SUMMARYThis paper is concerned with the design of steel frames using friction damped slotted bolted connections (SBCs) in the diagonal braces. A dynamic model is developed to describe the behaviour of a single-degree-offreedom (SDOF) steel frame that uses bilinear hysteretic behaviour for the damper. This model is generalized to MDOF systems. A novel algorithm for displacement reversal in the transition from slip to stick is presented. It uses numerical noise for its success. A design procedure that attains the sti!ness of the individual braces and their elongation at the threshold of activation is then applied to a 10-storey steel frame. This design process is a two-phase iterative procedure that converges quite fast.
The paper consists of two parts. The first part describes the results of a limited survey of damage to elevator systems during the 1995 Gulf of Eilat earthquake. The second part summarizes an analytical study on the seismic response of counterweight guide rails. The analytical part utilizes a mathematical model that the authors developed earlier, showing its effectiveness in guide rail design with reference to the damage revealed by the survey. Results clearly indicate that the rails that are commonly used in Israel cannot withstand earthquakes in the Eilat area (PGA = 0.2g). Facts observed in the field are verified analytically. The observation that very few rails were bent despite derailment of counterweight at weight levels of 1000 kg is noted. Practical recommendations and design charts for the commonly used rails in Israel are provided as well.
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