Investigation on the Behavior of Posttensioned Energy Dissipation Connections under Fire Loading

Posttensioned energy dissipation (PTED) connections are systems developed to be usedin structures which are located in seismic prone areas. These structural systems reduce theearthquake damage by removing the residual drift and dissipating the seismic energy.Following an earthquake, one of the most probable scenarios is a fire event. Therefore,understanding the behavior of PTED connections, which their primary application is inseismic areas, is of significant importance. This paper presents an analytical study on thebehavior of a PTED connection with bolted top-and-seat angles subjected to the fireloading. Finite element model of a PTED connection is developed and verified based onexperimental results. Another experimental study is selected which includes a beam-tocolumnsubassembly with web cleat joints subjected to the fire loading. This connectionis also modeled using finite element analysis and is validated using experimental results.Since no experimental data is available for PTED connections under fire condition, thisverified model is employed to make sure that the behavior of an angle connection atelevated temperature is modeled accurately. Afterwards, PTED connection model issubjected to the fire loading. The analysis is conducted assuming three cases of PTEDconnection with unprotected strands, with protected strands and without strands.Temperature-rotation curves are derived and compared. The results show that thebehavior of a PTED connection with unprotected strands is not considerably differentthan that of a typical semi-rigid connection subjected to the fire. However, using fireprotection coating for strands significantly reduces the connection rotation and thereforeprevents the structural collapse.

Keywords:

finite element modeling , fire loading , posttensioned strands , PTED connection