Narrow Results

This paper presents experimental and numerical studies for predicting the seismic responses of welded and bolted steel beam–column connections, namely, welded unreinforced flange and bolted web connection, and welded unreinforced flange and welded web connection. Cyclic tests of these connections composed of members applied widely to steel structures are conducted to examine their seismic performance. Numerical simulations with a focus on the bolted joint are conducted using a nonlinear finite element code. Two different strategies of modeling bolted parts are provided to improve the computational efficiency of numerical analysis: solid contact elements and more simply using shell connector elements. Numerical solutions obtained for full connection models are experimentally validated. The rotational capacity and dissipated energy of the welded and bolted connections are discussed. The local responses for stress and strain in the vicinity of welded and bolted joints are also investigated.

A great number of reinforced concrete building structures were damaged or collapsed during the earthquake that hit Sivrice district of Elazığ city located in the southwest of the Eastern Anatolia Region of Turkey on January 24, 2020. Magnitude of the earthquake were announced as $M_w=6.5$ and $M_w=6.8$ by Kandilli Observatory & Earthquake Research Institute (KOERI) and Earthquake Department of the Disaster and Emergency Management Presidency (AFAD), respectively. More than a thousand of aftershocks with the magnitude of 1.2–5.1 occurred between January and February 2020. The magnitude of the structural damage was relatively high compared with the peak value of recorded ground acceleration (2.85m/s²) at the epicenter (Sivrice district) of the earthquake. It was determined that 584 buildings were demolished, 6845 were severely damaged, 1207 were moderately damaged, 14,389 were slightly damaged and 14,317 were undamaged. Also, there were 235 buildings that required urgent demolition. In this paper, the performance of the reinforced concrete buildings during the Sivrice-Elazığ earthquake is presented along with time-histories of ground motion records and response spectrums. Observed design and construction practices were carefully evaluated and compared with Turkish Earthquake Code. It was seen that the most significant causes of the failures were due to the poor concrete quality, the use of non-ductile detailing, the poor project design and construction quality. According to field inspections of our technical team, it is concluded that performances of the undamaged buildings following earthquakes do not prove that they have adequate seismic safety.