عملکرد لرزه ای اتصالات داخلی بتنی ستون میله ای با الحاق فولاد T-section تحت بارگیری چرخان Seismic performance of interior precast concrete beam-column connections with T-section steel inserts under cyclic loading

1 Introduction Earthquakes are natural disasters that have the potential to devastate and destroy cities. Efforts are being made to mitigate or minimalize this damage. Earthquake resistant buildings are imperative to prevent buildings from collapsing and causing subsequent fi nancial losses. The northern, western and middle regions of Thailand have been designated as seismic zones equivalent to a moderate seismic zone; specifi cally, seismic zones 2A2B according to UBC design provisions (1997). The region has been declared a seismic zone based on the geological evidence and past earthquake records. Midyear 2014, an earthquake with a magnitude of 6.3, the biggest earthquake to have occurred in Thailand, struck the Chiang Rai province located in northern-Thailand, causing severe damage to numerous concrete buildings. Most buildings in Thailand have been constructed using a traditional cast-in-place system. However, the system is being replaced by one that is prefabricated due to the reduction of construction time. The precast construction offers several advantages, such as better quality control and lower overall construction costs. Normally, the performance of precast concrete structures is infl uenced by the quality of their connections. From previous studies, most damage and abrupt failures of precast concrete structures during earthquakes was mainly due to the failure of joint assembly and inadequate ductility. There were several investigative studies showing the importance of ductile connections in precast structures (Arslan et al., 2006; Chayanon et al., 2017; Gülkan, 1998 and Park, 2002). To design a precast connection, PCI standards have been widely adopted as a standard design guideline. However, the most explicit precast connection detailing from the PCI manual (1973) and handbooks (2010) was designed specifi cally to support the gravity load rather than the lateral load. The current precast connections used in seismic areas have been adopted from in-house research information. Hence, despite the many advantages of precast concrete, it has not been widely adopted due to concern about its seismic performance and building stability during strong ground motions. The NEHRP Provision (1998) described two alternative precast connection designs for a lateral load resisting system. One is a monolithic reinforced concrete emulation exhibiting rigid-elastic behaviors, while the other is a precast concrete connection with unique performance that allows certain deformations. Gosh et al. (1997) illustrated precast concrete connection designs based on the high seismic regions described in the 1997 UBC provisions. The connections were designed to remain elastic, while the connecting elements behaved nonlinearly. To avoid connection failure, the connection capacity must be higher than the plastic moment capacity of the beams. When the location of the plastic hinge on the beam moved further away from the connection they exhibited better seismic performance.