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The seismic behavior of the steel connection equipped with the lead extrusion damper (LED) is examined through the experimental and analytical studies. The LED implemented has spherical type bulge and does not consist any lubricant layer. The experimental study is performed in Structural and Earthquake Engineering Laboratory of Istanbul Technical University (STEELAB). In the experimental part, force-displacement relations of the connections with and without LED are achieved for the reversal displacement cycles. The measures of the dissipated energy, the equivalent damping ratio and the effective stiffness are obtained from the experimental study and compared for the connections. The total energy dissipated by the connection with the LED is approximately 175% greater than the total energy dissipated by the bare connection. In the analytical part of the study, nonlinear dynamic time history analyses are performed for the selected earthquakes and mass condition using the analytical models for the connections with and without LED. The maximum top displacement decreases approximately 50% for the connection equipped with the LED respect to the bare connection for the considered earthquakes. The maximum value of restoring force for the connection equipped with LED is approximately 25% greater than the bare connection for the accomplished analyses. Finally, the LED responses obtained in the nonlinear time history analyses are compared with the isolated LED test results.

An attempt to estimate the displacement demands of precast cantilever columns has been presented here. The purpose of the findings presented is to set up a more reliable design philosophy based on dynamic displacement considerations instead of using acceleration spectrum based design which initiates the action with unclear important assumptions such as the initial stiffness, displacement ductility ratios etc. The sole aim of this chapter is to define a procedure for overcoming the difficulties rising right at the beginning of the traditional design procedure.For that purpose first 12 groups of earthquake records cover the cases of far field, near field, firm soil, soft soil possibilities for 2/50, 10/50 and 50/50 earthquakes with minimum scale factors are identified associated to the present fundamental period of structure. And they are reselected for each new period of structure during the iterative algorithm presented here and they are used to remove the displacement calculations based on static consideration. Nonlinear time history analysis (NLTHA) are employed within the algorithm presented here which takes into account the strength and stiffness degradations of structural elements and the duration of records which are ignored in the spectrum based design philosophy.

Single-storey precast frames with pinned beam-column connections are widely used in Turkey. This type of precast structures had suffered extensive damages during the recent major earthquakes (Ceyhan (1998), Kocaeli (1999), Duzce (1999). The damages had been generally concentrated on the pinned connections as failure of dowels or at the column bases as large plastic deformations.A special lead extrusion damper (LED) has been developed in an ongoing PhD study in Istanbul Technical University. The damper is going to be installed into the pinned connection regions of the single storey precast frames.Nearly half scaled specimens representing existing features of precast frames are planned to be tested on the shake table. Prior the experimental work, an extensive blind prediction study has been carried out through the nonlinear dynamic time history analyses of the numerical models which are representing the specimens with and without damper. The numerical models are generated with Seismostruct. The comparison of the structural behaviors between the bare frame and the frame with LED has been discussed. Although the relative drifts of the precast frame has been significantly reduced, the observed base shear demand moderately increased by the installation of the LED.