting connection known as a through rib stiffener beam connection, which is directly passed through a pre-slotted circular column with concrete infill. Four half-scale cruciform specimens with orthogonal beams were tested under cyclic loading. The failure modes, hysteretic performance, rotation capacity, strength and stiffness degradation, ductility, and energy dissipation of the connections were analysed. The effect of different parameters, such as through rib stiffener and beam section size, on the connection performance was investigated. The experimental results indicated that the new through rib stiffener beam connected with circular columns exhibited a large hysteretic enclosed area, good ductility, and excellent energy dissipation. The results proved that the proposed connection satisfies the seismic provisions and ductility design requirements for it to be utilized as moment-resisting frames in a seismically active area

Experimental assessment of channel shear connectors under monotonic and fully reversed cyclic loading in high strength concrete

Two series of modified push-out tests under monotonic and low cycle fatigue load were performed to study the behaviour of channel shear connectors embedded in high strength concrete (HSC) slab. In each series, four push-out specimens were tested covering different sizes of channel shear connector and different strength level of HSC. Evaluation of National Building Code of Canada (NBC) for load capacities of channel shear connectors in HSC is also covered. The results show adequate ductility of channel shear connectors in HSC. All specimens have channel fracture type of failure and showed 8-17% strength degradation under low cyclic fatigue loading compared to the monotonic loading. In application of channel shear connectors embedded in HSC, achieved strength degradation rate is lower than the other concrete types (other types of concrete means those studied in previous investigations, which included plain concrete, reinforced concrete (RC), fiber reinforced concrete (FRC) engineered cementitious composite (ECC), polypropylene (PP) concrete and light weight aggregate concrete (LWAC)). Also, it was determined that the Canadian design code is quite unconservative for the prediction of strength capacity of channel shear connectors in HSC.</p

Seismic performance of a new through rib stiffener beam connection to concrete-filled steel tubular columns: An experimental study

This paper proposes a new moment-resisting connection known as a through rib stiffener beam connection, which is directly passed through a pre-slotted circular column with concrete infill. Four half-scale cruciform specimens with orthogonal beams were tested under cyclic loading. The failure modes, hysteretic performance, rotation capacity, strength and stiffness degradation, ductility, and energy dissipation of the connections were analysed. The effect of different parameters, such as through rib stiffener and beam section size, on the connection performance was investigated. The experimental results indicated that the new through rib stiffener beam connected with circular columns exhibited a large hysteretic enclosed area, good ductility, and excellent energy dissipation. The results proved that the proposed connection satisfies the seismic provisions and ductility design requirements for it to be utilized as moment-resisting frames in a seismically active area.</p

Behaviour of C-shaped angle shear connectors under monotonic and fully reversed cyclic loading: An experimental study

This paper presents an evaluation of the structural behaviour of C-shaped angle shear connectors in composite beams, suitable for transferring shear force in composite structures. The results of the experimental programme, including eight push-out tests, are presented and discussed. The results include resistance, strength degradation, ductility, and failure modes of C-shaped angle shear connectors, under monotonic and fully reversed cyclic loading. The results show that connector fracture type of failure was experienced in C-shaped angle connectors and after the failure, more cracking was observed in those slabs with longer angles. On top of that, by comparing the shear resistance of C-shaped angle shear connectors under monotonic and cyclic loading, these connectors showed 8.8-33.1% strength degradation, under fully reversed cyclic loading. Furthermore, it was concluded that the mentioned shear connector shows a proper behaviour, in terms of the ultimate shear capacity, but it does not satisfy the ductility criteria, imposed by the Eurocode 4, to perform a plastic distribution of the shear force between different connectors along the beam length.</p

Experimental assessment of angle shear connectors under monotonic and fully reversed cyclic loading in high strength concrete

An experimental study was performed to investigate the behaviour of angle shear connectors embedded in high strength concrete (HSC) slab. Eight push-out specimens were tested covering various geometries of angle shear connector. On top of the experimental study, the accuracy of the available equations to estimate the load capacities of angle connectors is also evaluated for the angles embedded in HSC. The results show inadequate ductility behaviour for the angle shear connectors embedded in HSC. Nonetheless, the angle connectors exhibited good behaviour in the case of strength degradation under cyclic loading. All specimens experienced the angle fracture type of failure and showed a very low strength degradation (0.1%-1.4%) when they were subjected to low cyclic fatigue loading. This study also concludes that the current available equations estimated the shear capacity of angle connectors embedded in HSC either are conservative or overestimate the ultimate capacity.</p

Comparison of behaviour between channel and angle shear connectors under monotonic and fully reversed cyclic loading

Channel shear connectors are used to transfer longitudinal shear forces through the steel-concrete interface in composite beams. Angle shear connectors without bottom flange compared to channel shear connectors could be cheaper and more economic by saving more steel material. This paper presents an experimental evaluation for comparison of the behaviour of channel and angel shear connectors under monotonic and fully reserved cyclic loading based on 16 push-out tests. The connection shear resistance, ductility and failure modes are presented and discussed. By comparing the channel and angle shear connectors, it was concluded that angle shear connectors showed 7.5-36.4% less shear strength than channel shear connectors under monotonic loading and 23.6-49.2% under fully reversed cyclic loading. Connector's fracture type of failure was experienced for both channel and angle connectors. After the failure, more cracking was observed in slabs with channels compared to slabs with angles. Furthermore, in despite of sufficient ductility for all channel connectors, angle connectors showed less ductility. The results indicate that the angle shear connector gave good behaviour in terms of the ultimate shear capacity; however, this type of connector cannot satisfy the ductility criteria imposed by some codes. In the end, the shear load capacities obtained from the experiments are compared with those suggested by the design codes.</p