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Seismic behaviour of connections between prefabricated RC flat slabs and square steel tube columns ABSTRAC T Reinforced concrete (RC) flat slab column structure is a typical vertical support system and is often used in regions of moderate seismicity. Additionally, a steel structure is easy to assemble and exhibits good mechanical property, ductility and energy dissipation performance. Thus, this study presents a new type of connection between a prefabricated RC flat slab and square steel tube column. The connection effectively improves seismic performance and stress mechanism and leads to plastic deformation in the cantilever beams that can be replaced after an earthquake. The connection consists of a column base with four cantilever beams, a channel steel connection, and an RC flat slab. A gap connected by four square crossing I-steel cantilever beams is left between the column and channel steel connection, and this forms an opening around the column. An experiment was performed to study the seismic behaviour of the prefabricated slab column connection. The effects of the key parameters including the I-steel web thickness of the cantilever beam and axial compression ratio were in-vestigated. The failure modes, hysteretic curves, and stress–strain curves with respect to relevant components were presented. A numerical simulation verified by the tests was performed to analyse the section stress and bolt forces for making up the test deficiency. The results indicated that the prefabricated slab column connection exhibits a superior seismic performance, thereby leading to earthquake-resilience. Finally, design considerations were presented to guide engineering practice for the proposed prefabricated slab column connection. منبع zhang2018.pdf

Numerical simulation of seismic collapse mechanisms of vertically irregular steel high-rise buildings Reza Ramezani Azghandi a, Hamzeh Shakib a,⁎, Maedeh Zakersalehi b a Tarbiat Modares University, Tehran, Iran b Niroo Research Institute, Tehran, Iran a b s t r a c t The effect ofmass and stiffness vertical irregularities on the collapse mechanismand resistance of steel high-rise structures is investigated using 3-D numerical simulations. Simulations are carried out utilizing a verified modelling approach in which the collapse processes of a regular and four irregular structures are studied under 11 earthquake records. It is indicated that the utilized finite element model, related considerations and calibrations present a reliable and efficient technique for collapse simulation. The findings showthat vertical irregularities adversely affect the collapse resistance and mechanism of steel high-rise buildings. Especially, mass vertical irregularity with concentration in the lower half of the structure is the most vulnerable one; while the stiffness irregularity with distribution in the top and bottom parts of the structure is the least affecting one. Studying the simultaneous effect of frequency content and vertical irregularities shows that, generally, records with wide frequency content mostly reduce the collapse resistance of the structure and have no significant effect on the collapsemechanismof irregular structures in comparisonwith regular structure;while records with medium frequency content are most effective on the collapse mechanism. منبع 10.1016@j.jcsr.2019.105914.pdf