The use of precast concrete elements in construction has various advantages, including better construction quality, proper product control, and reduced construction time. In the case of structures with precast members, an important design issue is finding an economic and general solution for connecting members to resist lateral loads. The connection between members must have sufficient strength and stiffness against seismic loads to reach the minimum expected ductility under cyclic loads. This research aims to investigate the behavior of new connections between precast concrete beams and column members by measuring the stiffness, strength, ductility, and energy dissipation and comparing them with the same in-situ specimen. After various studies, five new beam-to-column flexural connections have been developed and constructed. An in-situ type connection was also made as a control specimen. Two specimens of each type of proposed connection with different flexural strengths are designed. Finally, twelve connections were constructed and tested. In developing the details of the proposed connections, ease and speed of construction, good integrity, and no need for a lot of formwork at the construction site have been considered. Considering the high cost of specimen construction and the impossibility of repeating the tests before the construction of the specimens, the finite element model of the connections was made with the help of Abaqus software. The behavior performance of the specimens has been compared by eva‎luating the energy dissipation and ductility factor. By considering the failure modes, The potential weaknesses of each connection have been resolved. The first connection was designed using an embedded I-section steel beam and welding connection. The second connection used an L-section steel corbel and bolt-type connection. The third connection was constructed with a bolt connection and T sections. The fourth connection has been developed with the help of a box-shaped mechanical splice. The fifth connection is similar to the third connection, but the upper rebars of the beam section are connected like the rebars of the lower side. After constructing the connections, each of them was subjected to a displacement-control cyclic loading, and the responses of each were recorded. Load-displacement curves of each specimen were used to obtain the ultimate strength, initial stiffness, ductility, strength degradation, stiffness deterioration, and energy dissipation. The calculated parameters of the precast connections have been compared together with the in-situ connection. The initial strength and stiffness of the connections are according to the design assumptions and are similar to the in-situ connection. The ductility of precast connections is at the level of monolithic connections, and they can be classified in the range of frames with intermediate ductility. In general, the performance of the connections is satisfactory, and they can be used in buildings located in places with high seismicity risk. In order to increase the accuracy of the numerical models, numerical modeling has been done according to the laboratory results. According to the analysis, it can be said that due to the limitations of the experiment tests, the initial stiffness of the joints did not match well with the numerical analysis, but the behavior of the joints in the final cycles is in good agreement with the numerical simulations.

مرتضي مدح خوان

عبدالرضا عطائي

محمدرضا افتخار , فرهنگ فرحبد , فريدون رضائي